http : //www.cigre.org C4-1106 AORC Technical meeting 2014 Operational Issues and Solutions for Photovoltaic Power Generation Facilities T. KISHI, K. INOUE, T. SEKI Nishimu Electronics Industries Co., Ltd. Japan SUMMARY Power generation from renewable energy sources such as photovoltaic power, wind power and smallscale hydroelectric generation is attracting attention as a means to deal with global environmental issues and, as a result, large numbers of small-scale decentralized power plants are now under construction. Because renewable energy generation facilities power producers have been rapidly introducing are scattered throughout their service areas, they have to expend a great deal of labor and money on the operation and management of those facilities. This has given rise to a demand for measures to facilitate tasks including the remote collection of facility-related information such as the amount of electricity generated and remote facility monitoring in order to efficiently manage smallscale decentralized power plants. To realize remote monitoring of decentralized photovoltaic power generation facilities, we have developed a system that enables centralized aggregation and management at the data center of monitoring information and video information over an Internet connection. In addition, since the system has the capability to support power conditioners of major domestic manufactures, we can promptly provide the system to power producers. Moreover, the system enables realization of speedy recovery from failures through e-mail notification of facility abnormalities to power producers. Introduction of this system has made possible the centralized management of decentralized information and efficient operation, monitoring and maintenance of photovoltaic power generation facilities. In the future, we plan to even further improve convenience for large-scale photovoltaic power generation facilities (mega solar power plants) by providing the system with string monitoring functions. KEYWORDS Photovoltaic Power - Power Conditioner - Decentralized Power kishi@nishimu.co.jp
1. Background 1.1. Issues and Needs of Power Producers With the spotlight on renewable energy, power producers are in the process of introducing small to medium size photovoltaic power generation facilities, with the result that the number of photovoltaic power plants is increasing every year. Power producers are now faced with the issues and needs listed below to realize the efficient operation of the photovoltaic power generation facilities they have deployed in their multiple plants. - In many cases, photovoltaic power generation facility monitoring data are aggregated in local monitoring equipment, making it difficult to remotely check such data. - To ensure stable power generation, abnormalities must be identified quickly to understand the status and speedy recovery carried out. - Power conditioners need to be capable of being operated locally as well as remotely. - The aggregation of information from each plant and the production of reports on actual power generation performance are labor intensive and time consuming. - It is difficult to remotely check solar panels for damage, foreign material stuck on the surfaces and other abnormalities. - It is not possible to check for intruders in power generation plants. Plant PCS Manufacturer A Power Producer (Plant Manager) Plant PCS Manufacturer B Plant PCS Manufacturer C PCS (Power Conditioning System) Figure 1. Issues of Power Producers 1
2. Solutions to the Issues and Needs 2.1. System Requirements To resolve the issues and meet the needs listed above, we sorted out requirements for power producers and the system as shown below. - Centralized management at the data center of power generation facility monitoring data managed by each power generation plant - A method for centralized management of monitoring data to ensure long-term storage, reliability and expandability - Information transmission equipment installed at power generation plants that is low-cost and compatible with power conditioners of major domestic manufactures - Web-based viewing of monitoring data - Notification by e-mail of fault information to mobile phones and PCs - Capability to remotely control power conditioners - Use of a secure Internet connection to provide a link between power generation plants, the data center and power producers - Use of monitoring cameras to monitor power generation plants for intruders 2.2. Handling the System Requirements We developed a managment server that implements centralized management of monitoring data from power generation facilities and information transmission equipment compatible with power conditioners of major domestic manufactures. In addition, the management server have been provided with functions that enable web-based viewing of monitoring data, e-mail notification when a fault occurs and remotoe control of power conditioners. We combined the management server and information transmission equipment to construct a photovoltaic power generation facility monitoring system as well as monitoring cameras and an image monitoring server provided with functions allowing web-based distribution and recording of camera footage to construct a video monitoring system. We have provided these systems to power producers. 2.3. System Configuration The photovoltaic power generation facility monitoring system consists of information transmission equipment installed at each plant and the management server. Similarly, the video monitoring system consists of monitoring cameras installed at each plant and the image monitoring server. In addition, an Internet connection is used to connect between the components of the photovoltaic power generation facility monitoring system and between the components of the video monitoring system. Power producers can view information from the management server and image monitoring server over an Internet connection and also receive power generation facility fault information by e-mail. 2
Meteorograph Pyranometer Nishimu Data Center Solar panel Power conditioner Information transmission equipment Internet Management server Image monitoring server Monitoring camera PV power generation business operator [Brower access] Mobile phone Fault information notification Data viewing Graphical display Figure 2. System Configuration Numerical display Video display 3. System Description 3.1. Photovoltaic Power Generation Facility Monitoring System 3.1.1. Identification of Information Collection and Monitoring Requirements relating to Photovoltaic Power Generation Facilities Items of information to be collected and monitoring requirements relating to photovoltaic power generation facilities were identified with reference to Guidelines for PV Power Generation Field Test Project (Facility Management and Data Management) and Guidelines for PV Power Generation Field Test Project (System Measurement) of New Energy and Industrial Technology Development Organization (NEDO). 3.1.2. List of Items of Information to be collected (Excerpt) - Amount of electricity generated, including the power output of solar cells and inverters and charge/discharge power of storage batteries - Amount of solar radiation - Temperature 3.1.3. Monitoring Requirements (1) Real-time Monitoring - Display of items including facility abnormalities, facility faults, operating status and communication failures - E-mail notification (2) Monitoring of the Amount of Electricity generated relative to the Amount of Solar Radiation 3
