Distributed Renewable Energy Generation Interconnection Policy

Transcription

1 Distributed Renewable Energy Generation Interconnection Policy Dominica Electricity Services 2010 Version

2 Table of Contents Executive Summary Interconnection Policy Introduction Interconnection of portable generators Interconnection of conventional generators Process Leading to Execution of Interconnection Service Agreement Policy and Practices for New Generation Interconnection with Distribution System Distributed DG Facility Classification Construction of the Distribution Facilities Upgrades General Considerations Distribution Facilities Upgrades Charge Delivery and Measurement of Electricity Access and Control Back Up Rates Insurance Technical Requirements Voltage Level Machine Reactive Capability Study and Analysis Protection Requirements Protection System Testing and Maintenance Protection System Changes Grounding Requirements: Monitoring Requirements: Appendix A - Notice of Intent to Interconnect Form Less than 10 kw Appendix B Notice of Intent to Interconnect Form 5KW and Higher Appendix C - Distribution Facilities Impact Study Agreement Appendix D - Distribution Facilities Detailed Study Agreement Appendix E - Glossary of Terms... 1 List of Figures: Figure 1-1. Flow Chart of Interconnection Approval Process... 9 List of Exhibits: Table 2-1. Generation Category Table 2-2. Technology Type Table 2-3. Summary of Requirements Dominica Electricity Services Limited i

3 RESOLUTION OF CONFLICT BETWEEN ENGINEERING STANDARDS. In the event that there is conflict, contradiction or confusion between the required engineering standards that are stated in this policy and any other documents pertaining to the interconnection of renewable energy sources to DOMLEC s transmission or distribution system the prevailing local standards shall apply. Executive Summary The Interconnection Policy has been drafted to address requests from customers to install embedded generation on to the Domlec distribution network. This policy details the process and requirements of Dominica Electricity Services Limited (Domlec) for Customers who desire to connect a customer-owned Distributed Generating (DG) Facility to Domlec s Distribution System. It is firmly established that significant damage to Domlec s and/or the Customer s facilities as well as risk of physical injury to personnel can occur if a DG Facility is interconnected in a manner that does not comply with Domlec s requirements. Hence, any customer who plans to install any form of DG Facility and remain connected to Domlec s Distribution System must comply with Domlec s requirements. The Policy addresses DG Facilities that will be connected electrically to Domlec s Distribution System and operate in harmony with the voltage and frequency maintained by Domlec during normal operating conditions. The policy does not apply to Standby Plant nor does it allow the interconnection of conventional plant, but strictly applies to Plants using renewable energy. Under such circumstances, the interconnection of the power source with Domlec's Distribution System must meet the technical requirements of the Interconnection Policy. In addition, the Interconnection Policy does not impact or supersede provisions of the 2006 Electricity Supply Act or rules for obtaining a license. For the purpose of ascribing varying levels of engineering and administrative effort based on the nature of the DG facility, the DG facilities have been classified as follows: Category Maximum Output Voltage Level 1 <= 5 kw >5 - <=100 kw 230V/400 V or 11 kv Dominica Electricity Services Limited 2

4 3 >100 kw 1 MW 11 kv This policy does not apply to proposed systems greater than 1 MW. Type Technology Type A-1 Inverter-based, 1 phase A-3 Inverter-based, 3 phase B-1 Induction generator, 1-phase B-3 Induction generator, 3-phase C-3 Synchronous generator, 3-phase Dominica Electricity Services Limited 3

5 Application process The process of interconnecting a DG Facility with Domlec s Distribution System is described and summarized below: 1) The Customer submits a Notice of Intent to Interconnect ( Notice of Intent ) to Domlec. The typical requirements of Notice of Intent are provided in Appendix A. The notice should be sent to Domlec s designee at the address specified by Domlec. 2) After receiving the Notice of Intent, Domlec s designee will work with the Customer and serve as the point of contact for all future activities. The Notice of Intent will be reviewed and verified for completeness. If any of the requirements specified in the interconnection policy are not met, then Domlec will inform the Customer in writing and the application process will be delayed until the Customer has addressed the deficiencies in writing. 3) If the Notice of Intent is for an Inverter-based DG Facility 5kW or less, it will be treated as Fast Track. Fast Track Interconnection for Small inverter based DG Facilities: For systems that are under 5 kw, Domlec provides a faster interconnection process as long as the DG Facilities meet the stated codes and standards, and provided that Domlec has been satisfied that the installation is safe for operation. If Domlec determines that the interconnection does not fall under the Fast Track provisions, the process is as described below. 4) Upon reviewing the Notice of Intent, Domlec will determine if a Distribution Facilities Impact Study (Impact Study) is required.. 5) If an Impact Study is required, Domlec will prepare a cost estimate to perform the study and will submit such estimate to the Customer. The scope of this review will be be based on the size, location, and technical characteristics of the proposed DG 6) If the Customer elects to proceed with the Impact Study, the Customer and Domlec will execute a Distribution Facilities Impact Study Agreement. Dominica Electricity Services Limited 4

