Method for evaluating withstand current of high-resistant neutral point small reactor

Abstract

The invention provides a method for evaluating a withstand current of a high-resistant neutral point small reactor, which is based on an electromagnetic transient simulation method, sufficiently considers different fault types and working conditions, and calculates the current withstood by the high-resistant neutral point small reactor in the actual operating process. The method comprehensively considers an operation mode of a 750k double-circuit transmission line according to different faults and working conditions, and obtains maximum temporary currents probably withstood by the high-resistant neutral point small reactor in the process of various faults and working conditions. The current is the maximum current actually and probably withstood by the high-resistant neutral point small reactor in the process of system operation. Thus, the current can guide the design and the manufacturing of the small rector better.

Description

technical field [0001] The invention relates to the field of power systems, in particular to a method for evaluating the withstand current of a high-resistance neutral point and a small reactance. Background technique [0002] In the E / UHV power transmission system with high-voltage shunt reactor (high reactance), it is generally installed with high-voltage shunt reactor neutral point small reactance to reduce the latent supply current and recovery voltage. Its schematic diagram is as follows figure 1 Shown, X in the figure L Indicates high voltage shunt reactor, X N Indicates a small reactance at the neutral point. [0003] Under normal circumstances, due to the balance of the three-phase voltage, the voltage and current flowing through the small reactance at the neutral point are very small; when an asymmetrical fault occurs in the system or some special working conditions, the small reactance at the neutral point has to withstand a higher voltage and current. 750kV d...

AI Technical Summary

Problems solved by technology

750kV double-circuit line on the same tower, due to the coupling between circuits, under certain working conditions, the small reactance current at the neutral point is very large. If it is not considered in the design and manufacture, it may be detrimental to the safety of the small reactance and endanger the system operation.

[0012] (1) The faults considered are relatively limited, and only the case of single-phase ground fault load shedding in the line is considered;

[0013] (2) The calculated steady-state current is the current after the fault occurs and reaches the steady state, without considering the development process of the fault;

[0014] (3) The influence of non-linear components such as lightning arresters is not considered;

[0015] (4) The calculated current is an estimated value, and it is impossible to know the current that the small reactance of the neutral point can withstand in the actual operation process

Images