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Now the measurement means of access capacity at all levels of distribution network are insufficient and it is difficult to calculate effectively based on limited data. This paper proposes a hierarchical evaluation method of access capacity of distribution network with multiple prosumer group load forecasting. Firstly, a load dynamic prediction model is constructed. According to the typical load model of historical data mining, a unit prediction model of typical users is established by using the conjugate gradient RBF neural network learning algorithm. Then, according to the charge-discharge dynamic model of the energy storage power station and the load dynamic prediction results, an assessment model of access capacity at the 10kV side was constructed. By analyzing the known load type, load type ratio and transformer capacity on the low-voltage side, the conversion coefficient of 10kV side load to 0.4kV side transformer capacity is obtained by weighting different types of loads proportionally. Then, access distribution capacity of different prosumer group can be obtained based on conversion coefficient. It can ensure the effective measurement of access capacity at all levels of distribution network under the premise of meeting N-1 safety criteria. Finally, an example is given to demonstrate the effectiveness of the proposed method.

In order to meet the demand of prosumer for power quality and new load in distribution network, an open capacity expansion model of distribution network with mobile energy storage system (MESS) is proposed in this paper. The model gives priority to the problem of voltage violation of prosumer group on feeders. Combined with the mobile energy storage path model, the open capacity of distribution network is calculated. Firstly, the actual distribution network geographic information and traffic routes are combined to establish the distribution network model based on mesh generation. Secondly, the traffic route model of the mobile energy storage system is established on the distribution network model based on mesh generation. Then, the optimal power flow of distribution network is calculated with the optimal network loss, and the mobile energy storage system is scheduled according to the situation of voltage violation. And the specific vehicle model and its scheduling are determined, which can better deal with the problem of distributed energy consumption and make prosumer operate safely and economically. Finally, according to the proposed N-1 security check constraint of distribution network with mobile energy storage system, the maximum open capacity of distribution network is calculated after the voltage regulation is completed. The example shows the practicability and correctness of the model in this paper. This paper formulates a mobile energy storage operation strategy to improve the open capacity of distribution network. The strategy not only fully meets users’ needs, but also better guides the operation of power grid. It is conducive to releasing more potential power supply space of distribution network and improving asset utilization.

In recent years, the key work of power grid company is to provide voltage sag management service for high-precision and sensitive load. The current voltage sag treatment scheme mainly determines the capacity of the standby power supply through the equipment tolerance assessment, and the treatment cost is too high. In this paper, the configuration method of voltage sags control device is put forward, and the comprehensive benefit evaluation index system of power quality control for power user’s is established, the quality problem of a large number of products caused by voltage sags in the customer’s production line is solved, and the unnecessary economic loss is reduced. The research results presented in this paper effectively reduce the equipment trip, production process interruption, reduce user’s loss, improve product quality.

It is necessary to evaluate the reliability of the system's operation after grid-connected offshore wind power, to comprehensively evaluate and further improve the reliability of the grid including the receiving end of offshore wind power, which is beneficial the receiving power grid with large-scale offshore wind power runs safely and stably. Improve the power supply reliability of the offshore wind power receiving terminal. Considering the harsh operating conditions of offshore wind power, the frequent occurrence of extremely bad weather such as typhoons on the eastern coast, and the mutual influence of certain situations are frequent and involve a wide range, which brings serious harm to the offshore wind power connect system. At the same time, offshore wind power maintenance has poor accessibility, high maintenance costs, and reduced the reliability level of offshore wind power systems. In addition, when offshore wind power is connected to the receiving power grid through a combination of high-voltage AC and DC, it will have complex interactions with multi-level AC and multi-type DC external incoming calls, which may expand the scope and depth of the fault. Therefore, it is necessary to take into account the effects of severe weather at sea, offshore wind power maintenance plans, and various complex interactions to conduct a more comprehensive and in-depth study of the reliability assessment of offshore wind power connect to the power grid.

Most of the small-size hydropower stations are runoff hydropower stations and their output is determined by the upstream water supply. Consequently, the rainfall brought by typhoons will lead to the increment of runoff, increasing the output of small-size hydropower stations. The uncertain increment of the output of small-size hydropower stations will bring adverse effects on the security of power system, such as the voltage over-limit and the power overload of transmission lines. In this paper, a risk assessment method is proposed to assess the shutdown risk of small-size hydropower station under typhoon disaster. Firstly, Monte Carlo Method is employed to calculate the probabilistic load flow of power system with small-size hydropower station and the probability of node voltage over-limit and branch power overload is set to be the shutdown probability of small-size hydropower station. Secondly, the cost of load shedding which is optimized by Adaptive Particle Swarm optimization (APSO) algorithm is set to be the shutdown cost of small-size hydropower station. Finally, the IEEE-33 bus system is used to assess the shutdown risk of small-size hydropower station under typhoon disaster.

With the increasing of electric vehicles (EVs) users, a large amount of reserve charging infrastructure have to be deployed in distribution systems to the uncertain charging demand, which may lead to redundant investment. In order to reduce unnecessary investment and optimize the plan of charging station and distribution network, a multi-objective planning model is proposed. The objectives of planning model include the benefits of both distribution network and EV user. The proposed method has been verified on a modified 54-bus distribution and 19-node road system. The results shows that the proposed model can give collaborative plan, and ensure the benefits of both the distribution side and user side.

The fast charging and discharging characteristics of energy storage technology provides an effective way to solve the problems of peak clipping and valley filling on the grid side, large-scale access to renewable energy on the power generation side, and stable operation of isolated networks. In view of the economics of current energy storage equipment, there is still no good evaluation method. The life cycle cost is proposed as an indicator to evaluate the economics of energy storage equipment. The dynamic and static model of the energy storage system is established. Taking a demonstration work as an example, the calculation is carried out. It correctly displays the long-term cost advantage and efficiency advantage of the equipment in the whole operation process and provides a decision-making basis for the comprehensive evaluation of the economics of energy storage equipment.

Thepaper studies the effect of automatic generation control(AGC) on power frequency based on the full dynamic simulation. First modeling of AGC for the full dynamic simulation according to the three components of AGC, which is calculation of area control error (ACE), simulation of control strategy, and calculation of generating power regulation. Second the effect of key-parameters of AGC including dead band, transient frequency-deviationon and rate of generating power regulation on power frequency is studied by simulating. Finally, the paper takes Fujian power as an example to analyze the effect of AGC on under-frequency loading shedding(UFLS) by the serious faults and study on the coordination control between AGC and UFLS.

In order to analyze interaction between wind farm and electric power system, research transient voltage characteristics of large-scale wind farm in system fault and after fault, and realize large-scale wind farm fault ride through, it is necessary to build wind turbine modeling suitable for large electric power system simulating calculation program. Various power system simulators are used in many research institutes and power operators home and abroad, and there are different processing methods for wind turbines and wind farms modeling designed for different research purposes, as well as different running characteristics with different wind turbine manufacturers and technical specifications, so whole process simulation under multiple working conditions shall be realized by carrying out corresponding work. Based on basic theory of wind power generation, this paper analyzes structure and characteristics of double fed induction generator (DFIG), researches models of its mechanical system, electric system and other main constituents, and gives basic requirements and characteristic simulation of wind turbine modeling with transient response characteristics under multiple working conditions.