Shunt reactive compensation of voltage dips and unbalance

[摘要] ENGLISH ABSTRACT: The use of power electronic converters provides a more efficient, accurate anddynamic solution to reactive compensation. In this thesis the application of powerelectronic converters to shunt reactive compensation will be discussed. In particularvoltage dips and voltage unbalance are considered as both can be mitigated bymeans of shunt reactive compensation.A pre-existing uninterruptible power supply is adapted to operate as a shunt reactivecompensator. The uninterruptible power supply consists of a 250 kVA three phasevoltage source inverter. The modifications are limited to software and controlalgorithms that do not alter the normal operation of the uninterruptible power supply.Control algorithms are designed and discussed in detail. A typical double loopcontrol strategy is implemented on the power electronic converter. The inner loopconsists of a dead-beat current controller. The outer loop consists of threeproportional and integral controllers controlling the DC-bus voltage, AC voltage andvoltage unbalance respectively.Voltage dips and unbalance are compensated for using only reactive power. Focusis placed on producing a result can be used easily in practice.

[发布机构] Stellenbosch University