Distributionally Robust Frequency Constrained Unit Commitment with Frequency Support of Wind Power and Synchronous Condenser
Jiang Yihang1, Zhao Shuqiang1, Wang Hui1, Wang Yingshan2
1. State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University Beijing 102206 China; 2. School of Electrical and Electronic Engineering North China Electric Power University Beijing 102206 China
Abstract In the process of energy transition, the reduction of online capacity of the synchronous generators and the large scale integration of renewable energy sources have led to the deterioration of power system frequency dynamics. The frequency security problem of power systems is becoming increasingly prominent, while the existing dispatch methods fail to balance the requirement of frequency security and wind power consumption. To cope with this problem, a distributionally robust frequency constrained unit commitment dispatch method with the frequency support of wind power and synchronous condenser is proposed. Firstly,based on inertia control and power reserve control, a modeling approach for the frequency characteristics of wind power under full wind conditions that suitable for dispatch model is proposed. Additionally, the frequency characteristics of synchronous condenser (SC) and synchronous generator with synchronous condensing clutches (SS) are analyzed and modeled, and the system frequency response model that integrated with the frequency characteristics of all the units is established. Furthermore, the set of frequency security constraints is extracted with the alternating time-frequency domain solving, a modified piece-wise linearization method is proposed to linearize the nonlinear terms. Finally, the data-driven distributionally robust optimization is employed to model the wind power uncertainties and the two-stage distributionally robust unit commitment model that incorporating the frequency constraints is established. An enhanced column and constraint generation algorithm is applied to solve the problem. Case studies based on the modified IEEE six-bus system and the IEEE RTS-79 system indicate that the active power substitution effect of synchronous condensers has a positive impact on reducing wind curtailment and improving the systems rotational inertia level. Considering the frequency characteristics of wind power and synchronous condenser in the dispatch framework can enhance economic efficiency while ensuring frequency security of power system. Compared with existing research, the total scheduling cost and carbon emission cost of the proposed dispatch method have decreased by 24.1% and 9.7%, respectively. The scheduling of SCs and SSs has reduced the wind curtailment by 89.3 MW throughout the dispatch periods. Additionally, the proposed piece-wise linearization method has excellent computational performance, especially when the number of hyperplanes is 4, the solving time decreases by more than 7 000 seconds, while the root mean square error only increases by 0.024. The following conclusions can be drawn from the case studies: (1) The proposed modeling method for wind power frequency response characteristics can accurately reflect the frequency support capacity of wind power under different wind speeds and control methods in dispatch framework. (2) SC and SS can reduce the system wind curtailment by replacing the minimum technical output of thermal generators. The sensitivity analysis results indicate that when the number of synchronous condensers in the power system reaches a certain scale, the substitution effect tends to saturate. (3) The modified piece-wise linearization method can balance the fitting speed and accuracy, and the two-stage distributionally robust unit commitment model incorporated with frequency security constraints can ensure the frequency security of the power system. Compared with other uncertainty modeling methods, the proposed model can balance economy and robustness, and has better risk management capabilities.
Jiang Yihang,Zhao Shuqiang,Wang Hui等. Distributionally Robust Frequency Constrained Unit Commitment with Frequency Support of Wind Power and Synchronous Condenser[J]. Transactions of China Electrotechnical Society, 2025, 40(1): 80-95.
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2025, Vol. 40 
