Electrical Loads and Power Systems for the DEMO Nuclear Fusion Project

Abstract

EU-DEMO is a European project, having the ambitious goal to be the first demonstrative power plant based on nuclear fusion. The electrical power that is expected to be produced is in the order of 700–800 MW, to be delivered via a connection to the European High Voltage electrical grid. The initiation and control of fusion processes, besides the problems related to the nuclear physics, need very complex electrical systems. Moreover, also the conversion of the output power is not trivial, especially because of the inherent discontinuity in the EU-DEMO operations. The present article concerns preliminary studies for the feasibility and realization of the nuclear fusion power plant EU-DEMO, with a special focus on the power electrical systems. In particular, the first stage of the study deals with the survey and analysis of the electrical loads, starting from the steady-state loads. Their impact is so relevant that could jeopardy the efficiency and the convenience of the plant itself. Afterwards, the loads are inserted into a preliminary internal distribution grid, sizing the main electrical components to carry out the power flow analysis, which is based on simulation models implemented in the DIgSILENT PowerFactory software.

Preliminary Design of the Electrical Power Systems for DTT Nuclear Fusion Plant

“…PowerFactory is a power system software for the analyses and simulations of generation, transmission, distribution and industrial electrical power systems, covering the full range of models and functionalities [24,25], from the traditional algorithms to real-time simulations. The same software was adopted for the preliminary design of the DEMO electrical power system [9,16]. In the present paper PowerFactory was used to implement the power flow method [26] and the fault analysis to verify the correct design of the main electrical components.…”

“…Tables [13][14][15][16] report the withstand values, grouped by categories, that shall be compared with the outcomes of the simulations to verify the correctness of the selected fault withstand ratings: rms value I k of the permanent short-circuit current for the duration t k of the event, its maximum allowable value I kmax and the peak short-circuit current. In particular, a maximum temperature of 250 • C was considered for the calculation of I kmax for the cables (insulated in EPR).…”

“…Nevertheless, the power systems are not trivial in terms of size and complexity, especially in terms of power density [12][13][14]. In fact, all the main types of loads present in ITER (and maybe in DEMO) will be implemented in DTT [12,15,16]: Converter for superconducting and copper coils [14], electron cyclotron resonance heating (ECRH) [17], ion cyclotron resonance heating (ICRH) [18], negative neutral beam injector (NBI) [19], cryogenic and water cooling systems and so on [10,16]. Therefore, DTT may also be a good reduced-scale experiment for the study and the optimization of the power systems for possible ITER upgrades and for DEMO.…”

“…As a part of the process to define the electrical supply system of DTT, the identification of the electrical loads is the first necessary step [16]. Since the loads have been characterized from a quantitative and a qualitative point of view, it is possible to proceed to the preliminary design and sizing of the internal distribution network.…”

“…To allow a smooth design process of the electrical distribution system, all electrical loads are characterized according to the above-mentioned criteria and categories and collected in an Electrical Load List (ELL), a database clustering the loads as functional macro-areas, in a Plant Breakdown Structures (PBS) [16].…”