The 2nd Smart PV O&M Seminar, sponsored by Huawei Technologies Co., Ltd. and supported by China Renewable Energy Society, was successfully held on September 8, 2016 in Sanya, Hainan, China. More than 600 representatives from global power plant investors, operators, and design institutes gathered at the summit to share their experiences on smart plant operation and maintenance (O&M), explore for advanced smart O&M concepts, decode the valuable DNA of smart PV in a push to promote healthful development and technological advance of the PV industry. The participants include the China Renewable Energy Society, State Power Investment Corporation, CGN Solar Energy Development Co., Ltd., China Three Gorges New Energy Co., Ltd., State Grid China Electric Power Research Institute, Huaneng Hainan Power Inc., Hubei Energy Group Co., Ltd., GCL New Energy Holdings Limited., CMIG New Energy Co., Ltd., Zhongli Talesun Solar Co., Ltd., Jingke Power Co., Ltd., China Merchants New Energy Group Limited, Suzhou Zhongkang Electric Power Development Co., Jingyuntong Technology Co., Ltd., Qingdao New Energy Solutions Inc., Beijing Enterprises Clean Energy Group Limited, Shanghai Aerospace Automobile Electromechanical Co. Ltd., Tongwei New Energy, PowerMAX, Daiwa House Industry Co., Ltd., and West Holdings.
Shi Dinghuan, Chairman of China Renewable Energy Society, attended the summit and delivered an opening address. As China and the USA submitted a protocol to the United Nations at the just-concluded G20 Summit upon approval at their national congresses or parliaments, renewable energy is officially incorporated into the legal framework. To solve climate change problems caused by greenhouse gas emissions, the fundamental action is to change the energy structure dominated by fossil energy. According to Mr. Shi, the installed PV capacity of China reached 43 GW last year and will reach 30 GW this year. However, there is still a long way to fulfill China’s commitment on ensuring that the percentage of non-fossil energy will account for 15% until 2020 and more than 20% until 2030. Technical innovation, especially cross-domain technical breakthrough for improving efficiency and expanding the application market, is the key to the development of renewable energy. Driven by the “Internet+” strategy, building smart power plants that deliver higher energy yields is an important target of industry players and a significant direction of the Forerunner Plan in the PV industry. Mr. Shi emphasized that, as the PV plant scale expands rapidly, whether the plants can work efficiently depends on O&M to a great extent.
Conventional people-intensive O&M is inefficient as the PV plant scale expands and the plant diversity increases. Use the Golmud 590 MW PV plant as an example. Shi Tianze, General Manager of the Haixi New Energy Yield Dept, Qinghai Huanghe Hydropower Development Co., Ltd., told us that, the Golmud PV plant had difficulty in plant supervision, inspection, and troubleshooting as the plant covers an area of 14.62 square meters and involves a great number of devices. Faults are found on both AC and DC sides during O&M. AC faults occur less frequently and mainly relate to cables, box-type transformers, civil work, and step-up transformers. They account for 9.82% of total faults. DC faults occur more frequently, are not easily to be found, and mainly relate to PV modules, inverters, and combiner boxes. They account for 90.18% of total faults. Mr. Shi shared us the Smart Online IV Curve Monitoring technology, an achievement of joint innovation between Huanghe Hydropower and Huawei. The technology is used at the Golmud PV plant to scan all PV strings and can precisely and rapidly identify hidden troubles in PV modules so that early maintenance can be conducted to remove any faults. A smart PV management system and PV controller collaborate to monitor each PV string online at high precision equal to a professional outdoor IV tester, and remote operations can be performed in one click without needing professionals and devices onsite. This considerably reduces the inspection workload and lowers the requirements for test personnel and test costs.
According to data shared by Li Hongtao, a senior engineer with the Solar Power Generation Experiment and Inspection Lab of the Renewable Energy Research Department of State Grid China Electric Power Research Institute, PV modules can attenuate severely and the attenuation rate reaches 9.08% on average. Mixed use of different modules causes a high adaption rate for serial connection of strings. If three types of PV modules are installed in the same string, the adaption rate can reach 2.62%. A hot spot test on 2000 PV modules sampled from a 40 MW PV plant reveals that the hot spot effect is largely caused by PV module shading and quality problems. The occurrence rate of hot spots reaches 3%. With unsatisfactory quality of PV plants, it is a big challenge to conduct efficient O&M.
Shi Tianze and Li Hongtao both believe that smart O&M will be a must-be direction. Call for promoting smart renewable energy is stipulated in the Guiding Opinions on Promoting the Development of “Internet+” Smart Energy jointly promulgated by China’s National Development and Reform Commission, National Energy Administration, and Ministry of Industry and Information Technology in 2015. According to the Innovation Action Plan for Energy Technology Revolution (2016–2030) issued by the National Development and Reform Commission and National Energy Administration, the solar technology innovation strategy aims at smart PV, and developing smart PV plant O&M technology that delivers high energy efficiency and slashes the costs is one of the key guidelines to follow.
As the PV manufacturing cost and subsidies decrease, leveraging smart O&M to improve energy yield efficiency has become an urgent demand of PV enterprises in China. The mainstream Forerunner project for the PV industry poses higher requirements on device performance and smart plant operation.
