Intelligent operation and maintenance throughout the full life cycle of pv power stations
The full life cycle of a photovoltaic power station lasts for 25 years. Among them, 3 to 6 months is the construction period, and the nearly 25 years following that is the operation and maintenance period. The revenue of the power station and the stability of the equipment are mainly guaranteed through operation and maintenance.
（The full life cycle diagram of the photovoltaic power station）
The importance of operation and maintenance is self-evident. Then, what are the key points for the operation and maintenance of power stations?
1. The Current Situation of Photovoltaic Power Station Operation and Maintenance
（The problems of power station operation and maintenance at the present stage）
With the construction of the new power system, photovoltaic power stations have developed from manual operation in the past to fewer personnel or even unmanned operation. First of all, the intelligence of equipment. Take inverters as an example. From the earliest simple DC/AC function to the previous adaptation to the power grid and now the support for the power grid, it can achieve intelligent functions such as active and reactive power regulation, reactive power compensation, PID repair and anti-PID, IV scanning and diagnosis, AFCI, RSD, etc.
Secondly, the intelligence of the monitoring system. With the vigorous development of the county-wide household projects, the number of distributed power stations has increased and they are widely distributed. From a single local monitoring, it has developed into a centralized monitoring system for multiple power stations of groups and regions. Integrated station control systems such as GoodWe’s Smart Energy System, SolarOS System, SEMS System, etc., provide technical support for the centralized intelligent operation and maintenance of groups.
2. Typical Problems of Photovoltaic Power Stations
2.1 Installation Location of Inverters
The installation location of inverters has a certain influence on the power generation of the power station and the stability of the equipment: The inverters should maintain a certain installation spacing and installation height to facilitate ventilation and heat dissipation of the inverters and to facilitate the inspection of the power station. The installation of inverters should avoid direct sunlight. Direct sunlight can easily lead to the aging of components inside the machine, and the increase in temperature will affect the overall service life and power generation efficiency of the inverter. If necessary, baffles should be installed.
2.2 Inverter DC String Wiring and DC Terminal Crimping
Virtual connection or poor contact of the DC string wiring may cause abnormal heating or even fire, so this detail also needs attention in operation and maintenance. Make sure that the DC switch of the inverter is in the off state before connecting the photovoltaic modules; Make sure that the polarity of the photovoltaic module matches the DC connector, with the positive pole connected to PV+ and the negative pole connected to PV-; Make sure that the voltage and current of each string of components are within the input range of the inverter. PS: When wiring the string or operating and maintaining the string, the components of each DC input of each MPPT of each channel should be consistent, including the number of components, azimuth angle, tilt angle, component parameters, etc.
Many on-site workers directly use inferior or even universal tools (such as pliers) for crimping DC terminals. In this way, it is difficult to guarantee the crimping quality and it is easy to cause poor crimping, such as bending of the copper wires of the cable at the joint, some copper wires not being crimped in or mistakenly crimping the insulation layer of the cable, etc. First of all, it is necessary to ensure that the stripping length of the cable is about 8-12mm, and there should be no broken strands or missing wires; in addition, a crimping plier is needed for crimping in place; secondly, the crimping of the copper guide sheet and the DC connector should be stable. For example, with Dianwei, a “click” can be heard.
（Schematic diagram of DC cable crimping ）
2.3 AC Cable Outlet
The cable should not operate under an overload condition, and the lead sheath of the cable should not show expansion or cracking; The MC4 connector should be in good contact and not loose; The grounding wire and grounding flat iron should be connected intact and should not have severe rust; The parts of the cable where it enters and exits the equipment should be well sealed. There should be no holes with a diameter greater than 10mm. Otherwise, use fire
2.4 Common Failures of Components
Movable obstructions such as dust, dirt, and foreign matters caused by the environment can affect the power generation of components and the revenue of the power station; Fixed obstructions such as bird droppings and caked dirt may cause hot spots on components in severe cases, eventually leading to problems such as fires; Component damage caused by the component itself or during the construction, operation and maintenance process, such as broken grids, hidden cracks, black spots and other problems, resulting in reduced power generation and potential safety hazards.
