With the large-scale development of photovoltaic power station construction, the photovoltaic management system, as the operation and maintenance management solution of the photovoltaic power station, will mainly focus on two core objectives: to protect the power generation to enhance the benefits, and to operate and maintain the cost effectively to reduce the operation and maintenance costs.
Under normal circumstances, a third-party commercial company can be involved in the information gathering and real-time monitoring of the power station as long as it meets the requirements of the power grid specification. However, for a large-scale power station in a certain area, such as more than 300MW, power generation owners may prefer to use more domestic large-scale power plant monitoring and control vendors.
The photovoltaic industry not only involves large ground power stations, but also a large number of distributed power plants. From the actual situation, there are also many new monitoring companies in the country currently entering the field of photovoltaic monitoring.
In addition to the information acquisition and real-time monitoring that meets the grid requirements, with the large-scale development of photovoltaic power station construction, the photovoltaic management system, as the operation and maintenance management solution for photovoltaic power plants, will mainly focus on two core objectives: ensuring power generation to increase revenues. , Efficient operation and maintenance to reduce operation and maintenance costs.
In order to achieve the above double-efficient management objectives, the photovoltaic power plant management system must better match the rapid development of the photovoltaic industry in recent years, and introduce a new type of photovoltaic with a more adaptable scene that incorporates modern digital information technology, communication technology, and big data mining technology. Power station operation and maintenance solution. Therefore, the change of the monitoring system in the following aspects will better meet the needs of customers and increase the efficiency of operation and maintenance while ensuring the increase of power generation:
First, from "a single power logical view and device tile" to "intuitive topology and power logic multi-view combination"
Existing photovoltaic power plant monitoring and management systems have many predecessors, and the systems of mainstream manufacturers have come from traditional thermal power or hydropower industries. However, in terms of management, the management of hydropower and thermal power systems, including wind power, is different from that of photovoltaic power plants, the most important of which is the management volume. A medium-sized photovoltaic power plant of about 30MW will involve more than 100,000 photovoltaic panels, combiner boxes, inverters, and box transformers. With such a large number of management objects, traditional power monitoring systems that focus on power distribution with a small number of management systems need to have relatively strong professional backgrounds and application experience, or they must be qualified for multiple trainings by manufacturers.
Due to the rapid construction of the photovoltaic industry in recent years, there are also a large number of new talents influxing into the photovoltaic industry. These people are very familiar with the Internet and combine the Internet-based system operation experience design with the traditional power design human-computer interaction interface. Topological structure organization to improve management efficiency will help users to more easily integrate into operation and maintenance activities.
Second, from "participation in the analysis process" to "only focus on results"
No user will continue to observe the data such as voltage and current, which are inexhaustible for each level. What is needed is the presentation of results. However, the results rely on accurate monitoring and intelligent online analysis to achieve automated and accurate reporting.
If the inverter is used as a carrier for monitoring, the centralized inverter tracks the maximum power point of the PV string relatively to some extent, ignores the inconsistency of the maximum power point of the string, and faces insufficient management and management. Fine problems, and by detecting the voltage and current of each channel of the DC combiner box, not only increase the cost, but also the detection accuracy can not meet the requirements.
The string inverter solution can accurately monitor the current and voltage of each string of the inverter, and the data sampling accuracy can reach over 0.5%. It is used to support different strings, between different inverters, and different types of PV. The collection and analysis of real-time power between arrays can promptly identify faults and power generation units. More importantly, it is intuitively displayed to the operation and maintenance personnel in real time, thereby reducing the manual participation in operation and maintenance and pushing the results in an intuitive manner.
Third, from the "unreliable, low bandwidth" to "high reliability, high bandwidth" within the square network
Low-cost network formation and high-efficiency care and management of power generation are the most primitive requirements of photovoltaic power plant monitoring and networking. At present, each PV square array mainly uses RS485 mode and inverters, intelligent combiner boxes, box transformers, and measurement and control devices, and environmental monitoring. Instrument and other communications. With the increase in the number of bus-connected devices and the transmission distance, the influence of interference causes the RS485 communication mode to be unstable.
For example, when a large-scale ground power station in China was built for the first time, the percentage of down-linked smart devices obtained by the various parties' communication management machines or data collectors was less than 60%, and the remaining 40% needed to be connected through hardware troubleshooting or software debugging. After adjustment, the monitoring system can be normally connected.
At the same time, the laying of a large number of RS485 communication cables also requires the expenditure of engineering and material costs. Once the communication is abnormal, locating faults on the physical lines will become a highly complex activity.
For this reason, in the construction of a new type of power station, a more reliable, wider bandwidth, and more convenient maintenance of communication methods is needed to solve the problem of communication collection within each photovoltaic square array. Because power is transmitted through power cables regardless of the type of photovoltaic array deployed on the terrain, power cables cannot be saved. Therefore, the PLC (Power Line Communication) power line carrier method is a method worthy of research and promotion. . Using PLC communication technology, the main flow production of the chip built-in inverter in the way, the supported bandwidth can reach more than 5Mbps, much higher than the existing 9485bps communication speed commonly used by RS485. The guarantee of greater communication bandwidth can greatly reduce the communication abnormality, and the transmission distance can reach 3000 meters at the maximum, meeting the deployment requirements in the PV array. At the same time, the deployment of RS485 communication cables is saved, and troubleshooting will become easier.