CGN won the bid for a 100 MW PV plant in the first Datong Forerunner PV base project. Bai Shi, General Manager of the Shanxi Forerunner Project, CGN Solar Energy Development Co., Ltd., said that the CGN Datong project is located in an area with abandoned farmland, forestland, suitable land for forest, and barren hills. The lands are irregular with many valleys and bushes. The project occupies 11 plots of land. Farthest plots are nearly 10 kilometers from each other. Central construction would be hard on the land. Due to complex geography, future plant troubleshooting will be difficult and time-consuming. Coal ashes from the coal mining area are harmful to devices, and communications cables can be easily broken by land subsidence. Smart O&M that enables fast fault diagnosis is an ideal solution. According to Mr. Bai, smart devices and precise management are fundamental to smart O&M. So, CGN decided to use string inverters in its 100 MW plant. After the smart management system is connected, intra-array fault elimination is almost accomplished within one month. The plant is now in the routine O&M stage. This measure avoids energy yield loss of 402.088 MWh and improves the energy yield performance ratio (PR) by 2.52%, regaining an income of RMB 382,000 and achieving an increase of 96.77% in O&M efficiency compared with a conventional solution.
Ma Song, General Manager of the O&M Business Dept of Jingke Power Co., Ltd., believed that customers call for reliable devices and expect that plant O&M can improve the plant quality in addition to rapidly locating and removing string-level faults. PV plant management units are complex and need to collaborate with an efficient and reliable O&M system. Jingke Power has leveraged the Shanghai-based FusionSolar Smart Cloud Management Center to systematically and efficiently manage its 1.4 GW PV project. The smart O&M system requires fewer people in attendance. In future, unattended PV plants will become reliability.
Actually, besides the Forerunner PV plants deployed in coal mining subsidence areas, more innovative PV applications will emerge in the market as the “PV+” strategy unfolds. Dong Xiaoqing, Deputy General Manager of Hebei Energy Engineering Design Co., Ltd., said that “PV +” involves a number of aspects. For example, a solar-fishery plant is built on the water surface, which increases the land usage and provides more energy yield advantages compared with a ground plant. As O&M and servicing are difficult in a water-based PV plant, the protection level of devices should be higher, for example, IP65 for inverters, and smart O&M should be a priority for consideration. Considering cost reduction, system efficiency improvement, and O&M security, it is recommended that string inverters be adopted and fixed on PV supports or small buoyancy tanks.
In addition to basic requirements of plant investors, Jin Rongzu, Deputy General Manager of HT-SAAE Electric Power O&M Co., Ltd., believed that smart application will help solar asset owners and investors maximize solar energy yields and revenues, and it should be a key strategy to cut expenses. Smart O&M management comes with Big Data. Mr. Xu stresses that high-quality data and efficient data management will ensure authentic and valuable analysis results, and factors that affect data quality include sensors, collectors, and transmission equipment (communications network). The key of smart O&M lies in collectors. The quality may be different. For example, we bought a smart combiner box, but it does not function as expected. Using inverters to collect data in the way Huawei FusionSolar smart O&M does could achieve the accuracy precision of 0.5%.
Xu Hailiang, Vice President of TUV SUD Greater China, showed a group of actual measurement data, indicating that the annual failure rate of string inverters in the 220 MW Golmud PV plant is below 0.4%, 0.189% at the lowest; the availability is above 99.99%. The data answers why string inverters are widely used in large ground PV plants for recent years. The string inverter solution used in PV plants of PowerMAX Japan increases the energy yield by 5% and works steadily as it uses simple design and does not contain fragile components such as combiner boxes or fans.
Xu Yingtong, President of Huawei Smart PV Business, shared with guests the value proposition and panorama of Huawei Energy Internet: Focus on the Core, Build an Open Ecology. Mr. Xu stressed the point that Huawei always adheres to the Focus strategy and chooses the right way to do the right things to create benefits for customers. We focus all our strength on the fields where Huawei is expert at: research and develop PV inverters and management systems; focus on developing automated, IT-based, and smart PV plants. With “Openness, Cooperation, and Win-Win” in mind, we will cooperate with all players of the industry chain in building an open and mutually beneficial smart PV ecology to better serve customers and deliver cost-effective PV energy yields. Mr. Xu interprets the strategy into four aspects: integrate and optimize PV plant systems and components through the life cycle; implement the “Huawei Inside” strategy that authorizes key technologies and has them integrated to build automated, IT-based, and smart PV plants; authorize and customize open interfaces based on Huawei cloud computing platform; set up joint innovation centers with strategic customers to share market and technology roadmaps and to jointly develop solutions and technologies. Mr. Xu envisioned that in the era of “Smart” with cloud computing, Big Data, and artificial intelligence, Huawei hopes to better its expertise and become an enabler and driver of the energy Internet.
After the keynote speeches, awards were presented to 25 enterprises that excel in smart PV O&M as a commendation of their outstanding contributions to building a smart PV ecology and promoting smart O&M in the PV industry.As the global PV industry is booming, the scale of each plant and the total capacity of global plants are expanding. The achievements at the 2nd Smart PV O&M Seminar reflect that smart O&M has become an inevitable development trend.