6 7) Upon execution of the Distribution Facilities Impact Study Agreement and receipt of payment in full, Domlec will conduct the Impact Study.Upon completion of the work, issue a Distribution Facilities Impact Study Report to the Customer. The Report will indicate whether a Detailed Engineering Study is required. 8) If a Detailed Study is required and the Customer elects to proceed with the project, Domlec will prepare a cost estimate to perform the study and will submit such estimate to the Customer. 9) The Customer and Domlec will execute a Distribution Facilities Detailed Study Agreement, a form of which is provided in Appendix C. 10) Upon execution of the Distribution Facilities Detailed Study Agreement and receipt of payment in full, Domlec will conduct the Detailed Study and, upon completion of the work, issue a Distribution Facilities Detailed Study Report to the Customer. This report will contain a detailed cost estimate for any equipment and/or modifications to the Distribuition System required to interconnect the DG facility. 11) After reviewing the Distribution Facilities Detailed Study Report, if the Customer elects to proceed with the interconnection the DG Facility, Domlec will require the Customer to execute an Interconnection Service Agreement. 12) Upon execution of the Interconnection Service Agreement and payment in full for any equipment and/or modifications specified in the Detailed Study, Domlec and customer will proceed to construct the required facilities. The terms of the Interconnection Service Agreement will depend upoin the size of the DG Facility, and other customer-specific parameters particular to each individual interconnection request. Dominica Electricity Services Limited 5

7 1. Interconnection Policy 1.1 Introduction This Interconnection Policy describes the process and requirements of Dominica Electricity Services Limited (Domlec) for Customers who desire to connect a customer-owned Distributed Generating (DG) Facility to the Company s Distribution System. Significant damage to the Company s and/or the Customer s facilities as well as risk of physical injury to personnel can occur if a DG Facility is interconnected in a manner that does not comply with the Company s requirements. For that reason, it is required for any Customer who plans to install any form of DG Facility and remain connected to the Company s Distribution System to comply with the Company s requirements. This Interconnection Policy addresses DG Facilities that will be connected electrically to the Company s Distribution System and operate in synchronism with the voltage and frequency maintained by the Company during normal operating conditions. Under such circumstances, the interconnection of the power source with the Company's Distribution System must meet the technical requirements of this Interconnection Policy. In addition, the Interconnection Policy does not impact or supersede provisions of the 2006 Electricity Supply Act or rules for obtaining a license. The document focuses on what steps and requirements are necessary for interconnection into the Company s Distribution System with a customer-owned Distributed Generating Facility. The interconnection may also require an upgrade or other modifications to the Distribution System in order to meet such requirements. Any costs incurred by the Company in making such modifications or upgrades are to be paid in advance by the Customer. Once the requirements contained in this Interconnection Policy are met, the Company will interconnect the Customer to the Distribution System, subject to the terms of an Interconnection Service Agreement. This Interconnection Policy is published for the convenience of Customers in order to provide guidance as to what the Company will require. The procedures and requirements in this document are based on the Company s current distribution system. As future changes occur to the distribution system, the Company reserves the right to modify the processes and requirements contained in this publication and in some cases may decline interconnection requests. Future changes or special circumstances may cause re-evaluation of the size of DG facilities that can be interconnected to the Distribution System. Customers should be aware that the procedures and requirements are subject to change. The Company holds sole rights in declining any interconnection request if the interconnection is found to be inconsistent with Company s system plans. NOTE: This Interconnection Policy uses special capitalized terms throughout the text. For the convenience of the reader, a Glossary is provided in the Appendix E. Dominica Electricity Services Limited 6

8 1.2 Interconnection of portable generators The process and requirements contained in this Interconnection Policy are not applicable to portable emergency generators. Such generators must be installed in accordance with the IEE 16 th Edition Electrical Regulations and Article 700 of the National Electrical Code publication. Guidelines in these publications require that adequate measures will be taken to ensure that the generator cannot be operated in parallel with the Company s Distribution System. Attempting to interconnect a generator of this type with the Company s Distribution System, except as specified in the National Electrical Code or equivalent and the publication referenced above poses a significant risk of injury or death to personnel, and can potentially cause damage to the Company s Distribution System and significant damage to the Customer s generator and premises and is specifically prohibited. 1.3 Interconnection of conventional generators In an effort to encourage and promote renewable and clean generation sources Domlec will not consider interconnection of reciprocating (internal combustion) or large gas turbines fueled by liquid fuels. Domlec considers the category of renewable, clean generation sources to include Photovoltaic, Hydro, Wind, Fuel Cells, or Microturbines (under 250kW in unit size) and renewable fuels to include biogas and landfill-gas. 1.4 Process Leading to Execution of Interconnection Service Agreement The process of interconnecting a DG Facility with the Company s Distribution System is described below and shown in the flowchart shown in Figure 1-1: 1. The Customer submits a Notice of Intent to Interconnect ( Notice of Intent ) to the Company. The information that is typically required in the Notice of Intent is provided in Appendix A. The notice should be sent to the Company designee at the address specified by The Company. 2. a) After receiving the Notice of Intent, the Company designee will work with the Customer and serve as the point of contact for all future activities. 3. The Notice of Intent will be reviewed and verified for completeness. 4. If the Notice of Intent is for an Inverter-based DG Facility, the Company will determine if the DG Facility complies with UL Standard 1741 or equivalent. Dominica Electricity Services Limited 7

