Anvendelse og kontrol af CUPS i distributionsnettet / Employment and Control of CUPS

During the period work has been done with different control strategies to a DVR to achieve minimum use of active power. Good results to achieve balanced sinusoidal voltages from unbalanced and disturbed voltages are achieved. The most used control strategy in this part of the local compensation project is the "p-q-r-theory", which is a control method developed during the project. This method is based on a separation of the active and reactive power where the reactive again is split up so one can see if the reactive power is due to purely inductive or capacitive loads or it is generated by disturbances and unbalance in the signals. The method can also be used to determine the voltage quality. The new control method is compared with another control method "d-q-control strategy" (developed in the project Design and Control of power converters for CUPS) on a model of the network grid around Farsø, where a DVR is inserted different places in the network grid to evaluate the effect of such a device to protect a sensitive load (hospital). Different simulations with two- and three phase faults on the 60 kV network are made with and without windmills connected to the 20 kV network grid. Further, the transient arising when connecting and disconnecting the windmills are analysed. From the simulations it is concluded that the two control methods behave nearly identical, and that the DVR are able to restore the voltage drops arising from the faults. The project is finished August 2001. (Hoysung Kim, Birgitte Bak-Jensen, Frede Blåbjerg, Hans Nielsen, John K. Pedersen; Peter W. Christensen, Allan Norsk Jensen, Jesper Bak-Jensen, Leif Juul Jørgensen, Bent Cramer, Elfor)