Pilot protection method and system for photovoltaic power generation grid-connected tie line

Abstract

The invention discloses a pilot protection method and system for a photovoltaic power generation grid-connected tie line. The method comprises the steps of judging whether a current break variable of a certain phase in three phases meets a first condition or not or whether a zero-sequence voltage meets a second condition or not; if the current break variable of a certain phase in the three phases meets the first condition or the zero-sequence voltage meets the second condition, starting pilot protection, selecting a data window of a preset time period in a delayed mode, and calculating the current sum and the voltage sum of the tie line photovoltaic side and the tie line system side according to the phases; performing zero-sequence compensation on the sum of the voltages of the tie line photovoltaic side and the tie line system side of each phase, then solving a derivative of the sum, and calculating a correlation coefficient of each phase based on the sum of the currents of the tie line photovoltaic side and the tie line system side of each phase; and comparing the calculated correlation coefficient of each phase with a setting threshold value, and executing a corresponding protection action based on a comparison result. Accurate action can be realized under the condition that different fault types occur at different fault positions.

Description

technical field [0001] The invention belongs to the technical field of relay protection of electric power systems, and in particular relates to a method and system for longitudinal protection of grid-connected tie lines of photovoltaic power generation. Background technique [0002] Solar energy is clean and non-polluting, widely distributed, and inexhaustible. It has unique advantages in development and utilization, and has become a hot spot in the development of new energy. Affected by the characteristics of the photovoltaic power supply itself and its inverter control strategy, the fault characteristics of the photovoltaic system are different from the traditional synchronous machine system. The protection principle formed on the basis of the analysis of the fault characteristics of the traditional synchronous machine may not be suitable for large-scale centralized photovoltaics. The protection performance may decline due to the change of system fault characteristics, or ...

AI Technical Summary

Problems solved by technology

[0004] The purpose of the present invention is to provide a method and system for longitudinal protection of photovoltaic power generation grid-connected tie line, which solves the problem that the existing longitudinal differential protection may decrease in sensitivity or even refuse to operate in photovoltaic power generation grid-connected tie line

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