Grid Impedance Monitoring for Real-Time LFO Detection
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Solution Overview
Problem
Existing methods for monitoring low frequency oscillations (LFO) in electric power systems, particularly for PCS-based energy sources, are hindered by the time-consuming calculation of PCS impedance, making real-time monitoring difficult.
Innovation Solution
A power grid monitoring system that includes a storage unit for PCS impedance data, a real-time calculation unit for calculating power grid impedance based on measured power flow, and a stability check unit that performs real-time stability checks to detect LFO at the point of connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If PCS impedance is calculated using EMT model, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The patent pre-calculates and stores PCS impedance values at multiple operation points before actual monitoring. When monitoring is needed, the system retrieves pre-calculated impedance data corresponding to the current operation point, eliminating the need for real-time EMT model calculations while maintaining measurement precision.
Solution Approach 2:
The patent creates a lookup table containing pre-calculated impedance data from EMT models. Instead of running the complex EMT model during real-time monitoring, the system copies and uses the pre-computed impedance values from the lookup table, significantly reducing calculation time while preserving accuracy.
2Productivity
If real-time calculation of power grid impedance is performed, then productivity is improved, but device complexity increases
Solution Approach 1:
The patent divides the monitoring task into two independent parts: retrieving pre-stored PCS impedance data from a lookup table, and calculating power grid impedance using measured voltage and current. This segmentation allows each part to be optimized independently, reducing overall system complexity while maintaining real-time capability.
Solution Approach 2:
The patent introduces a lookup table as an intermediary data structure that stores pre-calculated impedance information. This intermediary eliminates the need for complex real-time EMT simulations by providing ready-to-use impedance values, simplifying the monitoring system architecture.
Data Source
AI summary
A power grid monitoring system includes a storage unit that stores power control system (PCS) impedance data indicative of a PCS impedance that is an impedance of a PCS-based energy source at a plurality of operation points, the PCS-based energy source being connected to an electric power system, the PCS-based energy source including a voltage source and a PCS that regulates power generated by the voltage source and supplies the power to the electric power system, a real time calculation unit that calculates a power grid impedance based on a power flow measured at a point of connection where the PCS-based energy source and the electric power system are connected to each other, the power grid impedance being an impedance of the electric power system, and a stability check unit that performs a stability check to detect low frequency oscillation (LFO) at the point of connection based on the PCS impedance data and the power grid impedance.