With modern power utilities going green by utilising renewable energy technologies and the development of the smart power grid, high-voltage direct current (HVDC) technologies become more and more important in the energy transmission. In particular, HVDC cable systems play a prominent role in undersea power transmission and offshore renewable energy integration. As an essential part of a complete HVDC cable system, the cable termination is one of the most critical components. The mathematical and physical background of HVDC cable systems is discussed and the development of various types of HVDC cable terminations is reviewed. Regarding the non-uniform field distribution, the influence of temperature on the nonlinear conductivity is briefly discussed. Furthermore, faults of terminations caused by inappropriate installation and testing of cable systems are discussed.

Power system interconnections using high-voltage direct-current (HVDC) technologies between different areas can be an effective solution to enhance system efficiency and reliability. Particularly, the multi-terminal dc grids that could balance and ensure resource adequacy increase asset utilization and reduce costs. In this paper, the technical feasibility of building dc grids using the line-commutated converterbased (LCC) and voltage source converter-based (VSC) HVDC technologies is discussed. Apart from presenting the technical challenges of building LCC dc grids and LCC/VSC hybrid dc grids, the reliability modeling and analysis of these DC grids are also presented. First, the detailed reliability model of the modular multi-level converters (MMCs) with series-connected high-voltage and low-voltage bridges is developed. The active mode of redundancy design is considered for the reliability model. To this end, a comprehensive whole system reliability model of the studied systems is developed. The reliability model of each subsystem is modeled in detail. Various reliability indices are calculated using this whole system reliability model. The impacts of the redundancy design of the MMCs on these indices are presented. The studies of this paper provide useful guidance for dc grid design and reliability analysis. INDEX TERMS LCC-HVDC, VSC-HVDC, MMC, multi-terminal dc grid, reliability analysis, k-out-of-n.

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This article describes the main problems associated with, and potential strategies for, the design and manufacture of next-generation HVDC cable systems, with a focus on increasing power flows over long distances.

Nowadays, power utilities are adopting Asset Management as their framework in order to cope with the challenges introduced by the privatization and market competition in this sector. Stedin, a Dutch Distribution System Operator recognized the vital role that an Asset Management system has for its organization. Therefore, Stedin, has adopted the publicly available specification, BSI:PAS55, as a standard to perform the Asset Management responsibilities and tasks of their electricity and gas networks. Equipment life cycle and technical performance activities form an integral part of the implementation of an Asset Management system. In this context, Stedin felt the strong need to have access to systematic techniques and guidelines on how to deal with information of equipment lifetimes. In this paper a systematic method, based on Statistical Life Data Analysis, which deals with limited or incomplete life time data of large populations of assets with the aim of obtaining an indicator of the future failure expectancy is discussed. The methods and analytical tools developed in this contribution share a basic framework for decision-making and specify the evolution of the failures of asset population over time.