Non-linear observers for power grid stability estimation
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Solution Overview
Problem
Existing methods for estimating power grid stability rely heavily on traditional load flow solutions and state estimation, which are computationally intensive and dependent on real-time grid topology, often failing to provide guaranteed solutions due to the complexity of large-dimensional problems and uncertainty in grid topology.
Innovation Solution
The use of highly accurate frequency and phase angle measurements at lower voltages, combined with non-linear Luenberger observers and extended Kalman filters, allows for the estimation of grid stability by comparing measured data to a power grid model, enabling the calculation of electrical properties and power flow across the network.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional load flow solutions and state estimation are used to estimate power grid stability, then comprehensive grid state information can be obtained, but computational complexity and solution time increase significantly
Solution Approach 1:
The patent segments the complex grid state estimation problem into two parts: (1) using phasor measurement units to directly measure frequency and phase angle at specific locations, and (2) using a simplified physical model to estimate stability from these measurements. This avoids the need for comprehensive load flow solutions across the entire grid while maintaining estimation accuracy.
Solution Approach 2:
The patent introduces phasor measurement units as intermediary devices that directly measure critical grid parameters (frequency and phase angle) at strategic locations. These measurements serve as intermediaries between the complex grid state and the simplified stability estimation model, enabling accurate assessment without comprehensive computational analysis.
2Reliability
If traditional state estimation methods are used, then grid stability can be estimated, but the method is highly dependent on real-time grid topology which is often uncertain
Solution Approach 1:
The patent uses feedback from phasor measurement units that continuously provide real-time frequency and phase angle measurements. These measurements feedback into the stability estimation model, allowing the system to adapt to changing grid conditions without requiring complete knowledge of the grid topology. The physical model inherently accounts for topology changes through the measured phase angle differences.
Solution Approach 2:
The patent replaces the complex computational mechanics of traditional state estimation (which requires solving large systems of equations based on detailed grid models) with a simplified physical model based on direct measurements. This substitution reduces dependency on complete topology knowledge while maintaining reliability.
3Measurement precision
If measurements are taken at higher voltage transmission substations, then direct grid stability data is obtained, but measurement costs and safety risks increase
Solution Approach 1:
The patent uses phase angle measurements as intermediaries that can be obtained at lower voltage distribution levels to infer stability conditions at transmission levels. The phase angle difference between locations serves as an intermediary parameter that reflects power flow and stability without requiring direct measurement at high-voltage transmission substations.
Solution Approach 2:
The patent substitutes direct high-voltage measurements with measurements at lower voltage levels combined with a physical model. The model uses measured frequency and phase angle data from distribution-level phasor measurement units to estimate transmission-level stability, replacing the need for physically installing measurement equipment at dangerous and expensive high-voltage locations.
Data Source
AI summary
In order to make accurate predictions on whether or not a power grid is stable, it is desirable to know the frequency and phase of at least each “control area” in the power grid. Each control area will ideally have power generation matched with its load. Rather than measure thousands of data points at low resolution in order to calculate potential grid instabilities, one may make few highly accurate measurements at low voltage to predict frequency and phase of high voltage transmission lines. Predicted data at the transmission points can then be used to calculate the relative stability of the power grid. The method includes the use of non-linear Luenberger observers and Kalman filters. The method can also be used to compute “Virtual measurements” for any component in the connected grid based on lower cost or easier to obtain measurement at other points on network. This method applies to any connected network of components.