Research Of Distribution Static Compensator Based On Adaptive Control Algorithm

With the rapid development of the industry and the improvement of people's life quality,more and more non-linear,unbalanced,impact loads are connected to the distribution systems,causing a series of power quality problems,such as harmonic,low power factor,three-phase unbalance,voltage fluctuation,asymmetry and so on,which has an adverse effect on the secure,stable,financial and efficient operation of the power grid.Static synchronous compensator(STATCOM)becomes the developing direction of reactive power compensation because of its advantages of quick dynamic response and wide operating range,and has been considered as one of the most effective solutions to power quality problems.In this paper,the control method of distribution static synchronous compensator(DSTATCOM)based on adaptive algorithm is studied theoretically and experimentally.First,this paper analyses the working principle of DSTATCOM,introduces the research status quo of compensation current detection algorithm for DSTATCOM,establishes the mathematical model of three-phase three-wire static synchronous compensator in detail based on the Kirchhoff's law and compares the indirect current control and direct current control.The adaptive algorithm calculates the reference source current and the PWM hysteresis loop comparator generates the pulse signals to realize the control of voltage source type inverter circuit.In addition,this paper also introduces the basic principle of DSTATCOM control model in three-phase circuit based on LMS adaptive algorithm.Then,we summarized the principle and drawbacks of current calculation method based on LMS algorithm,on the basis of the analysis,a variable step-size LMAT adaptive reference supply current calculation method is put forward.This method improves the convergence speed of the algorithm and reduces the steady-state error at the same time.When the load current is changed suddenly,the algorithm also has a strong tracking capability.In the simulation experiment,this algorithm has obvious advantages over the p-q algorithm,i_p-i_q algorithm and traditional LMAT algorithm in terms of compensation effect for three-phase unbalanced nonlinear loads.Finally,this paper proposes a reference supply current calculation method based on GMN algorithm,and establishes a DSTATCOM control model based on GMN algorithm.The GMN algorithm uses the convex combination of and l_p norm and l_q norm of the error as the cost function,which increases the convergence speed and reduces the steady-state error continuously.By building up the simulation model of three-phase three-wire DSTATCOM system in matlab/simulink environment,the experiment results verifies that no matter the three-phase load is symmetrical or not,no matter in steady state or dynamic state,the proposed control method in the paper has good function of harmonic elimination,power factor correction and common point voltage regulation.And the dynamic response of the system is very quick.