The impact of wind power plants on slow voltage variations in distribution networks

The connection of a wind power plant to a distribution network affects the voltage conditions in that part of the network. However, rather than assessing the worst possible cases regarding the voltage range, in this paper a more accurate methodology is presented for calculating the annual distribution network steady-state voltage profile and slow voltage variations after wind power plant connection. Commonly used simulation methods for the same problem based on probabilistic load flow analysis are only able to give probability distributions of the node voltages and network power flows. Here, a method is proposed which can also give chronological insight into the considered network state. This is realized through wind speed data modeling and generation using a Markov chain transition probability matrix and the Monte Carlo simulation method. The proposed methodology is tested using data from an existing distribution network in Croatia, a wind power plant planned for connection, and one year wind data measurements.