STATCOM Voltage Reference Control for Sub-Synchronous Damping
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Solution Overview
Problem
Conventional SSDCs are not flexible enough to handle the complex oscillations and resonance frequencies introduced by the increased integration of renewable energy sources, leading to sub-synchronous resonance (SSR) in power systems, which can cause mechanical stress and instability.
Innovation Solution
A method and controller for a STATCOM that uses low-pass and high-pass filters to measure AC power grid voltage, cross-couples active and reactive power orders, and combines them to provide a voltage reference for controlling reactive and active power injection to dampen a wider range of sub-synchronous oscillations, enhancing grid stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional SSDC is used to dampen sub-synchronous oscillations, then damping control is provided for narrow frequency range, but the control is not flexible enough to handle complex oscillations from renewable energy sources
Solution Approach 1:
The controller dynamically adjusts its operation based on detected oscillation characteristics. The system continuously monitors voltage signals, identifies oscillation frequencies and damping ratios in real-time, and adapts control parameters accordingly, enabling flexible response to varying oscillation conditions from renewable energy sources
Solution Approach 2:
The system changes control parameters based on detected oscillation characteristics. By calculating actual damping ratios and natural frequencies from measured voltage signals, the controller adjusts impedance parameters and control gains to maintain effective damping across diverse frequency ranges and system configurations
2Productivity
If series compensation is added to transmission lines to improve capacity, then power system performance is improved, but sub-synchronous resonance oscillations occur
Solution Approach 1:
The system converts the harmful sub-synchronous oscillations into useful control information. By detecting oscillation characteristics from voltage measurements and using them to adjust control parameters, the system transforms the resonance problem into an opportunity for adaptive damping control that improves overall system stability
Solution Approach 2:
The controller implements continuous feedback by monitoring voltage signals, identifying oscillation characteristics, and adjusting control outputs accordingly. The system measures actual system response, compares it with desired performance, and modifies control parameters to eliminate sub-synchronous resonance while maintaining series compensation benefits
3Productivity
If renewable energy sources are integrated to meet increasing electricity demand, then power system capacity is expanded, but oscillation frequencies become more complex and difficult to control
Solution Approach 1:
The system performs self-diagnosis and self-adjustment by automatically detecting oscillation characteristics from measured voltage signals. The controller calculates damping ratios and natural frequencies autonomously and adjusts its own control parameters without external intervention, simplifying the management of complex oscillations from diverse renewable energy sources
Data Source
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AI summary
There is disclosed herein a method (100) for sub-synchronous damping control, SSDC, for a STATCOM (20) connected to an alternating current, AC, power grid (2). The method comprises measuring (110) a voltage representative of the voltage of the AC power grid and subjecting (120) the voltage to a low-pass filter and a high-pass filter. The method further comprises cross-coupling (130) an active power order of the voltage with a reactive power decoupler of the voltage to receive a voltage phase angle parameter and cross-coupling a reactive power order of the voltage with an active power decoupler of the voltage to receive a voltage magnitude parameter, and combining (140) the voltage phase angle parameter and the voltage magnitude parameter to provide a voltage reference to the STATCOM. There is also disclosed herein a converter for a STATCOM and a system comprising a STATCOM and said controller.