Research On Intelligent Testing Method Of Mutual Transformer Secondary Polarity In Substation And Its Excitation System

Mutual transformer is one of the most important high voltage electrical equipments in substation. It converts large current and voltage of primary side into small current of secondary side and provides AC current and voltage datas for secondary equipments.It’s the contacting element between primary equipments and secondary equipments. Therefore, mutual transformer’s secondary polarity is correct or not is related to the secondary system’s reliable operation, thereby affecting the safe and stable operation of whole substation. At present, the test of mutual transformer secondary polarity in substation also remains in the level for a single mutual transformer test, that applies excitation in the primary side and distinguishes the secondary polarity by the acquisited signals in the secondary side. This method does not apply to the situation that primary side wiring terminals of transformer are far from the secondary side wiring terminals,and the mutual transformer secondary windings is numerous, this method requires replacing wiring constantly, and the workload is heavy. This paper presents a intelligent testing method based on the idea of whole station for mutual transformer’s secondary polarity and designs it’s corresponding excitation system.In this paper, polarity testing methods of 10kV 3-phase 4-star potential transformer are studied firstly, including the method of pulse voltage and sinusoidal voltage and their corresponding testing excitation are desgined. Based on summing up the above two kinds of methods,a whole station testing method is raised.It’s test requirements, test principles, polarity judging methods and test schemes are introduced. Synchronous acquisition system applied to station test has been studied.The system uses the time synchronization function of GPS to form the synchronous sampling pulse,and its hardware structure is introduced.The excitation system used for whole station test are studied, and its composition are introduced from the angles of hardware and software in detail.At last, the practicability of it is verified in experiments.