Integration of Distributed Generation and Wind Energy in Canada

Transcription

1 Invited Paper IEEE-Power Engineering Society General Meeting and Conference, Montréal Canada, June 18-22, 2006 Integration of Distributed Generation and Wind Energy in Canada C. Abbey, Student Member, IEEE, F. Katiraei, Member, IEEE, C. Brothers, L. Dignard-Bailey, and G. Joos, Senior Member, IEEE Abstract This paper provides an overview of the present and future status of distributed generation (DG) and wind energy in Canada. Emphasis is placed on the role that these technologies presently play in the modern power system structure, through discussion of four Canadian case studies. The role of Natural Resources Canada in removing barriers and facilitating greater introduction of these resources is presented. Taking the present situation and anticipated research and regulatory developments into account, we conclude with an outlook on the development and future role of DG and wind energy in Canada Index Terms network benchmark, renewable energy, distributed generation, wind energy, small hydro, planned islanding, wind-diesel, aggregation. Fig. 1. Present status of integration of wind in Canada 32 P I. INTRODUCTION resently, widespread integration of distributed generation (DG) and wind energy in Canada is still in its infancy. However, shifts in provincial and federal policies, together with new technological developments suggest that wind and DG will likely play increasingly important roles in the coming decades. In the province of Quebec alone, over 3000 new of wind will be integrated by Similar trends exist in many of the other provinces. The growth of wind energy will likely be complemented by that of small hydro and combined heat and power (CHP) DG. These technologies have the potential to provide part of the energy needs for urban, rural, as well as remote communities in Canada. With its unique structure, constraints, and generation mix, the Canadian power grid could greatly benefit from a greater integration of DG, should many of the challenges be properly addressed, in order to limit the impacts and make these energy resources functional units of the future power system. II. STATUS While the development of wind and other renewables in Canada has lagged somewhat behind leaders in other parts of the world, the recent growth and plans for future C. Abbey (cabbey@nrcan.gc.ca), F. Katiraei and L. Dignard-Bailey are with the CANMET Energy Technology Centre (Natural Resources Canada, Varennes, Canada). C. Brothers is with Frontier Power Systems (Charlottetown, PEI). G. Joos is with McGill University (Montréal, Canada). development are promising. The current level of installed wind in Canada is now around 600 (146 installed in 2005), which is expected to grow to around 7500 by 2012, representing 3.5% of Canada s total generation mix, [1]. The installation of wind has been predominantly at the transmission level, however it has also been integrated in distribution networks and helps to supply the energy needs of rural and remote communities, where it offers some interesting advantages. The continued growth of distributed generation will likely be fueled in part by the growth of distributed wind, complemented by run-of-river hydro and with CHP and fossil fuel based technologies in urban centers. At present, there are still a number of hurdles that need to be overcome in order to realize the full potential of these new technologies. A. Challenges There exist a number of barriers which impede the growth of DG in Canada, and may result in either delays or can even be sufficient to hinder potential developers altogether. As the interconnection of DG involves a number of specialized fields, the complexity of the problem and the various obstacles are aggravated by this fact. The different challenges that need to be addressed are summarized briefly here. 1) Relevant standards The connection of DG has been addressed to date in various studies and is reflected in various standards as are identified in [2],[3]. These standards have gone a long way

2 and are a good first step for increasing DG integration. They cannot however replace the engineering study for a typical installation and due to lack of experience and industry training required. The assessment of the technical feasibility of an installation on a distribution network can, at the very least, result in undesirable delays. 