Cost-effective Valve Test Circuit for MMC Based HVDC Power Station

This paper proposes a new valve performance test circuit for MMC based HVDC power station. It is necessary for the valve test circuit to satisfy the standard in IEC-62501. The standard requires the valve current resembles the actual arm current of the HVDC system in operation. The arm current contains fundamental ac component, the second harmonic component, and dc component. Conventional valve test circuits provide only fundamental ac component, therefore, they are not suitable for the valve test with actual arm current. Furthermore, the voltage magnitude of the power source for the valve test should be equal to the total sum of the submodule voltages consisting the valve. The proposed test circuit provides not only fundamental ac component but also the second harmonic and dc components, and the voltage magnitude of the power source is considerably reduced compared to that of the conventional methods. Simulation and experimental results show the usefulness of the proposed scheme.