Active Power Filter Without DC Voltage Sensor By

Strong and smart grid is a landmark sign of power grid construction in china.This means more power electronic equipment will be put into the grid system on the existing basis,to achieve the goals in Information technology,automation,interactive and so on.Both nonlinear and time-varying characteristics of power electronic devices will also bring prominent grid pollution problems.On the other hand,highly intelligent electronic products in daily life proposed new requirements about power quality.Therefore,harmonic control and reactive power compensation to eliminate the power grid pollution is an important part of building a green grid.As a main means of harmonic control and reactive power compensation,from the eighties of last century to today,active filter have relatively mature theoretical research and operational experience.During the period of active power filter startup,there will be a large impulse current.In this paper,the DC voltage and grid voltage are introduced into the control system as a feed forward,which can inhibit the large impulse current to some extent.This can avoid the malfunction of protection device and the loss of system equipment effectively.Considering the external disturbance and noise conditions,this paper designed the parameters of PI controller in active power filter's both voltage and current control loop.Therefore the active power filter has great band characteristics,improving the fast tracking performance as well.Based on the average switching model of single-phase active filter,this paper constructs a single neuron model.According to its discrete function,take the voltage value of two sample periods as the neuron model's adjustment weights,take the fixed system parameters as the input of the neuron model,achieving DC voltage identification online after continually learning algorithm.In this method does not require to directly detect the DC voltage of active power filter.On the basis of equilibrium theory,this paper select the grid current as direct control amount,avoid direct detection of the load current and the filter output current.Under the proposed control method,single-phase active filter simplifies complex testing links.Just a voltage sensor for grid voltage,a current sensor for grid current are needed in single-phase active power filter control system.Achieve active filter hardware streamlined while savingdevelopment costs.At last,with the PSIM simulation platform,this paper built a model of APF.Simulation results show that the proposed identification algorithm can achieve well tracking to the actual DC voltage,and have no effect on the performance of the active filter.On the basis of simulation,this paper developed a prototype APF.The operating results of active power filter do verify its industrial applicability.