First, an overview of the development of large-scale photovoltaic desert power station According to the planned installation volume data published by the state in 2014, the trend of such explosive growth has not diminished in any way. Currently, the final installed installation volume is 14 GW (6 GW for PV plants and 8 GW for DGs). This is almost equivalent to the sum of installed capacity of domestic PV power stations in all the past years. The trend of development of desert power plants toward a single power plant capacity is getting bigger and bigger, access to the voltage level is higher and higher direction. Second, large-scale photovoltaic power plant power quality problems 1, how is harmonic produced? The generation of photovoltaic power station harmonic mainly by the inverter, DC bus fluctuations, transformer core saturation nonlinearity and power grid distortion caused. The harmonic generated by the inverter is mainly composed of two parts: one is caused by the dead time, including 3, 5, 7, 9 and other low harmonics; the other part is generated by the modulation process, and the groups are distributed at integer times of the switching frequency nearby. DC bus disturbance is also a source of harmonics. The DC bus voltage has a transient adjustment process. The influence on the current waveform can only be weakened by improving the MPPT method, but it can not be eliminated. Isolation transformer core saturation nonlinear characteristics can also lead to the generation of harmonics, while severe grid distortion, if the inverter sends an ideal sinusoidal voltage, reactance will produce harmonic voltage difference, resulting in the grid current contains the corresponding Harmonic component. A6 Coke Testing Equipment,Convenient Coke Reactivity Tester,National Standard Coke Reactivity Tester,Coke Reactivity And Strength Tester Shaoxing Dongjing Machinery Instrument Equipment Co.,Ltd. , https://www.sxdj-machine.com
Figure 1. Schematic diagram of domestic PV installed capacity
Figure 2. System topology of a desert power plant