2) Technical The interconnection of DG inevitably changes the characteristics of the system to which it is being connected, due to the fact that distribution systems were traditionally designed with the assumption of a passive network. The consequence of the integration of DG is that this assumption is no longer valid. There are a number of technical challenges that needs to be addressed, which include: i) Distribution network planning and operation ii) Protection coordination iii) Voltage profile and voltage regulation iv) Power quality As the impact and consequently the level of DG that a particular network is able to accept is very system specific, the emphasis for removing the technical barrier needs to be on developing methodologies for addressing this level for a given distribution system and providing the necessary tools for these studies. Furthermore, the planning strategy also needs to be re-evaluated with the philosophy that DG may be integrated as part of this process and maximize benefits through, for instance, DG placement strategies for T&D upgrade deferral. 3) Regulatory The regulatory aspects related to DG, which includes the connection agreements that are required, policies on metering, as well as the financial value of the energy and ancillary services provided by DG, are critical issues and, in many cases, will serve as the balance that will ultimately decide whether a project will be feasible or not. That said, this is perhaps the area that has received the least amount of attention up to this point. As the technical and standardization aspects become resolved, more of the focus will inevitably need to be shifted towards these policy and regulatory issues in the coming years. B. Natural Resources of Canada (NRCan) support In 2003, 500 million dollars in Technology and Innovation funding was announced to help address greenhouse gas reduction and climate change. Part of this funding envelope was devoted to R&D and regulatory support of decentralized energy production (DEP) technologies, [4]. The primary goals under the DEP program are the removal of institutional barriers that prevent DEP installation (by 2010), and for 20% of new and replacement generation capacity to be met by DEP by Theme areas included in this R&D program are: grid integration; renewable energy use; and fossil fuel conversion. DG production generally refers to environmentally preferred on-site power generating plants of less than 1 capacity; however, for the scope of this program, highly efficient combined heat and power plants (up to 25 ) and wind farms are also included. These systems will increase the reliability of, and reduce GHG and air emissions from Canada s electric power system at an acceptable economic cost to Canadians. Preliminary analysis indicates that addressing the institutional barriers to grid integration needs to proceed quickly over the short term (by 2010). Appropriate regulatory regimes must be in place first for commercial applications to succeed. Electricity regulations mainly fall under provincial jurisdictions in Canada, requiring collaboration with many jurisdictions and provincial utilities. Several activities have been initiated to provide on-going support to regulatory agencies that may or may not be addressing the barriers to the grid integration of DG. Although, Canada has significant energy resources, conventional (e.g. natural gas) sources are declining and improved system efficiencies are required. Therefore, the DEP program will focus on unconventional and renewable sources. In technological areas where other countries already lead, DEP will focus on uniquely Canadian circumstances, such as: high-velocity, low-temperature wind regimes; cold climates, wind/hydro dispatch and storage opportunities; long-transmission distances; and applications for remote, northern communities. Through execution of the DEP program activities under the three technology theme areas (Grid integration; Renewable energy use; CHP Fossil fuel conversion), the DEP program will help deliver on the desired outcomes in the short, medium and long term as shown in Fig. 2. Short 2008 Outcomes Codes & standards Interconnection guidelines & regulations Resource forecasting Proof of concepts Grid integration modeling Systems with non - traditional fuels National /international innovation networks Med 2015 Outcomes Industry adoption of new concepts New national codes & standards Acceptance of DEP in provincial planning & policy Initial deployment of technology by industry partners Long 2025 Outcomes Provincial & utility recognition that DEP is legitimate concept Provincial strategies that lead to 35,000 of new renewable energy Institutional approaches enable consumers to use DSR & DEP technology Fig. 2. Anticipated outcomes targeted governmental R&D support Therefore, by 2010, the program aims to modify current codes and standards and interconnection guidelines and regulations such that on site production will be no more restricted than on site demand reduction. Grid integration modeling will help guide regulatory changes. Other activities will include resource assessments for renewable resources and the deployment of systems that use nontraditional fuels (waste, bioenergy). Federal research laboratories will work with universities and utilities to establish stronger research networks that will aid in understanding how to integrate large blocks of intermittent power and distributed generation into the grid.

