The Research On Radio Interference Prediction Of The HVDC-flexible Converter Station Based On MMC

In the background of a Shanghai HVDC-flexible project, This paper utilizes the method of simulation to predict the RI(radio interference) level of HVDC-flexible converter station. At the same time, backed by the existing project, this paper has finished much mesurment work about the elctromagnetic environment during its steady-state operation, so as to provide a reference for the simulation predicted.First, having analyzed the topology of Modular Multi-level Converter(MMC) and its operation mechanism, it builds the MMC’s FEKO electromagnetic radiation model based on the model of Hertz dipole. Then, it makes use of the PSCAD simulation to obtain all of the needed voltage and current waves, and gets the simulation resistor parameters through the method of Fast Fourier Transform (FFT).At last, it chooses the typical turn-on and turn-off voltage waves of IGBTs as the simulation excitation and analyzes the characteristics of the RI of HVDC-flexible qualitatively during its operation. The results showed that:as the frequency increases, the converter station RI produced decreases in value, and the directivity gradually increased, the lateral side valve’ E-field strength is higher than the longitudinal side valve and the maximum value is75.10dBμV/m which is within the limits.In addition to simulation, this paper makes use of electromagnetic measuring instruments to measure the near field of low frequency electric and magnetic fields, as well as the electromagnetic spatial fields during the converter station’s HVDC state, refering to the relevant national and international standards. As we know from the measurement results that the peaks value of the low-frequency and magnetic field of converter station is at the frequency50Hz, the electric field is about490V/m, at the same time, the valve hall at each frequency point are significantly higher than other places, with frequency increased, the amplitude of the electric field strength decreases. Overall, the peak electric field strength of each frequency electromagnetic fields of the two converter stations are at the exposure within the prescribed limits of ICNIRP.The trend of the simulation results is coincided with the measurments after being compared. It has reference value for the electromagnetic compatibility design and electromagnetic interference protection of the HVDC-flexible valve.