Hydropower Generator Voltage Synchronization Control
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Solution Overview
Problem
Hydropower generation systems face challenges in preventing power fluctuations and achieving high-speed voltage synchronization when switching between frequency converters and bypass breakers, particularly due to excessive inrush currents caused by voltage amplitude and phase differences.
Innovation Solution
A hydropower generation system with a control device that manages the operation of AC/DC converters and breakers to ensure voltage synchronization by calculating and adjusting gate signals, allowing for controlled switching between frequency converter and bypass breaker operations, thereby preventing power fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If circuit switching is performed from FC to bypass breaker without voltage synchronization control, then switching speed is improved, but excessive inrush current and power fluctuation occur
Solution Approach 1:
The control device performs preliminary voltage synchronization control by adjusting the generator voltage amplitude and phase to match the system voltage before the bypass breaker is closed. This preliminary action ensures that voltage synchronization is achieved prior to switching, preventing excessive inrush current and power fluctuation while enabling reliable switching operation.
Solution Approach 2:
The control device continuously monitors the voltage amplitude and phase difference between the generator and system, and adjusts the generator excitation and frequency accordingly. This feedback mechanism ensures voltage synchronization is maintained during the switching process, allowing fast switching without causing power fluctuation or inrush current issues.
2Reliability
If governor is used to adjust flow rate and rotation speed for voltage synchronization, then power fluctuation is prevented, but control response becomes slow
Solution Approach 1:
The invention replaces the mechanical governor system with an electrical control device that directly controls the generator excitation and frequency. This substitution eliminates mechanical inertia and friction delays, enabling rapid adjustment of voltage amplitude and phase to achieve synchronization. The electrical control system responds much faster than mechanical needle valve or guide vane operation, achieving both voltage synchronization and fast control response.
Solution Approach 2:
The control device changes the generator operating parameters (excitation voltage and rotational frequency) electronically to achieve voltage synchronization. By directly adjusting these parameters through electrical control rather than mechanical flow rate adjustment, the system achieves rapid voltage synchronization while preventing power fluctuation, overcoming the slow response limitation of governor-based mechanical control.
Data Source
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AI summary
The invention is directed to a hydropower generation system including a generator which is interconnected to a power system 102 via a frequency converter 104 and connected to a water turbine, a bypass breaker 103 which performs short-circuit of two AC output terminals 108a, 108b of the frequency converter 104, a control device 105 which controls the frequency converter 104 and the bypass breaker 103, and a voltage detector 110a, 110b which detects two AC voltages at both ends of the bypass breaker 103. The control device 105 adjusts an output voltage of the frequency converter 104 to a direction in which two AC voltage amplitudes at both ends of the bypass breaker 103 coincide with each other and two voltage phases at both ends of the bypass breaker 103 coincide with each other when the bypass breaker 103 is switched from opening to closing and outputs a closing command for closing the bypass breaker 103 when an amplitude difference and a phase difference of the two AC voltages at both ends of the bypass breaker 103 are within respective certain values.