Multi-level flexible VSC-HVDC power module protection and bypass strategy

Abstract

The invention provides a multi-level flexible VSC-HVDC power module protection and bypass strategy which aims to solve the problem and guarantee the integrity of a power module even in an extreme failure state. According to the specific scheme, a press-fitting IGBT (PP1) and a press-fitting diode (PPD) are adopted to replace an IGBT module PM1 packaged through plastics, and the two ends of a direct-current capacitor are respectively connected with a thyristor crow bar (Th2) in parallel. A thyristor, the power device IGBT and the diode are in press fitting together, and the thyristor is connected with the capacitor through a busbar. Compared with the prior art, the multi-level flexible VSC-HVDC power module protection and bypass strategy has the advantages that when a power module breaks down or is out of service, the Th2 is triggered to bypass the power module. Under large heat pressure generated by high currents, silicon and molybdenum wafers in the device can be melted to form alloy, and therefore a stable short circuit state of the device can be formed, and the device can be in the stable short circuit state.

Description

technical field [0001] The present invention proposes a thyristor crowbar based solid state bypass strategy, which can improve power module protection. Background technique [0002] Most of the existing modular multi-level commutation (MMC) technology platforms on the market use plastic-encapsulated IGBT modules and diodes (PMI) as semiconductor switching devices to implement power module architectures based on half-H-bridge solutions (such as figure 1 shown). [0003] Existing designs are based on the following conservation strategies: [0004] When the power module fails or fails (internal fault), a high-speed vacuum contactor Con connected to the AC bus of the power module is immediately closed and conducted, so as to realize the bypass of the faulty power module in time and avoid system shutdown. [0005] But this solution has the following disadvantages: [0006] In some faults, such as: when the power device T1 is faulty, due to the discharge of the capacitor C1, th...

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Problems solved by technology

[0006] In some faults, such as: when the power device T1 fails, due to the discharge of the capacitor C1, the closure of the contactor Con cannot prevent the large current from passing through

In this way, the power device T1 has a risk of explosion. If the power device T1 explodes, there will be a danger of spreading the fault to other power modules.

[0007] In addition, even if the explosion of the device is contained in a special mechanical container to prevent the material and plasma diffusion and fault propagation caused by the explosion, the excessive heat energy caused by the explosion of the device may still cause the water cooling radiator inside the power module to overheat. This will further damage the radiator and insulated water pipe connections (O-rings, gaskets, etc.), which will eventually lead to the risk of water leakage and flashing of the diverter valve

[0008] When a short circuit occurs between poles of the DC bus (external fault), the fault current flows through the diode D2 in all power modules of the converter valve bridge arm. Usually, the I2t value of the diode in the plastic package IGBT module is low and cannot withstand this level. DC fault current of

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