NSMP Business Requirements Work Stream Interval Energy Data Channels

Transcription

1 National Smart Metering Program NSMP Business Requirements Work Stream Version number: Version 1.0 Status: Author: Final Dr Martin Gill Date published: 6 th February 2011 File name: NSMP v1.0.doc

2 Table of Contents 1 DOCUMENT CONTROL VERSION CONTROL APPROVAL REFERENCES DISCLAIMER INTRODUCTION BACKGROUND DEFINITIONS TO BE USED FOR ENERGY FLOWS ACTIVE ENERGY REACTIVE ENERGY FOUR QUADRANT METERING ENERGY MEASUREMENTS FOR EACH METER CONFIGURATION GLOSSARY DEFINITIONS Accumulated Energy Interval Energy ENERGY QUANTITIES Single Phase Single Element Meters Three Phase Meters Single Phase Two Element Meters APPENDIX A GLOSSARY File Name: NSMP v1.0.doc Page 2 of 14

3 1 Document Control 1.1 Version Control Version Date Description Amended by 0.1 6/11/2009 First Draft Dr Martin Gill 0.2 5/1/2010 Included reference to AS , added disclaimer and updated figures to use varh /3/2010 Included discussion of the recorded measurements /4/2010 Update to include the new definitions agreed by the BRWG Dr Martin Gill Dr Martin Gill Dr Martin Gill 1.0 6/2/2011 Release as Final Dr Martin Gill 1.2 Approval Authorised by Signature Date NSSC Program Director 18/2/ References The following documents are referred to in this document. Document Name Version Electricity metering equipment (ac) Particular requirements Part 23: Static meters for reactive energy (classes 2 and 3) Handbook for Electricity Metering Edison Electric Institute AS th Edition National Metering Identifier Procedure (NMI) Version No: 5 16 July 2006 NMSP Function 11 Import/Export Version 1.0 NSMP Power Factor Measurement Version 1.0 NSMP Smart Metering Infrastructure Functionality Specification Version Disclaimer This discussion paper was produced by Dr Martin Gill of KEMA Consulting in order to assist the Business Requirements Working Group (BRWG) in the development of the Smart Metering Infrastructure Minimum Functionality Specification. This paper has not been vetted or endorsed by the BRWG or the National Stakeholder Steering Committee (NSSC). File Name: NSMP v1.0.doc Page 3 of 14

4 2 Introduction 2.1 Background The National Smart Metering Infrastructure Functionality Specification (SMI F.S.) supports the measurement and recording of both active and reactive energy. This document details the conventions that will be used for active and reactive energy measurement. The smart meter is also able to store the active and reactive energy in trading intervals. This document details the accumulated energy values recorded by each meter configuration and available for storage in interval energy channels. 3 Definitions to be Used for Energy Flows 3.1 Active Energy The SMI F.S requires that all meter are capable of measuring and recording bi-directional energy flows 1. The smart meter must be capable of separately recording active energy export and active energy import. The National Electricity Market (NEM) clearly defines the direction of active energy flow, which is viewed from the perspective of the electricity network. As such active energy export is energy supplied to the customer and active energy import corresponds to energy supplied from the customer to the grid (for example from on-site generation). Figure 1: Direction for Import and Export within the NEM By convention active energy flows are considered to align with the X-axis of a graph. The following figure depicts the two separate active energy values recorded by the smart meter: Figure 2: Active Energy Flows 1 In the original list of Ministerial Council on Energy (MCE) recommended functions this was Function 11 Import/Export File Name: NSMP v1.0.doc Page 4 of 14

5 3.2 Reactive Energy The SMI F.S requires the smart meter to be able to measure bi-directional reactive energy flow 2. Conventions for the direction of reactive energy flow are not as clearly defined as those for active energy flow. It is proposed that the SMI F.S. follow the conventions outlined in Australian Standard AS: , with the exception that the perspective is changed to align with the NEM pool rather than the meter. The following figure depicts the two separate reactive energy values recorded by the smart meter. These are drawn on the same axes as depicted in Figure 2 highlighting that reactive energy measurements align with the Y-axis. The difference will be explained in greater detail in Section Figure 3: Reactive Energy Flows 3.3 Four Quadrant Metering As outlined above the smart meter is required to separately record active energy import, active energy export, reactive energy import and reactive energy export. Measurement of these four values is often referred to as four quadrant metering. The NEM defines all energy flows relative to the pool. Energy export therefore describes flow out of the pool, while energy import describes flow into the pool. This applies to both active energy (kwh) and reactive energy (kvarh). Following the convention detailed in AS: and in the 10 th edition of the handbook for Electricity Metering from Edison Electric Institute we define the quadrants as shown in Figure 4 and Table 1. 2 In the original list of MCE recommended functions this was Function 10 Power Factor 3 For even greater detail the reader is referred to the NSMP Power Factor discussion paper. 4 Noting that in AS: Imported and Exported are taken from the perspective of the customer premise while the NSMP uses the NEM perspective of energy flow to and from the Pool. File Name: NSMP v1.0.doc Page 5 of 14

