Hebei's first virtual substation has achieved full functional operation in Yingli Township, Pingshan County

On June 19, with the success of the one-button black start experiment of the "Edge Control Service Center", Hebei's first virtual substation has achieved full functional operation and was officially put into use in Yingli Township, Pingshan County, opening up a new model for the development of terminal power supply power grids in mountainous areas.

What is a virtual substation?

It does not need to occupy several acres of land, nor does it require tens of millions of yuan in construction funds. It only needs to use the existing grid structure to build a switch station at the intersection of branch lines, and combine distributed power sources, energy storage devices and communication control devices to virtualize it into a substation to supply power to surrounding loads.

With the support of energy Internet technology, the Yingli Virtual Substation in Pingshan County, Hebei Province, the first virtual substation in Hebei Province that absorbs photovoltaic poverty alleviation and improves power supply in mountainous areas, was recently completed. With its commissioning, it can not only increase the utilization hours of local distributed power sources, increase farmers' income, and improve the reliability of rural power supply, but also greatly reduce grid investment, taking an exploratory and practical step towards the light-asset development of terminal power grids.

The virtual substation consists of three virtual parts.

At 11:00 a.m. on June 15, the sun was shining brightly. On the hillside near Taoyuan Village, Yingli Township, Pingshan County, rows of blue photovoltaic panels were shining brightly in the sun, continuously converting light energy into electrical energy.

Using the local superior light resources to achieve photovoltaic poverty alleviation has become a new path for many regions to get rid of poverty. However, because Yingli Township is located in a deep mountainous area and at the end of the distribution network, after installing village-level photovoltaics, power reverse transmission and photovoltaic grid-connected point voltage exceeded the limit, which impacted the safe and stable operation of the power grid. In addition, when the Yingli line fails, it will have a certain impact on the normal power consumption of the entire township. The power supply reliability is low. Once a power outage occurs, photovoltaic power generation will not be able to be sent to the grid, affecting the power generation income.

However, with the virtual substation, these problems no longer need to be worried. The reporter saw that, unlike ordinary substations, the Yingli virtual substation occupies only a few hundred square meters and is mainly composed of a switch station, an energy storage system, and a distribution network edge control service center. By using energy Internet technology, the three are virtualized into a substation, and the 10 kV outgoing line supplies power to the surrounding loads, saving 95% of the land compared to the construction of substations of the same voltage level.

16% of power remaining, 17% of power remaining... In the Yingli Power Supply Station not far from Taoyuan Village, the virtual substation is in trial operation, and the electricity converted by the photovoltaic panels on the hillside is being stored in the energy storage system bit by bit.

"By storing excess photovoltaic power in the energy storage device, the problem of distributed power grid connection and consumption can be solved, and power generation can be achieved during the photovoltaic off-peak period, releasing power, playing the role of peak-shaving and valley-filling, effectively improving the power supply reliability and power quality of the distribution network."

Chen Liyuan, director of the Yingli Township Power Supply Station, said happily that this move is expected to increase farmers' annual income by more than 200,000 yuan and help win the battle against poverty.

Virtual substation has a "smart" "brain"

In addition to empowering resource-scarce areas and increasing farmers' income, the Yingli virtual substation is also very "smart".

When the substation's energy management system was turned on, the reporter saw that the operating status of energy storage batteries, photovoltaic power generation, etc. was clearly visible. What's more impressive is that through the "brain" of the substation edge control service center, the substation can also effectively analyze the data of photovoltaic power stations, switchgear intelligent terminal equipment, and dispatching systems, and realize the coordinated optimization of "source (photovoltaic power source) network (distribution network) load (grid power supply load size) storage (charging and discharging operation of energy storage device) and use (power reliability, voltage and intelligent power use at the user end)".

"Yingli Township has a small electricity consumption, a long power supply radius, low voltage at the user end, and relatively poor power supply reliability. Once a fault occurs, the impact range is wide. In addition, the mountain roads are rugged, and fault investigation and repair take a long time." Li Guoguo, team leader of the operation and maintenance team of Pingshan County Power Supply Company, explained that after the virtual substation is put into use, it can quickly identify faults through data analysis, quickly isolate faults, and restore power to non-fault areas through energy storage devices, which also buys time for rapid repairs.

Chen Liyuan, director of Yingli Power Supply Station, told the reporter: One day in May last year, Yingli Township was hit by a strong wind and bad weather. Four repairmen climbed over mountains and crossed beams for nearly two hours before they found the fault point. After the virtual substation was built, the 10kV Yingli line was divided into four. Once a power outage occurs, the virtual substation can be used to analyze and isolate the fault, and the branch line where the fault is located can be determined immediately, saving an hour of repair time compared to before.

"After the Yingli virtual substation is put into use, energy interconnection can be formed. The township's power supply radius will also be shortened from 29 kilometers to 18 kilometers, improving the quality of terminal power." Relevant responsible persons from the Municipal Power Supply Company stated that the virtual substation proposed an active distribution network operation strategy of "source and storage mutual assistance" and "instant recovery upon disconnection", and transformed the traditional distribution network into an "active autonomous self-healing distribution network" that "can be connected to the grid, can be off-grid, has flexible operation modes, strong power supply capacity and high reliability".

Able to realize "microgrid" operation in emergency situations

During the interview, the reporter learned that the traditional method to solve the problems of low reliability of power supply at the end of the distribution network and weak absorption capacity of distributed power sources is to build a new 35 kV substation. Initially, Pingshan County Power Supply Company also submitted such an application to its superiors. However, after repeated demonstrations and multi-faceted investigations and studies by provincial and municipal experts, a new solution of building a virtual substation was proposed for the specific conditions of the Yingli Township power grid.

"Building a virtual substation can effectively reduce the investment cost of the power grid." Liu Zhihui, a level 5 employee of Pingshan County Power Supply Company, explained that the investment in a new conventional 35 kV substation is about 37 million yuan, and the investment in a virtual substation is about 10 million yuan, which can save 73% of the power grid investment.

According to reports, the project has an investment of 9.29 million yuan, with a new line of 1.94 kilometers, a new 1.6 MVA distribution transformer, three energy storage cabinets and other infrastructure. After the construction started on December 3 last year, 45 construction workers overcame difficulties such as cold weather and complex terrain, and worked day and night. They finally completed the cutting and modification on the 29th of that month, and completed the commissioning of the 1600 kVA box transformer on January 20, 2020, completing the construction task ahead of schedule.

"After the energy storage device of the Yingli virtual substation is connected to the grid and put into operation, it will be fully functional. The edge control center can also perform a one-click "black start" after the external fault is removed. The power grid in the power supply area can realize emergency power supply during the fault. The energy storage power plant + photovoltaic power plant can realize the operation of the Yingli Township microgrid for more than 2 hours to ensure the emergency power needs of residents." Ma Le, a specialist in the development department of Shijiazhuang Power Supply Company, said that in the future, they will also analyze and summarize the actual data after the operation of the virtual substation, continue to improve the comprehensive operation and management capabilities of the regional distribution network based on edge computing, and improve the operation and management level of the terminal distribution network. In addition, this technology can be promoted and applied to locations such as islands, isolated islands and remote areas, which will further improve the reliability of power supply and provide users with a high-quality power experience.