Device and method for online monitoring insulation level of multiple current convertors and direct current bus

Abstract

The invention provides a device for online monitoring the insulation level of multiple current convertors and a direct current bus. The device includes a central processing unit, an alarm unit and a detection unit, wherein the alarm unit and the detection unit are both connected with the central processing unit; the detection unit is also connected with a positive electrode and a negative electrode of the direct current bus and online detects the voltage of the positive and negative electrodes of the direct current bus to the ground under the current connection state of the direct current busand the current convertors; the central processing unit figures out the insulation resistances of the positive and negative electrodes of the direct current bus to the ground according to the voltageof the positive and negative electrodes of the direct current bus to the ground, compares the insulation resistances with a preset first resistance threshold value separately and further outputs a corresponding control signal according to a comparison result; the alarm unit enables an alarm function as a response to the judgement that the insulation level of the direct current bus or the connectedcurrent convertors exceed the standards according to the control signal or disables the alarm function as a response to the judgement that the insulation level of the direct current bus or the connected current convertors is normal. By implementing the method, online monitoring of the insulation level of the current converters and the direct current bus and alarming can be achieved in time, and safe and stable running of a whole UPFC is ensured.

Description

technical field [0001] The invention relates to the technical field of on-line monitoring of electric power equipment, in particular to a device and method for on-line monitoring of the insulation level of a converter and a DC bus. Background technique [0002] Flexible AC Transmission System (FACTS, Flexible AC Transmission System) technology is based on power electronics technology, combined with modern control technology to achieve fast and flexible control of the original AC transmission system parameters and network structure, which can greatly improve the transmission capacity of power grid lines and enhance the flexibility of the system It has become an important development direction of power grid construction. [0003] Unified Power Flow Controller (UPFC, Unified Power Flow Controller) is the most versatile FACTS device so far. Only by changing the control law, several different functions such as parallel compensation, series compensation and shifting can be realize...

AI Technical Summary

Problems solved by technology

[0005] However, the insulation level between the converter and the DC bus will directly affect the operation safety of UPFC

For example, the DC bus has a fault (such as ground fault, inter-pole fault and disconnection fault) or abnormal operation mode (such as insulation level drop, low voltage or overvoltage, etc.), which affects the safe and stable operation of the entire UPFC; another example , the converter fails (such as grounding, short circuit, AC intrusion, etc.), the fault will propagate to the DC bus and other converters, thus affecting the safe and stable operation of the entire UPFC

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