Recently, a piece of news has aroused the market's attention to energy storage in the Taiwan area - the largest distributed energy storage project in the Taiwan area in China has been put into operation. It is reported that a total of 149 sets of distributed energy storage equipment in the station area will be deployed and installed in the project, with a total scale of about 14.1MW/30.0MWh. With the development of new power systems, energy storage in Taiwan areas has emerged and will play an important role in the construction of new power systems. 01. What is station area energy storage?To understand what station area energy storage, we first need to understand what station area is. The basic architecture of the continental power system is mainly composed of five links: power generation, transmission, substation, distribution and consumption, among which power distribution is the link that directly connects with users in the power system and distributes electric energy to users, and the distribution network is the power network where distribution facilities are distributed locally or distributed to various users according to voltage. In the distribution network, the main role of the transformer is to convert the high-voltage electrical energy transmitted in the grid into the lower-voltage electrical energy to adapt to the user's use. The station area refers to the power supply range or area of a transformer in the power system. Energy storage in the station area refers to the energy storage system installed in the distribution station area for dynamic expansion, load fluctuation and smooth the output of new energy power generation in the station area, which can turn the entire station area into a stable load or power source, and improve power quality and grid security.
(Image source: GoodWe PV Community)
02.
The current situation of the Taiwan issue
With the rapid development of economy and society, the load of the distribution network in the mainland has risen sharply, and the load in some areas is dense, and the planned capacity of transformers in the station area cannot meet the surge of electricity load; the vigorous development of new energy vehicles in some rural areas such as tea making and tobacco making, the load shows strong seasonal and periodic fluctuation characteristics, and the peak-to-valley load difference is aggravated; the access of a large number of new energy sources such as photovoltaics will change the distribution of power flow or even reverse the power flow when it is connected to the grid on a large scale due to its inherent volatility and uncontrollability. It also poses challenges to the safe and stable operation of the power grid.
Due to the surging power load and the diversity of the distribution network, there are mainly the following pain points in the current power distribution in the station area:
(1) The power quality and reliability of power supply in the low-voltage distribution station area have a direct impact on the normal production and life of residents, which is the focus of current electricity complaints.
(2) In terms of improving the power quality of power supply in the low-voltage distribution station area, the distribution of active power and reactive power can have a significant impact on the node voltage, which will lead to voltage overrun and increase line loss in serious cases, and unreasonable single-phase load distribution will cause three-phase imbalance in the station area, which will affect the safety of electricity and reduce the power factor in serious cases.
(3) In terms of improving the reliability of power supply in the low-voltage distribution station area, the intermittent and seasonal power consumption characteristics of low-voltage users are obvious, which is easy to cause short-term heavy overload of the distribution transformer and bring hidden dangers to the safe operation of the distribution transformer.
In the context of carbon peak and carbon neutrality, distributed photovoltaic power generation, energy storage and other resources are growing rapidly, the uncertainty of two-way flow of power flow is increasing, and the operation and control of distribution network are facing new challenges.
Compared with the traditional treatment scheme, the energy storage system has obvious advantages and characteristics, and is the preferred solution for long-term governance.
03.
Innovative solutions to the pain points of the Taiwan area
In response to the above-mentioned series of station problems, there are some traditional single problem solutions on the market. However, with the continuous development of new power systems and new energy sources, different pain points may continue to emerge under the same power area, and the traditional single solution shows certain limitations. Next, we will focus on how to effectively solve this problem with energy storage in the station area!
Interaction diagram
The principle of dealing with high and low voltage is to use energy storage to discharge or store electricity to the grid in time through automatic decision-making through EMS algorithms to achieve grid balance;
The principle of dealing with three-phase imbalance is to use energy storage to control the discharge or storage of single-phase power through automatic decision-making through EMS algorithms, so as to achieve grid balance;
The principle of dealing with reactive power is to make automatic decisions through EMS algorithms, use energy storage to respond in time, and control PCS for reactive power output (including the control of capacitive reactive power and inductive reactive power);
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Generally speaking, there are three important components that energy storage in the station area is inseparable from in the management of the station area: the station EMS, PCS and the battery.
Key components of energy storage in the station area 1:
EMS in the station area
To realize a fully automated solution for energy storage in the station, it is essential to support the EMS equipment in the station, whose functional requirements include:
Collect power data in the station area in milliseconds and analyze it through algorithms.
In the case of triggering thresholds, control the PCS equipment for production work;
According to the current changes in the business of the station area, the backup power and capacity are reasonably adjusted;
Real-time monitoring of the overall operation of the energy storage equipment in the station area to ensure the long-term stable operation of the equipment.
Diagram of the EMS architecture of energy storage in the station area
Key components of energy storage in the station area 2:
Three-phase four-wire PCS
In addition to supporting the three-phase four-wire system, the PCS must also have other features, including:
Compatible with three-phase four-wire system;
Realize the reactive power output function;
Provides rapid AC-to-DC and DC-to-AC regulation, etc.
