Generally speaking, the process of converting AC power into DC power is called rectification, and the circuit of the rectification function is called a rectification circuit, and the device of the actual rectification process is called a rectification device or a rectifier, and the corresponding DC power is converted into AC power. The process is called inversion, and the circuit that completes the inverter function is called an inverter circuit, and the device that actually reverses the process is called an inverter device or an inverter. Photovoltaic inverter converts the direct current generated by photovoltaic modules into sinusoidal currents. It is connected to the load or incorporated into the power grid. It is the core device in the photovoltaic system. PV inverter types and main functions Photovoltaic inverters are classified into three types: grid-connected inverters, off-grid inverters and micro-grid energy storage inverters. The grid-connected inverters can be divided into micro-inverters and strings according to power and application. Inverters, Centralized Inverters, and Distributed Inverters are four categories, micro-inverters, also known as component inverters, with power classes of 180W to 1000W, suitable for small power generation systems; string inverters , single-phase inverters with power ranging from 1kW to 10kW, suitable for household power generation systems, three-phase inverter with grid voltage of 220V, 4kW to 80kW, suitable for industrial and commercial power generation systems, the grid voltage is three phase 380V, . Centralized inverters and distributed inverters, with powers from 500kW to 1500kW, are commonly used in large ground-based power stations. Grid inverter Grid-connected inverters are the key components for connecting PV arrays and grids. In addition to converting DC power from components into AC power that the grid can receive, the following special features are also available: 1) Maximum power tracking MPPT function When the sunshine intensity and ambient temperature change, the input power of PV modules shows a non-linear change. As shown in the figure, the PV module is neither a constant voltage source nor a constant current source. Its power varies with the output voltage. Change and change, and the load does not matter. Its output current is a horizontal line as the voltage rises. When it reaches a certain power, it decreases as the voltage rises. When the open circuit voltage of the component is reached, the current drops to zero. The output power of photovoltaic modules is affected by factors such as sunlight intensity and ambient temperature. When the light intensity decreases, the open circuit voltage of the photovoltaic module decreases, the short-circuit current decreases, and the maximum output power decreases. When the temperature of the photovoltaic module decreases, the short circuit current of the module decreases, but the open circuit voltage of the module increases, and the maximum output power increases. In the case of certain component temperature and sunshine intensity, the same module has only one maximum power output point, MPPT function is the maximum power tracking function, by adjusting the DC voltage and output current, so that the solar module is always working at the maximum working point, output Current temperature and maximum power in daylight conditions. Common maximum power tracking control methods include: Constant Voltage Tracking (CVT), which fixes the terminal voltage of photovoltaic modules at a certain fixed value. The characteristics are simple control and good stability; power calculation method, current seeking method, disturbance Observing methods, incremental conductance methods and other classical control algorithms, and optimal gradient methods, fuzzy logic control methods, neural network control methods and other modern control algorithms. 2) Detection and Control of Island Effect In normal power generation, the photovoltaic grid-connected power generation system is connected to a large-scale power grid to deliver active power to the grid. However, when the grid loses power, the photovoltaic grid-connected power generation system may continue to work and be in independent operation with the local load. This phenomenon is called islanding. When the inverter has an islanding effect, it will cause great safety risks to personal safety, power grid operation and the inverter itself. Therefore, the inverter network entry standard stipulates that the photovoltaic grid-connected inverter must have the islanding detection and control function. . The detection methods of islanding effect include passive detection and active detection. The passive detection method detects the amplitude of the voltage and current at the output of the grid-connected inverter. The inverter does not add an interference signal to the grid, and the current phase shift and frequency are detected. Whether the parameter exceeds the specified value to determine whether the power grid is out of power; this method does not cause grid pollution, nor will there be energy loss; active detection means that the grid-connected inverter actively and regularly imposes some interference signals on the power grid. If the frequency shifts and the phase shifts, since the power grid can be viewed as an infinite voltage source, these interference signals will be absorbed by the grid when there is a grid. If a power outage occurs in the grid, these interference signals will form a positive feedback and eventually form a frequency or Excessive voltage, which can determine whether the islanding effect has occurred. Pull-Out Faucet,Pull Out Kitchen Faucet,Pull Out Faucet,Pull Out Shower Handle Heshan Janno Kitchen and Bath Technology Co.,Ltd , https://www.janno-ks.com