Understand the Energy Storage "Brain" EMS in one article!

With the rapid development of Renewable Energy, energy storage technology, as a key means to address the imbalance between energy supply and demand and ensure the stable operation of the power grid, is gradually receiving widespread attention.

The Energy Management System (EMS), as a core component, plays an increasingly important role. This article will provide an in-depth introduction to the composition of an energy storage EMS system.

1. Introduction to EMS System Functions

When people think of energy storage, they usually think of batteries, whose quality directly affects energy conversion efficiency, system lifespan, and safety. However, for energy storage to realize its value as a system, the core component—the EMS (Energy Management System)—is equally important.

On the one hand, the EMS is directly responsible for the control strategy of the energy storage system, which affects the battery degradation rate and cycle life within the system, thus determining the economics of energy storage. On the other hand, it also monitors faults and anomalies during system operation, playing a crucial role in timely and rapid equipment protection and ensuring safety.

An EMS system is generally composed of four layers: equipment layer, communication layer, information layer, and application layer.

① Equipment Layer: Requires support from energy harvesting and conversion systems (PCS, BMS);

② Communication Layer: Primarily includes links, protocols, and transmission;

③ Information Layer: Primarily includes caching middleware, databases, and servers. The database system is responsible for data processing and storage, recording real-time and important historical data, and providing historical information queries;

④ Application Layer: Presented in forms such as apps and web applications, providing managers with a visual monitoring and operation interface. Specific functions include energy conversion decision-making, energy data transmission and acquisition, real-time monitoring and control, operation and maintenance management analysis, visual analysis of electricity/power consumption, and remote real-time control.

2. Different Demands of Energy Storage on the Source-Grid Side and Industrial/Commercial Energy Storage for EMS
Since the energy storage industry initially emerged from large-scale storage, i.e., power source and grid side, energy storage EMS was initially designed and implemented in source-grid side scenarios. We can call this type of energy storage EMS a traditional energy storage EMS.

Traditional Energy Storage EMS System Characteristics:

▶ Considering the data isolation of the power grid and the product design inertia of power system SCADA, energy storage EMS is designed as a standalone, localized system.

▶ Since data cannot be transmitted externally by default, a local maintenance team is required at the power plant for on-site monitoring.

▶ In addition, due to relevant monitoring standards on the power grid side, EMS also requires the configuration of related hardware, including but not limited to: workstations, printers, fault recorders, remote actuators, etc. The localized, standalone design of traditional EMS systems is simply not suitable for industrial and commercial energy storage, which is characterized by small capacity, large number, wide distribution, and high maintenance costs. Therefore, industrial and commercial energy storage EMS requires a new product design.

Industrial and Commercial EMS System Characteristics:

▶ Unlike traditional EMS systems, industrial and commercial energy storage sites have small capacity, large number, wide distribution, and high maintenance costs, making local on-site monitoring impossible. Remote operation and monitoring are essential.

▶ Assign regional-level operation and maintenance teams to conduct systematic and holistic operation and maintenance of multiple energy storage stations using a digital operation and maintenance platform.

▶ The digital operation and maintenance platform requires that data from industrial and commercial energy storage Power Stations be uploaded to the cloud in real time, and that operation and maintenance efficiency be improved through cloud-edge interaction. Based on the above-mentioned scenario differences, the design principles of the industrial and commercial energy storage EMS system are as follows:

01. Full Integration: Although commercial and industrial energy storage has a relatively small capacity, it still requires the integration of numerous devices: PCS, BMS, air conditioners, electricity meters, smart circuit breakers, fire alarm control panels, various sensors, indicator lights, etc. Therefore, the EMS must first be compatible with and support various protocols to fully integrate the devices and their data. Especially important is the real-time and comprehensive integration of device alarm information. This tests the EMS's data acquisition performance; to achieve relevant protection, the EMS needs to collect data once per second.

02. Cloud-Edge Integration: To achieve bidirectional data flow between the energy storage station and the cloud platform, the EMS must achieve cloud-edge integration at the system level. This means ensuring that station data is reported to the cloud platform in real-time without loss, and that cloud platform commands are securely and in real-time transmitted to the station.

03. Flexible Expansion: Commercial and industrial energy storage capacities range from 100kWh to tens of MWh, depending on the specific project. With standard energy storage cabinets becoming mainstream, these cabinets can be assembled like building blocks to meet different energy demands. This requires EMS (Energy Management System) to have flexible expansion capabilities, quickly accommodating different numbers of energy storage cabinets and enabling the integration of equipment of varying scales, especially for PCS (Power Control System) integration and group control. This allows for rapid project construction, delivery, and commissioning.

04. Intelligent Strategy: Commercial and industrial energy storage primarily focuses on peak shaving and valley filling, combined with demand control strategies and reverse current protection to achieve purposes such as dynamic capacity expansion and off-grid backup power. Due to variations in the number and capacity of transformers in actual projects, EMS has diverse requirements for demand control and reverse current protection. For example, with multiple grid connection points, demand protection for certain transformers and reverse current protection for the main transformer require flexible configuration within the EMS to achieve the protection objectives.

Simultaneously, with the recent surge in industrial and commercial photovoltaic (PV) power generation, the integration of energy storage and PV in the industrial and commercialsectors has gradually increased, placing new demands on energy storage strategies. For example, energy storage needs to rationally schedule battery charging and discharging based on PV power generation to maximize the use of Clean Energy while simultaneously implementing relevant protection strategies. Due to the uncertainty of PV power generation and the volatility of load, static energy storage strategies are difficult to meet the needs of such scenarios, requiring more dynamic and intelligent strategies.

Intelligent strategies, combining time-of-use pricing, PV forecasting, load fluctuations, and protection targets, dynamically formulate charging and discharging strategies in real time to effectively achieve overall economic efficiency. By rationally using batteries, excessive battery degradation is reduced, ensuring the economic viability of the energy storage itself.

Finally, EMS (Energy Management System) also requires corresponding strategies for the safety of Energy Storage Systems. This includes not only timely coordination of different devices to effectively complete local protection in response to equipment alarms, but also the ability to predict risks based on relevant algorithms and issue early safety warnings.