Static VAR Compensator Y-Connection Reduces Phase Voltage
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Solution Overview
Problem
Existing Static VAR Compensator (SVC) systems with a Thyristor Switched Capacitor (TSC) in delta connection face high phase voltages, leading to increased costs due to higher thyristor counts and capacitor volumes, and reduced device stability.
Innovation Solution
The SVC system is reconfigured to use a Y connection for the TSC, reducing phase voltage to 1/1.732 times the line voltage, thereby reducing the number of thyristor elements and capacitor volume, and incorporating a harmonic filter to minimize harmonic distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the TSC is connected in delta connection to the power system, then the reactive power compensation function is achieved, but the phase voltage becomes equal to the line voltage which increases the number of thyristor elements and capacitor volume, thereby increasing cost and reducing device stability
Solution Approach 1:
The patent changes the connection configuration parameter of the TSC from delta connection to Y connection. This parameter change transforms the voltage relationship from phase voltage equal to line voltage to phase voltage equal to 1/1.732 times line voltage, thereby reducing the voltage stress on thyristor elements and capacitors, reducing their volume and quantity, and improving device stability without compromising the reactive power compensation function
Solution Approach 2:
The patent inverts the conventional connection approach by using Y connection instead of the traditional delta connection for TSC in SVC systems. This inversion of the connection topology fundamentally changes the voltage characteristics applied to the compensation elements, allowing for reduced component specifications and improved system reliability
2Ease of manufacture
If the TSC is connected in delta connection, then the reactive power compensation is provided, but the phase voltage equals the line voltage requiring higher insulating level and greater capacitor volume, thereby increasing installation space and cost
Solution Approach 1:
By changing the connection parameter from delta to Y configuration, the patent reduces the phase voltage parameter from equal to line voltage to 1/1.732 times line voltage. This parameter change directly reduces the insulating level requirements and capacitor volume, thereby reducing installation space and manufacturing cost
3Power
If the TSC switches on and off bidirectional thyristors to supply reactive power, then the reactive power compensation function is achieved, but harmonic distortion is generated in the power system
Solution Approach 1:
The patent introduces a harmonic filter as an intermediary component connected to the TSC. This harmonic filter acts as a mediator that captures and filters out the harmonic distortions generated by the rapid switching of bidirectional thyristors, allowing the TSC to maintain its reactive power supply capability while preventing harmful harmonics from being injected into the power system
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
This configuration lowers the phase voltage applied to the TSC, reducing costs and improving device stability while also integrating a harmonic filter to reduce system volume and installation costs.
Implementation Method 1
The TSC switches on and off the three bidirectional thyristors 121, 122, and 123 to supply reactive power to the AC power system 130
Implementation Method 2
The TCR 110 switches on and off the three bidirectional thyristors 111, 112, and 113 to absorb reactive power of the AC power system 130
Implementation Method 3
The SVC system adjusts reactive power of the TSC and the TCR to supply reactive power to a power system or absorb reactive power
Data Source
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AI summary
A static var compensation apparatus including: a plurality of capacitor banks (310) supplying three-phase alternating current (AC) power; a plurality of bidirectional thyristors (320) opening and closing the plurality of capacitor banks; and a controller (330) calculating an amount of reactive power necessary to be compensated and controlling the plurality of bidirectional thyristors (320) to open and close the plurality of capacitor banks (310) in correspondence to the calculated amount of reactive power, wherein the plurality of capacitor banks (310) are in a structure of Y connection.