Voltage-Regulation Phase Shifter for Safe Grid Loop Closing
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Solution Overview
Problem
Current power distribution grids in China operate in an open-loop manner, leading to issues such as excessive loop closing current due to voltage phase differences, resulting in false tripping of protection systems and power failures, which cannot ensure uninterrupted continuous power supply.
Innovation Solution
A device and method for loop closing and breaking of a power distribution grid based on decoupled voltage regulation, utilizing a voltage-regulation phase shifter, control system, and voltage acquisition device to calculate and apply compensating voltage amplitudes and phase-angles, avoiding excessive loop currents through independent regulation of transformers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If power distribution grids operate in a closed-loop manner to ensure continuous power supply, then reliability of power supply is improved, but excessive loop closing current occurs due to voltage phase difference causing false tripping and power failures
Solution Approach 1:
The voltage-regulation phase shifter is activated before the loop closing operation to pre-adjust the voltage phase difference between the two busbars. By calculating the required phase shift angle based on the measured voltage difference and applying it in advance, the system ensures that when the loop closing switch closes, the voltage phase difference is minimized, preventing excessive loop closing current while maintaining the closed-loop configuration for continuous power supply.
Solution Approach 2:
The invention dynamically changes the voltage phase parameter by using a voltage-regulation phase shifter that can adjust the phase angle of voltage on one side of the loop closing switch. The control system calculates the optimal phase shift angle based on real-time voltage measurements and continuously adjusts the phase parameter to maintain minimal phase difference between busbars, thereby eliminating excessive loop closing current while preserving the reliability benefits of closed-loop operation.
2Adaptability or versatility
If voltage phase difference between busbars is large before loop closing, then closed-loop operation can be achieved, but false tripping of protection systems and power failures occur
Solution Approach 1:
The control system continuously monitors the voltage phase difference between the two busbars using voltage detection units. Based on the feedback signal from the voltage difference, the control system automatically adjusts the phase shift angle of the voltage-regulation phase shifter to minimize the phase difference before loop closing. This closed-loop feedback control ensures that the protection system does not experience false tripping due to large voltage phase differences, maintaining both adaptability and reliability.
3Ease of operation
If traditional load transfer method is used after power failure, then simple operation is maintained, but uninterrupted continuous power supply cannot be ensured
Solution Approach 1:
The voltage-regulation phase shifter acts as an intermediary device between the two power sources and the loop closing switch. It mediates the voltage phase difference issue that would otherwise prevent safe loop closing, enabling the system to transition from simple open-loop operation to controlled closed-loop operation. This intermediary device makes the loop closing operation as easy to execute as traditional load transfer while providing the additional benefit of continuous power supply through closed-loop configuration.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Effectively implements loop closing and breaking operations by compensating for voltage differences, preventing false tripping and ensuring reliable power supply by reducing excessive loop currents and improving operational stability.
Implementation Method 1
The voltage-regulation phase shifter comprises a parallel transformer and a series transformer; The parallel transformer is a three-phase three-winding auto-transformer
Data Source
AI summary
A device for loop closing and breaking of a power distribution grid based on decoupled voltage regulation is provided. The device comprises a voltage-regulation phase shifter, a control system, a voltage acquisition device and a loop closing switch. The voltage acquisition device acquires voltage signals on two sides of the loop closing switch performing a loop closing or breaking operation and transmits the voltage signals to the control system. The control system calculates a compensating voltage amplitude and phase-angle according to the voltage signals, and sends an instruction to the voltage-regulation phase shifter according to the compensating voltage amplitude and phase-angle. The voltage-regulation phase shifter outputs the compensating voltage amplitude and phase-angle according to the instruction from the control system, to compensate for a voltage difference between the two sides of the loop closing switch.