Factors Determining the Effectiveness of a Wind Turbine Generator Lightning Protection System

Abstract

As a result of the growing supply and demand for wind power, wind turbine generators are increasingly being installed at sub-optimal sites that have high soil resistivity and high incidence of lightning strikes. This means that lightning protection systems for wind turbines are becoming a critical component of wind farm design. Not only do effective lightning protection systems ensure the safety of the physical wind turbine structure and human operators, they also protect the electrical and control systems installed inside wind turbine generators and safeguard the lives of human operators. This work presents a framework to assess the effectiveness of wind turbine lightning protection systems at the wind farm design phase. Performing the analysis at this early stage reduces lightning-induced downtime, which leads to increased energy yield. Our results show that the grounding system plays a critical role in the wind turbine lightning protection system. For this reason we also analyse various influential parameters of a grounding system design. We present results from full-wave electromagnetic simulations of the complete wind turbine grounding system, including the foundation.

Lightning Overvoltage Protection of Step-Up Transformer Inside a Nacelle of Onshore New-Generation Wind Turbines

“…The main focus of previous research has been the lightning response of the WT as a structure [5][6][7][8][9], or its grounding system in particular [10][11][12]; the associated overvoltage stresses of some of its electrical components in connection with the study of the backsurge phenomenon, such as the signal cables [13]; and low-voltage equipment inside a switchgear cubicle at the base of the tower [14]. Previous research also considered lightning overvoltage stresses of the step-up transformer installed at the base of the WT tower or in a separate nearby structure [15].…”

“…(2) WT internal design details are often considered proprietary and undisclosed; (3) WT reinforced-concrete foundations serve as a large-volume concentrated grounding system, in addition to any extended grounding [12], which requires sophisticated models; (4) capacitances (to the ground and between windings) of the dry-type step-up transformer is often undisclosed and difficult to obtain; (5) down-conductors and bearings short-circuit connections, as well as other lightning protection system (LPS) design details, are often considered proprietary information [20]; and (6) medium-voltage cables are installed vertically inside the tower, which makes all existing wide-band cable models inapplicable [14]. Some of these issues have been resolved satisfactorily [12,14,20,21]; whenever this is the case, these solutions were incorporated (with improvements and/or adjustments) into the proposed WT model for the fast-front transient analysis, which will be developed using the EMTP-RV software package [22]. The proposed WT model features original contributions in the domain of modeling the tower, vertical single-core cables, and grounding system.…”

Investigation of Novel DC Wind Farm Layout During Continuous Operation and Lightning Strikes

“…Grounding system is crucial to effectively protect WT physical structure, nacelle switchgear and control cabinets against transient overvoltages via providing a low impedance path (below 10 Ω at low frequencies) into earth for surge currents [11], [12]. However, due to growing demand on wind energy, WFs may be sited at suboptimal territories having high soil resistivity that raises serious concerns about the grounding system efficacy [13], [14]. Poor grounding system (i.e., high grounding impedance) causes serious ground potential rise (GPR), and subsequently detrimental electrical stresses on power system apparatus and humans [?].…”

Bulletin of the Polish Academy of Sciences: Technical Sciences

“…A high factor of a power outage due to lightning has also been reported in some countries [1]. Despite recent progress in the area of overvoltage protection, current statistical data that has been used around the world show that lightning activity remains the dominant factor affecting the overhead failure rate [2][3][4][5][6]. Analyzing the basic causes of failures in power networks based on the data presented in Fig.…”

“…The failure rate of the other elements is about the same. The analyses can be divided into several categories: theoretical studies based on simplified analytical formulas [3,5,9,10], computer simulations based on the finite element method [11][12][13][14]. The results of the analysis of some models indicate that the impact on the level of overvoltages has wire location and grounding parameters [15][16][17].…”