9 5. If any of the requirements specified in the interconnection policy are not met, the Company will inform the Customer in writing and the application process will be delayed until the Customer has addressed the deficiencies in writing. 6. Fast Track Interconnection for Small inverter based DG Facilities: For systems that are under 5kW, the Company provides a faster interconnection process. This facilitates and simplifies the interconnection process for smaller DG Facilities as long as the DG Facilities meet the codes and standards stated by the Company, and provided that the Company has reviewed the design and/or tested the proposed inverter based DG facility and has been satisfied that the installation is safe for operation. 7. The Company will need to perform an engineering review of the project before allowing the interconnection. The scope of this review will be determined by the Company and will be based on the size, location, technical characteristics of the proposed DG. The Company may need to perform up to two engineering studies. One study is referred to as a Distribution Facilities Impact Study (or Impact Study ). The second is referred to as a Distribution Facilities Detailed Study (or Detailed Study ). The Facilities Impact Study is a first phase engineering study conducted by the Company to determine the required modifications to its Distribution System due to the interconnection of the proposed DG. Based on the study, The Company will provide the Customer cost estimates for the proposed modifications. The study will also provide an approximate estimate of the time required for such modifications to be executed for the requested interconnection service. The Impact Study is not suitable for finalizing agreements, contracts or commitments. The Facilities Detailed Study is a final phase engineering study conducted by the Company to determine the required detailed modifications to its Distribution System, resulting in project grade cost estimates (+/- 10%) and an estimate of the time required for such modifications that will be required to provide the requested interconnection service. Dominica Electricity Services Limited 8

10 1. DG Customer submits Notice of Intent (NOI) to The Company 2.a. The Company appoints an Account Manager 2.b. The Company reviews the NOI 2.c. NOI Submittal Complete? NO Asks DG Customer to address deficiencies and resubmit YES 3, 4. The Company conducts initial technical review 3. Inverter based, <10kW, and Meets codes Use Fast-Track Approval NO 5. Impact Study Required? NO YES 6. The Company provides Cost Estimates for the Study 12. Customer Decides to Install DG NO YES 7. Customer authorizes the Study 8, 11. Conduct Study; Provides Results YES 9. Facilities Detailed Study Required? 13. Execute Interconnection Service Agreement All Studies Complete NO End of Interconnection Approval process Figure 1-1. Flow Chart of Interconnection Approval Process Dominica Electricity Services Limited 9

11 1) Upon reviewing the Notice of Intent, the Company will determine if an Impact Study is required. In some cases, the Company may determine that an Impact Study is not required and may proceed directly with a Detailed Study. There may be instances, where neither an Impact Study nor a Detailed Study is required; the Company may determine that the DG Facility meets all the requirements for immediate interconnection to the Company s system. In such rare cases, the Company may permit the Customer to immediately interconnect, subject to executing an Interconnection Service Agreement. 2) If an Impact Study is required, the Company will prepare a cost estimate to perform the study and will submit such estimate to the Customer. 3) If the Customer elects to proceed with the Impact Study, the Customer and the Company will execute a Distribution Facilities Impact Study Agreement, a sample short form of which is provided in Appendix B. However, note that the Company reserves its right to include additional provisions and use a longer form of agreement 1 to the extent necessary to address any specific circumstances of the project. The Customer will be required to pay the Company for the costs incurred in performing the study. 4) Upon execution of the Distribution Facilities Impact Study Agreement and receipt of payment in full, the Company will conduct the Impact Study and, upon completion of the work, issue a Distribution Facilities Impact Study Report to the Customer. The Report will also indicate whether a Detailed Study is required. 5) If a Detailed Study is required and the Customer elects to proceed with the project, the Company will prepare a cost estimate to perform the study and will submit such estimate to the Customer. 6) If the Customer elects to proceed with the Detailed Study, the Customer and the Company will execute a Distribution Facilities Detailed Study Agreement, a form of which is provided in Appendix C. However, the Company reserves its right to change the terms or include additional provisions to address the specific circumstances of the project. The Customer will be required to pay the costs incurred by the Company in performing the study. 1 Compared to that provided in the Appendix B Dominica Electricity Services Limited 10