6 Figure 4: Four Quadrant Metering The direction of energy flow for active and reactive power corresponding to each quadrant is shown in Table 1. Table 1: Definitions Used for Four Quadrant Metering Quadrant Watts vars 1 Exported Exported 2 Imported Exported 3 Imported Imported 4 Exported Imported The voltage and current waveforms corresponding to each axis shown in Figure 4 are shown in Figure 5. These axis points depict purely active energy flow and purely reactive energy flows: Figure 5: Voltage and Current Waveforms Corresponding to Each Axis File Name: NSMP v1.0.doc Page 6 of 14

7 The voltage and current waveforms corresponding to each quadrant are shown in Figure 6 below. Figure 6: Voltage and Current Waveforms Corresponding to Each Quadrant 4 Energy Measurements for Each Meter Configuration 4.1 Glossary Definitions Terms in common usage within the metering community do not align with the terms used in chapter 10 of the National Electricity Rules. This section attempts to arrive at a common definition for each of the data types that can be read from smart meters Accumulated Energy The SMI F.S. provides the glossary definition of accumulated energy value as Accumulated energy value means the value resulting from the measurement representing a flow of energy at a metering point. If we consider a simple spinning disk electricity meter then a single value is displayed on the meter, this accumulated energy value represents a particular quantity (depending on how the meter is installed): Figure 7: Accumulated Energy Value A smart meter will have several different measurement quantities for which it records separate accumulated energy values. This leads to the glossary definition of accumulated energy data. File Name: NSMP v1.0.doc Page 7 of 14

8 Accumulated energy data means one or more accumulated energy values. Reading the Accumulated energy data is described in the following figure: Interval Energy Figure 8: Accumulated Energy Data With the addition of a meter clock it is possible to make measurements at specific times (or over specific time periods). This results in the measurement of energy flows in trading intervals. Identification of each of these data streams requires clarification. Interval energy value means the value resulting from the measurement representing a flow of energy at a metering point over a trading interval. Figure 9: Interval Energy Value When a series of consecutive Interval energy values are collected this is results in an Interval energy channel. The glossary definition is given as: Interval energy channel means a series of interval energy values measured and stored over consecutive trading intervals. Figure 10: Interval Energy Channel File Name: NSMP v1.0.doc Page 8 of 14

9 When a number of interval energy channels are read we refer to this as interval energy data: Interval energy data means the interval energy channels stored by a meter. Figure 11: Interval Energy Data 4.2 Energy Quantities A smart meter complying with the SMI F.S. will be capable of measuring active and reactive energy flow in a power conductor. The SMI F.S. has chosen to separately record imported and exported energy flows, so the measurement of an energy flow into the premises (exported from the pool) will be recorded separately from energy flow from the premises (Imported to the pool). There is a fundamental limitation on a single measurement element, it can only measure the difference between the energy flows in the power conductor. So while we record two separate values they actually refer to the same measurement. It is only when that single value is positive we have chosen to record the value as an exported accumulated energy value and when negative as an imported accumulated energy value. Metering configurations may contain different numbers of measurement elements which may result in different energy quantities. This is discussed in the following sections Single Phase Single Element Meters Single phase single element meters have a single measurement element. They are only capable of measuring the total energy flow at the connection point. The measurement of active and reactive energy flow results in the record of four accumulated energy values. Corresponding to total imported active energy, total exported active energy, total imported reactive energy and total exported reactive energy. The four recorded accumulated energy values can be selected for storage in Interval energy channels. This metering configuration and the supported accumulated energy values are shown in Figure 12. File Name: NSMP v1.0.doc Page 9 of 14

10 Figure 12: Energy Data Values Supported by Single Phase Single Element Meters Three Phase Meters Three phase meters typically employ three measurement elements 5 to measure energy flows through a metering point. The total active and reactive energy is calculated as the sum of the energy flow measured on each measurement element. The calculation results in the active and reactive energy flows through the metering point. As for the single phase single element meter this results in four separately recorded accumulated energy values, referred to as total imported active energy, total exported active energy, total imported reactive energy and total exported reactive energy. The four accumulated energy values can be selected for storage in interval energy channels. This metering configuration and the supported accumulated energy values are shown in Figure 13. Figure 13: Energy Data Values Supported by Three Phase Meters The accumulated energy values recorded each of which can be selected for storage in trading intervals for the meter configurations single phase single element and three phase are detailed in Table 2: Table 2: Accumulated Energy Values Recorded by Single Phase Single Element and Three Phase Meters 5 Three phase four wire meters will employ three measurement elements while three phase three wire meters can employ two measurement elements. The summation of all measurement elements applies regardless of the actual number of measurement elements. File Name: NSMP v1.0.doc Page 10 of 14

