SOLUTION

Against the backdrop of global efforts to promote the development of clean energy, photovoltaic and wind power, as important renewable energy sources, continue to expand their power generation scale. In the generation, transmission and grid connection of these two energy sources, transformers play a key role and become the core equipment to ensure stable operation and efficient power supply of the system.

▷The role of transformers in photovoltaic systems

1. Voltage conversion

1.1 Boosting after DC to AC: Photovoltaic modules generate DC power, with a voltage usually between 600 and 1500V. After the DC power is converted to AC power by an inverter, it is necessary to use a step-up transformer to increase the voltage to the grid required level, such as the common 10kV, 35kV or even higher, in order to reduce the power loss during the transmission process, because it needs to be connected to the grid for long-distance transmission. For example, in large ground photovoltaic power stations, the AC power output by the inverter is increased from several hundred volts to medium and high voltage through a box-type step-up transformer to meet the grid transmission conditions.​

1.2 Adapting to different grid voltages: There are differences in grid voltage standards in different regions. Transformers can be customized according to local grid specifications. By adjusting the winding turns ratio and other methods, the output voltage of the photovoltaic system can be adapted to the local grid voltage to ensure that the power is smoothly connected to the grid. ​

2. Application of transformers in different types of photovoltaic power stations

2.1 Centralized power stations: Large-scale ground-based centralized photovoltaic power stations are large in scale and have high power generation. The "string/centralized inverter + box-type step-up transformer" structure is often used. After the AC power output by multiple inverters is connected in parallel, it is uniformly connected to the box-type step-up transformer for step-up. This structure is highly economical, easy to centrally manage and maintain, and can efficiently step up large-scale photovoltaic power and connect it to the grid.

2.2 Distributed power stations: For small distributed systems such as rooftop photovoltaics, if the power is small, low-voltage grid connection (such as 400V) can be directly used without an additional step-up transformer; when the power is slightly larger and needs to be connected to the medium-voltage distribution network, the voltage is increased to an appropriate level through a low-voltage step-up transformer. Transformers in distributed power stations are usually small in size and flexible in installation to adapt to installation spaces such as roofs of different buildings. ​

If you are interested for more information, pls ckick here.AISITE-PRODUCT SELECTION GUIDE.(1).pdf   

▷ Transformers in wind power systems ​

1. Voltage matching and boosting ​

1.1 Boosting inside wind turbines: The voltage of the electric energy generated by wind turbines is relatively low, generally around 690V. In order to reduce the loss of electric energy during transmission and meet the requirements of subsequent access to the power grid or collection system, it is necessary to equip transformers inside or near the wind turbines to increase the voltage. For example, it is common to boost the voltage of 690V to 35kV to facilitate the transmission of electricity in the internal collection lines of the wind farm. ​

1.2 Overall boosting and grid connection of wind farms: A wind farm consists of many wind turbines. After the boosted electric energy of each wind turbine is collected together, it needs to be boosted again to connect to the power grid with a higher voltage level. At this time, a large step-up transformer will be used to further increase the output voltage of the wind farm from medium voltage levels such as 35kV to high voltage levels such as 110kV and 220kV, so as to achieve connection with the regional power grid and transmit wind power to the load center over long distances. ​

2. Adapt to complex environments and special needs ​

2.1 Protection design: Wind farms are often built in coastal areas, plateaus, wilderness and other harsh environmental areas, facing the test of wind and sand, high temperature, high humidity, salt spray and other tests. Wind power transformers must have a high protection level, such as IP54 or above, to prevent the intrusion of dust, rain and other materials to ensure the normal operation of internal electrical components. In wind farms in coastal areas, transformers must also use special anti-corrosion materials and processes to resist salt spray corrosion. ​

2.2 High efficiency and heat dissipation optimization: The output power of wind turbines fluctuates greatly during operation, requiring transformers to have high efficiency and good heat dissipation performance. Transformers made of low-loss silicon steel sheets or amorphous alloys can reduce their own energy consumption and improve energy utilization. At the same time, combined with natural cooling, forced air cooling or oil cooling and other heat dissipation methods, ensure that the temperature of the transformer remains within a reasonable range and operates stably under high load fluctuations. ​

3. Application cases of different voltage levels ​

3.1 35kV voltage level: In some small and medium-sized wind farms, the 35kV voltage level is more common. After the wind turbine is boosted to 35kV, the electric energy is collected to the booster station through the 35kV collector line. 35kV all-aluminum oil-immersed transformers are widely used in wind farms of this voltage level due to their advantages such as light weight, good heat dissipation and relatively low cost. They are responsible for the voltage boost of wind turbine outlets and the voltage matching of collector lines. ​

3.2 66kV and above voltage levels: With the development of wind power technology and the expansion of wind farm scale, some large wind farms have begun to use 66kV or even higher voltage level collector lines. Compared with 35kV, 66kV collector lines have higher voltage and larger carrying capacity, which can greatly improve the efficiency of power transmission and reduce line active power loss. In such projects, 66kV dry-type transformers and other equipment are used to provide reliable guarantee for high-voltage wind power transmission.

For more information, pls click here.AISITE-PRODUCT SELECTION GUIDE.(1).pdf   

Manufacturer's View