Zero-sequence current judgment-based series compensation protection method capable of effectively preventing misoperation

Abstract

The invention discloses a zero-sequence current judgment-based series compensation protection method capable of effectively preventing misoperation. The series compensation protection method comprises the following steps of 1, selecting a mode of a zero-sequence current integrator; 2, monitoring currents of sampling passages of three phases A, B and C by the zero-sequence current integrator; 3, performing abnormality judgment on a series compensation system; 4, performing abnormality judgment on current sampling; and 5, performing fault phase judgment on the passages with abnormally sampling. By monitoring and judging the currents of the sampling passages of the three phases A, B and C, the monitoring on the sampling abnormality of the series compensation system can be achieved, a current warning can be provided for a sampling error and CT open circuit in a series compensation sampling loop, a warning is provided for current distortion, so that the series compensation system is prevented from performing misoperation due to the abnormality of the series compensation sampling loop.

Description

technical field [0001] The invention relates to the field of series compensation protection, in particular to a series compensation protection method based on zero-sequence current judgment that can effectively prevent misoperation. Background technique [0002] Series compensation is also called series compensation device, that is, the capacitor bank is connected in series to the transmission line. Series compensation technology and high-voltage direct current transmission technology belong to one of FACT (flexible power transmission technology). Due to its characteristics of small investment, quick effect, high performance and easy maintenance, it has been adopted more and more in China, especially in large-span , a large power grid with a wide area. [0003] The reliability of the series compensation AC sampling circuit is a problem worthy of people's attention. According to the statistics of the operation of various series compensation devices in actual production, ther...

AI Technical Summary

Problems solved by technology

[0015] However, in the series compensation protection, since the voltage difference of the A, B, and C phase platforms is relatively high, up to 500kV, and the ground voltage of the secondary cable is the same as that of the series compensation platform, the secondary cable of the traditional current transformer The voltage to ground is 0, so the secondary cable of the series-compensated current transformer cannot be wired like traditional protection, and zero-sequence current can be obtained

Moreover, the traditional zero-sequence current alarm time is relatively long. For example, the NARI relay protection needs a 200ms delay before the protection can be blocked. However, in the series compensation protection, the series compensation protection misoperation time due to abnormal sampling is often short. within a few ms

Therefore, after such a long delay, it is impossible to effectively avoid the misoperation of series compensation protection.

Images