As in any power plant, photovoltaic (PV) power plants in operation require maintenance. In addition, more than 10 years after the first Italian feed-in tariff that is dated 2005, as the power plants become older, operation and maintenance (O&M) becomes more and more important for improving or keeping the performance of the plants.
Another aspect to be taken into account is that usually utility-scale grid-connected PV plants are in remote locations with unreliable communication and middle voltage (MV) distribution infrastructure. Most of the remote monitoring systems need an Internet connection, and in the absence of a reliable connection, there could be problems of lack of data logging for long periods of time. In addition, high penetration level of renewable distributed PV generation into current MV distribution grids is often impeded by technical barriers mainly due to their intermittent and non-dispatchable nature that poses serious problem for the energy management and operational planning of the grids and, in prospective, the future smart-grids.
System O&M and management of PV plants is a broad area and is the continuing focus of several industry/government/national laboratory working groups.
The proposed research - that will be developed in collaboration with a multi-stakeholder team in order to be a real-world research activity directly applied in their existing plants ¿ is aimed at defining, assessing and testing new methodologies, approaches and best practices in the O&M, monitoring and management of utility-scale grid-connected PV plants. The final ambitious goal is to develop widespread consensus approaches over the next two years.
The goal of the research is to develop through analytical, numerical and conceptual models novel methodologies and practices in PV systems that will be directly validated by means of the collaboration with the industrial partners. We believe that the rigorous demonstration and validation in real-world plants will accelerate the widespread adoption of these innovative methodologies.
Obviously innovations will require the technician involved in the PV systems to acquire new skills and knowledge that must be properly defined and explained.
Entering into the details, the research will proceed towards the aforementioned adjectives.
As concern Objective-1 Innovative solutions for operation and maintenance, a huge database of all the problems detected in existing utility-scale PV plants of the industrial participants will be established. The relevant data will be collected, e.g., general data of the plant, operational event data, maintenance classification, and contributing factors analysis. Successively, corrective actions will be conceived and their suitability and effectiveness will be assessed through direct testing on the plants. The focus will be on all the innovative aspects that can promote improvements in the solution of common problems and that consequently reduce failures and enhance performance. Specifically:
1. New design rules will be defined for the control of overvoltages making use of FEM-MoM-FDTD numerical codes that will be properly developed;
2. New practices will be defined for the effective earthing and grounding of equipment making use of a MoM numerical code for stratified media whose set-up is ongoing;
3. New configurations and layout will be developed for the reduction of radiated and conducted electromagnetic interferences in order to reduce the susceptibility of sensitive control equipment; to this end a macro-modeling approach will be used.
4. New schemes will be developed about the use of the lightning protection system (LPS), SPDs and MOSAs; a simulink-matlab approach will be used to carry out the simulations in the time domain and accounting for the nonlinear behaviour of the surge arresters;
5. The reliability of new modern optic fiber intruder alarm systems will be investigated and assessed.
In addition, a particular attention will focused on the innovative smart use of UAVs in monitoring different PV plants in a cooperative way. In the last decade, UAVs started to appear in many application areas like power transmission lines inspection, disaster relief, oil and gas pipelines, and so on. Nevertheless, one of the most signi¿cant applications of UAVs is energy equipment monitoring. Typically, they are used in inspection purposes since they present some special advantages like large area coverage, precise imagery, fast detection, high ¿exibility, light weight, low cost, ability to operate in hostile environments. The research will investigate UAS applications in PV management in order to propose a low cost, rapid and reliable method to inspect energy plants, achieve and maintain high performance during operations.
With regards to Objective 2: Remote monitoring, generally speaking, remote control and monitoring can be performed by various remote connections: analog modem, ISDN, GSM, satellite connections, etc. The most common connection for local/remote control are USB (sometimes even RS232) for local monitoring, RS485 for inverter interconnection. For wireless connection Bluetooth and Wi-Fi are most common used. Firstly, the suitability of innovative PV DC field Wi-Fi control and supervision links will be investigated, also paying attention to the electromagnetic compatibility with other sensitive equipment, e.g., TVVC and intruder systems. Successively, the suitability of innovative systems based on power line communications (PLC) will be investigated for local/remote control and monitoring.
As concern Objective 3: Smart-grid integration the main innovative idea of the research is to develop distributed decentralized prediction techniques for the forecasting of the power generated by PV plants. The techniques are mainly intended for asset owners that hold a wide portfolio of PV systems that are usually geographically spread out over large areas. Consequently the underling idea is to keep the algorithms manageable for the single agent, which processes only the generated power data that are always available also due to ¿scal laws, and to use more agents located in different plants that share only relevant information to minimize communication among the plants. Our methods will require only a reliable communication channel (linked to Objective-2) that is always present nowadays for O&M purposes.