Photovoltaic reactive power compensation scheme: An investigation for the Cyprus distribution grid

Voltage deviation resulting from the power generation of distributed Renewable Energy Sources (RES) can be a serious problem especially as the penetration of RES is increased in the distribution grids. For example, residential photovoltaic (PV) systems can raise the voltage of the low voltage distribution feeder due to reverse power flow. Especially at the peak PV power production, the network voltage might even deviate from the upper voltage limit as defined by the grid regulations, causing cascading problems to neighboring consumers and to the grid. This paper investigates the residential PV reactive power (Q) compensation scheme adopted in Cyprus by the local authorities in order to restrict the voltage from deviating over the maximum allowable 10% limit. This paper performs a simulation-based investigation regarding the effectiveness of the existing regulations of the Electricity Authority of Cyprus (EAC). The investigation is enabled by applying the Q-compensation scheme on several PVs installed in a typical low voltage distribution feeder. The current EAC grid regulations are fixed for all PV systems irrespective of the PV system size and the distance/location from the secondary distribution transformer. Modified compensation schemes consisting of shifting forward or reverse the Q-compensation characteristic line are also investigated in this paper. The results of this case study show an improvement to the grid voltage by providing necessary compensation based on their distance from the substation.