A centralized resistance energy consumption device and its control method

Abstract

The invention discloses a centralized resistance energy consumption device. The device is composed of a switch unit and an energy consumption resistor. The switch unit is composed of at least one switch module connected in series in the same direction. The energy consumption resistor is centrally arranged and connected in series with the switch unit. The series connection of the energy consumption resistor and the switch unit is connected across the high and low potential DC lines, and a DC capacitor voltage equalization circuit is arranged in the switch unit. The present invention also includes a control method for a centralized resistance energy consumption device, which can realize flexible input and exit of energy consumption resistors, and improves the problem of excessive du / dt and di / dt in the input and withdrawal process of energy consumption resistors in the existing method, and The device also has the advantages of low cost and high reliability.

Description

technical field [0001] The invention belongs to the technical field of high-voltage direct current transmission, and in particular relates to a centralized resistance energy consumption device and a control method. Background technique [0002] There are clear normative requirements for new energy grid-connected low-voltage ride-through capabilities at home and abroad. For new energy systems that adopt high-voltage flexible DC transmission technology to be connected to the grid, such as the inertial power source similar to wind power at the power generation end, when the power receiving end fails and causes When the voltage of the AC grid drops, since the converter at the sending end is power-controlled, the active power cannot be sent or can only be partially sent to the AC grid. The surplus active power will cause the voltage of the DC transmission line to rise, which will endanger the safety of flexible DC converter valves and other equipment. Safety. [0003] In the pri...

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Problems solved by technology

[0002] There are clear normative requirements for new energy grid-connected low-voltage ride-through capabilities at home and abroad. For new energy systems that adopt high-voltage flexible DC transmission technology to be connected to the grid, such as the inertial power source similar to wind power at the power generation end, when the power receiving end fails and causes When the voltage of the AC grid drops, since the converter at the sending end is power-controlled, the active power cannot be sent or can only be partially sent to the AC grid. The surplus active power will cause the voltage of the DC transmission line to rise, which will endanger the safety of flexible DC converter valves and other equipment. Safety

[0003] In the prior art, the method adopted is to directly connect the power semiconductor devices in series. When the DC voltage is too high, through the control of the power electronic device, a resistor is put in. The input of the resistor will reduce the DC voltage. When the energy consumption speed of the resistor exceeds the DC voltage The speed at which the side accumulates energy, the DC voltage will drop. At this time, turn off the resistance discharge circuit, the DC voltage will rise again, and repeatedly turn on and off the resistance branch, forming the effect of hysteresis control. The main problem of this method is The problem is that when turning off, it is difficult to ensure consistency because multiple power semiconductor switching devices are turned off at the same time. Once the shutdown is not synchronized, the slow-turning device or the fast-turning-off device will be damaged due to overvoltage; Moreover, the high-speed on and off state switching will also result in a large voltage and current change rate, resulting in magnetic field interference

In addition, in the prior art, each switch module includes a large number of power semiconductor devices, and the cost is relatively high

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