Renewable Power Plant Control Using DSCR for Weak Grid Stability
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Solution Overview
Problem
Renewable energy power plants connected to weak AC power grids face instability due to high voltage sensitivity, leading to temporary grid strength reductions and resulting in long-term power curtailment and revenue losses, necessitating intervention from the Transmission System Operator.
Innovation Solution
A method that involves measuring power characteristics at the point of interconnection, determining the dynamic short circuit ratio (DSCR) and equivalent DSCR at the collection point, and controlling renewable energy generators by dispatching active power set points based on these values to maintain grid stability and avoid TSO intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If renewable energy power plants are connected to weak AC power grids, then renewable energy generation capacity is increased, but grid stability deteriorates due to high voltage sensitivity
Solution Approach 1:
The system performs preliminary assessment of grid strength by calculating DSCR and EDSCR values before power injection. Based on these pre-assessments, the control system proactively adjusts active power set points to prevent grid instability, rather than reacting after instability occurs. This preliminary action allows the system to maintain high renewable energy generation while preventing grid collapse.
Solution Approach 2:
The system continuously monitors grid conditions by receiving measurement signals and recalculating DSCR and EDSCR values in real-time. This feedback loop enables the control system to dynamically adjust active power set points based on current grid strength, ensuring stable operation while maximizing renewable energy injection. The feedback mechanism transforms the open-loop generation process into a closed-loop controlled system.
2Reliability
If Transmission System Operator curtails power to maintain grid stability, then grid stability is improved, but revenue generation deteriorates due to long-term curtailment
Solution Approach 1:
The renewable energy power plant performs self-assessment of grid strength and self-adjustment of power output through automated DSCR/EDSCR calculation and active power set point control. This eliminates the need for TSO intervention and manual curtailment decisions, allowing the plant to autonomously maintain grid stability while maximizing its own revenue generation. The system serves its own stability needs without external control.
Solution Approach 2:
The system proactively calculates DSCR and EDSCR values and adjusts active power set points before TSO curtailment would be necessary. By anticipating grid strength issues and pre-adjusting power injection, the system prevents the need for revenue-reducing curtailment while maintaining grid stability, thereby preserving revenue generation.
3Productivity
If active power levels are increased to maximize revenue, then revenue generation is improved, but grid stability deteriorates due to voltage sensitivity in weak grids
Solution Approach 1:
The system dynamically adjusts active power set points based on real-time DSCR and EDSCR values rather than operating at fixed or maximum power levels. This dynamic control allows the system to optimize revenue generation at each moment while adapting to changing grid conditions, preventing voltage instability that would occur with static high-power operation in weak grids.
Solution Approach 2:
The system changes the operating parameter (active power set point) based on calculated DSCR and EDSCR values. By continuously adjusting this parameter according to grid strength assessment, the system maximizes revenue when grid conditions permit while preventing instability when grid strength is insufficient, resolving the contradiction between revenue and stability.
Data Source
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AI summary
Aspects of the invention relate to a method (200) of operating a renewable energy power plant (12) connected to a power network (16) at a point of interconnection (20). The renewable energy power plant (12) comprises: one or more renewable energy generators (14) connected to a collection point (17a, 17b, 17c) of the renewable energy power plant (12), and a connecting network (18) connecting the collection point (17a, 17b, 17c) to the point of interconnection (20). The method (200) comprises: receiving one or more measurement signals indicative of measured power characteristics of the renewable energy power plant (12) at the point of interconnection (20); determining a dynamic short circuit ratio (DSCR) at the point of interconnection (20) based on the one or more measurement signals; determining an equivalent dynamic short circuit ratio (EDSCR) at the collection point (17a, 17b, 17c) based on the determined DSCR at the point of interconnection (20)and one or more components of an impedance of the connecting network (18); and controlling the one or more renewable energy generators (14) by determining and dispatching active power set points based on the determined EDSCR.