Research On Paralle Operation Smulation Of Three Phase Transformer

A common running way of power transformer is running in parallel, in power plants and substations, in order to improve the reliability of power supply, we usually use two or more power transformers to operate in parallel, thus when a transformer quits running because of fault, the other transformer still can continue to supply electricity. In substation, two or more transformers operating in parallel can also meet the needs of economical operation, part of the transformers will quit running at low load in order to reduce energy loss. In the construction of substation, sometimes because of the voltage quality can't meet the requirements, the voltage ratio of the two purchased transformers will be different, or short circuit voltage is different as a result of the type of transformer is not the same, there may be some problems if they are running in parallel. Transformer is a very important equipment and it's very expensive, parallel operation experiment has a great deal of risk and even causes the damage of transformer if it is carried out directly. Using Matlab/Simulink software to carry out the simulation of the three-phase transformer's parallel operation, you can easily change the transformer parameters, set the size of load and alter the operation mode; it is an effective method to research the parallel operation of three-phase transformer. The simulation of three-phase transformer's parallel operation can provide the correct basis for transformer's parallel operation in actual substation, can also be used to verify the transformer's parallel operation theory, since the theoretical analysis ignore the influence of transformer's internal resistance, using Matlab/Simulink software to do the simulation is closer to the actual situation.This paper introduces the function and the programming system of Matlab/Simulink, the magnetic circuit system of three-phase transformer as well as the winding connection and the T equivalent circuit; derives the model parameters of transformer, of which the excitation resistance is in parallel with the excitation reactance; makes the Matlab calculating program of transformer model parameters; sets up the Matlab/Simulink simulation circuit of three-phase double-winding transformer's parallel operation and three-phase three-winding transformer's parallel operation; simulates two double-winding transformers in parallel operation of which the voltage ratios are different; simulates two double-winding transformers in parallel operation of which the short circuit voltage percentages are different; simulates the load distribution of two three-winding transformers in parallel operation.The three-phase transformer's parallel operation simulation circuit that is built is operated in the Matlab/Simulink environment, the simulation results are analyzed and compared with the theoretical calculation, which shows that the simulation results are right, at the same time, has verified that the design of the transformer's parallel operation simulation circuit based on Matlab/Simulink is reasonable.