scholarly journals Control Strategies and Economic Analysis of an LTO Battery Energy Storage System for AGC Ancillary Service

Energies ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 505 ◽  
Author(s):  
Bingxiang Sun ◽  
Xitian He ◽  
Weige Zhang ◽  
Yangxi Li ◽  
Minming Gong ◽  
...  

With the rapid growth of renewable energy and the DC fast charge pile of the electric vehicle, their inherent volatility and randomness increase a power system’s unbalance of instantaneous power. The need for power grid frequency regulation is increasing. The energy storage system (ESS) can be used to assist the thermal power unit so that a better frequency regulation result is obtained without changing the original operating mode of the unit. In this paper, a set of different charging/discharging control strategies of the lithium titanate battery (LTO) is proposed, which are chosen according to the interval of the State of energy (SOE) to improve the utilization rate of the ESS. Finally, the cost-benefit model of the ESS participating in automatic generation control ancillary service is established. Case analysis proves that after a 1.75 MWh ESS is configured for a 600 MW thermal power unit, Kp and D is increased from 1.42 to 6.38 and 2857 to 6895 MW. The net daily income is increased from 20,284 yuan to 199,900 yuan with a repayment period of 93 days. The results show that the control strategies and the energy configuration method can improve the performance and economic return of the system.

Author(s):  
Qingru CUI ◽  
Yanqiu ZHENG ◽  
Yaohan WANG ◽  
Deliang ZENG

In China, the improvement of thermal power unit's operational flexibility is an important way to solve the clean energy absorption problem. The comprehensive utilization of steam turbine energy storage is an effective way to improve the load regulation performance of thermal power unit. A turbine energy storage utilization comprehensive evaluate method is presented. In the method the unit performance influence and equipment safety influence of energy storage are normalizes as a single object optimization problem. The comprehensive index calculation result is used in online optimization of storage power utilizing range limiting. Test result shows that the comprehensive index calculation method can help restrain the negative influence of turbine energy storage utilization on equipment operation safety, thereby improves availability of the energy storage system and improves the operating flexibility of thermal power unit.


Processes ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 120
Author(s):  
Francisco Fernández ◽  
José Díaz ◽  
María Folgueras ◽  
Inés Suárez

Thermal energy storage systems help to couple thermal energy generation and process demand in cogeneration facilities. One single deposit with two design temperatures and one main temperature step in sensible thermal energy storage define the thermocline systems. Performance of one high size real thermocline thermal energy storage system is analysed. Starting from temperature and mass flow rate data registered by the plant control system, one advanced thermodynamic analysis is performed. The quality of heat storage is analysed in terms of evaluation of the stratification in the thermocline zone. The temperature data registered at 21 positions is extended by displacement analysis generating detailed profiles. Fraction of recoverable heat, thermocline width, stratification indices based on energy and exergy analysis, and mean temperature gradients in the thermocline region are calculated. These parameters are monitored under real operation conditions of the plant. The calculated parameters are studied to check their distribution and correlation. First and Second Law indices show parallel behaviour and two values are found that delimit situations of high and low values of mean temperature gradients. It was observed that buoyancy generates uniform forced movement with the right water temperature entering the diffusers, but good control strategies are essential to avoid mixing. The system demonstrated great stability in this use.


Author(s):  
Md. Asaduz-Zaman ◽  
Md. Habibur Rahaman ◽  
Md. Selim Reza ◽  
Md. Mafizul Islam

Several microgrids can be interconnected together to enhance the grid reliability and reduce the cost of supplying power to an island area where conventional power grid cannot be connected. Source and load demand do not properly balance always. Besides that, sometimes power and frequency fluctuation has occurred in MG at island mode. Need to design a special control for maintaining the state of charge (SoC) of energy storage system. This paper proposes a new power supply system for an island area that interconnects two microgrids with a single energy storage system (ESS). An algorithm has been proposed that control the microgrids energy storage system for spinning reserve and load power/frequency regulation purpose. The minimum loading constraints of diesel engine generator (DEG) is considered and the SOC of the ESS is properly maintained.


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