A strict vector check must be conducted on relay protection before its commissioning, as vector errors will cause maloperation or refusal to operate of relay protection during normal operation or fault conditions. The traditional vector check is performed with operating voltage and load current by organizing on-site loads after commissioning, which is a post-verification method. However, at the initial commissioning stage of a substation, it is often difficult to organize sufficient loads—such as in cases of light load, reverse power supply from power plants, power transmission to high-speed railway traction substations, etc.—resulting in incomplete detection that may affect the normal operation of the substation.

Recently, XX Power Supply Company of State Grid Corporation of China made advance preparations and thorough arrangements, and successfully completed the vector check of primary and secondary circuits before the commissioning of a 220kV smart substation. The test adopted a complete set of relay protection vector check devices, which inject constant current/constant voltage into both ends of the primary circuits of CT/PT in the main wiring of the substation. The current/voltage is transformed by mutual inductors and then injected into the secondary circuits, with the protection devices acquiring real sampled values. This technology effectively resolves the contradiction between the high demand for simulated load current of the substation and the insufficient capacity of the test power supply. In addition, a primary system voltage and current boosting scheme was formulated for the 3/2 main wiring configuration, which can be used to simulate and replace the on-load check of busbars, transmission lines and transformers. It provides a reliable verification basis for ensuring the correctness and integrity of relay protection devices and secondary circuits.

△ Test Structure Diagram

△ Test Equipment - Complete Set of Relay Protection Vector Check Devices

The Complete Set of Relay Protection Vector Check Devices is a primary and secondary circuit phase calibration device independently designed and developed by Wuhan Haomai Electric Power, based on extensive collection of user opinions and suggestions. It is suitable for the vector check of relay protection in substations of 1000kV and below voltage grades.

The device is equipped with independently output high-precision current and voltage sources with adjustable amplitude and phase, capable of completing phase and amplitude tests for line protection, bus differential protection, transformer differential protection and other protections of all voltage grades. Key features include:

Two current source units achieve wireless online synchronous output, enabling phase and amplitude tests for transformer differential protection bays (e.g., hexagonal diagram testing before commissioning).

The current source and voltage source units support wireless online connection, allowing synchronous phase calibration of CT and PT, as well as phase and amplitude tests for line protection bays.

While meeting test requirements and achieving a wide measurement range, the device adopts a split-type program-controlled voltage and current source with the advantages of small size and light weight. It effectively solves the long-standing problems of large volume, heavy weight and difficult transportation of traditional test equipment caused by the high demand for input capacity.