11 Accumulated Energy Values recorded by the meter Total Imported Active Energy (kwh) Total Exported Active Energy (kwh) Total Imported Reactive Energy (kvarh) Total Export Reactive Energy (kvarh) Single Phase Two Element Meters The SMI F.S. describes a single phase two element meter. It was initially assumed that the two element meter could be used in place of two single phase meters, however this would result in eight accumulated energy values corresponding to the values listed in Table 2 for both element 1 and element 2. There are two issues with this assumption. Firstly it would not support the measurement of net energy flows at the metering point and secondly this would provide too many channels of reactive energy data. These will now be discussed: The discussion paper NSMP Function 11 Import/Export highlights that legislated feed-in tariffs require the meter to measure the instantaneous net flow through the metering point. The total active energy through the metering point is calculated as the sum of the energy flow measured on each measurement element. This is exactly the same requirement as depicted for three phase meters (described in section 4.2.2) where the meter calculates the flow across the measurement elements. For active energy this results in six different active energy values, total imported, total exported, element 1 imported, element 1 exported, element 2 imported and element 2 exported. Reactive energy measurement was added to the SMI F.S. for audit purposes, as such the values are only required per connection point (not per measurement element). In a similar manner to the calculation of total active energy, the reactive energy flows across the measurement elements are summed resulting in only two reactive energy values, total imported reactive energy and total exported reactive energy. The resulting eight accumulated energy values are shown in Figure 14. File Name: NSMP v1.0.doc Page 11 of 14

12 Figure 14: Single Phase Two Element Meters For two element meters the accumulated energy values recorded by the meter and the corresponding interval energy channels that can be selected for storage in trading intervals are detailed in Table 3. Table 3: Accumulated Energy Values Recorded by Single Phase Two Element Meters Accumulated Energy Values recorded by the meter Total Imported Active Energy (kwh) Total Exported Active Energy (kwh) Total Imported Reactive Energy (kvarh) Total Exported Reactive Energy (kvarh) Element 1 Imported Active Energy (kwh) Element 1 Exported Active Energy (kwh) Element 2 Imported Active Energy (kwh) Element 2 Exported Active Energy (kwh) File Name: NSMP v1.0.doc Page 12 of 14

13 Appendix A Glossary The following acronyms are in the NSMP Glossary. ACOSS AEMC AEMO AER AMI AS B2B BPRG BPPWG BRDRG BRWG CATS COAG DNSP DRET EEEC ENA ERAA ESC FRC FRMP HAN IEC IHD LNSP MCE MDA MDF MDFF MOU MRG MSATS MTWG NCRE Australian Council of Social Services Australian Energy Market Commission Australian Energy Market Operator Australian Energy Regulator Advanced Metering Infrastructure (Victorian smart metering program) Australian Standard Business to Business B2B Procedures Reference Group (established under the IEC) Business Processes and Procedures Working Group (established under the NSSC) Business Requirements Definition Reference Group (established under the AMI program) Business Requirements Working Group (established under the NSSC) Consumer Administration and Transfer Solution Council of Australian Governments Distribution Network Service Provider Commonwealth Department of Resources, Energy and Tourism (also referred to as RET) Equipment Energy Efficiency (E3) Committee Energy Networks Association Energy Retailers Association of Australia Essential Services Commission Full Retail Contestability Financially Responsible Market Participant Home Area Network Information Exchange Committee (established under section 7.2A.2 of the Rules) In-home Display Local Network Service Provider Ministerial Council on Energy (established under the COAG) Metering Data Agent Metering Data File Metering Data File Format Memorandum of Understanding Metrology Reference Group (established under the RMEC) Market Settlement and Transfer Solution Metering Technology Working Group (established under the AMI program) National Consumer Roundtable on Energy File Name: NSMP v1.0.doc Page 13 of 14

14 NECF NEL NEM NEMMCO NEO NER NSMP NSSC NT OMRV PDRG PwC PTWG RET RIS RFP RMEC RP RPWG RWG SCO SM SMCN SME SMI SMMS SMWG SWIS TFWG TOR TRWG WA WAIMO WEM WIGS WG National Energy Consumer Framework National Electricity Law National Electricity Market which excludes Western Australia and Northern Territory National Electricity Market Management Company National Electricity Objective (as set out in section 7 of the NEL) National Electricity Rules National Smart Metering Program National Stakeholder Steering Committee (National Smart Metering Program) Northern Territory Operating Model Requirements Version (Victorian AMI Program) Business Process & Data Reference Group (established under the RMEC) PricewaterhouseCoopers Pilots and Trials Working Group (established under the NSSC) Commonwealth Department of Resources, Energy and Tourism Regulatory Impact Statement Request for Proposal Retail Market Executive Committee (an advisory committee to AEMO) Responsible Person Retail Policy Working Group (established under the MCE) Regulation Working Group (established under the NSSC) Standing Council of Officials (as established under the MCE) Smart Metering Smart Metering Communication Network Subject Matter Expert Smart Metering Infrastructure Smart Metering Management System Smart Metering Working Group (established under the SCO) South Western Interconnected System in Western Australia Testing Framework Working Group Terms of Reference Technical and Regulatory Working Group (established under the AMI Program) Western Australia Western Australian Independent Market Operator Wholesale Electricity Market (Western Australia) Wholesale Inter-connector Generator and Sample Working Group File Name: NSMP v1.0.doc Page 14 of 14