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型聚乙烯的，因此存在两个主要问题。聚乙烯在相对较低的温度(~90℃至110℃)下熔融，因此使用交联剂来提高热机械稳定性。然而，这只会导致安全的最高工作温度为~95℃，同时使材料在电缆寿命结束时极难回收。这些因素限制了电缆电路的性能，一旦资产达到其使用寿命结束，就会产生问题。由于英国和全球中压(MV)和高压(HV)电力公用事业市场的不断增长，解决这些问题尤其及时。这一需求的驱动因素包括更换现有陈旧的暖通空调系统、为发达国家的可再生能源(尤其是高压直流输电)提供新的电力系统连接以及发展中国家的基础设施发展。在高压系统中，还需要在灵活的交流输电系统(FACTS)框架内在更高的峰值负载下运行电缆。这项建议将通过开发具有高温运行能力的新一代低损耗可回收材料、在电缆设计中评估其性能以及开发和应用终身评估工具来量化operational/economic/environmental/sustainability的好处，从而消除当前的性能和可回收性限制。其结果将是通过一种从根本上可回收的技术以及创造具有全球市场开发潜力的新材料来提高网络性能。这个问题将由一个财团解决，该财团包括一家主要的聚合物供应商、一家主要的公用事业公司、一家大学合作伙伴和一家中小企业研究提供商。该项目将由国家电网协调，并由Gnosys提供技术项目管理支持。材料开发将由南安普顿大学、GnoSys和陶氏化学联合进行。陶氏化学将提供材料和模型电缆，南安普敦将对它们进行电气/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有线电视案例研究。为实现项目目标，将采用以下方法。方案1A。首先将对替代材料技术进行详细审查，以确定新的高性能聚合物高压和中压电缆绝缘系统的最佳候选材料。方案1B。根据第一阶段的结果，将开发具有高电气强度、高热稳定性和良好柔韧性的热塑性聚合物混合物，使电缆绝缘能够在140至150摄氏度的限制下持续运行，即比目前的绝缘系统高50至60摄氏度。在制造过程中易于挤压和在使用寿命结束时易于再加工以便于回收是基本要求。然后将制造模型电缆，并从热机械稳定性、电缆灵活性、介质损耗、增强的电击穿和耐压性能以及加工简易性方面进行评估。方案2A。将使用新开发的LEETS方法和软件工具构建全寿命性能-经济-环境电缆模型，并对其进行适当修改，以确定以现有材料为基准的新一代材料的整体可持续性能和好处。该模型将为考虑到网络运行需要的几种电缆设计探索最佳解决方案。方案2B。然后，选定的候选材料将在中压和高压电缆设计中接受终身运行、经济和环境评估，并获得与LEETS工具相关的新电缆额定值和系统研究的信息。

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.