Research On Compensation Strategy Of Series Power Quality Compound Regulator

With the growing of power quality problems, the demand of voltage quality in power supply system is becoming higher. So the equipments that can compensate the disturbances in power system have been developed. Series power quality compound regulator (SPQCR) is such a kind of equipment which could ensure the voltage quality of users by regulating all the voltage disturbances in power supply system.The compensation objective of SPQCR is flexible. The compensation strategies have been analysis in details to ensure the loads'voltage quality as much as possible in equipment's ability. (1)The optimal compensation objectives of in-phase compensation, pre-sag compensation and minimum energy compensation have been got. And the coordinate strategy of "three lines of defence" on them has been proposed which can ensure the loads'voltage quality in diffrent system and equipemt's situations. (2) The new idea of therotical analysis on compensation strategies'characteristics has been proposed. The influence factors and the characteristic curves on each compensation strateies' optimal objectives have been got which can be used as the basis of compensation strategies'choice and parameters'design. (3) The response schemes of three-phase four-line system and three-phase three-line system compensation strategy in the equipment's voltage limitation have been proposed. The power system situations and load's voltage demands have been considered. So the schemes can satify both symmetrical and unsymmetical loads. (4) The geometry method has been proposed to solve the coupling problems when compensating the line-voltage in three-phase three-line system by the equipemnt's phase compensation voltage. The decoupling method can avoid the complication of symmetrical component method and the equipment's export voltage can be as same as possible. (5) A stages compensation strategy has been proposed to the series compensation equipments which supplied by DC-capacitor. The strategy has three stages-steady operation stage, overrun operation stage and recovery operation stage. The pre-sag voltage compensation, minimum energy compensation and maximum energy compensation strategies are adopted to the three stages respectively. The load-side voltage quality can be ensured accurately in the steady operation stage, the compensation time can be prolonged by minimizing the active power exchange in the overrun operation stage and the DC-capacitor voltage could be recovered to the permission value as soon as possible in the recovery operation stage. The simulation and experiment outcomes of closed loop experiments with real time digitial simulation (RTDS) and physical controller show the feasibility and efficiency of the proposed compensation strategies.A power quality comprehensive evaluation method based on the disaster level has been proposed to evaluate the efficiency of SPQCR. The evaluation method based on the concepts of power quality event and power quality disaster level which uses the times of power quality events and its economic losses to get the disaster level of power quality. The evaluation results can reflect the power utility and users'real losses. The efficiency and decision support of SPQCR design can be got in the way of investigating the disaster level by changing the frequency of power quality events. And the evaluation method can be used in the other power quality compound regulators'design too.