Study On T-S Fuzzy Modeling And Control For Active Power Filter

Active Power Filter (APF) is an important means for restraining power harmonics and then improving the quality of power system. With modeling the shunt APF in T-S fuzzy control and researching on the control strategy of APF, the feasibility and application of these kinds of method were analyzed. While the reference current detection way and current tracking control means were discussed, a control strategy for minimizing the capacity of APF was put forwards.As an important branch of the fuzzy control theory, T-S fuzzy control can be used for modeling the nonlinear systems and managing those nonlinear systems conveniently. The shunt APF were analyzed and then modeled by means of this T-S fuzzy control, the fuzzy controller were designed, simulation and experimentation were carried through that the method were feasible for APF reference current measurement and nonlinear control. Analyzing the single-phase shunt APF and modeling with T-S fuzzy control, setting the error of DC-link and its integral as its antecedents, considering three cost logic to setup control rules, basing on the parallel distributed compensation and linear matrix inequality to obtain state feedback coefficient matrix for the fuzzy controller. Analyzing the three-phase-three-wire shunt APF and modeling with T-S fuzzy control, in order to depress the complexity of system control, two antecedents combined in the error of DC-link and its integral were set, which consider double cost logic to setup control rules, and then the fuzzy controller designed. In the condition of power source distortion, T-S fuzzy H control was presented to the three-phase-three-wire shunt APF, under the stabilization of system, the corresponding H controller was designed which provides one kind of solution for APF control in the descending power quality that increasing the proportion of new energy. In allusion to split capacitor midpoint three-phase-four-wire APF, the two routes of DC-link errors and their integral were set as antecedents, and the corresponding T-S fuzzy controller was designed. Reference currents were detected and the problem of balancing the splited voltage was also solved. After establishing the dynamic equation of four-arms three-phase-four-wire APF, T-S fuzzy controller was constituted under stabilization pledged, the compensated currents were attained and the puzzle of multi-variable coupling strongly of nonlinear control to the APF was also raveled out. The nonlinear currents and the imbalance currents of the nonlinear load were compensated too.Several kinds of reference currents detection methods were discussed, those applicability were indicated under condition of power source normal or distorted. A novel currents detection method by means of RBF dynamical model forecast control was put forward, which can obtain the reference currents. A kind of reference currents detection method which can automatically do compensation even power voltage distorted or imbalance by means of T-S fuzzy feedback control was mentioned. The currents tracking control techniques such as hysteresis control, delta modulation PWM control, space vector PWM control were argued. Double hysteresis SVPWM currents tracking was indicated that has better precision and rapidly response may achieve better compensation preferment.The compensation goal of APF is indicated that main of eliminating the harmonics then of compensating the reactive power. While analyzing the control strategy of APF, a novel control strategy of reducing the APF capacity was brought forward. An improvement of generating the voltage fundamental positive-sequence was taken into use for obtaining the reference currents except fundamental positive-sequence active power and reactive power, which offering a way to make the APF capacity miniaturization in reforming the traditional reactive power compensation of power delivery systems.Simulations and experimental results indicate the correctness of the theories above and the validities of the T-S fuzzy control strategy described.