When it comes to energy storage, the public usually thinks of batteries, which are crucial in terms of energy conversion efficiency, system life, and safety. However, if energy storage is to function as a system, the Energy Management System (EMS) becomes equally important as the core component, often referred to as the 'brain.'
EMS is directly responsible for the control strategy of the energy storage system. The control strategy significantly impacts the battery's decay rate, cycle life, and overall economic viability of the energy storage system. Furthermore, EMS plays a vital role in swiftly protecting equipment and ensuring safety. If we liken the energy storage system to the human body, EMS acts as the brain, determining the tasks performed, establishing reasonable work and rest patterns, and enabling self-protection in case of accidents.
Different demands exist for EMS in source-grid side energy storage and industrial and commercial energy storage:
Since the energy storage industry initially gained traction from large-scale storage projects, specifically those associated with the power supply and grid, the design and implementation of energy storage EMS were originally tailored for source-grid side scenarios. Due to data constraints on the source network side and the product design inertia of SCADA (Supervisory Control and Data Acquisition) in the power system, the energy storage EMS was initially developed as a localized standalone version. This meant that default external data transmission was not possible, necessitating the configuration of a local operation and maintenance team at the power station. Additionally, relevant monitoring specifications on the source network side required the inclusion of related hardware, such as workstations, printers, fault recorders, telemotors, and more. This type of energy storage EMS is commonly referred to as a traditional energy storage EMS.
However, the traditional EMS cannot be directly used for industrial and commercial energy storage due to different scenarios and cost requirements.
Industrial and commercial energy storage sites typically have smaller capacities, larger numbers, wide dispersion, and higher operation and maintenance costs. These sites cannot support on-site manned duty, making remote operation and maintenance monitoring necessary. It involves establishing regional-level operation and maintenance teams responsible for the systematic overall operation and maintenance of multiple energy storage stations, aided by a digital operation and maintenance platform. For industrial and commercial energy storage EMS, real-time uploading of power station data to the cloud is necessary, improving operation and maintenance efficiency through cloud-side interaction. The traditional EMS, designed as a localized standalone version, does not align with these requirements, thus demanding a new product design for industrial and commercial energy storage EMS.
Based on the aforementioned scenario differences, the industrial and commercial energy storage EMS should adhere to the following design principles:
Full Access:
Although industrial and commercial energy storage has relatively small capacities, it involves numerous devices that need to be connected to EMS, including PCS (Power Conversion System), BMS (Battery Management System), air conditioners, electric meters, intelligent circuit breakers, fire control hosts, sensors, and indicator lights, among others. Therefore, EMS should be compatible with various protocols and support comprehensive device integration. Real-time and comprehensive access to device alarm information is particularly important, testing the collection performance of EMS. Relevant protection measures require EMS to collect data at least once every second.
Cloud and Edge Integration:
To facilitate bidirectional data flow between the energy storage station and the cloud platform, EMS must integrate seamlessly at the system layer, ensuring real-time and lossless reporting of station-side data to the cloud platform. Similarly, instructions from the cloud platform should be transmitted to the station securely and in real time. While several technical routes exist for cloud-edge integration, the chosen approach should consider the operational effect. Notably, since many industrial and commercial energy storage systems connect to the internet via 4G (without the capability of establishing a wired network), the chosen approach must ensure data consistency between the cloud and edge, continued data transmission during communication interruptions, quick self-healing of the communication channel, and secure cloud-to-edge remote control. Careful consideration is required to avoid overwhelming the system and incurring high costs and risks. Emerging technical routes, such as the Nova IoT platform developed by Qingzhou Nengke, aim to address these challenges, ultimately reducing network communication costs, server storage costs, and power plant operation and maintenance risks.
Flexible Expansion:
Industrial and commercial energy storage capacities range from 100 kWh to dozens of MWh, depending on the specific project. Given the growing popularity of energy storage standard cabinet products, which are modular and allow for flexible configuration to meet different energy demands, EMS must support quick and compatible integration with different numbers of energy storage cabinets. Furthermore, it should enable seamless connection and group control of equipment with varying orders of magnitude, particularly PCS. This facilitates swift construction, delivery, and operation of projects.
Strategic Intelligence:
Industrial and commercial energy storage primarily focuses on peak load shifting, valley filling, demand control, and anti-backflow protection to achieve objectives such as dynamic capacity expansion and off-grid backup. Due to variations in the number and capacity of transformers on site, EMS has diverse requirements for demand control and anti-backflow protection. The EMS should be flexible in configuration to provide the necessary protection. With the increasing integration of industrial and commercial photovoltaics, energy storage strategies face new requirements. For instance, energy storage needs to optimize battery charging and discharging based on photovoltaic power generation conditions to maximize the use of clean energy while implementing relevant protection strategies. Static energy storage strategies may not suffice in scenarios characterized by the uncertainty of photovoltaic power generation and load fluctuations, necessitating more dynamic and intelligent strategies. Smart strategies consider factors such as time-of-use electricity prices, photovoltaic forecasts, load fluctuations, and protection objectives, enabling real-time and dynamic formulation of charging and discharging strategies to achieve overall economic benefits. Rational battery usage reduces excessive battery attenuation and ensures the economic viability of energy storage. Additionally, EMS should incorporate appropriate strategic protections to enhance the security of the energy storage system. This includes timely coordination of different devices for effective local protection and early risk prediction through relevant algorithms, issuing advance safety warnings.
The functions of industrial and commercial energy storage EMS are both similar to and different from those of traditional energy storage EMS. Generally, they include:
System Overview:
This function displays the current operational overview of the energy storage system, including energy storage charge and discharge capacity, real-time power, state of charge (SOC), revenue, energy graphs, multi-power operation graphs, and more. It serves as the main monitoring page.
Equipment Monitoring:
EMS allows users to view various equipment individually, including but not limited to PCS, BMS, air conditioners, electricity meters, intelligent circuit breakers, fire control hosts, and various sensors. It also supports equipment control.
Operating Income:
This function displays energy storage income and power information, which is of primary interest to system owners.
Fault Alarm:
EMS summarizes and presents fault alarms from different equipment, allowing users to query alarms by time, status, level, and other parameters.
Statistical Analysis:
EMS enables users to access historical operation data and related reports for the equipment, with support for data export.
Energy Management:
The core function of EMS involves configuring energy storage strategies, including manual and automatic modes, to accommodate commissioning, maintenance, daily operation, and other scenarios.
System Management:
This function encompasses the management of basic power station information, equipment management, electricity price period management, operation logs, account management, language switching, and other related functionalities.
Edit by editor