Sustainable Power Cable Materials Technologies with Improved Whole Life Performance

目前的挤出聚合物电缆材料技术是基于交联聚乙烯，因此，遭受两个主要问题。聚乙烯在相对较低的温度下（~90 ~ 110℃）熔化，因此采用交联来提高热机械稳定性。然而，这只导致安全的最高工作温度为~95℃，同时在电缆寿命结束时使材料极其难以回收。这些因素限制了电缆电路的性能，一旦资产达到使用寿命，就会产生问题。解决这些问题是特别及时的，由于日益增长的中压（MV）和高压（HV）电力公用事业市场在英国和世界各地。这一需求是由迫切需要取代现有的老旧HVAC系统，为发达国家的可再生能源（特别是HVDC）提供新的电力系统连接以及发展中国家的基础设施发展所驱动的。在高压系统中，还需要在灵活的交流输电系统（FACTS）框架内以更高的峰值负载运行电缆。该提案将通过开发具有高温操作能力的新一代低损耗可回收材料，评估其在电缆设计中的性能，并通过开发和应用全寿命评估工具来量化运营/经济/环境/可持续性效益，从而消除当前的性能和可回收性限制。其结果将是，通过一项从根本上可回收的技术，以及创造具有全球市场发展潜力的新材料，改善网络性能。这个问题将由一个财团来解决，这个财团包括一个主要的聚合物供应商、一个主要的公用事业公司、一个大学合作伙伴和一个中小企业研究提供商。该项目将由国家电网协调，由Gnosys提供技术项目管理支持。材料开发将由南安普顿大学、GnoSys和陶氏化学共同承担。陶氏将提供材料和电缆模型，南安普顿将对其进行电气/物理测试。Gnosys将提供额外的材料支持和全寿命评估工具，并与国家电网一起将其应用于电缆案例研究。为了达到项目目标，将采用以下方法。项目1。最初将对替代材料技术进行详细审查，以确定新型高性能聚合物高压和中压电缆绝缘系统的最佳候选材料。项目1 b。从第一阶段的结果来看，将开发出具有高电强度、高热稳定性和良好柔韧性的热塑性聚合物共混物，使电缆绝缘能够在140至150℃的极限下连续工作；也就是说，比目前的绝缘系统高50到60摄氏度。项目1 c。在制造过程中易于挤压，在使用寿命结束时易于再加工，以促进回收是基本要求。然后，将制作和评估模型电缆的热机械稳定性、电缆灵活性、介电损耗、增强的电气击穿和耐压性能以及易于加工。项目2。将使用新开发的LEETS方法和软件工具构建一个全寿命性能-经济-环境电缆模型，并对其进行适当修改，以确定总体可持续性性能和新一代材料对现有材料的基准效益。该模型将探索考虑到网络运行需求的几种电缆设计的最佳解决方案。项目2 b。然后，选定的候选材料将在中压和高压电缆设计中进行全寿命运行、经济和环境评估，并根据与LEETS工具相关的新电缆等级和系统研究提供信息。

Current extruded polymeric cable materials technologies are based on crosslinked polyethylene and, consequently, suffer from two major problems. Polyethylene melts at a relatively low temperature (~90 to 110C) and therefore crosslinking is employed to give improved thermomechanical stability. However, this only results in a safe maximum working temperature of ~95C, whilst rendering the material extremely difficult to recycle at the end of the cable's life. These factors limit cable circuit performance and create problems once the asset has reached the end of it's useful life. Addressing these problems is particularly timely due to the growing medium voltage (MV) and high voltage (HV) power utility markets in the UK and worldwide. This demand is driven by the imperitive to replace existing aged HVAC systems, to provide new power system connections to renewable generation sources in the developed world (particularly HVDC) and for infrastructure development in developing countries. In HV systems there is also a need to operate cables at higher peak loads within a flexiable AC transmission system (FACTS) framework.This proposal will remove current performance and recyclability limitations by developing a new generation of low-loss recyclable materials with high-temperature operational capabilities, evaluating their performance in cable designs and by developing and applying a whole-life assessment tool to quantify the operational/economic/environmental/sustainability benefits. The result will be improved network performance through a technology that is fundamentally recyclable as well as creating new materials that have global market development potential. The problem will be addressed by a consortium that includes a major polymer supplier, a major utility company, a University partner and a SME research provider. The project will be coordinated by National Grid with technical project management support supplied by Gnosys. Materials development will be jointly undertaken by Southampton University, GnoSys and Dow. Dow will supply materials and model cables and Southampton will undertake electrical/physical testing of them. Gnosys will provide additional materials support and the whole life assesment tool and, with National Grid, apply it to cable case studies. The following methodology will be adopted, in order to meet the project objectives. Programme 1A. A detailed review of alternative materials technologies will be initially undertaken to define best candidate materials for new high performance polymeric HV and MV cable insulation systems. Programme 1B. From the results of Phase 1, thermoplastic polymer blends with high electric strength, high thermal stabilty and good flexibility will be developed to enable the cable insulation to operate continuously at limits of 140 to 150C; that is, 50 to 60C higher than present insulation systems.Programme 1C. Ease of extrusion during manufacture and ease of reprocessing at end of life to facilitate recycling are essential requirements. Model cables will then be fabricated and assessed with respect to thermo-mechanical stability, cable flexibility, dielectric loss, enhanced electrical breakdown and voltage endurance behaviour, and ease of processing. Programme 2A. A whole life performance-economic-environmental cable model will be constructed using the newly developed LEETS methodology and software tool, appropriately modified to determine the overall sustainability performance and the benefits of the new generation materials benchmarked against existing materials. The model will explore optimum solutions for several cable designs taking into account network operational needs.Programme 2B. The selected candidate materials will then be subjected to whole-life operational, economic and environmental assessment within MV and HV cable designs informed by new cable rating and system studies linked to the LEETS tool.