The power generation level during operation is a key factor affecting the economic benefits of power stations. Therefore, how to ensure efficient power generation of photovoltaic power plants has become the primary problem facing operators. Before solving this problem, we first need to analyze the loss of photovoltaic power plant equipment, understand where the power station loss occurs, and then clearly determine the means to control the loss of the power station within a reasonable range.
Photovoltaic power plant common loss
★Photovoltaic module and combiner box equipment fault loss
For photovoltaic arrays and combiner boxes, the losses will be directly affected by the pre-construction and later operation and maintenance, and the loss factors involved are more. There are many types and types of equipment involved in the DC terminal of photovoltaic power plants. For example, for 30MW photovoltaic power plants, according to the general situation, there will be 420 DC combiner boxes, and each branch has 16 branches (a total of 6,720 branches). Each branch has 20 panels (a total of 134,400 panels), and the total amount of equipment is huge. The more the number, the higher the frequency of equipment failures and the greater the power loss. Common problems include the attenuation of PV modules, the ignition of junction boxes, the cracking of battery boards, the soldering of leads, the hot spots of the combiner box, and the faults of the branch.
At the same time, if the above type of fault occurs in a component of a single string, the overall output of the string will be directly reduced; due to the failure of a single string, the voltage and current of each string in the same combiner box are greatly different, resulting in High mismatch loss. The above situation will directly affect the power generation on the DC side of the PV power plant.
★Recommended loss reduction one
Strengthen product quality control, ensure product quality of solar mounting bracket components and combiner boxes, and avoid loss of power generation of the entire power station caused by product quality problems. In order to control the entire production process, production process and raw materials of the solar mounting structure components, strengthen the inspection of the acceptance of the solar panel support components; for the DC combiner box, control the quality of the electrical components used in production, and at the same time do the acceptance inspection to ensure the arrival of goods. The quality of PV modules and combiner boxes is controlled during production and transportation.
★Reducing the loss of the second
Strengthen the completion acceptance, ensure the quality of PV modules and combiner boxes in the construction process through effective acceptance means, and ensure the construction quality of the power station. The recommended acceptance contents are as follows: component EL test; Voltage and current test (open circuit voltage, short circuit current, working current, working voltage); electrical connection check of the combiner box (avoid polarity error, virtual connection, etc.)
★Reducing the loss of the three recommendations
Improve the intelligent operation level of the power station, monitor the work status at the string level, and then analyze the data, find out the fault source in time, perform point-to-point troubleshooting, improve the work efficiency of the operation and maintenance personnel, and generate electricity due to the DC terminal fault. The amount of loss is minimized.
Inverter losses are mainly reflected in two aspects, one is the loss caused by the inverter conversion efficiency, and the other is the loss caused by the MPPT maximum power tracking capability of the inverter. Both of these aspects are determined by the performance of the inverter itself, and the benefit of reducing inverter losses through later operation and maintenance is small. Therefore, the equipment selection at the initial stage of power plant construction is locked, and the loss is reduced by selecting an inverter with better performance. In the later operation and maintenance stage, the inverter operation data can be collected and analyzed by intelligent means to provide decision support for the equipment selection of the new power station.