Control of Q/U for connecting remote farms of wind power plants in 110 kV networks

In many cases, renewable energy sources are built in locations where the distribution system has not sufficient capacity for connecting their power output into the network. Relatively long MV cable routes – even 15 to 20 km long – with a corresponding capacitive reactive power are being built for the connection of these sources to the distribution system at a suitable point of connection. Distribution system operators require from the manufacturer, in the whole range of output power, to maintain a neutral power factor at the point of common coupling (PCC) and/or, in the case of sources with higher power, their integration into the voltage regulation system. For fulfillment of these conditions, a regulator of the reactive power flow must be included into the connection of the wind park into the network. INTRODUCTION The Rules of distribution network operation, Amendment 4 [1] chapter 9, define the requirements for reactive power control. This paper describes possible solutions of Q control in the point of common coupling (PCC) suggested for a specific application of a wind power-plant, connected to the middle voltage network by means of a long cable route. The capacity of a long cable influences the voltage conditions and should be compensated either using the generator control or, in case the generator produces minimal power, by means of decompensation coil. WIND FARM AND CONDITIONS IN PCC Wind farm description The suggested solution of U/Q control is proposed for a wind power farm with total power of 16 MW. It consists of eight 2 MW generators produced by VESTAS. The main parameters of this generator are summarised in the following Table 1. Regulation characteristics of generator and available reactive power in all regimes of operation are illustrated in Figure 1.