Inverter And The Grid Together With The Guardian

Hit from the day I was born, my fate will be decided to marry the grid to do a very traditional security guard has abide by the good wife.

My work is three from the start: When the first ray of sunshine rises from the east in the morning, I began to dress myself from the inside to the outside, adjust my own phase sequence, adjust your own voltage amplitude and phase, adjust your own Current phase, consistent with the grid, follow the phase sequence of the grid, follow the grid voltage amplitude and phase, follow the grid current phase, when all the parameters are detected, the grid switch is closed, the power generated by the PV module The regulation, a steady stream to the grid.

If you can not abandon, I will depend on life and death, I am during work, always check whether the grid is also working, once the grid power failure, it will be in a few cycles with the power grid disconnected, and stop running Is my anti-island effect. There are usually passive or active two detection methods. Passive island protection: real-time detection of grid voltage amplitude, frequency and phase, when the power outage, the grid voltage amplitude, frequency and phase parameters, resulting in jump signal, by detecting the jump signal to determine the power grid Active power offset detection method, active frequency offset method and sliding mode method, such as pulse current injection method, output power change detection method, active frequency offset method and sliding mode method, are used to determine whether the power grid is affected by the inverter. Frequency offset method, etc., when the power grid, the disturbance on the frequency of the grid voltage has no effect, when the power loss, the disturbance will cause the grid voltage and frequency changes occur, to determine whether the power grid loss.

After years of continuous exploration, and now grid-connected inverter anti-island technology has been fully mature, under any conditions can accurately determine whether the power grid is lost, so the distributed photovoltaic power plant, is no need to match any anti-islanding device.

Love than Kim Jong, suffering help. Zero (low) voltage through function: When the power system accident or disturbance, causing the photovoltaic power station and network voltage voltage drop, in a certain voltage drop range and time interval, the photovoltaic power plant can ensure that non-off-line continuous operation, This function is realized by the inverter. The reason for the voltage sag is as shown in the following figure. When the short circuit fault occurs in a branch D, the current increases abruptly. At this time, the protection device in the fault branch D moves to isolate the fault point and the voltage returns to normal. Failure to detect and disconnect, take some time, will lead to ABCEFG the branch voltage suddenly reduced, forming a short voltage drop. This time if the solar power plant if immediately removed, it will have an impact on the stability of the power grid, and even other trouble-free slip is also open, will cause a large area power grid failure. At this time the need for photovoltaic inverter can support a period of time (1 second), until the grid voltage back to normal.

Zero (low) voltage traversal function to adapt to large ground power plants, solar power all the Internet, not directly available to the load. However, in distributed photovoltaic power plants, no zero (low) voltage crossing function is required. , The solar power generation using self-use, the balance of the Internet, when the load side of the electric shock, short circuit, grounding and other failures, causing the branch voltage drop or the main switch QF1 trip, this time the inverter should immediately stop running to prevent further deterioration of the accident.

In some industrial plants with impact load distributed photovoltaic power plant, if a large crane, welding machine and other heavy load start, will also cause voltage drop, which is characterized by less amplitude, irregular rectangle, long duration, this time reverse The inverter will start and stop frequently, but the inverter's zero (low) voltage traversal function can not solve this problem, need to use isolated inverter, or power quality AVC to solve.