12 7) Upon execution of the Distribution Facilities Detailed Study Agreement and receipt of payment in full, the Company will conduct the Detailed Study and, upon completion of the work, issue a Distribution Facilities Detailed Study Report to the Customer. 8) After reviewing the Distribution Facilities Detailed Study Report, if the Customer elects to proceed with the construction of facilities to interconnect the DG Facility, the Company will require the Customer to execute an Interconnection Service Agreement. 9) Upon execution of the Interconnection Service Agreement and payment in full, the Company and customer will proceed to construct the required facilities. 10) The terms of the Interconnection Service Agreement will depend upon the size of the DG Facility, the expected operating characteristics of the DG Facility, and the configuration of the Company s Distribution System in the area, as well as other factors that may lead to potential impacts on the Company s Distribution System. The Agreement will also require the Customer to pay for certain costs incurred by the Company in constructing and/or upgrading facilities. IMPORTANT NOTE: In performing its engineering reviews, the Company will not be reviewing or making recommendations relating to the protection of the DG Facility or other Customer facilities against possible damage resulting from parallel operation with the Company s DG systems. The Company s review is designed to determine what must be constructed or installed to protect the Company s Distribution System. The Customer is responsible for installing its own protective relays or other equipment to protect itself against damage that can be caused by the unexpected flow of electricity fed from the Company s Distribution System into the DG Facility or other Customer facilities. Dominica Electricity Services Limited 11

13 2. Policy and Practices for New Generation Interconnection with Distribution System 2.1 Distributed DG Facility Classification The following sections discuss the approach that would accommodate Distributed Generation (DG) installations in the Company s Distribution System to take advantage of the benefits of DG without affecting the operations of existing distribution system. The interconnection requirements depend on the capacity of DG and the type of technology used in producing power. For the purposes of developing the interconnection policy requirements for a DG facility to be interconnected to the Company system, the following Categories and Types have been established listed in Table 2-1 and Table 2-2. Based on the size of the DG facilities, a summary of technical requirements is provided in Table 2-3: Table 2-1. Generation Category Category Maximum Output Voltage Level 1 <= 5 kw >5 - <=100 kw 230V/400 V or 11 kv 3 >100 kw 1 MW 11 kv This policy does not apply to systems greater than 1 MW. Table 2-2. Technology Type Type Technology Type A-1 Inverter-based, 1 phase A-3 Inverter-based, 3 phase B-1 Induction generator, 1-phase B-3 Induction generator, 3-phase C-1 Synchronous generator, 1-phase C-3 Synchronous generator, 3-phase Dominica Electricity Services Limited 12

14 Table 2-3. Summary of Requirements Requirements Distribution Facilities Impact Study Category 1 Type A-1 Type A-3 Type B-1 Inverter must comply with UL 1741 or equivalent. Photo-voltaic inverters must comply with IEEE 929 or equivalent. Inverter must comply with UL 1741 or equivalent... Photo-voltaic inverters must comply with IEEE 929 or equivalent. Must meet protection requirements specified in this document May not be required May not be required Required Type B-3 Must meet protection requirements specified in this document Required Category 2 Type A-3 Type B-3 Inverter must comply with UL 1741 or equivalent. Photo-voltaic inverters must comply with IEEE 929 or equivalent. Must meet protection requirements specified in this document Required Required Type C-3 Must meet protection requirements specified in this document Required Category 3 Type B-3 Must meet protection requirements specified in this document Required Type C-3 Must meet protection requirements specified in this document Required Category 4 Type B-3 Must meet protection requirements specified in this document Required Type C-3 Must meet protection requirements specified in this document Required Notes: 1. Based on The Company s existing distribution system, it is assumed that DG will be interconnected to a radial distribution system. Dominica Electricity Services Limited 13

15 2.2 Construction of the Distribution Facilities Upgrades General Considerations The Company will arrange to construct the Interconnection requirements of the DG Facilities, if required, at the Customer's expense. The Company will determine a schedule for construction and final interconnection. The Company will use reasonable efforts to meet the schedule in order to permit interconnection with the DG Facility in a timely manner. The Company will specify that the selected contractor use standard equipment customarily employed by the Company for its own system in accordance with the Company s Construction Standards in making the final interconnection Land Interests The Customer should recognize that the Interconnection requirements for the DG Facilities may require acquisition of land interests, including but not limited to rights of way, which may require individual agreements between the Company and third party landowners. The Customer will be required to pay to the Company all reasonable costs incurred that are associated with these acquisition agreements in advance of their execution. The Company reserves the right to draft any and all documents creating land interests that it will receive to effectuate interconnection service under this Interconnection Policy. In the event the Customer acquires the land, the necessary permits, licenses, franchises or regulatory or other approvals required for the construction and operation of the Distribution Facilities Upgrades, the Company has the right to approve or reject any terms and conditions related to such acquisition prior to the start of service. The Customer will submit adequate proof of availability of land for DG construction along with the Notice of Intent Distribution Facilities Upgrades Charge If Distribution Facilities Upgrades are required to accommodate interconnection of the DG Facility, the Customer will be required to pay a Distribution Facilities Upgrades Charge that reimburses the Company for all reasonable costs 2 incurred by the Company in constructing a reliable and safe interconnection that has no adverse impacts on the Distribution System. Any such charges will be reflected in the terms of the Interconnection Service Agreement. 2 These costs typically include - Engineering design, construction costs, taxes and fees, and costs of ancillary facilities (such as, reactive power support). Dominica Electricity Services Limited 14

