What is energy storage?
Energy storage mainly refers to the storage of electrical energy. Energy storage is a term in petroleum reservoir, which represents the ability of reservoir to store oil and gas. Energy storage itself is not a new technology, but it is in its infancy in terms of the industry.
So far, China has not reached the extent that the United States and Japan regard energy storage as an independent industry and issue special support policies. In particular, in the absence of a payment mechanism for energy storage, the commercialization model of the energy storage industry has not yet taken shape.
What is photovoltaic?
Photovoltaic (Photovoltaic) : short for Solar power system. It is a new power generation system that directly converts the Solar radiation energy into electric energy by using the Photovoltaic effect of the semiconductor material of the Solar cell. It has two modes of independent operation and grid-connected operation.
At the same time, solar photovoltaic power generation system classification, one is centralized, such as the large northwest ground photovoltaic power generation system; One is distributed (with >6MW as the boundary), such as the rooftop PHOTOVOLTAIC power generation system of industrial and commercial enterprises and residential buildings.
What is a photovoltaic system?
Photovoltaic power generation system can be divided into grid-connected photovoltaic power generation system and independent photovoltaic power generation system according to whether connected to the grid. Grid-connected PHOTOVOLTAIC power generation system mainly refers to the photovoltaic system that is connected to the power grid for operation and dispatching, such as various centralized or distributed photovoltaic power stations. Independent photovoltaic power generation system mainly refers to a variety of photovoltaic power generation systems that operate independently from the power grid, such as solar street lights, rural household photovoltaic power supply, etc., collectively referred to as photovoltaic system.
What is PV + Energy storage?
The combination of photovoltaic and battery as an energy storage device is photovoltaic + energy storage.
Working mode of photovoltaic energy storage system
Photovoltaic (pv) power generation has the output level is high, short time at noon have a low level of output and other time day efforts, night no output, the characteristics of energy storage technology is able to achieve translation of time and space characteristics of electric power and energy storage for photovoltaic power station configuration between will contribute to the noon of photovoltaic (pv) transferred to other periods, cut power station output peak, reduce discard.
In order to prolong the service life of the battery energy storage system, the charging and discharging times of the battery energy storage system should be reduced as much as possible. During the peak hours of photovoltaic power generation, the battery energy storage system is charged and the photovoltaic power station output is peak-clipped. After the peak period of photovoltaic power generation, the discharge control of the battery energy storage system can help smooth the fluctuation of photovoltaic output and assist the system to adjust the peak, so as to maximize the energy storage effect. According to the different functions of energy storage discharge, the energy storage system can be divided into three working modes: peak clipping, peak clipping + suppression and peak clipping + transfer
Working mode 1: peak clipping
During the peak output period of photovoltaic power station, the charging of battery energy storage system is controlled with peak cutting as the application objective. After the peak output period of photovoltaic power and during the daytime output period of photovoltaic power, the power amplification of battery energy storage system is controlled, and the power is discharged to the lower limit of SOE working range of battery energy storage system, and then the energy storage system stops working. Ensure that the working hours of the energy storage system are within the power generation time of the photovoltaic power station, and do not increase the working hours of the photovoltaic power station, so as to reduce the impact of the configuration of the energy storage system on the work arrangement of the photovoltaic power station.
Working mode 2: peak cutting + smoothing
In the peak output period of photovoltaic power station, the charging of battery energy storage system is controlled with the application goal of peak cutting. The output fluctuation of large-scale photovoltaic power station can be divided into two categories. One is the slow change of the output of photovoltaic power station, such as the cyclical change of the output of photovoltaic power station caused by the alternation of day and night; The other is the sudden change of photovoltaic power station output, such as the sudden drop of photovoltaic power station output caused by floating clouds. The first round of change was large, but slow; The second kind of change has unpredictability and suddenness, serious when output is in 1~2s from full hair to 30% rated value below. After the peak period of photovoltaic output, the discharge of the energy storage system is controlled to the lower limit of the SOE working range of the battery energy storage system in order to smooth the declining fluctuation of the photovoltaic power station output in the process of day-night rotation. If it has entered the night and the output of the photovoltaic power station drops to 0, the SOE of the energy storage system is still greater than 0.2. Control the energy storage system to discharge at rated power constant power to 0.2 SOE, and then control the energy storage system to stop working.
Working mode 3: peak cutting + transfer
In the peak output period of photovoltaic power station, the charging of battery energy storage system is controlled with the application goal of peak cutting. The output period of photovoltaic power station is from 8:30 to 18:30, and the evening peak of the load occurs between 18:00 and 22:00. During this period, the photovoltaic power station has no output, and the discharge of the battery energy storage system can be controlled to assist the peak regulation of the system. In order to reduce the operation times of the energy storage system and simplify the operation of the battery energy storage system, Control the battery energy storage system to discharge at constant power, discharge within the SOE operating range of the battery energy storage system, and then the energy storage system stops working.
