Wang Jinhao

The interaction research between public grid and traction power supply system

In this paper, comprehensive testing of the power quality in a typical utility grid in existence of the electric railway traction load is taken, the measurement and simulation results are analyzed, it is verified that the electrified railway grid is an important factor in pollution of typical utility grid. Firstly in this paper, the typical utility power grid and traction power supply system model are established. The interaction between typical public grid and traction power supply system is analyzed then, through PSCAD/EMTDC simulation, the result of the improvement is got. The simulation results show that once SVC is installed in a substation, its power quality can be improved significantly, the level of harmonics and three-phase voltage imbalance can be decreased.

Analysis on grid-friendly microgrid economic operation

The ability of the grid-friendly microgrid responding the system operation demand is analyzed by exploiting potentialities of grid operation from the traditional load side. The volatility of DGs output is balanced by including controlling EVs the charging and discharging. The output of microgrid is scalable through coordinating all kinds of DGs based on which a microgrid economic operation model is built. The simulation result shows the microgrid can absorb internal intermittent power and achieve system dispatching well by coordinating kinds of powers. Its dispatching potentiality is sizable.

The maximum entropy probability distribution and the improvement of its solving method for negative sequence current of a traction substation

In this paper, improved solving method are proposed to calculate the maximum entropy probability distribution of negative sequence current. Negative sequence current is got from the process of the measured data obtained from power quality monitoring system first. Second, curve fitting method is used to calculate probability distribution of negative sequence current based on maximum entropy method. Logarithmic function and the method of deleting small probability value points at ends of probability distribution are proposed to improve the parameters solution method of curve fitting. The probability distribution obtained from the improved solving method is more consistent with the actual distribution of measured data compared with the original parameter solution method. Finally, fitting error parameters are used to evaluate the fitting effect of probability distribution and prove the feasibility of the method.