With the acceleration of China's energy structure transformation, the installed capacity of new energy continues to grow, and the pressure on power grid peak shaving is increasing. In this context, large-scale energy storage technology has become the key to supporting new power systems. A 350MW compressed air energy storage innovation demonstration project came into being, and Huiyeda was honored to provide all-weather and highly reliable power guarantee for the whole plant control, protection and power equipment for this project.

Project Overview

The project has a planned site area of about 87,000 square meters and plans to build a set of energy storage power stations with an installed capacity of 350MW. The project uses local abandoned salt caverns as compressed air storage space, which not only effectively reduces construction costs and land occupation, but also realizes the efficient reuse of waste resources, but the pressure of underground salt caverns exceeds 10MPa, and the control system needs to complete the command response within milliseconds. The interruption of the control power supply will lead to chain risks such as protection failure, valve control, and equipment damage, so the power supply system must achieve "zero-second interruption, global coverage, and intelligent early warning", which is the lifeline of project safety.

Project 3 core challenges:

The complex operation conditions of energy storage power stations pose three core challenges to the power supply system:

First, the project implements a high-frequency cycle of "8 hours of compression + 4 hours of power generation" every day, and the control system needs to operate 24 hours a day 7× It is also required that under the extreme working conditions of AC power loss in the whole station, the DC system will continue to supply power for ≥ 4 hours to ensure safe shutdown and smooth communication;

second, the protection system needs to have a high degree of accuracy, which can quickly identify and isolate the fault area when a fault occurs to prevent the accident from expanding;

The third is the full-scenario adaptability, which needs to adapt to the climate characteristics of the mountainous area of central Shandong, meet the rigid requirements of continuous power supply for communication equipment for ≥4 hours in the event of AC failure in the station, and have a perfect online monitoring function of battery internal resistance.

Fourth, the urgency of intelligent operation and maintenance, the project positioning is "unattended, intelligent operation and maintenance", and the power supply system needs to have real-time diagnosis and fault prediction capabilities of battery health, reducing the frequency of manual inspections and operation and maintenance blind spots.

The project puts forward clear technical indicators for the DC power supply system: voltage regulation accuracy ≤±0.5%, current stabilization accuracy ≤±1%, ripple coefficient ≤0.5%, and the insulation monitoring device strictly prohibits the use of AC injection method, and the system is required to have perfect insulation monitoring, battery internal resistance online monitoring functions, and meet the requirements of electromagnetic compatibility.

Solution

In response to the project needs, we provide an overall solution of "dual power supply + intelligent monitoring" high-reliability DC power supply system, which mainly includes two core systems: a 2500Ah large-capacity DC220V DC system in the main plant and a 500Ah DC220V system in the network relay room.

Precise implementation of core configuration:

DC220V system in the main plant: equipped with 2 sets of 2500Ah/103 pcs/group of lean fixed valve-regulated sealed lead-acid batteries, equipped with 3 sets of 520A/250V high-frequency switching charging devices; The system has a total of 21 screen cabinets (3 charging screens, 2 incoming screens, 4 feed screens, and 12 distribution screens);

DC220V system in the network relay room: equipped with 2 sets of 500Ah/103 batteries, 3 sets of 160A/130V charging devices, and a total of 11 screen cabinets in the system;

Communication power supply system: independent -48V system, ensuring that the power supply time of communication equipment is ≥ 4 hours in case of AC failure, meeting the power supply needs of key equipment such as dispatching telephones, optical fiber communications, and telemotion devices.

Technical Highlights:

Multiple redundancy design: The charging device adopts N+1 redundancy configuration, and the AC input adopts dual main and standby power supplies to automatically switch, and the failure of a single module does not affect the overall operation of the system

Intelligent monitoring system: integrates three intelligent units: microcomputer monitoring device, insulation detection device, and battery internal resistance monitoring device to monitor key parameters in real time

Precise protection strategy: Configure a three-stage protection tripper to accurately match the parameters of the upper and lower circuit breakers to ensure accurate isolation of faults and prevent leapfrog tripping

Environmental adaptability: IP30 protection level cabinet, intelligent air-cooled cooling system, meet the working requirements of -22.4°C to 42.1°C wide temperature range

Implementation effect

Since the commissioning of the system, our DC power systems have demonstrated outstanding performance and reliability:

Operational reliability has been significantly improved: Since the system was put into operation, there has been no downtime due to power failure, which provides a solid guarantee for the safe and stable operation of energy storage power stations under the test of multiple power grid fluctuations and extreme weather.

The value of intelligent operation and maintenance is highlighted: it is seamlessly connected with the factory power monitoring system through the RS485 communication interface, realizing remote monitoring, fault warning and diagnosis functions.

The safety value is immeasurable: the multiple protection mechanisms have successfully intercepted abnormal events in the power grid many times, and the insulation monitoring system detects potential grounding faults in time, avoiding possible equipment damage and safety accidents. The system has passed the strict grid connection acceptance of the State Grid and meets the requirements of technical specifications.

In the critical period of the country's energy transition, highly reliable power supply guarantee systems are the cornerstone of the successful operation of new energy storage projects. In the future, we will continue to deepen the field of power supply, provide safe, intelligent and efficient power solutions for more major national energy projects, and help the implementation of the national energy strategy.