3 The technology early action measures (TEAM) program has also been set up to support the demonstration of innovative products that have not yet reached the commercial stage and can offer measurable reductions in greenhouse gases, [5]. Together these R&D and demonstration programs will help to accelerate the integration of renewable and distributed energy resources in Canada. III. CANADIAN INNOVATION The growth in interest in DG in Canada to date can be attributed to innovative utilities and developers that have taken the initiative to integrate DG into their systems, despite the formidable challenges that have existed and in lack of the appropriate technical and regulatory support. In many cases, these efforts have led to an improvement in the operation and reliability of these same power networks. In this section, four industry case studies are presented to serve as a sample of some of the best Canadian examples and benchmarks against which to measure future projects. A. BC Hydro Boston Bar Planned islanding of an area downstream of a distribution substation is a microgrid application that has already been implemented in Canada. Fig. 3 shows the oneline diagram of the BC Hydro Boston Bar 69/25 kv substation comprising of three radial feeders and an 8.6- MVA run-of-river hydro-electric plant [6]. The hydroelectric plant is connected to one of the feeders with winter peak load of 3- and operated by an independent power producer (IPP). Power outages between 12- and 20-hour periods, a couple of times per year are typically experienced due to permanent outages on the 69-kV line connecting the substation to the BC Hydro grid. The hydropower plant is equipped with islanding capability to accommodate planned islanding of primarily the interconnected feeder and in some occasions the adjacent substation feeders as well, depending on power generation level and load demand. Fig. 3. One line diagram of BC Hydro Boston Bar The planned islanding practice has been functioning since 1995 and has resulted in significant reliability improvements for this BC Hydro system and financial gains for the local IPP. The project provides excellent experience basis for other utilities. B. Sherbrooke Hydro Sherbrooke Hydro is a small distribution company in the province of Québec that purchases electricity from Hydro- Québec. The rate at which Sherbrooke Hydro buys electricity is based on a particular rate structure, whereby the cost of electricity depends on the amount of energy (h), the maximum power () and a surcharge for any power level exceeding a predefined upper limit. This structure provides a strong incentive for peak load management as is described in a recent CANMET report, [7]. Fig. 4. Aggregation of back-up units for peak load shaving To address this issue Sherbrooke Hydro launched a program which compensates facilities for the controlled use of their back-up generators for peak demand management, Fig.4. During peak periods, which are strongly correlated with the coldest days of the year, Sherbrooke Hydro dispatches the back-up generators of the 22 participating clients in order to limit the power required from the substation. In this way, they are able to aggregate the capacity of the individual units and can dispatch up to 6.5 for demand response. Each of the customers are paid a rate for the energy supplied during these periods, in addition to any initial costs related to equipping their generators with grid parallel operation. The use of these back-up units, together with a demand response programs for controllable loads has led to significant savings for the utility, while a portion of the profits have been transfer to those participating parties in the form of a reduced energy bill. The premise of the program, while seemingly simple, provides the architecture for more elaborate approaches, such as the virtual power plant or local microgrid concept, that could combine a wider variety of distributed energy resources in a coordinated demand response resources (DRR) program strategy. C. Newfoundland Labrador Hydro Traditionally, remote communities in Canadian have been supplied electricity almost exclusively by diesel units,

4 due to the reliability and confidence in the technology. Newfoundland and Labrador Hydro has challenged the norm by incorporating a significant amount of wind into the island community of Ramea. The developer, Frontier Power Systems, with support from the TEAM demonstration program, [5], integrated 325 kw of wind into a community with a peak load of 1.2, Fig. 5. While the utility remains ultimately responsible for supply of the load, wind generation from this independent power producer can feed its total output into the system as long as the diesel unit is loaded at least 50%. The control system facilitates the smooth integration of wind and ensures interoperability with the existing remote grid. This project is the first of its kind in Canada with the hope that this will help to increase the acceptance of this wind-diesel hybrid solution as a competitive alternative for remote systems applications. to collaborate has been very useful in documenting real problems and assessing limitations of conventional tools that are currently used to assess the impact of distributed generation on power systems. In this case the DGs are not allowed to operate in an islanded mode and must automatically disconnect if there is a fault on the feeder. Fig. 6. Wind-hydro rural distribution feeder integration E. Benchmarks and tools Through the federally funded program, NRCan is focusing on a structured approach to removing the technical barriers, through the development of Canadian benchmarks to study the different issues, as well as supporting the development of the necessary models and tools for planning and simulation of DG in current power systems. This involves participation in the CIGRE Benchmarking Taskforce and working with CYME International in