Research On AC Electronic Load In Dynamic Simulation Of Power Load

Power system dynamic simulation is a kind of physical simulation, which is used to study the dynamic characteristics of the power system, where special custom load is in need. With the rapid development of power electronics technology, the study of the electronic load is processed increasingly. If the same input characteristics are existed in the current of input side as the actual load current in dynamic simulation, the power load can be completely replaced by electronic loads, which is applied to the power system dynamic simulation, by controlling the AC electronic load reasonably. And finally the test is get simplified and flexible, the cost is reduced, the degree of automation of dynamic simulation is increased, energy is saved and so on. The deficiencies of the traditional power load device are made up.According to the objective and requirement of AC electronic load instead of the traditional load in dynamic simulation, the research status of electronic load is introduced in this paper, and the control method of AC electronic load and the models of the power load are researched.Through the analysis and comparison of the different converter structures, the intermediate DC link AC-DC-AC converter structure as the topology structure of the main circuit of the electronic load and the voltage type PWM rectifier VSR (Voltage Source Rectifier) as the mathematical model of the electronic load circuit converter are determined in this paper. The types and characteristics of the load in the power system dynamic simulation experiment are discussed, and the mathematical models of the inductive load and the asynchronous motor are established.Control of the VSR at the simulated load side should meet the requirement of rapid and accurate current tracking and insensitiveness to the load parameters. For this purpose, specific research of double hysteresis current control method based on space vector has been done, with which artificial neural network is used to predict the compensation current value, in order to solve the problem of beat existing in the VSR controller of load side. The control of VSR at the net side should meet the requirement of current unit power factor output and maintaining a constant DC voltage. And thus the double closed-loop structure gets determined, where outer loop is voltage loop and inner loop is current loop. In order to limit power switching loss, a kind of current control method based on fixed switching frequency is proposed.By using the mathematical model, which consists of the main circuit structure of electronic load, control method and dynamic simulation of power system load, the RL load and RC load in dynamic simulation experiments and validate the effectiveness and feasibility of the design by analyzing the waveforms is studied in this paper. The simulation model of the entire system is built on MATLAB/Simulink platform. Additionally the load of the asynchronous motor in the dynamic simulation is simulated, by testing the starting, voltage jump and the mechanical load disturbance of the different types of mechanical load and various waveforms and associated results are analyzed, the effectiveness of this design and feasibility is verified.