Analysis of wind farm temporary overvoltages in regards to surge arrester selection
Abstract
A wind farm consists of several individual wind turbines, interconnected into a single electrical network. The surge protection of the aforementioned wind farm system is represented by a set of metal oxide (MO) surge arresters. The analysis of expected temporary surges of the wind farm system is an integral and important part of the procedure for selecting the electrical parameters of the aforementioned MO surge arresters. Temporary surges are oscillatory surges that occur between phase and ground or phase and are caused by various causes, such as: ground faults, load failures and nonlinearities (ferroresonance). Knowledge of temporary surges that occur as a result of the aforementioned causes (especially their expected amplitudes and durations) is extremely important for the correct selection of the basic electrical parameters of MO surge arresters for protecting the wind farm system. It is particularly important to assess the most unfavorable temporary surges (and their parameters) that can realistically be expected in each specifically considered wind farm. This paper will present the basic theoretical foundations and mathematical expressions for determining the basic parameters (amplitude and duration) of some of the previously mentioned types of temporary overvoltages. The analyses performed will be accompanied by specific calculations on a typical example of a wind farm.
