As more and more wind turbines are connected to the grid, the impact of wind power generation on grid power quality 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 can 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 still generate a large inrush current when starting. When the wind speed exceeds the wind cut-off speed, the wind turbine automatically exits rated operation. exit state. If all the wind turbines in the entire wind farm operate almost simultaneously, this impact has a very obvious impact on the distribution network. Additionally, changes in wind speed andthe shadow effect of the wind turbine tower will cause fluctuations. Wind turbine output and fluctuations can produce voltage flashes. In the variable frequency range (below 25 Hz), wind turbines will also cause flicker issues on the power grid during normal operation. main negative impacts of wind power generation on grid power quality.
Grid-connected wind power generation should be monitored using a grid-connected wind power monitoring system. power quality, and power quality requirements are clearly defined. The "Wind Turbine Power Quality Measurement and Evaluation Method" (GB/T 20320-2013) formulated by the National Standards Committee was officially implemented on October 1, 2014. This standard focuses on various aspects of the power quality of wind turbines before they are connected to availablesitions were taken: 1. Voltage fluctuations and flickering; 2. Current harmonics, interharmonics and high frequency components; 3. Response to voltage drops; 4. Measurement of active and reactive power; 5. Network protection; .
The current Chinese grid-connected wind power quality system that strictly meets the standards is the power quality monitoring system of Zhiyuan Electronics. Not only is the power quality monitoring device very reliable, but its background software monitoring system is also very mature.
There are certain conditions required for the wind turbine to be connected to the grid, mainly when the wind speed reaches the wind start speed, the unit starts to enter sleep state. At this time, the unit starts to wait for the turbine speed to reach the starting state, then the unit blades start to movetowards the optimal tilt angle. Once the turbine speed reaches the grid connection speed, the unit begins to connect to the grid. Before connecting to the network, the unit must quickly pass through the resonance zone of the tower.