16 2.2.3 Delivery and Measurement of Electricity Voltage Level All electricity across the Interconnection Point will be in the form of single-phase or three-phase, fifty-hertz alternating current at a voltage class determined by the Company Machine Reactive Capability Category 1 Facilities: Category 1 and smaller Category 2 Facilities will not typically be required to provide reactive capability Category 2 and small Category 3 Facilities Category 2 and small Category 3 DG Facility interconnected with the Company s Distribution System may not be required to provide reactive capability Large Category 3 Facilities: Large Category 3 DG Facility interconnected with the Company s Distribution System may be required to provide reactive capability to regulate and maintain system voltage at the Interconnection Point. The Company will establish a scheduled range of voltages to be maintained by the DG Facility. The reactive capability requirements will be reviewed as part of the Distribution Facility Impact Study and Distribution Facility Detailed Study Metering, Related Equipment and Billing Options: The Company will provide all metering equipment, for which the Customer may be required to pay to the Company a monthly charge to cover expenses associated with the meter. The Customer will provide suitable space within the DG Facility for installation of the metering, telemetering and communication equipment, including fiber optic links, at no cost to the Company. The Customer will pay for the installation software, hardware and/or other technology that may be required by the Company to read billing meters. All metering equipment installed pursuant to this Interconnection Policy and associated with the DG Facility will be routinely tested by the Company at Customer's expense, in accordance with applicable Company metering criteria, rules and standards. If, at any time, any metering equipment is found to be inaccurate by a margin greater than that allowed under applicable criteria, rules and standards, the Company will cause such metering equipment to be made accurate or replaced. Dominica Electricity Services Limited 15

17 The cost to repair or replace the meter will be borne by the Company. If the Metering Point and the Point of Receipt or Point of Delivery are not at the same location, there may be losses in current and voltage levels that occur between the two points. In such cases, the Company may utilize metering equipment that will record delivery of electricity in a manner that accounts for losses occurring between the Metering Point and the Point of Receipt or Point of Delivery. Losses between the Metering Point and Point of Receipt will be reflected pursuant to applicable Company criteria, rules or standards. The type of metering equipment to be installed at a DG Facility is dependent on the Category (size) of the facility. One of the following equipment options and associated requirements will apply, depending upon the size of the DG Facility: Category 1 Facilities: For Categor 1 Facilities (systems of 5 kw or less) a single, a standard non-reversing distribution class meter shall be installed. There will be no accounting for energy produced in excess of consumption. All metering equipment included in this type of installation, including selfcontained meters and instrument transformers and meters, shall meet ANSI C12.1 Metering Accuracy Standards and ANSI C57.13 accuracy requirements for instrument transformers Category 2 Facilities: Category 2 facilities shall be equipped with two standard distribution class meters. One meter will record energy flow from the company to the DG facility. The second meter will record energy flow from the DG facility to the Company. All metering equipment included in this type of installation, including selfcontained meters and instrument transformers and meters, shall meet ANSI C12.1 metering accuracy standards and ANSI C57.13 accuracy requirements for transformers.category 3 Facilities: Category 3 facilities will be equipped with the same type metering as Category 2 Facilities. In addition, Category 3 Facilities will be required to provide tele-metering equipment (and related equipment) and to supply accurate and reliable information to system operators regarding metered values for MW, MVAR, MVA, MWh, volt, amp, frequency, breaker status and all other information deemed necessary by the Company for reliable system operation. Customer will be required to provide all necessary communications media (telephone lines, fiber, etc.) and any necessary protection for said communications media, and will furthermore be responsible for all communication with the company. The Customer shall maintain all telemetering and transducer equipment at the DG facility in accordance with the Company s rules and standards. The Company will, at Customer s request, supply, own and maintain all telemetering equipment located on the Customer s Facility at the Customer s expense. Dominica Electricity Services Limited 16

