This paper deals with the modelling, hardware results and model validation by measurements of a VSC assisted resonant current (VARC) dc circuit breaker (CB) and the application within a future network by simulation. The newly emerging VARC dc CB can be used as a solution for the protection of offshore multi-terminal HVDC (MTDC) grids. In this paper, the proposed VARC dc CB is modelled in detail in a PSCAD environment, by taking into account dielectric strength of the vacuum gap, high-frequency current quenching ability and parasitic components. The PSCAD-model is then verified by data from the testing of a 27 kV VARC dc CB prototype with maximum current interruption capability of 10 kA. Additionally, the initial transient interruption voltage and current slope at zero-crossing during the interruption are analyzed. With respect to scaling to a higher voltage level, three types of series connected modules are presented and the performances are compared. The performance of the series connected modules is simulated in a model of a 4-terminal HVDC grid. The obtained results validate the VARC dc CB as a promising solution for the dc fault isolation in MTDC grids. Index Terms-HVDC circuit breaker, VARC, PSCAD, circuit breaker performance, HVDC grid, transient analysis. I. INTRODUCTION HE integration of sustainable and renewable technologies is changing the existing transmission system [1]. Significant progress has been made toward the development of Voltage Source Converters (VSCs) in the last few years, which enable meshed HVDC grid to provide a promising This work has received funding from the European Commission under project 691714-PROMOTioN (Progress on Meshed HVDC Offshore Transmission Networks) through Horizon 2020 program."

This paper presents the VSC assisted resonant current (VARC) direct current circuit-breaker concept, which comprises a vacuum interrupter, operated by an ultra-fast actuator, together with a power electronic converter that creates a zero-crossing in the arc current. A few main circuit topologies are shown and discussed and a dynamic model of the DC link voltage in the VSC is presented. A module rated for 10 kA against 40 kV transient interruption voltage has been built and tested at an independent test laboratory, and some test results are presented.

The European Union's 2020 target aims to be producing 20 % of its energy from renewable sources by 2020, to achieve a 20 % reduction in greenhouse gas emissions and a 20 % improvement in energy efficiency compared to 1990 levels. To reach these goals, the energy consumption has to decrease which results in reduction of the emissions. The transport sector is the second largest energy consumer in the EU, responsible for 25 % of the emissions of greenhouse gases caused by the low efficiency (<40 %) of combustion engines. Much work has been done to improve that efficiency but there is still a large amount of fuel energy that converts to heat and escapes to the ambient atmosphere through the exhaust system. Taking advantage of thermoelectricity, the heat can be recovered, improving the fuel economy. A thermoelectric generator (TEG) consists of a number of thermoelectric elements, which advantageously can be built into modules, arranged thermally and electrically, in a way such that the highest possible thermal power can be converted into electrical power. In a unique waste heat recovery (WHR) project, five international companies and research institutes cooperated and equipped a fully drivable Scania prototype truck with two TEGs. The entire system, from the heat transfer in the exchangers to the electrical power system, was simulated, built and evaluated. The primary experimental results showed that approximately 1 kW electrical power could be generated from the heat energy. In this paper the entire system from design to experimental results is presented.

No abstract

No abstract