Small Micronet's Big Future Intelligent Transmission Control Platform

From photovoltaic power generation to energy storage and then to two-way interaction with the large power grid, the small microgrid, in parallel with the large power grid, builds an intelligent transmission control platform for the development of new energy.

At 14:45 on May 11, the temperature was 26 degrees Celsius. At the Henan University of Finance and Taxation College (Henan Finance University) micro-grid operation control room, a large number of data and curves are constantly changing. These data visualize the form of the sun's sustained release of energy. . In 20 seconds, one kilowatt-hour of electricity was “produced” through a 380 kV photovoltaic power generation system. The entire process did not consume primary energy and produced no emissions.

As the place where the State Grid Corporation's smart grid pilots the Henan distributed photovoltaic power generation and micro-grid pilot project, Henan Finance University has built a micro-grid system that includes photovoltaic power generation, energy storage, and control systems. This micro-grid system is equivalent to a small-scale distribution and distribution system. It is an autonomous system capable of self-control, protection, and management. It can operate either in parallel with the external power grid or in isolation. The photovoltaic power generation system is a photovoltaic power generation panel installed on the top of seven dormitory buildings. It can generate 36,000 to 45,000 kilowatt-hours of electricity per month, which can basically meet the daily electricity needs of the 7 dormitory buildings and student canteens. .

The control system and energy storage system of the micro-grid occupy only about ten square meters of space in the micro-grid operation and control room of more than 80 square meters of Henan Finance University. "The main control system is equivalent to the brain of the micro-grid. Judging whether the micro-grid system is in grid-connected or off-grid state, the energy storage control system is equivalent to the nervous system. It accepts signals from the main control system and responds to them. When used as a voltage source, they are switched as current sources when connected to the grid, and the energy storage system is equivalent to the terminal nerve.” Wang Yan, head of the project department of the Smart Grid Research Center of Henan Electric Power Co., Ltd., gave a vivid image.

The energy storage system of the microgrid uses a lithium iron phosphate battery that is also used in electric vehicles. Dozens of batteries are neatly arranged in an energy storage cabinet that is the size of an ordinary two-door closet. The cooling system that is cooling the storage battery emits a "click" sound in the ear. It is difficult to imagine such batteries, which are so small in size and occupying such limited space, can support 3-4 hours of normal electricity usage in 1,100 student dormitories in the micro-grid system when the grid is off-grid!

“Zhengzhou Power Supply Company has established a communication channel for this project. Information control is achieved through remote control. Although it is unattended, we still have an inspection system and visit the site every few days.” Zhu Xi, an employee of Zhengzhou Power Supply Company, who is responsible for controlling the daily maintenance of the protection system, showed us the real-time microgrid operation, photovoltaic power generation, and energy storage operation.

"Since the launch of the micro-grid, we have indeed saved a lot of electricity. By the summer and winter vacations, we have a surplus of electricity to sell, and we have a certain degree of economic benefits. But what we value more is the social benefits. We must instill in our students a low-carbon economy. The development of new energy, environmental protection and other concepts and the demonstration role of the project itself.” Wang Jun, Vice President of Henan Finance College, valued the impact of the project in more depth. “The construction of the second phase of the school will start soon, and we plan the next step. Photovoltaic panels are installed on the facades of the library and academic exchanges in the exterior, family building and office buildings.The significance of the project can be diffused to the society through the students.As universities, we have the responsibility to advance the most advanced and advanced technologies. Applied to the school.” Mr. Wang’s notion of complacency contained an affirmation of the micro-net demonstration project.

As President Wang expected, nearly six months after the micro-grid was officially put into operation, Henan Finance students formed a preliminary understanding of micro-grid, clean energy, and energy conservation and environmental protection. In the student dormitories, the children have developed a good habit of water conservation and extinction. The school’s public baths have used solar water heaters extensively, which shows that Henan Finance College is dedicated to the use of clean energy and low-carbon environmental protection.

The first-year student Wang Lile believes that the photovoltaic power generation and the application of microgrids in the school dormitory are "very environmentally friendly and fashionable." “Every bed has a separate power outlet. The use of mobile phones, computers, lighting, and electric fans in the dormitory will not be limited. Apart from being more energy-efficient and environmentally friendly, I don’t see any difference from ordinary electricity. When asked about his understanding of the micro-grid, Wang Lile's answer surprised us. "Because of learning finance, I am very concerned about the stock market, so I know that the State Grid Corporation of China and the smart grid, plus our school is micro Network pilots, so I'm more concerned about the smart grid, which is very important in the smart grid."

On the roof of the student dormitory building, rows of neatly arranged photovoltaic panels are receiving sufficient light. The area around the campus of the Henan Financial College is open. Not far away, a thermal power plant is clearly visible. The smoke at the top of the chimney is gradually rising and spreading. On the other hand, the clean energy from the sun through this small system of micro-grid, will smoothly output a bright future for a strong smart grid.

[Link] - Overview of Distributed Photovoltaic Power Generation and Microgrid Control Projects in Henan This project was carried out in conjunction with the solar photovoltaic building application project on the campus roof of the Henan College of Finance and Taxation. On December 31, 2010, the joint adjustment was successful.

Achieve the goal ● Build an actual operation system demonstration project that includes photovoltaic power generation, electrical energy storage, and micro-environment;

● Achieve the friendly access of the distributed photovoltaic power supply and energy storage system to the grid, and realize coordinated operation with the distribution network and the grid;

● Application platform for microgrid operation status monitoring, distributed power generation access microgrid control, power distribution dispatching and power generation control, power balance and load control;

● A system for controlling and protecting coordination under a bi-directional power flow environment of a micro-grid;

● Completed the intelligent coordination of distributed photovoltaic power supply and energy storage systems, and successfully realized the automatic switchover from off-grid to on-grid, on-grid and off-grid.

Technological innovation ● Realize the engineering application of the “black start” of the energy storage system, and realize the smooth switching between the microgrid and the transition away from and away from it;

● During the off-grid operation of the microgrid, the off-grid operation control strategy of the microgrid is automatically activated, and the microgrid can be operated smoothly by adjusting the energy storage and photovoltaic output.

● When the energy storage system is transient, it can be used as a voltage source to support the micro-grid system. In steady state, it can be used as a schedulable current source for smooth photovoltaic power generation output and load fluctuations;

● The lithium iron phosphate battery was first applied in the power storage of the distribution network;

● On-site micro-grid panoramic measurement experiment (power quality, load characteristics, transient characteristics and other experiments), and obtained transient, dynamic, steady-state measured analysis data.