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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.

Power quality monitoring involves multiple types of interrelated data information, and the relationship between data entities is complex and dense, so graph database is more suitable for storage. Based on graph database and power graph computing platform, a power quality monitoring and visualization system based on the graph database is proposed. The power grid spatial data, real-time data of power grid users and equipment, and geographic environment data of power grid topology and its connection are stored through the graph database, so as to calculate the power graph related to power quality monitoring. Through the human-machine interface of the graph database query design, the multi-directional multi-angle visual display of power quality monitoring applications such as voltage sag location and voltage sag risk assessment are carried out.

Typhoon disaster can result in wind farms shutdown. With the large-scale integration of wind farms in power system, the wind farms shutdown may affect the operation of power system, causing the power shortage and voltage violation. In this paper, a shutdown risk assessment method is proposed to evaluate the risk of wind farms operation under typhoon disaster. Firstly, the distribution of forecast error of wind power under typhoon conditions is analyzed according to the historical data and is established as T distribution. Next, the real-time shutdown probability of wind farms is generated by the known cumulative error distribution. Then, the shutdown cost of wind farms are expressed by the cost of shedding load after wind power exiting, which is solved by particle swarm optimization method. Finally, the adjusted IEEE-33 node system with wind farms are adopted to verify the effectiveness of proposed method.

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.

This paper starts from the power demand side, which proposes a time-sharing peak-valley pricing method for power users. Firstly, the OCHNN-Kmeans algorithm is adopted for the clustering of power load curves. This algorithm can overcome the disadvantages of K-means clustering instability. The use of OCHNN-Kmeans to cluster power consumer load data can meet the high-dimensional characteristics of power load data. On the other hand, the calculation speed of this algorithm is relatively fast and can be used in the practical application of power industry; According to the clustering results, typical user load data are extracted from each type of electricity consumers. The parameters of peak-to-peak, peak-flat, and valley-bottom load transfer rates were estimated using the constrained least-squares method. The estimated load value after the peak-to-valley time-of-use electricity price is changed, the estimated load value is fine-tuned in combination with the electricity price elasticity matrix, and the design optimization example is used to formulate optimal time-average peak-to-valley prices for different classes; finally, the domestic south is combined. An empirical analysis of the real data of a city provides that the development of specific time-of-the-hour peak-valley tariffs for different power users can reduce the electricity cost of demand-side power users, enable peak load-filling of load curves, and increase the efficiency of energy use. Meet the diverse needs of power users.

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.

The battery energy storage system (BESS) is developing from the demonstration project to the stage of business promotion Due to the unsound Economic benefit evaluation, which restricts the large-scale promotion and construction of BESS. This paper establishes the life cycle cost and income model of BESS and uses the dynamic investment payback period, net present value (NPV), internal rate of return (IRR) and other economic indicators to analyze the economy of offshore wind power with BESS in reducing forecast deviation penalty. At the same time, aiming at stimulating the enthusiasm of the wind farm to allocate energy storage, we studied the improvement of the penalty rules of wind power forecast deviation. The research results can provide an engineering economic reference for the investment decision of BESS.

After Xiamen VSC-HVDC Project is put into operation, it can improve the power supply capacity and reliability of Xiamen Power Grid.But at the same time,it also brings new problems to the operation of the power grid, among which the short-circuit current problem is particularly prominent.In the preliminary analysis of power grid operation, using the short- circuit current program (PSD-SCCP) commonly used in domestic power grid simulation analysis to calculate to be found that:VSC-HVDC will provide a large short-circuit current when the AC grid is short-circuited, causing the short-circuit current levels of multiple 220kV busbars of the Xiamen Power Grid to approach or exceed 50kA, which brings greater pressure on the adjustment and arrangement of the grid operation mode.Therefore, it is necessary to study the true level of the impact of Xiamen VSC-HVDC on the short-circuit current of the AC grid based on the actual control logic of the Xiamen VSC-HVDC project, in order to propose more accurate short-circuit current suppression measures to achieve bipolar operation of Xiamen VSC-HVDC.

VSC-HVDC has been widely used at home and abroad, but there is no clear conclusion about the characteristics and calculation method of the short-circuit current contributed by VSC-HVDC during the AC Short-Circuit Fault near the converter station. The calculation methods in the field of short-circuit current engineering have not been unified, and the adaptability and error of different methods have not been analyzed in detail. Through electromagnetic transient simulation, this paper analyzes the transient characteristics of VSC-HVDC contribution short-circuit current, and combs the key influencing factors of VSC-HVDC contribution short-circuit current. Finally, taking a VSC-HVDC system in China as an example, the adaptability of the commonly used short-circuit current algorithm is analyzed. It is verified that the existing engineering algorithms have made great progress compared with the original. However, compared with the electromagnetic transient refined simulation, there is still a large error in the calculation results of individual nodes under some control modes / fixed values.

In recent years, with the development of distributed generation(DG) technologies, a large number of DG are connected to the distribution network, however, the output of DG is intermittent and random. Considering the timing characteristics of DG and loads, this paper establishes a generalized power optimal configuration model of energy internet which takes power purchasing cost, investment cost, operation and maintenance cost, network loss cost, fuel cost and government subsidies comprehensive cost as the objective functions. The invasive weed optimization(IWO) based on cloud model is used to solve the model. The model and the algorithm proposed in this paper are simulated by IEEE 13 nodes to verify its validity.

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.