Fourth, from the "position of the problem location and inspection" to "remote all-round coordination"
The dedicated wireless high-speed communication system for photovoltaics based on 4G technology provides a convenient channel for barrier-free communication between experts on site and central control centers. It can not only return real-time video and voice, but also return information of on-site infrared thermal imagers. For experts to immerse in the problem diagnosis. Reduce the skill requirements of on-site maintenance personnel. In the future, after building a centralized control center, the remote centralized control center will retain expert personnel to guide local maintenance.
Fifth, from "manufacturer's custom report" to "big data analysis engine"
For the management of large-scale photovoltaic power plants, currently existing production management systems mainly use historical reports to present historical data analysis. The reports of mainstream manufacturers mainly focus on fixed formats. When users have new demands for diversification and different formats, they need to look for manufacturers to make customizations. The big data analysis engine will be able to solve the needs of customization and flexibility. Using this engine, you can discover potential defects in time and perform proactive operations.
Current data collection and monitoring issues and solutions
Existing photovoltaic power plants are not fully information-based. Most of the monitoring data have been collected, but there is a lack of integration with production management systems and information sharing with users' ERP systems. This has led to the inability to obtain accurate information on stock assets and the cost of day-to-day operations during the evaluation of the plant.
Only by collecting all the above information, and doing comprehensive big data analysis on the basis of this, customized output and financial, power plant business operations related to the report, used to support assessment and trading. In the end, through centralized control centers, owners and power station buyers can clearly see the global strategic maps of each power station’s investment and operations, so as to better assess the future and deal clearly and transparently. At the same time, the financial assets of the power station assets are also transparent. It is beneficial to the mortgage and financing of power station assets, which will help the owners to further expand their business scale.
Current data collection and monitoring issues:
1, monitoring data can not be adopted, can not be trusted. There is no string monitoring or only simple string data collection, monitoring accuracy is not high, measurement data is not accurate;
2. It is difficult to report communication data. The monitoring data is uploaded through the RS-485 bus. The transmission rate is low, communication failures are numerous, and false alarms and missed reports are serious.
3, fault location difficult. The number of PV power plant components and nodes is huge, and there is no effective fault location method. The fault detection mainly depends on the manual station, manual measurement and comparison through a multimeter, long fault handling cycle, affecting power generation output, low maintenance efficiency, and large manpower investment;
4. There is a lack of digital means for power station management. The monitoring information is simply collected and presented. A large number of data reports are handled manually by Excel. The ability of comprehensive data analysis is poor. The lack of quantitative measures for the analysis and improvement of power plant operations cannot achieve multi-power station management.
Taking Huawei's intelligent photovoltaic power plant solution as an example, the current integrated solution of smart power plants can accurately monitor the current and voltage of each string of the inverter, and are used to support different strings, between different inverters, and different Real-time power acquisition and analysis between PV arrays, any fault and power generation units can be found in a timely manner. More importantly, it is intuitively displayed to the operation and maintenance personnel in real time, thereby reducing the manual participation in operation and maintenance and pushing the results in an intuitive manner.
It mainly has 3 characteristics:
1. Global operation and maintenance
Cloud computing-based centralized operation and maintenance center:
Based on the cloud computing platform, it has the ability to manage data access of dozens of GWs and hundreds of power stations. It supports data storage for 25 years and hundreds of terabytes, complete permission control and authentication mechanisms to ensure data security.
Support multi-station access, expand access to new power stations, manage multiple power stations located at different locations in the country/world as local logic power stations, analyze the completion status and operation and maintenance investment of each power station throughout the year and month, and assist Group leader decision analysis;
Summarize multiple power plant production data and fusion analysis to form a set of KPI indicators across the power station to evaluate the operation of the power station, assess the health status of the power station, quickly identify short boards, and give optimization advice;
Front and rear co-operation and maintenance, the group experts can guide the on-site engineers to handle faults through voice and real-time video;
2. Intelligent operation and maintenance
Throughout the entire life cycle of the power station, monitoring and management of the entire production chain, truly visual, credible, substantial and controllable:
The use of PV terminals and dedicated applications to assist in the rapid and accurate entry of assets, record equipment models, manufacturer information, electrical topology, and GPS location information for all assets. Each module and each node is managed, traceable, and traceable.
Photovoltaic power plant production all-round monitoring, accurate control of multi-dimensional production status information from the string, inverter, combiner box, box change, collection station, step-up change, real-time monitoring data per MW sub-array reaches 100kbps;
Using big data analysis technology, the monitoring data are aggregated and analyzed, and targeted optimization suggestions are given to achieve refined operation and maintenance, preventive operation and maintenance, such as component cleaning suggestions.
According to the operation status and maintenance data of the assets, it supports the evaluation of equipments of different batches or different manufacturers, and gives an asset assessment report;
3. Efficient operation and maintenance
From the overall situation to the details of in-depth visual monitoring, can monitor and display the production and operation status of power plants, regions, sub-arrays, inverters and strings in real-time, and automatically recognize backward components.
Precise positioning of faults and health check of power plant equipment to improve fault closed loop efficiency;
The new mobile operation and maintenance centered on photovoltaic terminals and App, mobile ticket and operation ticket are mobile and electronic;
UAV technology was introduced to achieve rapid inspections over a wide range of areas and improve the efficiency of operation and maintenance.
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