incorporating the necessary functionalities for modeling of DG into these tools. These activities are described in more detail in sections IV and V of this paper. Fig. 5. Ramea wind-diesel remote site configuration D. FortisAlberta FortisAlberta is an electricity distributor that operates networks in Southern Alberta and has integrated large amounts of DG into their systems. One particular feeder incorporates both wind and hydro generation, a combination that will likely become more common in Canada, particularly for rural systems. On the Fortis Alberta rural feeder of interest, the installed capacity of the generation exceeds that of the load and during times of high generation the DG may produce more than the local requirements, Fig. 6. This results in reverse power flow across many of the voltage regulators, which has caused unpredictable operation and in some cases unfavorable voltage profiles, [8]. This base case is of interest as it combines a number of renewable technologies (total 3 hydro and 3.78 wind) and illustrates some of the technical problems that can occur when DG is interconnected to systems with long lines. The participation of the utility and their willingness IV. RESEARCH AND DEVELOPMENT The modern power system has greatly benefited from microprocessor based devices as well as recent developments in communication for applications ranging from protection to control and operation. DG as an emerging technology also offers the potential to improve power system reliability, increase diversity, and provide greater flexibility to help match the increasing and ever changing energy needs of the world s population. Small capacity generators essentially operate in three types of modes: grid connected, remote grids, and capability to operate grid connected or in islanded mode. The third mode can greatly benefit from experience gained operating the former two. In all cases, the flexibility and ease with which DG can be integrated will depend in large part on the monitoring and communication capabilities present in the network of interest. A. Distribution System Automation The power of communication in a power system is that one has greater access to information, enabling improved

5 control, observability and planning of the system. It is apparent that DG will depend on an improved communication infrastructure and therefore would benefit from increased investment in distribution system automation. As many distribution companies are currently implementing distribution system automation (DSA) programs (e.g. Hydro-Québec), they are at the same time investing in DG although this is usually not the primary driving force. Not only will this permit monitoring of DG operation but it can also be used in the future to aid in planning and optimized system operation. Communication between DGs, and between DG and the distribution system operator will increase the likelihood of high penetration of DG. At present it is not clear how this distribution infrastructure should be designed and, more importantly, who will be responsible for these network system upgrade costs. In the case of large wind parks, communication is vital to properly coordinate its operation with that of the power system. In many cases the transmission upgrades required to bring wind power to regional loads was spread among rate payers since it was seen as a public good objective. Similarly, widespread integration of DG on the distribution network will not occur until the necessary communication and distribution automation and protection infrastructure is in place and the integration costs are accounted for. B. Demand Response Resources (DRR) The connection of DG to the main grid can bring about a number of benefits, which can be maximized by coordinating the response of the different units in order to achieve various objectives. Combining the response of generators with on demand load curtailment can further improve the effectiveness of this type of a program. The benefits of DG as part of a demand response program design, such as Sherbrooke Hydro, needs to be considered. The province of Ontario has set a target of 250 for demand response, and the aggregation of DGs can be considered when considering deferral of investments by utilities and non-wires solutions. Targeted requests for proposal for demand response projects can favour specific regions where the benefits are valued. Favourable pricing signals can be established in order to show partiality towards the interconnection of DG in those areas. This needs to be supported by the necessary regulatory framework and demand response program design. C. Remote applications In many countries the use of diesel generation in remote applications and communities is quite important. In Canada, there is a great interest to consider environmentally preferred options, such as integration of small hydro and wind. In addition, methods for load following in these communities could be demonstrated and validated as part of these research activities. The economics associated with diesel and other fossil fuel technologies is tightly tied to the price of fuel and the transportation and maintenance costs, which are typically much higher in remote locations; therefore, there is a greater incentive to consider the application of renewable energy, combined heat and power retrofits, and demand response strategies. D. Microgrids Applied research on microgrids that consider integrated network infrastructure and a power delivery system that can operate in parallel with the grid or in an intentional island mode is being supported by several international research programs. In Canada, there is an interest in considering the opportunity of linking distribution system automation infrastructure upgrades and the benefits for greater integration of distributed and renewable energy technologies. However, the economic argument for configuring a system for microgrid is