The PV power generation system is divided into grid-connected inverter and grid-connected transformer. It mainly consists of PV modules, inverter, sink box, control equipment and power supply system. PV grid-connected power generation system is a device that converts electricity into electrical energy, mainly consisting of solar panels, PV inverters, transformers, and power supply systems to form a new energy system with electricity as the energy source. With the continuous development of PV technology, this new energy system is becoming more and more popular among users for its high power generation efficiency, high capacity, stability, reliability and other characteristics.
Photovoltaic module is the smallest component that combines many factors such as light intensity, density and color. It can be used as a carrier for photovoltaic power generation, and is installed on the roof of a building to form a "stand" for power generation. It is made of light-concentrating materials of different thicknesses or colors and is welded to glass or plastic film, or made of metal. Since the main working principle of photovoltaic modules is to convert light energy from sunlight into electricity, the modules have a good photoelectric conversion efficiency, usually up to 15% or more. Therefore, for the average user, its main task is to generate and convert it into electricity.
Solar cell is the most used type of solar cell in PV projects. Literally understood, it is a collection of several monocrystalline silicon solar panels. According to the process can be divided into three types of silicon-based solar panels, monocrystalline silicon solar panels. Each type has its unique process characteristics, and their efficiency and conversion efficiency are not the same. In large power stations due to space constraints, it is more difficult to use large-capacity cells.
The main role of the inverter is to convert electrical energy into mechanical energy for power supply. The inverter uses direct current as the power source, and its output voltage and current are transformed by power electronic switching devices. The input current of DC is directly connected to the load through PWM rectification, and the output voltage is independent of the grid voltage, so it can directly provide power supply to the grid. It has better inductance anti-vibration capability and lower ripple current, stable output current and high reliability. PV inverter generally adopts full AC power structure and DC bus adopts half-bridge DC structure.
The sink box is used to protect the safety of the load on the basis of the DC voltage level. The sink box is required for monitoring of power-using equipment. Because the voltage level of the power grid is different, in order to prevent accidents, the power-using equipment needs to be protected from the voltage of the power. At the same time, in order to protect the environmental health around the substation, the sink box needs to be cleaned and disinfected. Since the temperature of PV modules affects the power generation efficiency of PV modules, the grid-connected inverter generates low-temperature protection measures in order to prevent damage to PV modules due to high temperature. At the same time, because PV modules are very sensitive to temperature changes, so in addition to adding insulation sleeves on PV modules, it is also necessary to add insulation measures to the inverter to make the power station in a safe and reliable operation.
5、Control equipment and power supply system
In the PV grid-connected power generation system, the control equipment is the core of the whole system, mainly composed of inverter controller, current box, power supply system and inverter distribution cabinet. The control equipment is generally a microcomputer protection device with superior electrical performance, communication interface and computer control system, in which the microcomputer protection device is suitable for low-voltage DC network to prevent DC overcurrent accidents; the communication interface is used for data communication to realize monitoring, sending and feedback of functional parameters and fault status information of the inverter; the computer-controlled current box enables the PV boost power supply (i.e. grid-connected transformer) to run continuously at rated voltage; the protection equipment can monitor the abnormal operation or misoperation of PV power generation system. Microcomputer protection devices are mainly used for grid fault location, monitoring and alarm to provide protection for PV power plants; relays are the most important devices to automatically control the work of energy storage devices. Low-noise amplifiers must be used in the grid operation. The current box mainly completes the electrical energy conversion work of the whole solar power system, which can adopt AC and DC power supply methods.