Area-Level Inertia Estimation for Power System Frequency Stability
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Solution Overview
Problem
Low-inertia power systems face challenges in maintaining frequency stability due to the lack of inertial response from power electronics interfaced renewable power generation, leading to potential frequency cascading collapses and power system blackouts, especially with large-scale renewable energy penetration.
Innovation Solution
An online area-level inertia estimation method is developed using inter-area equivalent frequency dynamics, which allows for estimation with only one phasor measurement unit (PMU) per area, reducing the requirement for extensive PMU placement and enabling accurate estimation of area-level inertia under small disturbance conditions, even with time-varying virtual inertia and varying system partitioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If power electronics interfaced renewable power generation is used to replace synchronous generators, then renewable energy penetration is increased, but power system inertia level decreases
Solution Approach 1:
The patent introduces virtual inertia control as an intermediary mechanism that allows power electronics interfaced renewable power generation to simulate inertial response. The virtual inertia controller processes the frequency deviation signal and generates a virtual inertial response that is injected back into the system, effectively mediating between the renewable energy source and the frequency stability requirement without requiring physical synchronous generators
Solution Approach 2:
The patent changes the operational parameters of renewable power generation systems by implementing virtual inertia control that dynamically adjusts the inertial response based on frequency deviations. This involves modifying the control parameters of power electronics interfaces to emulate the inertial characteristics of synchronous generators, thereby changing the system's frequency response behavior without altering the physical composition
2Measurement precision
If boundary-based method is used for area-level inertia estimation, then measurement accuracy is improved, but PMU placement requirements increase
Solution Approach 1:
The patent extracts the essential measurement requirement from the complex boundary-based method by identifying that only frequency measurements at a single bus within each area are necessary for inertia estimation. This extraction simplifies the measurement architecture by removing the requirement for extensive boundary bus measurements while retaining the core estimation functionality
Solution Approach 2:
The patent segments the power system into multiple areas and develops an inter-area equivalent frequency dynamics model that allows independent inertia estimation for each area using local measurements. This segmentation approach enables distributed inertia monitoring without requiring system-wide measurement coordination, reducing overall PMU placement requirements
Data Source
AI summary
Online estimation of area-level inertia can be used for frequency stability control in low-inertia power systems. This disclosure provides an area-level inertia online estimation method considering inter-area equivalent frequency dynamics. The disclosed method only needs one phasor measurement unit placed at any bus within each area. The inter-area equivalent frequency dynamics model for the multi-area power system is developed, which is employed to estimate area-level inertia under the small disturbance situation. Then, the area-level inertia estimation model boils down to a nonlinear parameter identification problem. The other boundary conditions of the disclosed method are derived by parameter identifiability.