Simplified Risk Assessment of DC Bias for Ultra-High-Voltage Direct-Current Transmission

At present, there are some technical difficulties in the risk assessment of DC bias in the power grid of the UHV project. A simplified assessment method for considering the risk of DC bias in the power grid of the UHV project is proposed in this paper. Firstly, a simple calculation method of earth surface potential is proposed based on the equivalent of point and source of DC grounding electrode surface based on the multi-layered earth model, and on this basis, a bias risk assessment method is proposed that only the power station/DC grounding electrode position and the system resistance network is needed to be provided. By using an calculation example, the calculation accuracy of the simple calculation method of earth surface potential is proved to meet the engineering application requirements, and by considering the DC bias risk assessment calculated-example of the Hebei South Network of the UHV project, the practicality of this method in the early warning and management of DC bias risk is proved.