Grid Impedance Estimation Using Recursive Adaptive Filtering
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Solution Overview
Problem
Existing methods for estimating grid impedance in power grids are either limited to linear networks or require frequent recalculations due to variations in grid conditions, making them inefficient for real-time, precise power feed control, especially in renewable power plants.
Innovation Solution
A method using a recursive adaptive filter algorithm to estimate grid impedance by determining voltage, active, and reactive power parameters, creating a model representation, and calculating a system DC gain vector to derive resistance and reactance, allowing for dynamic and precise power feed adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If Thévenin equivalent model is used to estimate grid impedance, then the estimation method is simple, but it only holds for linear electrical networks and requires frequent recalculations when grid conditions change
Solution Approach 1:
The patent implements a dynamic grid impedance estimation method that continuously adapts to changing grid conditions. The system uses real-time measurements of voltage, active power, and reactive power to dynamically calculate grid impedance parameters, allowing the estimation to automatically adjust when grid conditions change without requiring manual recalibration or reconfiguration.
Solution Approach 2:
The patent employs a feedback mechanism where the power generating unit continuously monitors grid conditions (voltage, active power, reactive power) and uses this information to update the grid impedance estimation. The controller receives feedback from the grid and adjusts the power feed accordingly, creating a closed-loop system that maintains accuracy under varying conditions.
2Measurement precision
If grid impedance is recalculated frequently to account for grid variations, then the precision of power feed control is improved, but the computational complexity and time consumption increase
Solution Approach 1:
The patent implements continuous grid impedance estimation by continuously measuring voltage, active power, and reactive power at the point of interconnection. Rather than periodic recalculations, the system maintains a continuous estimate of grid impedance parameters, ensuring that power feed control remains precise at all times without interrupting operation for recalibration.
Solution Approach 2:
The system performs self-updating of grid impedance parameters using its own operational data. The power generating unit uses its own measurements of voltage, active power, and reactive power to automatically recalculate grid impedance without requiring external intervention or additional measurement infrastructure, making the process efficient and self-sufficient.
3Ease of operation
If traditional grid impedance estimation methods are used, then the system is easier to operate, but it cannot adapt to changes in grid impedance over time
Solution Approach 1:
The patent transforms the static grid impedance estimation into a dynamic process that automatically tracks changes in grid conditions. The system continuously updates impedance parameters based on real-time measurements, enabling it to adapt to grid variations while maintaining simple operation through automated calculation and control adjustment.
Solution Approach 2:
The patent changes the approach from using fixed grid impedance parameters to dynamically varying parameters that reflect current grid conditions. By continuously updating the impedance parameters based on measured voltage, active power, and reactive power, the system adapts to parameter changes in the grid while maintaining ease of operation through automated processes.
Data Source
AI summary
Estimating components of a grid impedance, Z, of a power grid being coupled to a power generating unit at a point of interconnection is disclosed. A voltage, Vmeas, across the point of interconnection; an active current, IP, and/or an active power, P, delivered by the power generating unit to the power grid; and a reactive current, IQ, and/or a reactive power, Q, delivered by the power generating unit are determined. A parameter estimation vector is estimated using a recursive adaptive filter algorithm, and on the basis of Vmeas, IP, P, IQ and/or Q. A model representation of the power grid is created on the basis of the parameter estimation vector, and a system DC gain vector for the power grid is calculated, using the model representation. Finally, Z, and/or a resistance, R, of Z, and/or a reactance, X, of Z, is derived from the system DC gain vector.