The ITER reactive power compensation and harmonic filtering (RPC & HF) system: Stability & performance

The ITER Pulse Power Electrical Network (PPEN) is capable of supplying 500 MW of pulse power and to compensate 750 Mvar of reactive power. In addition, the AC/DC conversion plant is always operated in dynamic conditions in terms of plasma control requirements. The AC/DC converter power supplies produce numerous harmonics, and with the large installed power compared to short circuit capacity and complex integration with the supply grid, results in stability of the power system and performance requirements becoming significant issues. Power flow simulations have been carried out to evaluate the performance requirements in terms of reactive power, voltage profile at the main busbars (400 kV, 66 kV and 22 kV), maximum steady state reactive power import at 400 kV; and performance during contingencies which may appear due to the nature of the nuclear fusion process, such as the occurrence of superconducting coil current quench, plasma disruption or during major transient disturbances of the power system, e.g. 400 kV single phase faults with fast re-closure, 66 kV single, two or three phase short circuits. Such events cannot be completely ignored and must not lead to dangerous harmonic voltages in the 66/22 kV system or to overload or damage to any RPC&HF component. The RPC&HF system must also withstand transient overvoltage or overcurrent caused by energisation of capacitor banks, load rejection and perturbation at the 400 kV/66 kV busbars. This paper focuses on the assessment of the ITER electrical network where three identical RPC&HF units of 250 Mvar at 66 kV are included in the plant, to support the voltage level and regulate the large dynamic pulse reactive power demand from the AC/DC converter power supplies, and to stabilise the internal and external electrical networks under normal and abnormal operational events whilst ensuring the proper and correct performance of the RPC&HF unit.