从太阳到屋顶到电网：电力系统和分布式光伏（英文版）--世界银行.pdf

1 FROM SUN TO ROOF TO GRID Power Systems and Distributed PV TECHNICAL REPORT Public Disclosure Authorized Public Disclosure Authorized Public Disclosure Authorized Public Disclosure Authorized© 2023 International Bank for Reconstruction and Development / The World Bank 1818 H Street NW | Washington DC 20433 202-473-1000 | www.worldbank.org This work is a product of the staff of The World Bank with external contributions. The findings, interpretations, and conclusions expressed in this work do not necessarily reflect the views of The World Bank, its Board of Executive Directors, or the governments they represent. The World Bank does not guarantee the accuracy of the data included in this work. The boundaries, colors, denominations, and other information shown on any map in this work do not imply any judgment on the part of The World Bank concerning the legal status of any territory or the endorsement or acceptance of such boundaries. 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All queries on rights and licenses should be addressed to World Bank Publications,1818 H Street NW, Washington, DC 20433, USA; e-mail: pubrights@worldbank.org. PRODUCTION CREDITS Designer | Circle Graphics, Inc. Images | Satellite imagery from Maxar Technologies analyzed and processed by NEO B.V. (www.neo.nl) to show building type and/or rooftop PV potential. Front and back covers: Manila, Philippines; page 8: Dhaka, Bangladesh; page 12: Lagos, Nigeria; page 38: Grenada; page 46: Izmir, Türkiye; page 82: Manila, Philippines. ©World Bank. Used with permission. Further permission required for reuse. All images remain the sole property of their source and may not be used for any purpose without written permission from the source.3 TABLE OF CONTENTS 5 ABSTRACT 6 ABOUT THIS SERIES 7 ACKNOWLEDGMENTS 9 KEY MESSAGES 13 CHAPTER 1: HOW IMPORTANT IS DPV FOR POWER SYSTEM PLANNERS AND OPERATORS? 13 DPV has Distinct Implications for Power Systems Around the World 16 Different DPV Systems Feed All, Some or None of Their Output to the Grid 18 DPV Impacts on Power Systems Evolve as Deployment Grows 23 CHAPTER 2: TE CHNIC AL SOLUTIONS FOR GRID-FRIENDLY DPV 24 Solutions Menu 1: Local Load Balancing 30 Solutions Menu 2: Enhancing Hosting Capacity 39 CHAPTER 3: GRID CODES FOR GRID-FRIENDLY DPV 39 Suggested Grid Code Elements for DPV 41 The Rationale for Specifying DPV Inverter Behavior in Grid Codes 43 DPV System Equipment Standards and Certification are Important for Enforcement of Grid Codes 44 Procedures for DPV Connection Should be Simple and Pragmatic 4 7 CHAPTER 4: APPR O A CHE S T O POWER SYSTEM PLANNING WITH DPV 47 Traditional Power System Planning Approaches Vary by Country and Are Evolving 49 Power System Planning can Address DPV in a Variety of Ways 51 General Steps and Principles for Power System Planning with DPV 60 Conclusion: Beyond Technical Issues 6 1 ANNEX A: TE CHNIC AL DE SCRIPTIONS OF NINE DPV USE CASES FOR LMICs 61 Use Case 1: Bill Reduction 61 Use Case 2: Least-Cost Backup 64 Use Case 3: Least-Cost Generation 65 Use Case 4: Transmission Energynautics GmbH—Thomas Ackermann and Eckehard Tröster; Heymi Bahar (IEA); Toby Couture (E3 Analytics); US National Renewable Energy Laboratory—Owen Zinaman, Nate Blair, Francisco Flores-Espino, Julieta Giraldez, Adarsh Nagarajan; and NEO B.V.—Fang Fang. Management guidance was provided by Demetrios Papathanasiou, Gabriela Elizondo Azuela, and Rohit Khanna. Steven Kennedy and Fayre Makeig provided copy-editing. All views expressed and any shortcomings are those of the authors.Rooftops analyzed near substation in Dhaka, Bangladesh 9 Rapid growth of distributed photovoltaics (DPV) has upended how power system planners and operators think about electricity grids. Falling costs of solar electricity have made on-site generation and consumption a low-cost option for access to new, clean power globally. PV systems located close to consumers enable them to self-supply, and—if permitted—feed into the grid. DPV thus challenges how utilities traditionally generate, transmit, and distribute power as a one-way flow from central plants down discrete system levels to consumers. Many countries are learning to successfully manage DPV at increasing shares of total power generation. Low- and middle-income countries (LMICs) stand to benefit from emerging lessons. This report explains common technical challenges and opportunities to consider, and steps to take given the current and potential future levels of DPV. For technical readers wanting more details, the report points to examples of standards and technical procedures published by other institutions. Well-managed DPV offers potential technical benefits to power grids in several distinct ways. DPV systems can, with other distributed energy resources (DER), help in LMICs to variously: (a) supply least-cost generation to the grid, especially where land is constrained; (b) defer certain transmission and distribution upgrades; (c) provide ancillary grid services; and (d) “bootstrap” or upgrade underperforming utilities by improving service and increasing bill collections for consumers in a microgrid. 1 These and other potential use cases, plus rapid installation times, enhance DPV’s value as a contribution to least-cost decarbonization or low-emissions development plans. Benefits from DPV, however, depend on appropriate power system planning, investments and operations, suited to the local context. As DPV grows from low to higher levels of penetration, different technical risks typically emerge. These are summarized in Figure 1 (left column). Effects of DPV on power systems are gradual and the specific issues that arise as DPV grows can vary from place to place. At a low level of deployment, DPV may have negligible impacts, especially in larger grid systems. DPV power fed to the grid can usually be stepped up to higher voltage levels often without significant technical modifications to the distribution system. However, poorly managed DPV can cause system operating limits to be breached at certain times. Since DPV can be installed in a matter of weeks, at a much faster rate than bulk power plants, preparing for rising levels of penetration is imperative. The amount of DPV that a grid can integrate safely, while keeping within specific operational limits, is not fixed. Hosting capacity for DPV is a dynamic, multi-faceted threshold. It can vary within a grid and over time, depending on the design and operation of the power system and of DPV systems—in aggregate and large individual systems. A menu of potential technical solutions exist to help ensure DPV is grid-friendly. See Figure 1, middle and right columns, which correspond to two broad approaches as follows. 1. Local load-balancing. Matching DPV supply and local demand with each other as much as practical can help keep grids within specified system operating limits. This type of intervention aims to keep net load 2 relatively stable and certain, akin to load conditions without DPV or even, ideally, to improve upon them. 1 “Bootstrap” here means using initial minimal resources to lift oneself up out of a bad situation. 2 “Net load” here refers to demand for bulk grid electricity excluding demand for electricity served by distributed and/or bulk variable renewable sources. See Glossary for this and other key technical terms. KEY MESSAGES