Quantitative Analysis of Frequency Regulation Revenue Growth for Thermal Power Plants Integrated with Supercapacitor-Lithium Hybrid Energy Storage

In the thermal power AGC (Automatic Generation Control) frequency regulation auxiliary service market, plant revenue is mainly determined by four core indicators: frequency regulation performance coefficient (K-value), frequency regulation mileage, operational qualification rate, and dynamic response accuracy. Traditional frequency regulation schemes relying solely on thermal units or independent lithium-ion energy storage generally suffer from weak tracking capability for high-frequency grid fluctuations, low K-values, frequent grid assessment penalties, and accelerated battery degradation with high maintenance costs. These limitations cap the upper limit of frequency regulation revenue and bring substantial implicit operational losses.

The integration of a supercapacitor-lithium hybrid energy storage system establishes a coordinated hierarchical regulation mode, in which supercapacitors undertake high-frequency transient regulation while lithium batteries handle long-duration steady-state regulation. This optimized framework comprehensively improves the frequency regulation performance of thermal units, eliminates most grid assessment deductions, reduces coal consumption and equipment abrasion, and delivers dual benefits of revenue increase and cost reduction. Based on field operation data from multiple commissioned thermal power plants, this article quantitatively analyzes the actual revenue growth brought by hybrid energy storage retrofitting.

1. Improvement of Core Frequency Regulation Performance (Field-Verified Data)

The K-value is the core evaluation indicator that determines auxiliary service revenue. A higher K-value corresponds to a higher unit price of frequency regulation mileage and stronger market competitiveness.

Verified by practical operating data of multiple thermal power projects:

1. The overall frequency regulation performance of thermal units is significantly optimized. The composite K-value rises steadily from 0.6–2.5 (pure thermal operation) to 1.4–3.5 after hybrid energy storage integration, achieving 30%–50% improvement in comprehensive frequency regulation capability. Older thermal units with slow dynamic response gain the most substantial performance promotion and can reach a medium-to-high ranking in regional frequency regulation assessments after retrofitting.

2. AGC response qualification rate, waveform tracking accuracy, and regulation speed are greatly enhanced. The system effectively eliminates response delay, overshoot and tracking deviation issues, basically removing all grid frequency regulation penalties.

3. The hierarchical load-sharing mechanism avoids harmful high-frequency pulsed cycling for lithium batteries. Supercapacitors undertake all transient impact regulation tasks, while lithium batteries operate under stable and steady-state conditions without frequent polarization and deep charge-discharge cycling. This mechanism extends the lithium battery service life by 2–3 times, greatly reducing long-term costs of battery replacement, equalization maintenance and system upgrading, and extending the full-lifecycle profitable operation period of energy storage systems.

2. Direct Frequency Regulation Revenue Growth (Authentic Project Cases)

Field operational data of 4MW/8MW hybrid energy storage frequency regulation projects in Shandong, South China and Fujian regions show consistent and credible revenue growth indicators, providing solid references for industrial application:

1. Monthly AGC net revenue increase: RMB 2–2.4 million

A typical thermal power plant in northern Shandong achieved a monthly average AGC revenue of RMB 3.56 million before retrofitting. After the commissioning of the hybrid energy storage system, the monthly average revenue increased to RMB 5.94 million, realizing a net monthly revenue growth of RMB 2.38 million and a growth rate of 66.8%.

2. Overall frequency regulation revenue growth range: 50%–70%

Most standard retrofitted projects achieve a 50%–70% increase in comprehensive frequency regulation revenue compared with pure thermal regulation and single lithium storage regulation. For aged units with historically low K-values and frequent assessment deductions, the revenue growth can nearly double after optimization.

3. Stable revenue performance of benchmark projects

Benchmark hybrid energy storage projects in South China maintain a stable monthly frequency regulation revenue of RMB 4.3–4.6 million, with annual revenue exceeding RMB 50 million. A retrofitted plant in Fujian has accumulated over RMB 20 million in increased revenue in the early operational stage, showing stable and sustainable profitability.

3. Implicit Cost Reduction and Incremental Benefits

Beyond direct revenue growth in auxiliary services, hybrid energy storage brings considerable implicit economic benefits through operational optimization, which further improves the overall profitability of thermal power units:

1. Energy saving and unit life extension benefits

Supercapacitors undertake all high-frequency small-amplitude fluctuation regulation, freeing thermal units from frequent load ramping and rapid output adjustment. Boiler combustion status, steam parameters and valve actions become stable, effectively reducing unit coal consumption. Meanwhile, mechanical fatigue and abrasion of turbines, auxiliary equipment and pipelines are alleviated, extending the overhaul cycle of thermal units and reducing monthly equipment loss costs by hundreds of thousands of RMB.

2. Operation and maintenance cost reduction for energy storage systems

By isolating lithium batteries from high-frequency impact working conditions, the hybrid architecture slows down battery attenuation significantly. It avoids the high annual cost of cell replacement and regular maintenance faced by single lithium storage systems, greatly improving the long-term economic efficiency of energy storage equipment.

3. Elimination of grid assessment penalties

Traditional thermal operation is frequently penalized due to response delay, insufficient accuracy and waveform oscillation. After hybrid energy storage retrofitting, all AGC indicators fully meet grid standards, realizing zero penalty operation and further increasing net operational revenue.

4. Revenue Growth Differences Among Different Power Plants

The actual revenue improvement is mainly determined by the original AGC performance of thermal units and the fluctuation intensity of the regional power grid:

1. Aged thermal units with slow ramp rates, low original K-values and frequent penalty records achieve the highest revenue growth, ranging from 60% to 100%;

2. Conventional stable thermal power units realize a steady revenue increase of approximately 50%;

3. Power plants located in high-renewable-energy-penetration areas with intensive grid fluctuations and sufficient frequency regulation mileage enjoy higher upper limits of incremental revenue.

The integration of supercapacitor-lithium hybrid energy storage enables thermal power plants to achieve 30%–50% improvement in comprehensive frequency regulation performance, with most plants obtaining a monthly net revenue increase of over RMB 2 million and a stable overall revenue growth of 50%–70%. Aged units with poor original frequency regulation performance have greater profit growth potential. Furthermore, this solution realizes multiple implicit benefits including unit energy saving, equipment life extension and zero grid penalties. It serves as an optimal long-term retrofitting scheme for thermal power plants to improve AGC regulation performance and maximize auxiliary service economic returns.