difficult, particularly given the relatively high degree of reliability that is presently offered by most modern power systems. The extension from research to utility adoption will only follow with demonstration that microgrids provide both value and significant benefits. Although various utility case studies have been cited, it has yet to be established whether widespread utility adoption of the microgrid concept can be anticipated. Research on microgrid management and operation strategies that consider the use of renewables and environmentally preferred distributed power; peak-load management strategies; and automated distribution and protection system architecture, have been initiated as part of the DEP program activities. V. CANADIAN OUTLOOK Presently, a great deal of knowledge has been gained regarding DG technologies and their implementation. However, with the exception of wind parks, the actual number of these systems is still minimal. In order to increase the acceptance and level of DG, further steps are required, each of which have been incorporated into the design of the DEP research program. A. Standardized impact assessment and integration techniques Significant effort has been made to develop interconnection standard and codes, as well as application guides. To complement these, more effort is now required to improve the planning tools used by distribution engineers, since they currently do not provide any guidance specific to the integration of renewable and distributed generation. These software tools need to evolve in order to facilitate the technical assessment of DG integration. A schematic that described the Canadian strategy is shown in Fig. 7. NRCan is collaborating with CYME International and utility partners to improve the software tool to accommodate modeling of DG and integration studies, complemented with the development of case studies based

6 TEAM Fig. 7. Canadian technical strategy for addressing integration of DG. upon Canadian benchmarks. These will be used to educate and increase our knowledge base on the integration of DG and the use of these new software functionalities. Regulatory support While many of the technical issues can be addressed through the development of guides and interconnection standards, regulations are typically a greater barrier to DG integration. Due to the fact that the utility owns the infrastructure and are responsible for its operation, the responsibility for serving the client rest almost entirely with this entity. As a result, the motivation for integration privately owned generators is not great considering that these systems generally add a degree of complexity and decrease the ability to which the system can be controlled. Government policy changes can help to impose acceptance of certain amounts of renewable generation, however, equally important will be sharing of the responsibility for serving the load. Likely, DG will diverge into two general classes: those that are exempt from responsibility and simply disconnect in the event of disturbance; and those that share in the responsibility and aid in supporting the grid network and in providing ancillary services. For example, large wind parks are accepting more responsibility for grid support, whereas this additional complexity and costs for simple residential photovoltaic rooftop applications is not justified. The distinction should become clearer for all technologies in order to streamline the process for integrating different types of environmentally preferred DG sources. B. Cost benefit analysis Greater responsibility for certain DG as well as supply of various services should be compensated for economically. This will improve the economic viability of DG but also will encourage participation in operation of the system. While this is more or less apparent, what is not as clear is what the actual amount should be. In certain cases a DG may negatively impact the system whereas in different circumstances DG will greatly contribute to improvements in the overall operation of the system. Whereas methods for determining the technical impacts have already been developed methods for quantifying the benefits and costs associated with DG are not well defined, [10]. As the economics associated with DG presents itself as likely the most important barrier, it is imperative that methods for assessing the costs and benefits of DG be defined. Without properly defined methodologies much uncertainty remains regarding the actual costs that are charged to DG owners and benefits will never be appropriately acknowledged. C. Regional characteristics Distributed generation has experienced a greater degree of growth in certain countries where the technologies implemented may not necessarily have been those best suited to the area in question. As the industry matures, site selection of the DG and selection of the technology itself should reflect what makes most sense in terms of cost, benefits, and needs of the local community. While optimal placement of DG may be too limiting in the site selection a move towards favoring certain regions over others through price signals should be considered. Furthermore, the technologies that are chosen should be taken into consideration when selecting the site as well. Wind and small hydro are technologies that could certainly help to serve rural systems, however they are less likely to play a role in urban settings. Part of making renewables more competitive with conventional technologies may be in choosing where they are most beneficial for the regional requirements. The application of microgrids in Canada will be based primarily on cost and reliability. Currently there are a

