Calculation Method Of Short Circuit Current And Software Development In Distribution Network With Distrbuted Generation

The deoelopment of distributed generation have led to renewable energy based on the fossil energy crisis and climate pollution. However, distributed generation is not only small capacity, but also scattered position, the distribution network with distributed generation are different from the traditional distributed network when the short-circuit current characteristics happened in the network, resulting in distribution network with distributed generation protection configuration and setting difficult. This paper mainly studies the short-circuit curtent output chracteristics of the distributed generation after the short circult of the distribution network, the contribution of the short-circuit current of the distributed generation to the total short-circuit current of the distribution network, and the calculation method of the short-cireult current in distriibution network with distributed generation.Firstly.The types and chraracteristics of the disributed generation in the distribution network are introduced by this paper, which is divided into the motor type and the comverter type in accordance with the grid interface. The characteristics of the short circuit current of the grid connected distributed generation under the motor and different control modes are analyzed by this paper. The further studies the short-circuit current cakulation of the equivalent circult of the distributed power grid connected distributed generation, motor based on voltage source model with internal impedance, and distributed power grid connected converter with constant current source model, calculation method of the model parameters is given.This paper Mudied the general calculation method of short-circuit currmmt diswribution network with DGS, the short-circuit current is expressed as a superposition of normal component and fault component, using network structure and impedance matrix, calculates the branch current and branch current component failure under normal circumstances. Different from the traditional calculation method, all the distributed generation is characterized by the current source, and the normal component of short-circuit current can not be considered as the normal component of the node voltage approximately 1. The general calculation equations and calculation flow of distribution network with distributed generation under symmetrical short circuit and asymmetric short circuit are given.With the help of MATLAB and C++, with the help of MATLAB matrix calculation function and the friendly interface design of C++, a general calculation software of short circuit current is developed. MATLAB write short-circuit current calculation of the core program, C++design man-machine interface,through the VC call MATLAB method to achieve distributed power distribution network with short circuit current calculation software. With the help of software, the input current and node voltage can be calculated conveniently by inputting the network parameters and fault parameters of the distribution network.Finally, by using the calculation method mentioned in the text of the distribution network with distributed generation general short-circuit current in different network structure of the distribution network is calculated, and the calculated results and the theoretical calculation results and under the simulink system simulation results are compared, the result verifies the feasibility of calculating software correctness of calculation method in distribution network with distributed generation short circuit current general and short-circuit current.