A Review of Current Issues in State-of-Art of Wind Farm Overvoltage Protection

Abstract

This paper elaborates on several important outstanding issues in the state-of-art of overvoltage protection selection for modern wind farms. The lack of experience with this still-new technology, together with the inherent complexity of wind farm electrical systems, entails several unresolved issues pertinent to the topic of overvoltage protection, particularly in relation to lightning-initiated surges. Firstly, several aspects of the wind turbine lightning incidence, along with the issues related to the selection of lightning current parameters (pertinent to the wind farm overvoltage protection), are addressed in this paper. Secondly, several issues in the state-of-art models of the wind farm electrical systems-for the lightning surge analysis-are addressed and discussed. Here, a well-known ElectroMagnetic Transients Program (EMTP) software package is often employed, with all of its benefits and some limitations. Thirdly, the metal-oxide surge arrester energy capability and the issues related to the selection of the surge arrester rated energy-in relation to the direct lightning strikes to wind turbines-is addressed. Finally, some general considerations concerning the overvoltage protection selection for wind farm projects, particularly regarding the installation of the metal-oxide surge arresters, are provided as well.

Assessment of lightning current parameters suitable for wind turbine overvoltage protection analysis

“…27 In the course of the numerical analysis, one needs to mathematically represent lightning current at the attachment point of the WT. 8,28,29 This mathematical representation is often implemented through the Norton equivalent current source, i.e., an ideal current source in parallel with a resistance, which in turn has a value equal to the surge impedance of the lightning channel. 11,28,30 Mathematical representation of the ideal current source is obtained from the functional description, given by an analytical expression.…”

“…27 Finally, it should be accentuated that a selection of the current source representation (with exactly the same current parameters, i.e., amplitude and front duration) could have a profound impact onto the obtained numerical results, i.e., computed overvoltages on the associated equipment. 29,34 Hence, care should be exercised in the process of the selection of mathematical model for the lightning current representation, notwithstanding the selection of the lightning current parameters.…”

Analysis of Transient Phenomena Due to a Direct Lightning Strike on a Wind Energy System

“…As wind power generation undergoes rapid growth, lightning damages involving wind turbines have come to be regarded with more attention. The incidence of lightning strokes is a very serious problem, as it can produce dangerous overvoltages [3]. Hence, lightning studies are of major importance.…”

Differential Protection for an Outgoing Transformer of Large-Scale Doubly Fed Induction Generator-Based Wind Farms

“…Similarly, the amplitude of fundamental wave can be calculated in the same way. Therefore, we can get K according to Equation (19).…”

“…Sarajcev and Goic [19] performed a survey on several important issues, particularly focuses on lightning-initiated surges, for the selection of modern wind farms' over-voltage protection. To prevent maloperation, the setting points of different zones of distance relays change simultaneously with the variation of the wind farm's condition.…”