Design And Implementation Of Three-phase Electronic Load System For Frequency Converter

It is necessary to provide the corresponding electrical load conditions,in order to test the electrical performance of the frequency inv erters.Motor-engine load system and motor-electricity generator system are generally used to load the electric loads,during the traditional loading process.This kind of load system is complex and has enormous noise when loading.And there is no feedback for the energy consumed in the loading process.It is a waste of electricity and a huge burden on the electric grid.This design aims to use static electronic systems to simulate the operation of motors,and completely replace the rotating mechanical load syste ms.Increasing flexbility can simplify the progress,realize the feedback to grid of electricity,avoid the waste of electricity in test,and greatly reduce the size of load systems and the burden of the grid in the process of starting-up and working.To specify the requirements of inverter load current simulation,this paper combined relative standards and traditional tests to determine the load current type of electric load systems.Feasibility and key problems of electric load systems are analyzed,and the method to calculate the load current based on offline is determined.Therefore the preventive strategy is developed.The characteristic of load current depend on the types of load are determined,when frequency inverters are running accoring to the workding mode of inverter and the operation characteristics of asynchronous motors.Decrease the dependance of load current on motor models,and simplify the calculation of reference signal.This paper designed a topology of the electric system which can realize the simulation of active loads and passive loads,and the feedback of electricity.Design of load simulation control systems based on tracking direct current is completed to guarantee the accuracy and speed of tracking.Energy consumption,energy feedback,reactive compensation strategies are designed to minimize the effect generated by load test on the grid.At last,simulation model and hardware experiment platform are established,and the simulation verification and experiment analysis of design are made.