3D calculation method of ion flow field is required for the crossing issue of high-voltage direct-current (HVDC) transmission lines. Appropriate computational regions and boundary conditions are critical to the calculation. In this paper, a novel method combining charge simulation method-flux tracing method (CSM-FTM) and finite element method (FEM) is proposed to optimize the ion flow field calculation. The advantage of CSM-FTM in dealing with opening domain is fully utilized. Quadratic charges are applied in CSM to assure the calculation accuracy of space-charge-free electric field. In addition, a hemisphere calculation region is adopted in order to model the HVDC lines with arbitrary cross angle. The Dirichlet boundary condition on the spherical surface in FEM calculation is obtained based on FTM. Finally, the electric field of ±800kV and ±500kV lines at a cross angle of 60° is analyzed as an example. By utilizing the proposed method, the calculation area is substantially reduced and the calculation accuracy is significantly improved.

In this study, the corona‐induced vibration and audible noise (AN) on stranded conductor from positive and negative corona discharges were measured and analysed. The experiments were conducted in a semi‐anechoic chamber to reduce the inferences from environment. For the measurement of vibration, the conductor was kept in dry condition without water drops on the conductor, which is different from previous investigations and can reveal the contributions of corona‐generated space charges on the corona‐induced vibration. Besides, the measurement of vibration on the conductor was performed by using a laser vibrometer which was a non‐contact measurement device for measuring the vibration velocity. Furthermore, waveforms of corona‐induced vibration and AN were measured simultaneously to analyse the correlation between them. The time and frequency domains characteristics of the vibration velocity and AN from negative and positive corona discharge are carefully analysed and no correlated relationship in time and frequency domains can be found in the two corona effects. It can be concluded that disturbance of air molecules caused by the vibration of conductor does not contribute the corona‐generated AN.

The existence of residential houses will distort the ion flow field under high-voltage direct current transmission lines. High efficiency electric field computational method is required during the engineering design. In this paper, the surface charge method is applied in the space-charge-free electric field computation, and a half-analytical integration strategy is presented to accelerate the computational speed. Then, ion flow field around the house is computed based on Deutsch assumption. The calculation methods are validated by the experiment in the laboratory. Electric field intensity around the top edge of steeple rooftop is larger than other areas, and the field distribution characteristics on the steeple rooftop are significantly different from flat rooftop.

Distributed power supplies have gradually become a new trend in power supply development, but access to a large number of distributed energy sources has a certain impact on the stable operation of the power grid. A virtual power plant (VPP) can integrate a variety of distributed power sources for coordination and optimization; thus, it can effectively solve the difficulties faced by a distributed energy grid connection and promote the complementarity of energy sources. However, renewable energy often has a degree of volatility and randomness when distributed, which can bring certain risks to the operation of the VPP. In order to consider the risks brought by renewable energy, an optimal scheduling model of the VPP, based on an improved generative adversarial network (GAN) and the conditional value at risk (CVaR), was proposed to measure the relationship between the benefits and risks. Firstly, the uncertainty of new energy is analyzed, and wind power and photovoltaic scenarios are generated by the improved GAN; then, typical scenarios are generated by the k-medoids method. Finally, based on the CVaR, the optimal scheduling model of the VPP is established to study the effect of risk weight on VPP revenue. The results show that the model can effectively measure the relationship between the benefits and risks and can provide some references for the VPP to make reasonable operational decisions with different risk preferences.