A Voltage Full-Waveform Reconstruction Method Based on Radiative Near-Field of Electric Field for the Hybrid DC Breaker of MMC-HVDC

The conventional current or voltage signal-based condition monitoring systems for DC high-voltage equipment have the disadvantages of huge volume, inconvenient operation, and low measurement bandwidth and sampling rate. To overcome these drawbacks, a simplified calculational model of the radiative near-field of the electric field in the circuit breaker valve hall is proposed. This model is based on the analytical model of the finite-length current-carrying linear ideal conductor and reveals the physical mechanism of non-invasive situational awareness based on the transient electric field of electrical devices. Predicated on this model, a reconstruction method for calculating the port transient voltage of the hybrid DC breaker is then established and verified by an artificial short-circuit test in an actual ±200 kV MMC-HVDC system. To the best of the author's knowledge, this is the first pilot short-circuit test in a full-scale MMC-HVDC system involving the hybrid DC breaker. Based on the testing data, the reconstructed and measured voltage show a relatively high degree of consistency both in time and frequency domain. The reconstructed voltage signals based on the radiation near-field not only expose the action time sequence of various electrical equipment with the response time of micro-second order, but also disclose the operation of the key devices and fault types for situational awareness in power system.