As more and more wind turbines are connected to the grid, the impact of wind power generation on the power quality of the grid has attracted widespread attention. The uncertainty of wind resources and the operating characteristics of the wind turbine itself make the output power of the wind turbine fluctuate, which may affect the power quality of the power grid, such as voltage deviation, voltage fluctuation and flicker, harmonics, etc.
Most wind turbines adopt the soft grid connection method, but they will still generate large inrush current when starting. When the wind speed exceeds the cut-out wind speed, the wind turbine will automatically exit operation from the rated output state. If All wind turbines in the entire wind farm operate almost simultaneously, and this impact has a very obvious impact on the distribution network. Not only that, changes in wind speed and the tower shadow effect of the wind turbines will cause fluctuations in the output of the wind turbines, and the fluctuations can produce voltage flashes. Within the variable frequency range (below 25Hz), therefore, wind turbines will also bring flicker problems to the power grid during normal operation. Voltage fluctuation and flicker are one of the main negative impacts of wind power generation on power quality of the grid.< /p>
Wind power generation connected to the grid must be monitored using a power quality monitoring system, and the requirements for power quality are clearly defined. The "Wind Turbine Power Quality Measurement and Assessment Method" (GB/T 20320-2013) formulated by the National Standards Committee was officially implemented on October 1, 2014. This standard focuses on various power quality aspects of wind turbines before they are connected to the grid. Provisions were made: 1. Voltage fluctuations and flickers; 2. Current harmonics, interharmonics and high-frequency components; 3. Voltage drop response; 4. Measurement of active and reactive power; 5. Grid protection; 6. Voltage Imbalance.
The current wind power grid-connected power quality system in China that strictly meets the standards is the power quality monitoring system of Zhiyuan Electronics. Not only is the reliability of the power quality monitoring device high, but its background software monitoring system is also very mature.