DC High Current Test Cricuit
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The increasing share of decentralised electrical power generation in combination with an increasing number of DC loads leads to an ever-growing interest and demand for medium voltage direct current (MVDC) applications. In order to ensure safe grid operation in future meshed DC systems, reliable and powerful MVDC switchgear and equipment are required. For the development and investigation of these components, the behaviour in the event of a short circuit must be taken into account. To simulate the corresponding stresses and fault currents in future MVDC systems, a DC high-power test facility is available at IAEW.
The DC high-power test facility is divided into two test circuits. The simulation of high impulse currents is carried out by means of a modularised innovative high-power test circuit based on a power electronic buck converter. For this purpose, precharged capacitances are discharged by means of power electronic switching elements via a control inductance according to the freely definable control specification. It is thus possible to reproduce almost any unipolar current shapes, such as mathematical functions or current shapes from fault simulations or field measurements. The maximum possible characteristics of the impulse current test circuit are as follows:
- Maximum short-circuit current: Ik = 30 kA
- Duration of the maximum short-circuit current: TIk = 150 ms
- Current slope: di/dt > 8 A/µs
- Maximum charging voltage of the energy storage device: UCharge = 8 kV
- Maximum charging energy: ECharge = 1.92 MJ
The DC high-power test facility is complemented by a continuous current test bench. Here it is possible to condition test objects and to carry out continuous current tests on test objects. The characteristics of the high-current source are as follows:
- Maximum continuous current: IDC = 5 kADC
- Maximum output voltage: UDC = 24 VDC
- Rated continuous power: PDC = 120 kW
Thus, it is possible to develop and realistically test equipment such as DC circuit breakers, DC contactors, measurement technology, components of converters, fault current-limiting equipment and other components of DC technology in the laboratory.