First things first:
What is photovoltaic, what is energy storage, what is converter, what is inverter, what is PCS and other keywords
01 Energy storage and photovoltaic are two industries
The relationship between them is that the photovoltaic system converts solar energy into electric energy, and the energy storage system stores the electric energy generated by photovoltaic equipment. When this part of electric energy is needed, it is converted into alternating current through the energy storage converter for load or grid use.
02 Explanation of key terms
According to Baidu's explanation: in life, some occasions need to change AC power into DC power, which is the rectification circuit, and in other occasions, it is necessary to change DC power into AC power. This reverse process corresponding to rectification is defined as inverter circuit. Under certain conditions, a set of thyristor circuits can be used as both a rectifier circuit and an inverter circuit. This device is called a converter, which includes rectifiers, inverters, AC converters, and DC converters.
Let's understand again:
The English of the converter is converter, which is generally realized by power electronic components, and its function is to realize the transmission of power. According to the different types of voltage before and after the conversion, it is divided into the following types:
DC/DC converter, the front and back are DC, the voltage is different, the function of DC transformer
AC/DC converter, AC to DC, the role of the rectifier
DC/AC converter, DC to AC, the role of the inverter
AC/AC converter, the front and rear frequencies are different, the role of the frequency converter
In addition to the main circuit (respectively rectifier circuit, inverter circuit, AC conversion circuit and DC conversion circuit), the converter also needs to have a trigger circuit (or drive circuit) to control the on-off of the power switching element and to realize the regulation of electric energy, control circuit.
The English name of the energy storage converter is Power Conversion System, referred to as PCS, which controls the charging and discharging process of the battery and performs AC-DC conversion. It is composed of a DC/AC bidirectional converter and a control unit.
03PCS general classification
It can be divided from two different industries, photovoltaic and energy storage, because the corresponding functions are fundamentally different:
In the photovoltaic industry, there are: centralized type, string type, micro inverter
Inverter-DC to AC: The main function is to invert the direct current converted by solar energy into alternating current through photovoltaic equipment, which can be used by loads or integrated into the grid or stored.
Centralized: the scope of application is large-scale ground power stations, distributed industrial and commercial photovoltaics, and the general output power is greater than 250KW
String type: the scope of application is large-scale ground power stations, distributed industrial and commercial photovoltaics (general output power less than 250KW, three-phase), household photovoltaics (general output power less than or equal to 10KW, single-phase),
Micro-inverter: the scope of application is distributed photovoltaic (general output power is less than or equal to 5KW, three-phase), household photovoltaic (general output power is less than or equal to 2KW, single-phase)
Energy storage systems include: large storage, industrial and commercial storage, household storage, and can be divided into energy storage converters (traditional energy storage converters, Hybrid) and integrated machines
Converter-AC-DC conversion: The main function is to control the charge and discharge of the battery. The DC power generated by photovoltaic power generation is converted into AC power through the inverter. The alternating current is converted into direct current for charging. When this part of electric energy is needed, the direct current in the battery needs to be converted into alternating current (generally 220V, 50HZ) by the energy storage converter for use by the load or connected to the grid. This is discharge. process.
Large storage: ground power station, independent energy storage power station, the general output power is greater than 250KW
Industrial and commercial storage: general output power is less than or equal to 250KWHousehold storage: general output power is less than or equal to 10KW
Traditional energy storage converters: mainly use the AC coupling scheme, and the application scenarios are mainly large storage
Hybrid: mainly adopts the DC coupling scheme, and the application scenario is mainly household storage
All-in-one machine: energy storage converter + battery pack, the products are mainly Tesla and Ephase