18 2.2.4 Access and Control Properly accredited representatives of the Company or its Affiliate will at all reasonable times need to have access to the DG Facility to make reasonable inspections and obtain information required in connection with this Interconnection Policy. Representatives will be required to make themselves known to the Customer's personnel, state the object of their visit, and conduct themselves in a manner that will not interfere with the construction or operation of the DG Facility. The Company or its Designated Agent will have control such that it may open or close the circuit breaker or disconnect and place safety grounds at the appropriate Interconnection point Back Up Rates To the extent that a Customer will rely upon the Company to deliver electricity to the Customer when the DG Facility is not self-supplying the Customer, one of the Company s future Back-Up Service Rates may apply or as agreed in the Interconnection Service Agreement. The Account Manager assigned to the project can provide information to the Customer about these rates, upon request Insurance For Category 2, Category 3 and Category 4 Facilities, the Customer is required to provide and maintain insurance coverage, with the Company named as co-insured. 3. Technical Requirements This section describes the technical requirements that the Customer must adhere to in order to interconnect a DG facility to the Company s system. These requirements will serve as the interconnection guidelines and the Company reserves the right to modify or revise these requirements on a case by case basis. 3.1 Voltage Level All electricity across the interconnection point will be in the form of single phase or three phase fifty (50) Hertz alternating current at a voltage class determined by mutual agreement between The Company and the Customer. In accordance with the ANSI C84.1 standard, the voltage range will be between 0.95 p.u 1.05 p.u. Dominica Electricity Services Limited 17

19 3.1.1 Machine Reactive Capability Category 1 and smaller Category 2 will not be typically required to provide reactive capability. Category 2 and smaller Category 3 installations facilities may not be required to provide reactive capability. Larger Category 3 DG Facilities interconnected with the Company s distribution system may be required to install reactive power capabilities for system related issues or to maintain system voltage at interconnection points. This will also depend on the reactive power consumed by the facility. The specific requirement will be reviewed as a part of the Distribution facility impact study and Distribution Facility Detailed Study. The customer will be required to follow the reactive power schedule established by The Company. Category 4 interconnections involve additional requirements that will be specified by the Company Study and Analysis Without DG, the power flow in a radial system is unidirectional and decreasing with increasing distance from the power substation. Since DG can modify the power flow directions, difficulties in maintaining and adjusting voltage regulation may arise. Therefore, DG interconnection policy requires that studies be performed to assess the impacts of power flows in the system. Two separate analyses that will be performed for an interconnection are: Distribution Systems Impact Study, and Distribution Facilities Detailed Study (if required) These studies will evaluate generation interconnection feasibility, the impact of DG on the Company s system along with the impact of the system on DG, and then evaluate options for system upgrade as necessary. The interconnection policy requires that power flow analysis be performed to assess the impact of the interconnecting DG resource on the local system and to identify any known violations in the area based on a contingency set. The contingency set will be established by the Company and will be agreed upon with the Customer or entity making the request for interconnection. Similarly, stability analysis will be performed for resources where existing stability margins are limited. The Company will ensure that operational issues such as availability of spinning reserve are appropriately considered while conducting these studies and while developing the findings and recommendations. The Company reserves the complete rights to decline any interconnection request due to any system or operational constraints. Customers requesting interconnection of a Category 1 facility will generally not be required to do any of the studies except in exceptional circumstances that will be determined by the Company. Interconnection of Category 2 facilities and smaller Category 3 facilities will require a Distribution Systems Impact Study but may not be required to conduct a Distribution Facilities Dominica Electricity Services Limited 18

20 Detailed Study. For larger facilities such as large Category 3 and Category 4, a Distribution Facilities Detailed Study will be required in addition to Distribution Systems Impact Study in order to scope the required distribution facility system additions and/or upgrades necessary due to the addition of the distributed resource. The Company may decide to include all the analyses performed under Generation Interconnection Feasibility, System Impact, and Generation Interconnection Facilities Studies under one study. Typically, power flow analysis will be performed to ensure that local contingency criteria are not violated. Short circuit calculations will be performed to ensure that circuit breaker and protection equipment capabilities are not exceeded. The Company or its designee acting on its behalf will also evaluate the engineering details of the physical attachment of the resource, as well as the relaying and metering associated with the resource to ensure a safe and reliable interconnection. This may entail more detailed evaluation in certain cases and configurations. For example, a DG near a capacitor may be evaluated for transient impacts of capacitance switching on DG. Additionally, results from these studies need to be evaluated with the existing load profile on The Company s distribution system. This evaluation is important especially at lower voltages because voltage profile is usually not self-restoring and the transformers typically will not have voltage control devices Protection Requirements Any DG facility desiring to interconnect with The Company s distribution system or modify an existing interconnection must meet the technical specifications and requirements set forth in this section. Once interconnected, The Company, in keeping with Good Utility Practice and in its sole discretion, may disconnect the DG Facility if the DG facility deviates from the technical specifications and requirements contained in this policy. If disconnected or declared nonconformant, the DG Facility must return to full compliance with this protection policy prior to reconnecting with The Company s system. The specifications and requirements listed in this policy are intended solely to mitigate possible adverse impacts caused by the DG Facility on The Company s equipment and on other customers of the Company. These requirements are also necessary to ensure safety of personnel working on The Company system. These requirements are not intended to address protection of the DG Facility itself or the Customer s internal load. It is the responsibility of the DG Facility to comply with the requirements of all appropriate standards, codes, statutes and authorities to protect itself and its loads. The Company will conduct periodic inspections on an annual basis or as agreed upon between the Company and the DG facility. The Company will have the right to disconnect if the interconnection standards are not being maintained. Dominica Electricity Services Limited 19

