Science and Technology Daily Reporter Zhang Ye

On April 17, the world's largest capacity 5MW supercapacitor energy storage system successfully completed joint grid dispatch debugging at Huaneng Luoyuan Power Plant. All regulation indicators met grid requirements, marking the system's official transition to commercial operation.

The power grid system connects generation and consumption sides. When supply and demand are mismatched, grid frequency fluctuates, commonly observed as lights flickering in homes. In recent years, various energy storage systems, primarily lithium battery-based, have been deployed to improve power supply quality by participating in grid frequency and peak regulation. These systems store excess energy when generation exceeds demand and release stored energy back to the grid when demand exceeds generation.

However, grid frequency regulation commands can number several thousand per day. Lithium batteries, constrained by limited charge-discharge cycles, result in energy storage system lifespans falling significantly short of expectations. Recently, with substantial integration of weather-dependent renewable energy into the grid, frequency regulation requirements have intensified, creating an urgent need for energy storage systems featuring fast response and long lifespan for frequency regulation.

Supercapacitors function like specialized batteries. Unlike conventional batteries, they are ideally suited for short-duration, high-power charge and discharge cycles, achieving millisecond-level response times. Nevertheless, due to high technical requirements and lengthy development cycles, their application in grid energy storage for frequency regulation has been limited historically.

Initiated in late September 2022, this project was funded and constructed by China Huaneng Group's designated builder, Huaneng Luoyuan Power Company. It was led by Xi'an Thermal Power Research Institute under China Huaneng Group, with collaborative R&D support from entities including Nantong Jianghai Capacitor Co., Ltd.

The system employs a hybrid energy storage configuration of "5MW Supercapacitor + 15MW Lithium Battery," leveraging the supercapacitor's rapid response strength and the lithium battery's sustained energy storage characteristic, achieving performance synergy. During frequency regulation, the system operates with the supercapacitor as the primary responder and the lithium battery as secondary support. Specifically, second-level minor regulation commands are handled entirely by the supercapacitor, while minute-level major commands receive full-power response from the supercapacitor supplemented by the lithium battery, significantly enhancing the overall performance of the existing frequency regulation storage system.

Data released by the Fujian Electricity Spot Market Trading Platform indicates that after the system's commissioning, the frequency regulation response time of Huaneng Luoyuan Power Company's units improved by over 14 times, regulation rate increased by more than 4 times, and regulation precision enhanced by over 3 times, achieving a substantial leap in the unit's overall regulation performance.

The successful operation of the supercapacitor hybrid energy storage project fully validates the safety, reliability, and economic feasibility of large-capacity supercapacitor energy storage technology. It greatly enhances unit response speed and flexibility, filling a technological gap in China's supercapacitor energy storage sector.