Study On The Low Voltage Ride Through Technology For Frequency Inverters In Power Plant

In recent years,with the continuous development of the country,the scale of power grid is gradually expanding.The probability of power system failure is increased by power grid expansion,and then it will lead to the instantaneous low voltage drop in the power system of the power plant.The inverter,with its superior energy-saving and consumption-reduction advantages,has been widely used in power plant auxiliary equipment.The paper elaborated that the working principle of the general inverter power circuit and the principle of its low voltage ride through,the mathematical model of DC/DC(LVRTS)is established on the basis of the single BOOST circuit.The paper also analyzes the operation mode of the mathematical model and the criterion of starting and exiting in the running mode.On the basis of it,some important problems in the design of hardware and software(LVRTS)are discussed.In the aspect of hardware design,the BOOTST basic DC/DC circuit based on the design of BOOST circuit rectifier and phase transformation module as multiple parallel inverter power supply,to ensure the DC bus voltage of the inverter input fluctuation.In order to meet the requirements of the design,the actual parameters of the LVRTS components and the auxiliary control circuit of LVRTS are defined.In the aspect of software design,bang-bang hysteresis control algorithm and the fuzzy adaptive PI control algorithm combined,put forward the strategy of automatic control of composite DC voltage loop,we developed a RTDS controller and a real-time simulation system,the hardware in the loop simulation test loop.The simulation results not only prove the rationality in the LVRTS parameter the design,commissioning and guidance of PI controller parameters in the experiment.In order to verify the actual effect of the LVRTS,a low voltage power supply was made on the five coal feeder of power plant,and the no-load experiment was carried out.The experimental data show that the LVRTS established in this paper is different from the input voltage of the coal feeder.Can be stable under rated output DC,and ensure the reliable and stable operation of the coal feeder frequency conversion controller circuit.To achieve the inverter and some of the important equipment vulnerable to fluctuations in the external voltage,can still guarantee the normal operation of the power plant.