Micro-grid Voltage Stability Prediction via Local PCC Measurements
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Solution Overview
Problem
Existing methods for predicting voltage collapse in micro-grids connected to power distribution networks are inaccurate and require excessive information, often relying on approximations or synchronized phasor measurements that are unavailable, making real-time static voltage stability analysis challenging.
Innovation Solution
A method using local measurements at the point of common coupling (PCC) to derive a voltage stability index, which predicts impending voltage collapses and enables real-time control actions, allowing for timely prevention of voltage instability without requiring global communication or detailed phasor information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If synchronized phasor measurements from the entire power system are used for voltage stability assessment, then measurement precision is improved, but device complexity and information requirements increase significantly
Solution Approach 1:
The patent divides the power system into micro-grid units, each with its own voltage stability detector. Each detector only needs to measure local quantities (voltage, current, power) at its own connection point, rather than requiring synchronized measurements from the entire power system. This segmentation reduces measurement system complexity while maintaining assessment accuracy through localized analysis.
Solution Approach 2:
The invention implements localized voltage stability detection at each micro-grid connection point using local measurements only. The voltage stability detector at each micro-grid analyzes local power flow and voltage characteristics to assess stability, eliminating the need for global synchronized measurements and reducing device complexity significantly.
2Measurement precision
If parameter estimation for the entire power system is performed, then voltage stability prediction accuracy is improved, but loss of time increases due to computational complexity
Solution Approach 1:
The patent segments the power system into independent micro-grid units, each with its own voltage stability detector performing parameter estimation locally. This eliminates the need for time-consuming global parameter estimation while maintaining prediction accuracy through localized analysis of each micro-grid's stability characteristics.
Solution Approach 2:
The voltage stability detector continuously monitors local power flow and voltage characteristics in real-time, maintaining up-to-date stability assessments without requiring periodic global parameter estimation. This preliminary continuous monitoring enables timely detection of voltage collapse risks without computational delays.
3Loss of information
If global communication infrastructure is implemented for voltage stability assessment, then information completeness is improved, but device complexity and implementation difficulty increase
Solution Approach 1:
The patent extracts the voltage stability assessment function to the local level, where each micro-grid's detector uses only local measurements. This eliminates the need for global communication infrastructure while ensuring information completeness for local stability assessment, as each detector has all necessary information locally available.
Solution Approach 2:
Each micro-grid voltage stability detector performs self-assessment using local measurements without requiring communication with other parts of the system. The detector independently analyzes local power flow and voltage characteristics to determine stability status, eliminating complex communication requirements while maintaining assessment accuracy.
Data Source
AI summary
A method predicts a voltage collapse in a micro-grid connected to a power distribution network by measuring states at a point of common coupling of the micro-grid, and a connected bus of the power distribution network connected to the micro-grid through a connection link. Then, it is determined whether a reactive power generation limit of the micro-grid is reached based on the states, and if no, repeating the measuring, and otherwise determining parameters of the connection link using the measurements. A static voltage stability margin index is determined, and a voltage stability margin index is predicted using the static voltage stability margin index and a forecast of future load variations in the micro-grid. Then, it is determined whether the voltage stability margin index is smaller than a threshold, and if no, repeating the measuring, determining and predicting steps, and otherwise if yes, signaling a control action indicating the voltage collapse.