04.
The value of the energy storage system in the Taiwan area
1. Ensure the safe operation of the power grid. Improve the power quality of the power grid, enhance the reliability of the power supply system, and reduce the probability of system failure.
2. Enhance the consumption of new energy. It can be connected to the new energy photovoltaic system to improve the rate of photovoltaic spontaneous self-consumption, store the photovoltaic power that cannot be used up with batteries, release the stored electric energy at the peak load, optimize the photovoltaic output curve, store the part of the energy that cannot be absorbed by the power grid first, and connect it to the grid in other periods, so as to reduce the waste caused by solar curtailment and power rationing.
3. Improve investment in grid economy. In the case of no increase in the capacity of the distribution transformer, it is better to cope with seasonal and periodical heavy overload, delay the investment in lines and transformers, delay the expansion and upgrading of the distribution network, and improve the investment economy of the power grid.
4. Other social benefits. In the event of a sudden failure or power outage in the main power grid, it can run off-grid and start black to ensure the normal operation of the load.
Especially in areas where the installed capacity of distributed photovoltaics is growing rapidly and the consumption is insufficient, the use of energy storage system solutions in the station area to promote consumption has become a path that can be explored. At present, many places have successively announced the latest distributed photovoltaic open capacity. According to statistics, there are more than 150 regions across the country where there is no new access space for distributed photovoltaics.
In terms of operation strategy, the energy storage in the station area is mainly to offset the peak power generation period at noon to reduce the voltage rise of photovoltaic power generation on the station area and the impact of the power grid, and the discharge time is set in the stage of insufficient PV load to offset the impact of load increase in the station area.
From the perspective of the dispatching body, the energy storage equipment of a single station area does not need to accept the power grid dispatch at present, and can master the charging and discharging by itself, and in the case of multiple stations, it needs to be handed over to the power grid to dispatch the charging and discharging time and times.
05.
The policy is favorable for the development of energy storage in the Taiwan area
At present, the state has policies to clearly support the development of alternative energy storage for power grid functions: the "14th Five-Year Plan" New Energy Storage Development Implementation Plan emphasizes the allocation of energy storage at key nodes of the power grid, improving the level of safe operation, delaying investment in power transmission and transformation facilities, and exploring the inclusion of energy storage facilities in transmission and distribution prices. One of the main scenarios of grid-side energy storage layout is areas with weak power grids, such as remote areas with insufficient power supply capacity or uncovered areas. The "Guiding Opinions on the High-quality Development of Distribution Networks under the New Situation" proposes to guide distributed new energy sources to reasonably build or share new energy storage, improve the ability of new energy substitution, and promote consumption. New energy storage will be deployed at key nodes and terminals to enhance the regulation capacity and stability of the power grid.
In addition, many local governments have issued documents to encourage the construction of energy storage in Taiwan areas to alleviate the pressure of distributed consumption.
On August 26, 2023, the Anhui Provincial Energy Bureau issued the "Notice on Further Promoting the Standardized and Orderly Development of Distributed Photovoltaics", which pointed out that distributed photovoltaic investment enterprises and power grid enterprises are encouraged to comprehensively consider factors such as the scale of distributed photovoltaic development and load characteristics, and explore the centralized configuration or leasing of independent energy storage facilities in substations (Taiwan areas) with difficulty in consumption, and promise that projects with distribution and storage will be given priority access to consumption.
On August 23, 2023, the Hubei Provincial Energy Bureau issued the "Notice on Strengthening the Management of the Whole Process of Distributed Photovoltaic Power Generation Projects", which also proposes that all localities should guide the joint construction and sharing of independent energy storage in areas with difficulty in consumption, and the distributed photovoltaic development enterprises will lease or purchase energy storage capacity, so as not to increase the pressure on new energy consumption of power grid enterprises.
Previously, on May 30, 2023, the Henan Provincial Development and Reform Commission issued a notice on soliciting comments on promoting the healthy and sustainable development of the distributed photovoltaic power generation industry (draft for comments), which also pointed out that various market entities such as photovoltaic development enterprises and equipment manufacturers are encouraged to innovate and develop scenarios such as "community energy storage" and "station area energy storage", which are leased and shared by distributed photovoltaic projects such as household photovoltaics to improve the level of local consumption.
06.
A number of projects have been implemented
In 2023, a number of energy storage projects in Taiwan have been filed in mainland China, mainly in Shandong, Zhejiang, Henan, Fujian and other places. In addition, in April 2024, 149 sets of distributed energy storage equipment in Shaanxi Province will be completed and put into operation, making it the largest distributed energy storage project in mainland China.
Source: Energy Storage Science, EESA Energy Storage Cloud, InBev Electric, Wudun Technology, etc