- By monitoring the amount of electricity generated input from each power conditioner and the amount of solar radiation, an alert is issued in the event that the amount of electricity generated is significantly low relative to the amount of solar radiation. (3) Collection Cycle - Measurement cycle: 6 seconds - Calculation cycle: 1 minute and 1 hour (1-minute data and 1-hour data are stored.) 3.1.4. Output of Information The system displays information collected from each plant on the following screens and externally outputs such information: (1) Map display screens: Wide area map screen, detailed area screen (2) Equipment information (e.g. the amount of electricity generated) display screens: Power generation status screen, time series screen (3) Aggregation and analysis screens: Graphical display (comparative display of the amounts of electricity generated at multiple plants), CSV output (4) Alert monitoring screen: Fault information display, operating status display Figure 3. Screen Display of Graph showing Comparison of Amounts of Electricity generated at Multiple Plants 3.1.5 Information Collection and Accumulation (1) Centralized Management of Information The management server database has been configured so that centralized management of information collected can be implemented for each plant. In addition, for database management items, common and manufacturer-specific items were identified, thereby covering all items. (2) Accumulation of Information Information on photovoltaic power generation facilities is divided into categories including facility information, measurement information and fault information and can be stored over a long period of time. (3) Ensuring Database Reliability Factoring in security issues, the database is deployed in a physically separated internal network designed to block unauthorized access from the outside. In addition, redundancy is provided for the database to improve reliability. 3.2. Video Monitoring System 3.2.1. Video Viewing Power producers can view real-time footage from the monitoring cameras installed at their plants as well as view and download video recorded on the image monitoring server. 3.2.2. Video Recording The video monitoring system can record a maximum of 7 days of video on the image monitoring server and also record video only when sensors installed on monitoring cameras detect events. 4
4. Benefits of Introduction of the System Introduction of the system as described in this paper has enabled improvements in work efficiency and speed as well as enhanced convenience in a number of areas and centralized data management in the operation and maintenance of photovoltaic power generation facilities by power producers. (1) Improved Facility Maintenance Speed - Information on decentralized plants can be centrally managed. - Data on photovoltaic power generation facilities can be checked not only in offices, but anywhere and at any time. - Notification of faults sent by e-mail enables speedy maintenance response. - Power conditioners can be operated remotely, thereby realizing speedy response to load dispatching instructions and faults. - The system enables reduction in operation and maintenance personnel and improved efficiency. (2) Labor-saving and Improved Efficiency in Management - Use of the information transmission equipment manufactured by our company enables realization of compatibility with power conditioners of major manufacturers in Japan. - Centralization of data enables unified monitoring and management of all plants. - The system enables remote monitoring and operation without the need to travel to multiple plants in remote locations. (3) Effective Use of Accumulated Data - Basic data required for analysis can be accumulated and electric power output predicted based on weather conditions. - Actual performance data such as meteorological information and facility utilization rates can be utilized for the introduction of new facilities. - The accuracy of maintenance planning decisions can be improved through analysis of fault information. 5. Summary and Future Undertakings As well as centralized management of data collection, aggregation and display, introduction of this system has enabled realization of early-stage maintenance of facilities through the notification of fault information and video monitoring. Real-time centralized management from a remote location of information on decentralized photovoltaic power generation facilities and the effective use of various collected and accumulated data enable realization of increased efficiency and labor-saving in the maintenance and management of power generation facilities, resulting in stable supply of electric power. At the present time, as well as more than forty locations in Kyushu, the Feed-in Tariff Scheme for Renewable Energy has spurred the spread of construction of mega solar power plants nationwide in Japan. To cope with this situation, we will adopt a flexible approach toward the introduction of this system to meet increasing needs for the monitoring and collection of facility information from such photovoltaic power generation facilities (mega solar power plants). On the system functionality front, we will implement control functions that apply our technologies for monitoring and control of facilities such as hydro power stations and substations and establish a data mining techlonogy for accumulated information to enable prediction of power generation and deterioration diagnosis, so that convenience will be further enhanced, for example, by providing power generation efficiency data analysis. With regard to future developments, we are considering the following undertakings: - Use of smart devices to realize even greater mobility - Implementation of string monitoting functions for solar panels BIBLIOGRAPHY - NEDO, Guidelines for PV Power Generation Field Test Project (Facility Management and Data Management) - NEDO, Guidelines for PV Power Generation Field Test Project (System Measurement) *NEDO: New Energy and Industrial Technology Development Organization 5