Distributed photovoltaic power stations are more complex in geographical distribution, including roof, mountain and other occasions, the use of traditional monitoring platform is difficult to achieve effective monitoring and control of distributed photovoltaic power stations, and the efficiency and accuracy of monitoring are relatively low. Therefore, it is necessary to build an efficient distributed photovoltaic power station monitoring platform to realize the effective management of inverters and other equipment of different manufacturers, different categories and different models in the photovoltaic power station, and realize the complete and unified real-time monitoring and control of all photovoltaic power stations in the region, so as to better ensure the stable operation of distributed photovoltaic power stations. This paper first analyzes the development status of distributed photovoltaic and power generation characteristics, followed by the specific distributed photovoltaic power station intelligent monitoring principle and the monitoring system has the function, and finally analyzes the distributed photovoltaic power station management and control platform development technology, including network communication technology and network security technology.
1. Distributed photovoltaic power generation characteristics
1.1 Development status of distributed PV
At present, whether it is distributed photovoltaic or centralized photovoltaic, the installed capacity is increasing rapidly, the development situation is good, and the proportion of photovoltaic power generation in electricity consumption is also significantly increased. Distributed photovoltaic is generally connected to the distribution network, so that the power in the distribution network has the characteristics of two-way flow, and there will be a large number of distributed photovoltaic power stations connected to the system in the future. However, after large-scale distributed photovoltaic access to the system, it is necessary to monitor these distributed photovoltaic power stations to master the specific operation information of photovoltaic power stations, so as to guide grid dispatching operators and optimize the operation mode of the system.
1.2 Power generation characteristics of distributed PV
The photovoltaic power generation system mainly relies on solar panels to accept the intensity of solar light and convert solar energy into electricity, so its output size and the light intensity received in the photovoltaic array has a direct relationship. In terms of power generation characteristics, the output is larger during the day, and the output is zero when there is no sunlight at night. In addition to this volatility, the photovoltaic output also has randomness, which requires the power system to have a certain positive rotation reserve capacity and negative rotation reserve capacity to meet the requirements of real-time power balance of the system.
2. Intelligent monitoring technology of distributed photovoltaic power station
2.1 Principle of intelligent monitoring of distributed photovoltaic power stations
In order to realize the intelligent monitoring of distributed photovoltaic power station, it is necessary to use the monitoring function module, sensing function module and computing function module in the photovoltaic power station monitoring system. Among them, the monitoring function module can be used to monitor the inverter and other components and circuits in distributed photovoltaic power stations in real time. The sensor module is mainly composed of temperature sensor and optical sensor. The temperature sensor is used to collect the operating temperature information of the photovoltaic power station equipment. When the temperature exceeds the set threshold, it should reliably send alarm information. Optical sensors can be used to monitor the intensity of sunlight in photovoltaic power plants, so as to better manage distributed photovoltaic power plants. The calculation function module can analyze and process the collected operating data of photovoltaic power station, and get the specific operating status results of photovoltaic power station. At the same time, in the intelligent monitoring system of distributed photovoltaic power station, it can be divided into two levels of sub-station and main station, through a unified communication protocol and communication program, to achieve data collection and transmission and operation control instructions.
2.2 Function of intelligent monitoring of distributed photovoltaic power stations
The construction of an intelligent monitoring platform for distributed photovoltaic power stations also plays an important role in optimizing the operation of distributed photovoltaic power stations. When the installed capacity of distributed photovoltaic power stations is large, it will have a certain impact on the operation of the power grid, and even bring certain challenges to the stable operation of the power grid. The intelligent monitoring platform of distributed photovoltaic power station can effectively control the operation of each distributed photovoltaic power station within the jurisdiction. Figure 1 shows the basic flow chart of sending power control instructions for photovoltaic power stations.
As can be seen from Figure 1, the distributed photovoltaic power station monitoring platform can calculate the overall power distribution according to the current output of each power station, day plan, peak load constraint, photovoltaic acceptance capacity and other data information, and issue power generation plans to each distributed photovoltaic power station. The actual output data of each power station needs to be within the range of the planned value, so that it can carry out overall scheduling of each distributed photovoltaic power station within the global scope of the entire power grid normally, so as to optimize the operation of the power grid.
3. Development technology of distributed photovoltaic power station management and control platform
3.1 Structure of distributed photovoltaic power station management and control platform
Before developing the distributed photovoltaic power station management and control platform, it is necessary to design the structure of the distributed photovoltaic power station management and control platform, and evaluate whether the architecture can meet the requirements of monitoring and whether it also meets the requirements in terms of network communication security performance. Because distributed photovoltaic power stations are more dispersed in geographical distribution, it is difficult to use wired communication. Wireless communication systems are generally used to connect each distributed photovoltaic power station with each other, and wired communication methods are generally used in the communication of centralized photovoltaic power stations. Figure 2 shows the architecture diagram of centralized monitoring system of distributed photovoltaic power stations.
As can be seen from Figure 2, the distributed PV power station centralized control system is responsible for statistical centralized monitoring and control of several geographically dispersed PV power station subgroups. The centralized monitoring platform plays the role of uploading and controlling, which can not only accept the data information uploaded by the sub-station system, but also issue the corresponding control commands to each distributed photovoltaic sub-station group, so as to achieve the purpose of controlling the operation of distributed photovoltaic power stations. In the distributed photovoltaic power station centralized monitoring master station system network mode, can adopt Gigabit Ethernet network, and build dual network redundancy configuration, to improve the communication reliability of the master station network system.
3.2 Network communication technology in distributed photovoltaic power station management and control platform
According to the centralized control system architecture of photovoltaic power station in Figure 2, each distributed photovoltaic sub-station group needs to communicate with the centralized control center with the help of wireless communication network. The wireless communication network system not only has the advantages of flexible application, but also has some security problems such as being vulnerable to network attacks. In order to ensure the stable operation of the communication system in the distributed photovoltaic power station management and control platform, it is necessary to ensure the reliable operation of the optical fiber and other links in the communication system. Secondly, it is necessary to configure corresponding network security protection technical measures in the communication system to improve the security of the distributed photovoltaic power station data in the communication process between the sub-station and the monitoring master station. If the information encryption device can be deployed between the distributed photovoltaic sub-station group and the centralized control master station, the information encryption device of the corresponding capacity is selected according to the size of the data communication throughput. In addition, in the distributed photovoltaic monitoring master station system, malicious code protection procedures and security audit systems should be deployed, so that abnormal processes exist in the monitoring master station system can be found in time, and security audits are carried out on each network access behavior to ensure the network security of the distributed photovoltaic power station monitoring master station system.
4. Conclusion
Because of the wide distribution of distributed photovoltaic power stations, it is difficult to carry out unified monitoring, which is also the key technology to overcome in the development of distributed photovoltaic and achieve large-scale industrial applications. By realizing the intelligent monitoring of distributed photovoltaic power stations, the output and operation of distributed photovoltaic can be improved and optimized, and the absorption capacity of distributed photovoltaic can be improved. The development technology of intelligent monitoring platform of distributed photovoltaic power station analyzed in this paper has certain value for improving the operation stability of distributed photovoltaic power station.
