Static series and shunt-series PE voltage-quality controllers

Abstract

As presented in the Chap. 7 static shunt power electronics (PE) voltage-quality controllers protect the utility electrical system from the unfavorable impact of customer loads. Shunt controllers, as shown in Chap. 6, are recommended mainly for mitigation of the causes of disturbances, and not their effects in distanced nodes of a power-electronics system. In the case when reduction of disturbances effects is required, which leads to protection of sensitive loads from the deterioration in the supply-side voltage, we should rather apply dual arrangements - static series voltage PE quality controllers. Such controllers, operating as a synchronous voltage source, are included in the feeder in series between the supply voltage and the load, which is illustrated in Fig. 8.1 [1]. Series voltage controllers through inserting a voltage uC of a required waveshape maintain the required quality in the load-side voltage uL in case of various disturbances in terminal voltage uT. The type and allowable value and duration of mitigated disturbances in voltage uT, they depend on arrangement of the series voltage controller, its control system and capacitance of possible additional energy storage. In a distribution system we must maintain the energy balance, in which the following are taken into account: disturbance duration and instantaneous active powers pT, pC, pL, absorbed from the power source, energy storage and by the load. This chapter mainly discusses the most important responses and characteristics of static series controllers, designed on the basis of distribution static synchronous series compensator (D-SSSC) and AC/AC voltage regulators (VR). In addition, we also shall outline selected static shunt-series controllers, preserving a sensitive load from deterioration of supply voltage and at the same time protecting an electrical system from load impact.