AC Grid Condition Evaluation Using Dynamic Impedance Estimation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for estimating the strength of AC power grids, such as those using Phase Locked Loops and fixed phase estimates, fail to accurately measure grid condition due to phase deviations caused by fast power/current dynamics, especially in the presence of HVDC links, leading to potential trips and instability.
Innovation Solution
A method involving capturing voltage and current signals, transforming them using Park transformations, and estimating equivalent circuit parameters with least-squares optimization to determine a grid condition indicator, accounting for frequency variations and harmonic components, thereby enhancing the accuracy of grid condition evaluation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If Phase Locked Loop and fixed phase estimate methods are used to estimate grid condition, then the estimation process is simple, but the measurement precision deteriorates due to phase deviations from fast power/current dynamics
Solution Approach 1:
The patent applies dynamics by using a sliding window approach that continuously updates the equivalent impedance calculation based on recent voltage and current measurements. This dynamic adaptation allows the system to track fast power/current dynamics and frequency variations, improving measurement precision while maintaining reasonable computational complexity through efficient window-based processing.
Solution Approach 2:
The patent implements preliminary action by pre-defining the equivalent circuit model structure and impedance calculation framework before actual grid condition estimation. This preparation enables the system to quickly process incoming measurements and rapidly adapt to changing grid conditions, resolving the contradiction between simple estimation and accurate measurement.
2Measurement precision
If equivalent circuit parameter estimation is performed continuously to improve grid condition monitoring accuracy, then the measurement precision improves, but the computational burden and system complexity increase
Solution Approach 1:
The patent applies partial action by using a sliding window that processes only a subset of historical data points rather than continuously analyzing all available measurements. This selective processing maintains high measurement precision for grid condition indicators while significantly reducing computational burden and system complexity compared to full continuous analysis.
Solution Approach 2:
The patent extracts only the essential equivalent circuit parameters (impedance magnitude and angle) needed for grid condition assessment from the full set of possible measurements and calculations. This extraction focuses computational resources on the most critical parameters, improving accuracy for key grid condition indicators while limiting overall system complexity.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The present disclosure relates to a method and system for evaluating a grid condition of an AC power grid (1). A time series of voltage and current signals of the AC power grid (1) is captured (S1) and a local frequency of the AC power grid (1) is identified. The time series of the voltage and current signals is transformed at the identified local frequency of the AC power grid (1) into transformed signals. Equivalent circuit parameters are estimated from the transformed signals based on a description of an equivalent circuit (3) of the AC power grid (1) (S6) . A value of a grid condition indicator is determined based on the calculated equivalent circuit parameters and the identified local frequency of the AC power grid (1) and processed in a grid monitoring system for evaluating the grid condition of the AC power grid (1).