STRUCTURAL LIFE-CYCLE ENHANCEMENT OF NEXT-GENERATION ONSHORE AND OFFSHORE WIND FARMS

这项拟议的研究旨在开发一种创新的缓解装置，以保护下一代陆上和海上风电场免受极端自然事件造成的动态负载的影响。2020年，英国20%的电力来自使用陆上和海上风电场的风能。为了增加这一比例，并帮助英国实现其气候变化目标，计划建设新的风力发电场，配备更高、更大的风力涡轮机，并位于更极端的地点。增长预测还表明，正在向新兴市场扩张，并在发展中国家建设新的风力发电场。因此，这些下一代风力涡轮机将不得不应对由更强的风暴和更高的海浪以及地震和海啸等极端事件引发的更恶劣的气候条件。用于前几代风力涡轮机设计的几个简化假设不再适用，与发电效率和结构安全相关的新的关键因素和不确定因素将出现，影响其弹性和生命周期。这项研究的重点是传统的风力机过渡件，它是连接塔架和基础的结构元件，在极端自然事件中必须承受动态载荷引起的极端应力。其目的是用一种称为沙漏格子结构(HLS)的沙漏形状的新型机械接头来取代传统的连接器。这项创新将结合两项在地震工程中非常有效的成熟技术的独特特点，即“减少梁截面”方法和“摇动基础”设计。特别是，拟议的HLS装置，由于其沙漏形状，将促进摇动行为，以创建将保护风塔和基础的高度耗散的“保险丝”。将通过分析、数值和实验调查来评估拟议的新型装置在结构生命周期风险方面的性能，使用水平能量成本(LCOE)作为效率的量度，即基于项目生命周期内摊销资本成本的单位能量成本。此外，海上小型风力涡轮机的实验测试将通过创新的试验台进行，这是有史以来第一个安装在水力水槽中的水下振动台，它将被部署、校准，并用于模拟最近发现的被称为“风暴”的多种危险情景。这个及时的项目的成功结果将使下一代风力涡轮机具有更强的弹性和成本效益，从而使风能能够发展成为一种具有竞争力的可再生能源，而不需要政府补贴。将工业伙伴纳入项目的所有阶段，确保将技术发展纳入商业设备，产生中长期影响。

The proposed research aims to develop an innovative mitigation device to protect the next-generation onshore and offshore wind farms from dynamic loading caused by extreme natural events.In 2020, 20% of the UK's electricity was obtained from wind using both onshore and offshore windfarms. In order to increase this percentage and help the UK address its climate change target, new wind farms, with taller and larger wind turbines, and situated in more extreme locations are planned. Projections of growth also indicate the expansion into emerging markets and construction of new wind farms in developing countries. Therefore, these next-generation wind turbines will have to cope with harsher climate conditions induced by stronger storms and taller sea waves, and extreme events such as earthquakes and tsunamis. Several simplifying assumptions used for the design of previous generations of wind turbines can no longer be applied and new critical factors and uncertainties linked to power-generation efficiency and structural safety will emerge, affecting their resilience and life-cycle. The particular area of focus of this research is the traditional transition piece of a wind turbine, which is a structural element that connects the tower with its foundation and will have to tolerate extreme stresses induced by dynamic loading during extreme natural events. The aim is to replace the traditional connector with a novel mechanical joint of hourglass shape, termed an Hourglass Lattice Structure (HLS). This innovation will combine the unique features of two proven technologies extremely effective in seismic engineering, namely the "reduced beam section" approach and the "rocking foundation" design. In particular, the proposed HLS device, because of its hourglass shape, will facilitate the rocking behaviour in order to create a highly dissipating "fuse" which will protect the wind tower and foundation.Performance of the novel proposed device on the structural life-cycle risk will be assessed through analytical, numerical, and experimental investigation by using, as a measure of efficiency, the levelized cost of energy (LCOE), namely the cost per unit of energy based on amortized capital cost over the project life.In addition, experimental testing of offshore small-scale wind turbines will be carried out by means of an innovative test rig, the first-ever underwater shake-table hosted in a hydraulic flume that will be deployed, calibrated, and used to simulate multi-hazard scenarios such as those recently discovered and dubbed "stormquakes".The successful outcome of this timely project will allow next-generation wind turbines to be more resilient and cost effective so that wind energy can develop as a competitive renewable energy resource with less need for government subsidy. The inclusion of industrial partners in all stages of the project ensures that the technical developments will be included in commercial devices for a medium-long term impact.