Study On The Voltage Dip Immunity Of Adjustable Speed Drive Systems: Test, Assessment And Parameter Designation

With a large number of sensitive loads applied in industries,customers demand higher power quality than ever.The voltage dips cause great economic losses to industrial customers and threaten the safety in the people’s daily lives.The voltage dips have been taken more and more considerations.Understanding the voltage dip immunity of equipment is critical for the assessment of economic losses and safety hazards,planning of power grids,designation of product and configuration of mitigation devices.In order to understand the influence of voltage dip on adjustable speed drive system(ASD)fully,this thesis has studied on the simulation and experimental test of voltage dip immunity of ASD.Approaches of the threshold calculation in the voltage tolerance curves(VTCs),parameter designations and probable assessment of device failures have been proposed.The main jobs were given as follows:Firstly,a comprehensive test procedure was designed with consideration of the various components affecting the voltage dip immunity of ASD.A simulation model of ASD was established.The simulation tests were performed under the instruction of the test procedure.Simulation results were analyzed to obtain the voltage dip immunity of ASD.Secondly,an experimental platform was established to test the escalator with ASD.The voltage dip immunity test was performed with different operation conditions,voltage dip types and characteristics.The voltage dip immunity of ASD was analyzed with the test results.Thirdly,the mathematical method for the thresholds of VTCs was proposed based on Energy Conservation.Based on the method,the designation for the under-voltage protection value and the filter capacitance value of the converters was presented with the consideration of the voltage dip immunity.The calculation and parameter designation methods were verified with simulation and experimental test.Finally,the stochastic characteristics of the load were taken into account to assess the device failure.a method to evaluate the voltage dip immunity is proposed.And the failure probability of device can be calculated,with known the Residual voltage,Duration and load rate distribution characteristics.And the voltage dip immunity of ASD is evaluated.The voltage dip immunity of ASD can be understood comprehensively by a large number of simulation and experimental tests.The theoretical calculation method can provide guidance for the parameter designation of inverters.The probability assessment method can provide effective decision support for the mitigation of voltage dip.