Energy storage is the process of storing energy through a medium or device and releasing it when needed. Its flexible charging and discharging control realizes the matching of capacity and energy use in time and space, which is the dependence of flexibility.
From the perspective of the power system, energy storage can be divided into the power generation side/power supply side, grid side, and user side energy storage, of which the power supply side and grid side energy storage are also known as pre-meter energy storage or large storage. Pre-meter energy storage refers to energy storage that is directly connected to the grid and has independent power and electricity metering; conversely, it is behind-the-meter energy storage, and user-side energy storage is also known as behind-the-meter energy storage. User-side energy storage is divided into commercial and industrial energy storage and household energy storage.
From the business model point of view, the pre-meter energy storage should have the identity of an independent market entity, independent participation in the market quotation, direct acceptance of scheduling, and independent settlement, which can also be called independent energy storage.
Domestic user-side energy storage mainly refers to the energy storage system applied to the majority of industrial and commercial customers, and the energy storage device can be simply understood as a large charging treasure. Charging at low electricity prices, discharging at high electricity prices for enterprise production, earning the peak and valley electricity price difference, thus reducing the cost of electricity for enterprises.
Introductory Terms for Commercial and Industrial Energy Storage
Peaking
is the process of transferring excess electricity from a place that uses less electricity to an area that has a shortage of electricity. Because electricity cannot be stored on a large scale, it is generally used as much as it is generated. When the power generation capacity of a region remains unchanged, and the power here is not used up, it is necessary to transfer the excess power to the region with insufficient power through dispatch, or the common pumped storage.
Frequency regulation
is because China’s rated frequency is 50Hz, but the complexity and variety of electrical appliances in production and life, machine startup and operation will affect the grid frequency, which requires frequency regulation to improve power quality.
PCS (Power Conversion System)
is an energy storage converter that realizes the conversion of power between the grid and the battery, and monitors and manages the exchange process. PCS(Power Conversion System) can control the charging and discharging process of the battery, convert AC and DC, and directly supply power to AC loads in the absence of power grid, PCS consists of DC/AC bi-directional converter, control unit and so on.
BMS (Battery Management System)
is a battery management system, which is mainly used for monitoring, calculation, communication and protection of battery packs. The main components are battery management chip, analog front-end, embedded microprocessor, and embedded software.
EMS (Energy Management System)
is the energy management system, which can realize the real-time monitoring and intelligent management of each device of the system. It realizes data collection, storage, processing, uploading, operation control, operation strategy formulation, etc., and carries out generalized informationized monitoring and management.
“MW”
The unit of PCS refers to the power that can be input or output for a given electrochemical energy storage device under certain time conditions. The unit is W, kW, MW, GW, and the conversion ratio is 1:1000.
“MWh”
The unit of battery capacity refers to the amount of electricity discharged by the battery under certain conditions, and is also one of the most important performance indexes to measure the performance of the battery. The unit is Wh, kWh, MWh, GWh, TWh, and the conversion ratio is 1:1000.
DoD (Depth of Discharge)
represents the depth of charging and discharging, and is an indicator used to describe the degree of utilization of the battery capacity of the energy storage system in the charging and discharging process. It represents the percentage of the discharged amount of the battery relative to the total capacity of the battery. The smaller the number, the shallower the discharge. For example, a battery with a capacity of 5 kilowatt-hours (kWh) and a maximum allowable discharge of 4 kWh would have a depth of discharge of 80%.
