In essence, the economic analysis of battery energy storage technology is to analyze the operating economy of medium energy storage battery. It should be noted that in the process of independent operation, the main consideration and evaluation are the safety, stability and reliability of power supply, and generally do not evaluate and analyze the economy. In the case of access to distribution network, it is necessary to evaluate its economy. In order to improve the economy of medium energy storage battery, the key is to adjust and control the operation mode. Generally speaking, the operation structure mainly consists of photovoltaic power generation module, fan power generation module and energy storage battery. By optimizing the photovoltaic power generation module and fan power generation module, the load of the module can be adjusted so as to achieve the best operation state. So as to improve the overall operation economy. The following mainly analyzes several regulation and control methods of battery energy storage technology, from the operation control to analyze the economic cost benefit of battery energy storage technology.
1. Grid connection balance of battery energy storage system
After being connected to the distribution network, power resources need to be converted into the distribution network. Therefore, in the grid-connection process, the grid-connection balance with the distribution network should be realized in order to enable the micro-grid to absorb and transform renewable resources in the energy storage battery to the maximum extent. Microgrid is generally built at the end of distribution network, which contains a large number of three-phase unbalance control devices. The interaction with the unbalanced load and the unbalanced distributed power supply reduces the control performance of the inverter, resulting in three-phase voltage unbalance. To achieve grid-connected balance control, it is necessary to adopt a unified three-phase unbalance suppression strategy in the energy storage inverter, so as to improve the control performance of the energy storage inverter, reduce the three-phase unbalance degree, and improve the power quality of operation. Through grid-connected balance control, the battery energy storage system can effectively reduce the power loss in the transformation process of electric energy resources in microgrid and distribution network, and improve the economy of its operation.
2. Battery energy storage system peak and valley energy storage
The fundamental purpose of the application of battery energy storage technology is to improve the use efficiency of power resources, store power resources in energy storage batteries, and realize the transformation and utilization of power resources. When connected to the household power supply system, each household user will have power peak and power trough in the process of electricity consumption, so it is necessary to maximize the economic benefits of operation through the peak-valley energy storage operation control. It will be incorporated into the main network of household power consumption. When the user’s power consumption reaches the peak period, all the energy storage batteries in the micro-grid will start discharging. When the user’s power consumption returns to the low period, the energy storage batteries in the micro-grid can absorb the power resources in the distribution network to charge. Then, in the process of power supply, the power supply sequence can be adjusted more scientifically and reasonably, so that the microgrid and distribution network can achieve the best cooperation, so that the power resources stored in the energy storage battery can give full play to the maximum economic benefits.
3. Battery energy storage system can charge and discharge power control
According to the analysis of peak-valley power storage control, it can be seen that charging and discharging by energy storage battery can better realize the conversion and utilization of power resources. However, another issue that needs to be considered is whether the energy storage battery can be fully charged and discharged. When the energy storage battery is integrated into the distribution network, the discharge power of the energy storage battery is about 20 kW when the power consumption of the user reaches the peak, and the charging power of the energy storage battery is about 16 kW when the power consumption of the user returns to the trough. In order to keep the energy storage battery in the best state of charge and discharge, In the process of operation, it is necessary to adjust the power of the grid and the distribution network. Generally speaking, the most ideal grid-connected power value is 10 kW. However, in the process of practical application, the maximum charge and discharge power and power resource storage capacity of medium energy storage battery, namely lithium iron phosphate battery, will be limited to a certain extent.
A comparative analysis of the independent power and the power integrated into the distribution network shows that the charge-discharge performance of the battery energy storage system is reduced by about 20%, that is, when the power storage capacity of the lithium iron phosphate battery is reduced to 20%, it cannot be put into the discharge state, so it needs to stop working for charging. So in order to make the energy storage battery as far as possible to achieve 100% charge and discharge conversion rate, it is necessary to adjust and control the grid-connected power, ensure the balance of grid-connected power, keep it between 10 and 13 kW, reduce energy consumption as far as possible, and realize the unity of energy saving benefits and economic benefits.