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In order to reduce the probability of commutation failure in HVDC weak receiving system, and improve the recovery characteristics of the DC system after a fault, an interactive control strategy of STATCOM and VDCOL (Voltage Dependent Current Order Limiter) was proposed. AC voltage compensation was derived based on the Current -time Area, and added to the STATCOM constant AC voltage control of outer loop to adjust the reactive power of the STATCOM output. Meanwhile, an additional DC current control functions was applied to LCC-HVDC system VDCOL. Simulation in PSCAD/EMTDC showed that the proposed interactive control strategy can restrain commutation failure effectively when the short-circuit fault occurs in the AC bus of the weak receiving system, and the improved VDCOL can strengthen the ability of the DC system to resume stable operation as soon as possible.

As renewable energy penetration increases, the lack of flexibility in a multi-renewable power system can seriously affect its own economics and reliability. To address this issue, three objectives are considered in this study: power fluctuations on tie-line, operating cost, and curtailment rate of renewable energy. Presented also is an optimal day-ahead scheduling model based on the MREPS for distributed generations with flexibility constraints. The multi-objective particle swarm optimization (MOPSO) algorithm can be applied to obtain a set of Pareto non-dominated solutions for the day-ahead scheduling strategy with the proposed model. By using fuzzy comprehensive evaluation, the optimal compromise solution is determined in the set. The presented method sacrifices a small amount of economy and power fluctuation, but it can reduce the deviation between forecast and realized power fluctuations on the tie-line, while improving the utilization of renewable energy.

This article briefly analyzes the technical advantages of the wind-solar hybrid power generation system, builds models of wind power generation systems, photovoltaic systems, and storage batteries, focusing on the key to wind and photovoltaic power generation systems-maximum power point tracking (MPPT) control, and detailed analysis of the maximum wind and solar power. The principle of power tracking and several commonly used MPPT methods, and the simulation and analysis of the MPPT control strategy of wind and photovoltaic in the wind-solar hybrid power generation system on Matlab / Simulink.

Based on the near-area AC/DC system of Funing converter station and the electromagnetic transient model of STATCOM, this paper first studies the generation and transmission process of low-order harmonics of Funing converter station, and then analyzes the iron of the converter station transformer The core saturation characteristics and the principle of complementary resonance for the AC and DC sides have an effect on the mechanism of harmonic generation. It is concluded that there are two main reasons for the instability/non-attenuation of low-order harmonics (such as the second harmonic) in the DC converter station, one is It is caused by the saturation of the transformer core, and the other is caused by the complementary resonance for the AC and DC sides. Then, two conditions for the instability of low-order harmonics in the converter station are obtained. Finally, PSCAD/EMTDC simulation is used to reproduce the “5.29” event of the Funing converter station to verify that there are two main reasons for the non-attenuation of the low-order harmonics in the converter station. One is because the core is saturated with the fault process of the converter transformer, and the other is because the parallel impedance of the AC system near the 2 times frequency is relatively large, that is, there is a parallel resonance point.

The large PV medium-voltage (MV) DC power collection system is more efficient than the traditional AC collection system, which provides an alternative for future PV applications. As one of the core components of the PV MVDC power collection system, key techniques of DC transformer are presented here in detail, including the technical requirements, and fault operation analysis in the DC collection system. When part of the PV DC module in the low-voltage (LV) side of DC transformer fails and bypassed, the DC collection system continues working normally with only part of power lost. When the MV side of DC transformer is shorted, all the PV modules exist and the collection system splits without ride-through techniques. The fault operation principle of DC transformer in PV MVDC power collection system is verified by simulations.

IGBT, as a new generation of composite full-controlled voltage-driven power semiconductor devices, has been widely used in the field of modern power electronics. The study of IGBT device life prediction has important guiding significance for the stable operation and reliability management of power system. In this paper, the Cofin-Manson-Arrhenius extended exponential model based on thermal load is analyzed, and the model parameters are trained and modified by the Elman neural network in order to improve the prediction accuracy of life prediction model. The Coffin-Manson-Arrhenius extension exponential model and the new improved model are simulated and validated by experiments. The results are compared with the actual life of IGBT. It is concluded that the Coffin-Manson-Arrhenius extension exponential model based on Elman neural network has higher accuracy in life prediction than the Coffin-Manson-Arrhenius extension exponential model.