Power station loss based on photovoltaic array absorption loss and inverter loss
In addition to the impact of resource factors, the output of photovoltaic power plants is also affected by the loss of power station production and operation equipment. The greater the power station equipment loss, the smaller the power generation. The equipment loss of photovoltaic power stations mainly includes four categories:
- Photovoltaic Square Array Absorption Loss.
- Inverter Loss.
- Power Collection line.
- Box Transformer Loss, Booster Station Loss, etc.
- The absorption loss of the photovoltaic array is the power loss from the photovoltaic array through the combiner box to the DC input end of the inverter, including photovoltaic component equipment failure loss, shielding loss, angle loss, DC cable loss, and combiner box branch loss.
- Inverter loss refers to the power loss caused by inverter DC to AC conversion, including inverter conversion efficiency loss and MPPT maximum power tracking capability loss.
- The power collection line and box transformer loss are the power loss from the AC input end of the inverter through the box transformer to the power meter of each branch, including the inverter outlet loss, box transformer conversion loss, and in-plant line loss.
- The booster station loss is the loss from the power meter of each branch through the booster station to the gateway meter, including primary transformer loss, station transformer loss, bus loss, and other in-station line losses.
After analyzing the October data of three photovoltaic power plants with a comprehensive efficiency of 65% to 75% and an installed capacity of 20MW, 30MW, and 50MW, the results show that the photovoltaic array absorption loss and inverter loss are the main factors affecting the output of the power station. The photovoltaic array has the most extensive absorption loss, accounting for about 20~30%, followed by inverter loss, about 2~4%. In contrast, the power collection line, box transformer loss, and booster station loss are relatively small, with a total of almost accounting for about 2%.
Further analysis of those mentioned above 30MW photovoltaic power station’s construction investment is about 400 million Yuan. The power loss of the power station in October was 2,746,600 kWh, accounting for 34.8% of the theoretical power generation. If calculated at 1.0 yuan per kilowatt-hour, the total October loss was 4,119,900 Yuan, which had a massive impact on the economic benefits of the power station.
How to reduce the loss of photovoltaic power stations and increase power generation?
Among the four types of losses of photovoltaic power plant equipment. The losses of the collection line, box transformer, and the failure of the booster station are usually closely related to the performance of the equipment itself, and the losses are relatively stable. However, if the equipment fails, it will cause a considerable loss of power, so it must ensure its regular and stable operation. Technicians can minimize the loss of photovoltaic arrays and inverters through early construction and later operation and maintenance. The specific analysis is as follows.
(1) Failure and loss of photovoltaic modules and combiner box equipment
There is much photovoltaic power plant equipment. The 30MW photovoltaic power plant in the above example has 420 combiner boxes, each of which has 16 branches (6720 branches). Each branch has 20 panels (a capacity of 134,400 batteries). The total amount of equipment is enormous. The greater the number, the higher the frequency of equipment failures and the greater the power loss. Common problems mainly include burnt-out photovoltaic modules, fire on the junction box, broken battery panels, false welding of leads, faults in the branch circuit of the combiner box, etc. To reduce the loss of this part, on the one hand, we must strengthen the complete acceptance and ensure adequate inspection and acceptance methods.
The quality of power station equipment is related to the quality, including the quality of the factory equipment, equipment installation and arrangement that meet the design standards, and the construction quality of the power station. On the other hand, it is necessary to improve the brilliant operation level of the power station and analyze the operational data through intelligent auxiliary means. That is to find out in time fault source, carry out point-to-point troubleshooting, improve the work efficiency of operation and maintenance personnel, and reduce power station losses.
(2) Shading loss
Due to factors such as the installation angle and arrangement of the photovoltaic modules, some photovoltaic modules are blocked, which affects the power output of the photovoltaic array and leads to power loss. Therefore, during the design and construction of the power station, it is necessary to prevent the photovoltaic modules from being in the shadow. At the same time, technicians should install an appropriate amount of bypass diodes to reduce the damage to the photovoltaic modules by the hot spot phenomenon. That is to divide the battery string into several parts so that the battery string voltage and the current are lost proportionally to reduce the loss of electricity.
(3) Angle loss
The inclination angle of the photovoltaic array varies from 10° to 90°. Technicians usually select it depending on the purpose and the latitude. The angle selection affects the intensity of solar radiation on the one hand. On the other hand, the power generation of photovoltaic modules is affected by dust and snow—power loss caused by snow cover. At the same time, intelligent auxiliary means can control the angle of photovoltaic modules to adapt to changes in seasons and weather and maximize the power generation capacity of the power station.
(4) Inverter loss
Professionals mainly reflect Inverter loss in two aspects: the loss caused by the conversion efficiency of the inverter and the other is the loss caused by the MPPT maximum power tracking capability of the inverter. The performance of the inverter itself determines both aspects. The benefit of reducing the loss of the inverter through later operation and maintenance is negligible. Therefore, the equipment selection at the initial stage of the power station construction is locked, and the loss is reduced by selecting the inverter with better performance. In the later operation and maintenance stage, the operation data of the inverter can be collected and analyzed through intelligent means to provide decision support for the equipment selection of the new power station.
From the above analysis, we can see that losses will cause considerable losses in photovoltaic power plants. Technicians should improve the overall efficiency of the power plant by reducing losses in critical areas first. On the one hand, they use practical acceptance tools to ensure the quality of the equipment and construction of the power station. On the other hand, in the process of power station operation and maintenance, it is necessary to use intelligent auxiliary means to improve the production and operation level of the power station and increase the power generation. So these are the main causes of loss of photovoltaic power stations.