Design and Analysis of Three Phase UPQC for Power Quality Improvement of Solar Connected Utility System

Grid is always prone to various contingencies like faults, loss/failure of transmission line, feeder, generator etc. All these events result in deviations in rated voltage which results in loss of stability of the system. Power quality conditioners are installed at various locations in power system to retain the stability of the system under the conditions of contingencies. This paper presents the two-converter based conditioner design for three phase system commonly known as Unified Power Quality Conditioners (UPQC) to mitigate the voltage as well as current related issues at source side as well as load side. The converters are designed using series and shunt topology of voltage source inverter which are coupled at DC side. The DC coupling is done via linking capacitors to maintain the DC bus voltage of the UPQC. The capacitors are charged through solar power which also supplies the load of the grid in the range of its rated power. Else power is drawn from the grid. The voltage sag and swell events are created at source side and the load profile is analysed to validate the performance of the designed UPQC. UPQC successfully mitigates the PQ issues both at load side as well as source side and maintains the harmonics within the acceptable range of grid code. At the point of voltage sag/swell, THD of source voltage is between 5–6 %, which has been reduced to 0.3 % through UPQC.