21 Category 1: DG with capacity of 5 kw or less General Requirements: The DG Facility will provide a disconnect switch at the interconnection point with The Company that can be opened for isolation. The switch will be in a location accessible to The Company s personnel at all times. The Company will have the right to open this disconnect switch during emergency conditions and with reasonable notice to the Customer at other times. The Company will exercise such right in accordance with Good Utility Practice. The switch will be gang operated, have a visible break when open, be rated to interrupt the maximum generator output and be capable of being locked open, tagged and grounded on the Company side by Company personnel. The switch will be of a type generally accepted for use by the Company. The company shall cap the total permitted nameplate installed capacity of Category I Renewable Energy Distributed Generation at one percent of the total peak load Requirements for Inverter-based (Type A) installations: 1) The DG Facility is responsible for protecting its equipment from being reconnected out of synchronism with The Company s system by an automatic line reclosure operation. To meet these requirements, the DG facility s protection needs to be consistent with the auto-reclosing policies of The Company. 2) The following information must be submitted by the DG Customer for review and acceptance by The Company prior to The Company s approving the Customer s request for interconnection: Electrical one-line diagram or sketch depicting how the inverter will be interconnected relative to the service entrance panel and the electric meter. Make, model and manufacturer s specification sheet for the inverter. 3) For Facilities that utilize photovoltaic technology, it is required that the system be installed in compliance with IEEE Standard , IEEE Recommended Practice for Utility Interface of Photovoltaic (PV) Systems or equivalent. The inverter will meet the Underwriters Laboratories Inc. Standard UL 1741, A Static Inverters and Charge Controllers for Use in Photovoltaic Power Systems or equivalent. Based on the information supplied by the Customer, if The Company determines the inverter is in compliance with the appropriate Dominica Electricity Services Limited 20

22 internationally recognized standard, the Customer s request for interconnection may be approved without the need to conduct a Distribution Facilities Impact Study or a Distribution Facilities Detailed Study. However, The Company reserves the right to request special studies depending on the control technology and the physical characteristics used for the PV converters that may have certain impacts on the system. 4) For Facilities that utilize wind technology or other direct current energy sources and employ inverters for production of alternating current, the inverter will meet the Underwriters Laboratories Inc. Standard UL 1741, Static Inverters and Charge Controllers for Use in Photovoltaic Power Systems or equivalent. Based on the information supplied by the Customer, if the Company determines the inverter is in compliance with the appropriate international standard the Customer s request for interconnection will be approved without the need to conduct a Distribution Facilities Impact Study or a Distribution Facilities Detailed Study. However, the Company reserves the right to request special studies depending on the control technology and the physical characteristics used for the converters that may have certain impacts on the system Requirements for Induction Generator (Type B) installations: The following information must be submitted by the Customer for review and acceptance by the Company prior to the Customer finalizing the DG Facility s protection design and the Company s approving the Customer s request for interconnection: 1) Three copies of a DG Facility one-line drawing. 2) Three copies of a one-line drawing showing the relays, if required in this Interconnection Policy, and metering including current transformer ( CT ) and voltage transformer ( VT ) connections and ratios. 3) Three copies of a three-line drawing for three phase units or a two-line drawing for single phase units showing the AC connections to the relays, if required in this Interconnection Policy, and meters. 4) The generator nameplate information including rated voltage, rated current, power factor, HP/kW, rated speed and locked rotor current. 5) If the DG Facility owns the transformer between the Company and the DG Facility, the generator step up transformer nameplate information including rated Dominica Electricity Services Limited 21

