Grid Impedance Estimation via Angular Error Minimization
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Solution Overview
Problem
Existing methods for estimating the equivalent impedance of a power grid are complex and not effectively optimized for real-time adjustments during changing operating conditions or faults, such as those encountered in power plants interconnected with electrical generators.
Innovation Solution
A method that measures generator voltage and current values at multiple time points and operation points to generate a performance index, which accounts for angular errors and minimizes the equivalent impedance, allowing for online estimation and adjustment of grid impedance, including resistance and inductance, using a controller that can vary operation points or respond to faults.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If existing methods are used to estimate grid impedance, then the estimation can be performed, but the method is complex and not effectively optimized for real-time adjustments
Solution Approach 1:
The invention changes the parameter representation by using voltage and current phasors at different operating points to dynamically estimate grid impedance parameters (resistance and reactance). This allows real-time adaptation to changing grid conditions while maintaining a relatively simple estimation framework based on power system measurement data.
Solution Approach 2:
The method dynamically adjusts the grid impedance estimation by utilizing measurements from multiple operating points and applying optimization techniques. This enables the system to adapt to real-time changes in grid conditions, faults, or reconfigurations, improving productivity through continuous optimization while managing complexity through systematic data processing.
2Measurement precision
If measurements are taken at multiple time points and operation points, then the accuracy of impedance estimation is improved, but the amount of data processing and computation increases
Solution Approach 1:
The method performs preliminary data collection by gathering voltage and current measurements at multiple operating points before conducting the impedance estimation. This preliminary action organizes the measurement data in advance, allowing the optimization algorithm to work with pre-processed information, thereby improving accuracy while reducing the computational burden during real-time execution.
3Reliability
If the performance index is minimized with respect to angular error, then the robustness to frequency deviations is improved, but the computational complexity increases
Solution Approach 1:
The invention implements feedback by minimizing the performance index with respect to angular error, which accounts for frequency deviations. This feedback mechanism adjusts the impedance estimation to compensate for angular variations, improving reliability under frequency deviations. The complexity is managed by formulating the performance index in a way that systematically incorporates angular error correction through optimization.
Data Source
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AI summary
A method for estimating an equivalent impedance (Zeq) of a power grid (18) comprises: measuring a plurality of measurement values of a generator voltage (Vgen) and a generator current (Igen) of at least one generator (12) connected to the power grid (18); generating a performance index (J) from the plurality of measurement values, the performance index being a function of the measurement values and the grid impedance (Zeq); and determining an equivalent impedance (Zeq) as the grid impedance, which minimizes the performance index (J). The performance index (J) is additionally a function of an angular error (δ), which accounts for a deviation of a grid frequency at a measurement of a measurement value from a nominal grid frequency, and the performance index (J) is additionally minimized with respect to the angular error (δ).