Why are utility-scale wind and solar important to stability
In parts 1 and 2 we identified two different locations as examples of incoming voltage at locations that are either connected or not connected to distribution systems with signficant wind or solar supply. There are three types, or classes, of turbines including Type 1 for high wind conditions, Type 2 for medium wind, and Type 3 for low wind applications. With the IEEE standard series 1547* and the one under development, IEEE std P2800**, the focus in low wind and medium wind applications is the use of the inverters to provide voltage stability even while the turbines are not operating.
The benefits to the grid are voltage and frequency ride-through, active power control, dynamic voltage support, voltage support, and reactive power control for both wind and solar with inverter-based systems. A study performed jointly by NREL (US Department of Energy’s National Renewable Energy Laboratory) and General Electric tested improved controls for ‘grid-forming mode.’ This is when the generator can set grid voltage and frequency with and without power from the grid (Wind Turbines Can Stabilize the Grid | Department of Energy).
In effect, utility-scale solar as well as wind Type 3 turbines, which normally operate in low wind applications and are subject to under 35% load factor, are used to correct poor power in bulk grid applications, especially at long distances. As noted in Part 1 of this series locations that are relatively remote outside of an area with wind/solar while Part 2 is in a location with significant wind and solar.
*IEEE Std 1547 IEEE Standard for Interconnecting Distributed Resources with Electric Power Systems
The series includes:
• 1547.1: IEEE Standard Conformance Test Procedures for Equipment Interconnecting Distributed Resources with Electric Power Systems
• 1547.2: Draft Application Guide for IEEE 1547, Interconnecting Distributed Resources with Electric Power Systems
• 1547.3: Draft Guide for Monitoring, Information Exchange, and Control of Distributed Resources Interconnected with Electric Power Systems
• 1547.4: Draft Guide for Design, Operation, and Integration of Distributed Resource Island Systems with Electric Power Systems
• 1547.5: Draft Technical Guidelines for Interconnection of Electric Power Sources Greater than 10 MVA to the Power Transmission Grid
• 1547.6: Draft Recommended Practice for Interconnecting Distributed Resources with Electric Power Systems Distribution Secondary Networks
**P2800 IEEE Draft Standard for Interconnection and Interoperability of Inverter-Based Resources Interconnecting with Associated Transmission Systems.
