Day-ahead Optimal Dispatch Model for Coupled System Considering Ladder-type Ramping Rate and Flexible Spinning Reserve of Thermal Power Units

Abstract

In northern China, thermal power units (TPUs) are important in improving the penetration level of renewable energy. In such areas, the potentials of coordinated dispatch of renewable energy sources (RESs) and TPUs can be better realized, if RESs and TPUs connected to the power grid at the same point of common coupling (PCC) are dispatched as a coupled system. Firstly, the definition of the coupled system is introduced, followed by an analysis on its characteristics. Secondly, based on the operation characteristics of deep peak regulation (DPR) of TPUs in the coupled system, the constraint of the ladder-type ramping rate applicable for day-ahead dispatch is proposed, and the corresponding flexible spinning reserve constraint is further established. Then, considering these constraints and peak regulation ancillary services, a day-ahead optimal dispatch model of the coupled system is established. Finally, the operational characteristics and advantages of the coupled system are analyzed in several case studies based on a realworld power grid in Liaoning province, China. The numerical results show that the coupled system can further improve the economic benefits of RESs and TPUs under the existing policies.

Enhancing Renewable Energy Accommodation by Coupling Integration Optimization with Flexible Retrofitted Thermal Power Plant

“…To sum up, previous studies [9][10][11] that conducted macroscopic evaluations on the impact of retrofitted TPUs for improving the accommodation capability of RES did not fully exploit their potential for detailed coordination at the time-step level. On the other hand, the optimal scheduling models for TPUs and RESs in previous studies [12][13][14][15][16][17][18][19][20][21][22][23] lack the ability to quantitatively measure the improvements in RES accommodation of different coordination methods with TPUs. To address the aforementioned gaps, this paper proposes an evaluation framework to assess the enhanced accommodation capabilities of RESs following the coupling integration optimization of retrofitted TPUs with WT and PV.…”

“…In [21], an optimal scheduling strategy that fully considers the contributions of WT farms, PV parks, and TPUs to determine economic benefits and an environmental impact equilibrium in a hybrid generation system under natural limitations was proposed. In [22], a day-ahead optimal dispatch model of the coupled system was established based on the operation characteristics of DPR auxiliary services and the ladder-type ramping of TPUs. In [23], an optimal scheduling approach of CGS was presented to demonstrate that coupling integration can improve the economic benefits of the system.…”

“…In [22], a day-ahead optimal dispatch model of the coupled system was established based on the operation characteristics of DPR auxiliary services and the ladder-type ramping of TPUs. In [23], an optimal scheduling approach of CGS was presented to demonstrate that coupling integration can improve the economic benefits of the system. The above CGS studies have predominantly concentrated on the economic benefits facilitated by coupling integration, overlooking the quantitative evaluation of enhancements in RES utilization after coupling integration compared to the scenario before coupling.…”

“…This facilitates a broad adoption with minimal investment requirements for power-source operators. For instance, in the power grid of Liaoning, China, the capacity of RESs and TPUs that can be interconnected at the same PCC exceeds 42% [22].…”

Collaborative Control of Reactive Power and Voltage in a Coupled System Considering the Available Reactive Power Margin

“…The northern region of China is rich in wind, solar, and other resources, and the installed capacity of renewable energy continues to grow. The coupled system composed of wind, solar, and other new energy stations and traditional thermal power plants is commonly used to supply power to the outside through long-distance transmission channels, with the characteristics of multiple voltage levels and close electrical and gas connections [2]. However, wind and photovoltaic stations are susceptible to external environmental influences, which can impact the reactive power distribution, voltage stability, and active power loss within this coupled system.…”