Generator Stability Measurement Using Dynamic Reactive Power Reserve
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Solution Overview
Problem
The increasing proportion of new energy power generation in power grids leads to higher probabilities of sub-synchronous and super-synchronous oscillations, and existing systems struggle to maintain stability, particularly during sudden grid voltage changes, resulting in potential generator off-grid accidents and reduced power grid stability.
Innovation Solution
The proposed solution involves an optimized stability measuring method and controlling system for generators, electric transmission lines, power plant grids, transformer substation grids, and wide area power grids. This system collects electrical quantities, calculates dynamic reactive power reserves, and adjusts automatic stability regulation devices to damp oscillations, thereby preventing disturbance sources and enhancing grid stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If new energy power generation capacity is increased in the power grid, then power generation diversity and energy transition are improved, but the probability of sub-synchronous and super-synchronous oscillations increases
Solution Approach 1:
The patent implements a feedback mechanism by continuously monitoring oscillation characteristics through measurement devices and automatically adjusting control parameters of new energy generators and transmission lines based on the detected oscillation state, thereby suppressing oscillations while maintaining high new energy penetration
Solution Approach 2:
The patent changes operating parameters such as excitation voltage, reactive power output, and impedance settings of new energy generators and series compensation devices based on real-time grid conditions to prevent and suppress sub-synchronous and super-synchronous oscillations
2Power
If ultra-high voltage controllable series compensation and DC transmission lines are increased, then power transmission capacity is improved, but the risks of sub-synchronous oscillation and resonance increase
Solution Approach 1:
The patent introduces intermediate control devices such as static var generators (SVG) and power system stabilizers (PSS) that act as mediators between the ultra-high voltage transmission system and new energy generators, providing additional control degrees of freedom to suppress oscillations while maintaining high transmission capacity
Solution Approach 2:
The patent implements dynamic adjustment of series compensation impedance and DC transmission control parameters in real-time based on oscillation detection, allowing the system to adaptively change its electrical characteristics to prevent resonance conditions
3Ease of operation
If automatic excitation regulators and stability devices are installed, then generator control capability is improved, but the regulation is limited during sudden voltage changes causing low-frequency oscillation
Solution Approach 1:
The patent makes the automatic excitation regulator and stability devices multi-functional by enabling them to respond to both gradual and sudden voltage changes through multiple control modes, including fast response mode for sudden changes and normal regulation mode for steady-state operation, thereby eliminating the regulation limitation
4Ease of operation
If static var generator voltage tracking mode is used, then voltage control is improved, but generator off-grid accidents occur during sudden voltage changes
Solution Approach 1:
The patent implements preliminary protective actions by detecting early signs of voltage instability and pre-adjusting generator output and excitation before the voltage change becomes severe, preventing the generator from entering an off-grid condition during sudden voltage changes
Data Source
AI summary
A stability measuring method for a synchronous generator includes: S11: collecting electrical quantities, and setting an alarm PQ curve of the synchronous generator; S12: calculating a dynamic reactive power reserve, an inductive dynamic reactive power reserve and a capacitive dynamic reactive power reserve of the synchronous generator; S13: calculating a dynamic reactive power reserve target value, an inductive dynamic reactive power reserve target value and a capacitive dynamic reactive power reserve target value of the synchronous generator; and S14: calculating a capacitive stability, an inductive stability and a stability of the synchronous generator.