Flexible direct-current converter valve integrated with surplus power dissipation function and control method

Abstract

The invention discloses a flexible direct-current converter valve integrated with a surplus power dissipation function and a control method. The flexible direct-current converter valve comprises a three-phase unit and a control module, wherein each unit is divided into an upper bridge arm and a lower bridge arm, and each bridge arm is formed by connecting at least one submodule in series; the sub-modules comprise first sub-modules and second sub-modules; each bridge arm comprises a certain number of the first sub-modules and a certain number of the second sub-modules, and the second sub-modules are SM sub-modules; and the first sub-modules are SM sub-modules with energy consumption units. The flexible direct-current converter valve has the beneficial effects that wall bushings and insulating frames are reduced, and equipment cost and occupied area are reduced; the energy consumption units can share a water cooling, function and control protection system with the MMC sub-modules, so that the cost is reduced; the energy consumption units only bear the capacitive voltage during a fault period, direct current voltage is still formed by the capacitive voltage, the risk of insulation breakdown does not exist, and the three-phase bridge arm current is balanced; the topology does not influence the control logic of the converter valve during the energy consumption period; and the device cost is further reduced while the surplus power dissipation is ensured.

Description

Technical field: [0001] The present invention relates to the field of flexible DC transmission, and more particularly to a flexible DC converter valve for integrated surplus power dissipation function and a control method thereof. Background technique: [0002] In order to solve the global energy crisis, wind power is rapidly developed globally, and my country proposes the energy structure strategic adjustment of "carbon-up, carbon neutrics". my country's sea wind energy resources are rich and have broad development prospects. Modular Multiplevel CONVERTER, MMC) has become the preferred shift valve topology of a flexible DC transmission system. When a low pressure failure occurs on the receted grid side, the AC voltage drop causes the active power of the receiving power grid side conversion station to decrease, and the power input of the wind motor is basically unchanged during the fault, so the power of the wind farm cannot be sent out. The DC side line will continue to charge d...

AI Technical Summary

Problems solved by technology

This technology connects energy-dissipating resistors in series in the MMC. During a fault, the resistors and capacitors bear the DC voltage together, which will increase the DC line voltage, making the original converter valve control strategy no longer applicable and increasing the converter valve loss.

[0004] 此外,如中国专利CN 105099206 A,CN 105119305 A,CN 105305843 A,CN105939101 A,CN 107884696 A,CN 106711999 A,CN 106712072 A,CN 106655851 A,CN106887946 A,CN 207753632 U,CN 110829478 A, CN 209823437 U , CN 111416529 A, CN111431389 A, CN 111800027 A, CN 112542957 A, CN 112467742 A, CN 212462803 U, CN112886550 A and other existing technologies, after analysis, there is no energy-consuming unit in the MMC module. AC fault ride-through requires additional configuration of energy-consuming devices, resulting in a series of problems existing in existing energy-consuming devices

[0005] To sum up, there are still some deficiencies in the existing energy-dissipating devices integrated in the converter valve, and the converter valve topology, configuration strategy and control method that integrate the surplus power dissipation function need to be improved.

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