在可再生能源主导的中国电力系统情景下提高电网灵活性-20页_1mb

Summary of "Enhancing Grid Flexibility under Scenarios of a Renewable-Dominant Power System in China"

Core Content

This document explores the operational feasibility of achieving a near-complete decarbonization of China's power sector by 2030, with a focus on grid flexibility. It evaluates the effectiveness of various strategies, including coal plant flexibility, larger balancing areas, and transmission constraints, in supporting the integration of renewable energy into the grid. The study uses simulation and optimization tools to analyze the impact of these strategies under different carbon mitigation scenarios.

Main Viewpoints

• China's Power Sector Emissions: China is one of the world's largest emitters of energy-related carbon, contributing about 14% of global emissions. The country has pledged to achieve carbon neutrality by 2060 and aims to install 1200 GW of solar and wind power by 2030.

• Renewable Decarbonization Potential: Recent studies suggest that China could cost-effectively decarbonize up to 60% of its power sector by 2030, depending on renewable and storage cost trends.

• Operational Challenges: Despite the potential, there is considerable debate in China about how to maintain grid reliability and flexibility with high renewable penetration. Traditional approaches such as retrofitting coal plants offer limited benefits in this regard.

• Key Strategies for Grid Flexibility:

  • Larger Balancing Areas: Expanding balancing areas to a regional or national level significantly reduces renewable curtailment and improves system reliability.
  • Transmission Constraints: Implementing transmission hurdle rates encourages more localized renewable investment, which reduces curtailment and coal generation.
  • Market Reforms: Reforming electricity market rules to allow for more flexible dispatch and price signals can enhance grid flexibility and support renewable integration.

• Cost Considerations: The study incorporates cost assumptions, including capital and fuel costs, to evaluate the economic implications of different scenarios. It shows that regional and national balancing strategies can lead to substantial cost reductions in electricity generation.

Key Information

Scenarios Considered

• Business-as-Usual (BAU): Continuation of current policies and moderate cost decreases for renewables.
• Low-Cost Renewables (RE): Rapid decline in renewable and storage costs.
• Carbon Constraints (C50): Reducing carbon emissions by 50% compared to 2015 by 2030.
• Deep Carbon Constraints (C80): Reducing carbon emissions by 80% compared to 2015 by 2030.

Operational Strategies

• Coal Plant Flexibility: Two levels of flexibility are considered: 25% (Flex25) and 50% (base case) minimum generation levels. Ramping capability is also varied.
• Balancing Area Size: Three cases are evaluated: provincial, regional, and national balancing.
• Transmission Constraints: Two cases are considered: no transmission hurdle rate and a 1000 USD/MW-km investment cost for new transmission lines.

Results Summary

• Renewable Curtailment: Under the current provincial balancing model, renewable curtailment can reach up to 37% by 2030, which is not sufficient for a renewable-dominant system.
• Impact of Larger Balancing Areas:
  • Regional balancing reduces curtailment by 6-21% compared to provincial balancing.
  • National balancing further reduces curtailment to 0.2-13% and significantly lowers coal generation (8-58%).
• Transmission Hurdle Rate: A 1000 USD/MW-km hurdle rate encourages more local renewable investment, reducing curtailment and coal generation by 4-10% and 6-9%, respectively.
• Economic Impacts: Larger balancing areas and more localized renewable investment reduce average wholesale electricity costs. Under the RE scenario, regional balancing reduces costs by 5.1%, while national balancing reduces them by 6.1%. Under the C50 scenario, these reductions are 7.6% and 12%, respectively.

Conclusion

• Policy Recommendations:
  • Accelerate power system reform to enable regional and national balancing.
  • Strengthen the role of regional dispatch centers.
  • Develop wholesale markets that use price signals to manage demand and supply.
  • Encourage localized renewable investment through transmission constraints.
• Future Outlook: As renewable and storage technologies become more cost-effective, localized development will play a crucial role in enhancing grid flexibility and reducing reliance on coal.

Key Figures

• Figure 1: Installed capacity and generation by technology in 2030 under different carbon-mitigation scenarios (1a) and with the current provincial balancing (1b).
• Figure 2: National annual power generation by technology with two levels of coal flexibility under four renewable energy scenarios (2a) and average national dispatch under the RE scenario (2b).
• Figure 3: National annual generation (all scenarios) (3a) and average dispatch in typical months (RE scenario) with provincial, regional, and national balancing (3b).
• Figure 4: National annual generation (4a) and average dispatch (RE scenario) with no transmission hurdle rate compared with a 1000 USD/MW-km transmission hurdle rate (4b) under provincial balancing.
• Figure 5: National annual generation (all scenarios) (5a) and average dispatch (RE scenario) with no transmission hurdle rate and provincial balancing area compared with a 1000 USD/MW-km transmission line investment constraint (5b) with larger balancing areas.
• Figure 6: Average wholesale cost of electricity (fixed costs included) under different scenarios.

References and Data Sources

• PLEXOS and SWITCH-China: Used for simulation and optimization.
• Fuel Cost Assumptions: Coal at 4.5/MMBtu and gas at 12.9/MMBtu in 2017, with projected increases to 2030.
• Cost Trends: Based on studies from the Energy Foundation China, NREL, and others.

Appendices

• Appendix A: Contains detailed cost assumptions for capital and fuel costs used in the analysis.

Conclusion

This study highlights the importance of expanding balancing areas and encouraging localized renewable investment to enhance grid flexibility and achieve deep decarbonization in China's power system. These strategies, combined with market reforms, are essential for supporting the transition to a clean and reliable grid.