Optimising the Rating of the UPQC for Applying to the Fault Ride Through Enhancement of Wind Generation

The unified power quality conditioner (UPQC) is a combination of a shunt and a series compensator cascaded via a DC link capacitor which works on the combined principle of active filtering and dynamic voltage restoration. Therefore, the UPQC can be a potential solution to the grid integration problems associated with fixed speed wind generators including reactive power compensation and fault ride through capability. The hardware design of the UPQC can be made more cost effective by proper selection of the rating of the individual compensators of the UPQC. It is shown in the paper that the application of a fixed capacitor can lower the cost of the UPQC further, without compromising the performance. The fixed capacitor shares the reactive power load with the shunt compensator and the overall rating of the UPQC is reduced. The proposed scheme also helps in reducing the power loss occurring in the power electronic switches as current conduction of the switches is reduced. Simulation results are provided in the paper to support the theory.