7 number of applications that are of significant interest, such as to improve service on rural feeders (low probability, high impact events), to reduce the use of diesel fuel in remote communities, and where sensitive loads on the grid demand a higher level of reliability (emergency and backup power supply). VI. CONCLUSIONS Decentralized energy production has the potential to offer improvements in power system efficiency, reliability and energy diversity, as well as provide an opportunity to integrate a more significant level of renewable energy into our current generation mix in Canada. While significant knowledge has been gained through past experience, the practical implementation of smaller distributed generation has proved to be more challenging than perhaps originally anticipated. Numerous barriers have presented themselves in opposition to large-scale integration, namely technical challenges, lack of the necessary regulatory framework, and cost. The extent of future DG growth will depend in large part on a greater understanding of its impact on the power system, improvements in current utility system planning tools, and significant collaboration from all stakeholders in cooperatively developing a sustainable strategy for integration of renewable and distributed generation in Canada. VII. ACKNOWLEDGEMENTS The authors would kindly like to acknowledge contributions from BC Hydro, Canadian Wind Energy Association (CANWEA), Sherbrooke Hydro, CIMA, Newfoundland and Labrador Hydro and FortisAlberta. Financial support for this research project was provided in part by Natural Resources Canada through the Technology and Innovation Initiative as part of the climate change plan for Canada. VIII. REFERENCES [1] [2] connect.org [3] Joos, G., Grid code review, Integration of Renewable Energy Sources and Distributed Energy Resources Conference, Brussels, Dec. 1-3, [4] Dignard, L., Canadian program on decentralized energy production: a component of the technology and innovation initiative, Integration of Renewable Energy Sources and Distributed Energy Resources Conference, Brussels, Dec. 1-3, [5] [6] Fulton, R., and C. Abbey, Planned islanding of 8.6 MVA IPP for BC Hydro system reliability, Integration of Renewable Energy Sources and Distributed Energy Resources Conference, Brussels, Dec. 1-3, [7] Cantin, M., Use of emergency generators for peak load shaving in Quebec, report # CETC-Varennes (TR), CANMET Energy Technology Centre Varennes, Natural Resources Canada, July 2005, pp. 20. [8] Katiraei, F., C. Abbey, and R. Bahry, Analysis of voltage regulation problem for a 25 kv distribution network with distributed generation PES General Meeting 2006, accepted, Montreal, June [9] Natural Resources Canada, CANMET R&D program web link : [10] Rawson, M., Distributed generation costs and benefits issue paper, California Energy Commission (CEC), Public Interest Energy Research Staff Paper, July IX. BIOGRAPHIES Chad Abbey (S 01) received degree in electrical engineering from the University of Alberta in In 2004, he graduated with an M. Eng degree from McGill University, Montréal where he is currently pursuing his Ph.D. He is presented working with CANMET Energy Technology Centre, in Varennes, Québec where he is a Research Engineer and coordinates a joint research program on the modeling and integration of distributed generation. His current research interests include wind energy, distributed generation and their integration to the grid. Farid Katiraei (S 01, M 05) received B.Sc. and M.Sc. degrees in electrical engineering from Isfahan University of technology (Iran) in 1995 and 1998 respectively. He received his Ph.D. degree also in electrical engineering from University of Toronto (Toronto, Canada) in He is currently a T&D research engineer at the CANMET Energy Technology Center (Varennes, Québec). His research interests include power electronic applications on power systems and distributed energy generation systems for microgrid applications. Carl Brothers received his BSc in Mechanical Engineering from the University of New Brunswick (1976). Since 2004, he is General Manager at Frontier Power Systems, a wind-diesel systems integrator and developer responsible for the RAMEA project. He has been Site Manager, for twenty years at the Atlantic Wind Test Site, a national facility for testing and developing wind turbines. Previously, he has held engineering positions at Nitrochem Inc., CE Canada and Amoco Oil Company. Mr. Brothers has received the Canadian Wind Energy Association s R.J. Templin Award (1995) for his outstanding contribution to the development of Canadian wind-energy technology. Lisa Dignard-Bailey received her Ph.D. in Chemistry (1986) from the University of Western Ontario in London, Canada, and also worked as a post-doctoral fellow in the Engineering Physics Department of École Polytechnique in Montréal, Canada. She joined CANMET research laboratories of Natural Resources Canada in 1987 and is currently a science and technology program manager at the CANMET Energy Technology Centre based in Varennes, Québec. She is the R&D program leader for the application of renewable energy in remote communities and theme leader for the integration of decentralized energy resources. She is actively involved in the development of international standards and is a member of the Canadian Standards Association committee responsible for renewable energy standards. Géza Joós (M 82, SM 89) graduated from McGill University, Montreal, Canada, with an M.Eng. (1974) and Ph.D. (1987). His employment experience includes ABB, the Ecole de technologie supérieure, Concordia University, and since 2001, McGill University, Montreal, Canada. He is involved in fundamental and applied research related mostly to the application of high-power electronics to power conversion and power systems, an area in which he has published extensively. He is Vice-Chair ( ) of the Industrial Power Converter Committee of the IEEE Industry Applications Society (IAS) and is active on a number of IEEE Power Engineering Society working groups, including the DC and FACTS Subcommittee of the Transmission and Distribution Committee and Chair (2003-)