Reactive Power Compensation Standby Control for Fast Grid Restart
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Solution Overview
Problem
Reactive power compensation devices connected to AC power systems face challenges in restarting quickly after a power failure, as the DC capacitor voltage decreases due to discharge, preventing module control, and requiring time to restart when power is restored.
Innovation Solution
A reactive power compensation device with a central control protection device that shifts to a standby mode by opening all semiconductor switching elements and closing the switch during a power failure, allowing immediate restart when power is restored.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the reactive power compensation device continues operation during AC power failure, then the sub-module control becomes impossible due to DC capacitor voltage reduction, but stopping the device causes extended downtime after power restoration
Solution Approach 1:
The control device detects AC power failure and proactively sets all semiconductor switching elements to opened state before DC capacitor voltage drops below the threshold, preventing control loss while maintaining readiness for immediate restart upon power restoration
Solution Approach 2:
The system dynamically adjusts the state of semiconductor switching elements based on real-time detection of AC power system status, transitioning from normal operation to all-opened state during power failure and back to operational state after restoration, optimizing both reliability and restart time
Data Source
AI summary
A reactive power compensation device is connected with an AC power system via a switch, and includes an arm circuit having a plurality of sub-modules connected in series, and a central control protection device. Each of the sub-modules includes a DC capacitor, and a bridge circuit for switching whether or not to output a voltage held in the DC capacitor. The central control protection device is configured to shift to a standby mode in which all semiconductor switching elements constituting the bridge circuit of each of the sub-modules are set to an opened state, with the switch being set to a closed state, when the AC power system has a power failure during operation of the reactive power compensation device, and to shift from the standby mode to a stop mode in which the switch is set to an opened state.