A general method for designing the power and capacity of energy storage batteries

State Grid Hunan Electric Power Company Changsha Power Supply Branch, Hunan University School of Electrical and Information Engineering, China Power Construction Group Zhongnan Survey and Design Institute Co., Ltd. Researchers Huang Jiyuan, Li Xinran, Chang Min, Li Shujuan, Liu Weijian, in the 21st issue of 2017 The author of the Journal of Electrical Engineering pointed out that the problem of grid frequency caused by the grid-connected intermittent power supply has led to the more urgent research on the introduction of energy storage auxiliary frequency modulation. A capacity allocation method considering the energy storage battery to participate in the economic model of primary frequency modulation technology is proposed.

The general method of power and capacity design of energy storage battery is expounded. By analyzing the cost and benefit of energy storage battery in FM operation process, based on the life cycle theory, the net present value method combined with the simulation model is used to construct the energy storage battery to participate in the primary frequency modulation. Technical and economic model; a charging and discharging strategy for energy storage batteries participating in primary frequency modulation is designed. On this basis, considering the comprehensive load of the power grid affected by the fluctuation of wind power output, starting from the corresponding fluctuation characteristics of the grid frequency signal, it is determined. Under the constraint of grid frequency modulation and energy storage battery operation, the energy storage battery capacity allocation scheme with optimal frequency modulation effect, economical optimality and comprehensive optimal target is obtained.

The simulation results show the rationality and effectiveness of the proposed method. This research will help promote the demonstration and engineering application of energy storage batteries in auxiliary FM services.

In recent years, the energy Internet with the core of “smart grid + UHV grid + clean energy” has emerged rapidly. Among them, the volatility and uncertainty of clean energy such as wind power, the magnitude, frequency and distribution of its output fluctuations. It is weakly related to the trend of grid load fluctuations. This uncertainty challenges the grid to adjust the frequency band, and the limitation of the FM capacity also limits the ability of the grid to absorb clean energy.

The energy storage battery has the characteristics of rapid response and high control precision. Under this background, it is necessary to discuss the energy storage participation in the power grid frequency modulation. The scientific and rational allocation of energy storage capacity is an important part of energy storage application planning, and also the basis for promoting its entry into the FM market. At present, relevant scholars have conducted preliminary research on the capacity allocation of energy storage batteries.

Literature [2] reviews the research status of energy storage in frequency modulation, and points out the initial thinking of energy storage capacity allocation and economic evaluation, that is, based on the capacity allocation results, analyzes the economic value of energy storage in the field of auxiliary frequency modulation, and in turn guides and corrects Capacity configuration for energy storage.

In [3], a capacity optimization method based on chance constrained programming for energy storage participation in wind farm primary frequency modulation is proposed. An optimization model with minimum operating cost of wind storage system and meeting the requirements of primary frequency modulation is constructed.

In [4], a hybrid energy storage capacity allocation method based on the largest net benefit to stabilize the wind power fluctuation is proposed. By analyzing the differences of different power distribution methods, the benefits of reducing the capacity of the wind farm rotating standby and grid-connected channels are considered. The life cycle cost is the result of the highest net benefit.

Literature [5] proposes an energy storage capacity allocation algorithm suitable for large-scale centralized renewable energy fields, smoothing output fluctuations and tracking planned output as application modes, and extracting sensitive factors that affect the configuration results.

Obviously, the current capacity allocation of energy storage batteries is based on empirical analysis, and is not based on a systematic and detailed technical and economic model. The method is not adaptable and feasible, and more attention is paid to energy storage and auxiliary wind power. Capacity configuration of the network. Therefore, taking full account of the characteristics of the FM application and the technical and economic characteristics of the energy storage battery, it is meaningful to establish a technical and economic model of the energy storage battery to participate in the primary frequency modulation, and to carry out scientific and reasonable capacity allocation on this basis.

Therefore, this paper studies the energy storage battery (hereinafter referred to as energy storage) participating in the frequency allocation method of frequency modulation. Firstly, the general method of energy storage capacity allocation is expounded, and the technical economic model of energy storage participating in primary frequency modulation is constructed based on the whole life cycle theory.

Based on the corresponding energy storage and charging strategy of the first frequency modulation, the frequency modulation effect, the economic optimization and the comprehensive optimization of the two are aimed at the grid frequency modulation requirements and energy storage operation requirements. . Finally, the actual grid operation data is used for simulation verification.

Figure 1 Method for energy storage battery to participate in primary frequency modulation

in conclusion

This paper studies the capacity allocation method considering the energy storage battery to participate in the economic model of primary frequency modulation technology. Through the example simulation analysis, the conclusions are as follows:

1) The technical and economic evaluation model of energy storage includes a physical property model and an economic evaluation model. By combining the simulation model of energy storage with the method of energy storage participating in frequency modulation, the physical property model can be obtained; by analyzing the cost and benefit composition of energy storage in the whole life cycle, the economic presentity model can be established by using the net present value method.

2) Energy storage In the frequency modulation process, the energy storage power command corresponding to the frequency deviation needs to be completely tracked. Therefore, the rated power optimization range of the energy storage is determined by the maximum allowable frequency deviation of the power grid and the operating characteristics of the energy storage. The energy storage capacity is determined by the initial state of the state of charge and the actual power command sequence during the energy storage operation.

3) When the energy storage participates in the primary frequency modulation, the present value of the FM net benefit decreases with the increase of the configuration capacity, and the frequency modulation effect increases with the increase of the energy storage configuration capacity. The energy storage can be selected to participate in the primary frequency modulation according to the needs of the optimization target. The value of the control variable associated with the charge and discharge strategy.