23 voltage, rated kva, proposed winding connections, positive sequence impedance plus zero sequence impedance and zero sequence equivalent circuit. 6) A list of protective relay equipment proposed to be furnished to conform to this Protection Policy including relay types, styles, manufacturer s catalog numbers, ranges and descriptive bulletins. 7) Three copies of applicable relay instruction manuals may also be required if the Company does not already possess them. 8) Schematic drawings showing the control circuits for the interconnection breaker(s) or contactor(s). 9) Specifications for CTs and VTs relevant to the interconnection including their make, model, accuracy class, ratio, and available taps. 10) The proposed grounding method for the stator winding of the generator. 11) Other information that may be determined by the Company as required for a specific interconnection. 12) Relay settings for all DG Facility protective relays that affect the interconnection with the Company s system must be submitted at least four weeks prior to the scheduled date for setting the relays for review and acceptance by the Company. 13) A DG Facility using induction generator(s) connected in the vicinity of capacitance sufficient to self-excite the generator(s) must meet the requirements for synchronous machines of the same Category. The capacitors that enable selfexcitation may actually be external to the DG Facility and may belong to the Company or to other customers of the Company. The Company will not restrict the existing or future application of capacitors on its lines nor restrict their use by other customers to accommodate a DG Facility with induction machines. 14) As changes occur in the location and size of capacitors, the DG Facility may be required in the future to upgrade its interface to meet the requirements for synchronous machines if self-excitation becomes possible even if not initially possible. 15) A circuit breaker or contactor will be installed to isolate the DG Facility from the Company s system ( Interconnection Breaker or Interconnection Contactor ). Dominica Electricity Services Limited 22

24 If there is more than one Interconnection Breaker or Interconnection Contactor, the requirements of this Protection Policy will apply to each one individually. 16) The Company will review the relay settings as submitted by the Customer to assure adequate protection for the Company s facilities. The Company will not be responsible for the protection of the DG Facility or Customer s other facilities. The DG Facility will be responsible for protection of its system against possible damage resulting from parallel operation with the Company. If requested by the Customer, the Company will provide system protection information for the line terminal(s) directly related to the interconnection. This protection information is provided exclusively for use by the Customer in evaluating protection of the DG Facility or Customer s other facilities during parallel operation. 17) The Company reserves the right to specify the winding connections for the transformer between the Company s voltage and the DG Facility s voltage ( Step Up Transformer ) as well as whether it is to be grounded or ungrounded at the Company's voltage. In the event that the transformer winding connection is grounded-wye/grounded-wye the Company reserves the right to specify whether the generator stator is to be grounded or not grounded. The Customer will be responsible for procuring equipment with a level of insulation and fault withstand capability compatible with the specified grounding method. 18) In general, across the line starting of rotating machines is not permitted unless it can be demonstrated that the resultant voltage flicker is within the Company s limits for starting of similar sized motors. If an Interconnection Breaker or latching type contactor is to be tripped by protective relays to satisfy the requirements of this Protection Policy, then the Interconnection Breaker or Interconnection Contactor control circuits will be DC powered from a station battery or Company-approved equivalent. 19) A control interlock scheme that detects voltage on the Company s line(s) will be used to prevent the DG Facility from energizing or attempting to energize the Company s line(s). The logic for this scheme should be hardwired to prevent the Interconnection Breaker (or Interconnection Contactor where appropriate) from closing. No interposing computer or programmable logic controller or the like will be used in this logic. 20) The DG Facility will provide a disconnect switch at the interconnection point with the Company that is accessible to Company personnel at all times that can Dominica Electricity Services Limited 23

25 be opened for isolation. The Company will have the right to open this disconnect switch during emergency conditions and with reasonable notice to the Customer at other times. The Company will exercise such right in accordance with Good Utility Practice. The switch will be gang operated, have a visible break when open, be rated to interrupt the maximum generator output and be capable of being locked open, tagged and grounded on the Company side by Company personnel. The switch will be of a manufacture and type generally accepted for use by the Company. 21) Where protective relays are required by this Protection Policy, their control circuits will be DC powered from a station battery. Solid-state relays will be self-powered or DC powered from a station battery. If the DG Facility uses a non-latching interconnection contactor, AC powered relaying satisfying the requirements of this Protection Policy may be allowed provided the relay and its method of application is fail safe, meaning that if the relay fails or if the voltage and/or frequency of its AC power source deviate from the relay s design requirements for power, the relay will immediately trip the generator by opening the coil circuit of the Interconnection Contactor. 22) CT ratios and accuracy classes will be chosen such that secondary current is less than 100 amperes and transformation errors are less than 10% under maximum fault conditions. 23) If the interconnection voltage requires, a voltage transformer will be provided by the DG Facility and will be connected to the Company side of the interconnecting breaker or contactor. The voltage from this VT will be used in the interlock as specified above. For three phase applications, a VT for each phase is required. 24) All protective relays required by this Protection Policy will meet ANSI/IEEE Standard C37.90, C and C or equivalent, and be of a manufacturer and type generally accepted for use by the Company. 25) Voltage relays will be frequency compensated to provide a uniform response in the range of 30 to 60Hz. a) Tripping by protective relays required to satisfy the requirements of this Protection Policy must be hardwired to the device they are tripping. No interposing computer or programmable logic controller or the like is permitted in the trip chain between the relay and the device being tripped. Dominica Electricity Services Limited 24