Microgrid failure locating method

Abstract

The invention belongs to the field of power system microgrid protection and control, and relates to a microgrid failure locating method. A static switch is arranged in a common coupling point, and a relay protection device is arranged in a synchronization place of lines including distributed power supplies. The microgrid failure locating method comprises the steps of: 1, carrying out real-time data sampling on a current by using a line protection device; 2, when detecting that some phase has current mutation and a mutation quantity absolute value is more than a set threshold for the first, turning into the step 3, otherwise, returning the step 1; 3, continuously carrying out real-time data sampling on the current, detecting whether some phase current mutation absolute value detected again within a time period t is more than the set threshold, if so, turning into the step 4, otherwise, judging that a failure is not caused or the failure occurs outside a line protection area, interlocking a protection, returning the step 1; and 4, judging that the failure occurs in the line protection area, and opening the protection. According to the invention, the failure occurring area can be accurately judged.

Description

Technical field [0001] The invention relates to the field of micro-grid protection and control in power systems, and proposes a positioning method suitable for internal phase-to-phase faults in low-voltage micro-grids. Background technique [0002] When a phase-to-phase short circuit occurs in the traditional distribution network, the short-circuit current is much larger than the normal load current, so two protection methods, namely current quick-break and over-current protection, are mainly used. Compared with the traditional distribution network, the access of distributed generation (DG) makes the microgrid a multi-terminal power network with complex network topology and changeable power flow direction; in addition, DG is usually an inverter distributed Constrained by link current limiting measures, when a fault occurs, the fault current provided by DG will be limited within 2 times the rated current. Therefore, traditional protection schemes, fault detection and fault a...

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Problems solved by technology

For example, the output voltage characteristics of the inverter distributed power supply after a fault are obvious. Some scholars propose to perform dq0 transformation on the DG outlet voltage, and determine the fault type by comparing the transformed value with the given value, and combine the DG outlet voltage transformation value of the adjacent area to finally Determine the location of the fault. However, in general, the area covered by the low-voltage microgrid is small. After the fault occurs, the voltage of the entire network will drop and the difference is not obvious, so this method has certain limitations.

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