世界银行-从太阳到屋顶再到电网：电力系统和分布式光伏（英）-2023-84页_5mb

Summary of "From Sun to Roof to Grid: Power Systems and Distributed PV"

Overview

• Distributed Photovoltaics (DPV) is rapidly growing globally, offering low-cost, modular energy generation for low- and middle-income countries (LMICs). It provides benefits such as least-cost generation, deferred transmission and distribution upgrades, ancillary grid services, and utility bootstrap improvements.
• Risks emerge as DPV penetration increases, including voltage issues at low levels, thermal overloading at medium levels, and power quality or lack of synchronous generation at high levels. Proper planning and integration avoid costly fixes.
• Technical Solutions include local load balancing (e.g., optimizing PV sizing and angles) and hosting capacity enhancements (e.g., inverter programming, grid upgrades).
• Grid Codes are essential for ensuring DPV systems interact safely and efficiently with the grid, with updated standards reflecting future distributed energy growth.
• Power System Planning involves integrating DPV into capacity expansion models, using discrete studies or integrated approaches, and engaging stakeholders early.
• Benefits for LMICs include renewable energy access, job creation, and energy security, alongside the need for capacity building and supportive policies.

Technical Challenges and Risks

• Low Penetration: Voltage limit breaches due to DPV raising local voltage.
• Medium Penetration: Transformer and conductor thermal ratings exceeded; disruption to fault protection; increased net load variability.
• High Penetration: Power quality issues (e.g., harmonics), lack of synchronous generation; risk of worsening grid conditions if not managed properly.

Technical Solutions

• Local Load Balancing:
  • Optimize PV panel size and angles to match load patterns.
  • Use high DC:AC ratios in inverters to clip peak output, increasing non-peak generation.
  • Limit feed-in through dynamic curtailment or static caps.
• Hosting Capacity Enhancements:
  • Program inverters for reactive power control, low-voltage ride-through, and grid-forming modes.
  • Adjust grid equipment, such as voltage compensation and harmonic filters.
  • Enhance power system flexibility through improved forecasts and automation.

Grid Codes and Procedures

• Grid Code Elements: Mandate inverter behaviors, connection standards, and simple procedures for DPV approval.
• Pragmatic Procedures: Streamlined connection agreements based on system risk, using practical screening criteria.

Power System Planning Approaches

• Traditional Models: Adjust capacity expansion models to account for DPV as "negative loads."
• Discrete Integration Studies: Focus on renewable integration challenges if high DPV deployment is forecasted.
• Integrated Planning: Consider DPV's role in distributed systems, scenarios, and optimization for cost and reliability.

Conclusion

• Beyond Technical Issues: DPV rollouts require supportive policies, business models, and financial mechanisms, with planning tied to regulation for effective grid integration. Timely capacity building is crucial for LMICs to leverage DPV for sustainable development.