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In this paper, a fixed-time backstepping fractional-order sliding mode excitation controller (FTBFOSMEC) is proposed to enhance the performance of multimachine power system. The FTBFOSMEC is designed to achieve semi-global uniform ultimate boundedness of the multimachine power system within an upper limited convergence time irrelated to the initial operating states. The FTBFOSMEC can achieve the attractive qualities of sliding mode control with strong robustness and fast dynamic response, and the merits of backstepping control in globally asymptotic stability for parametric uncertainty. In addition, the FTBFOSMEC can avoid the singularity problem of conventional SMC. Furthermore, the nonlinear first-order filter is carried out to avoid the “explosion complexity” issue of traditional backstepping control. The fractional-order controller is designed to alleviate the chattering phenomenon of the conventional SMC. Meanwhile, the FTBFOSMEC is in a continuous description, which can further eliminate the chattering phenomenon. The Lyapunov function is taken to analyze the stabilization of the multimachine power system under the control of the FTBFOSMEC, and to estimate the upper limit of convergence time. Finally, comparative results, based on the New England 10-machine 39-bus power system, indicate that the power system under the proposed FTBFOSMEC can obtain effective, robust and superior performances compared with the existing control strategies under different operating circumstances. [ABSTRACT FROM AUTHOR]

Dynamic behaviors of distribution networks are of great importance for the power system analysis. Nowadays, due to the integration of the renewable energy generation, energy storage, plug-in electric vehicles, and distribution networks turn from passive systems to active ones. Hence, the dynamic behaviors of active distribution networks (ADNs) are much more complex than the traditional ones. The research interests how to establish an accurate model of ADNs in modern power systems are drawing a great deal of attention. In this paper, motivated by the similarities between power system differential algebraic equations and the forward calculation flows of recurrent neural networks (RNNs), a long short-term memory (LSTM) RNN-based equivalent model is proposed to accurately represent the ADNs. First, the adoption reasons of the proposed LSTM RNN-based equivalent model are explained, and its advantages are analyzed from the mathematical point of view. Then, the accuracy and generalization performance of the proposed model is evaluated using the IEEE 39-Bus New England system integrated with ADNs in the study cases. It reveals that the proposed LSTM RNN-based equivalent model has a generalization capability to capture the dynamic behaviors of ADNs with high accuracy. [ABSTRACT FROM AUTHOR]

This article proposes a novel distributed predefined-time sliding mode controller (DPTSMC) to gain exceptional performances of power system under input saturation. Firstly, considering the saturation of excitation input to avoid the overvoltage of the coil, an auxiliary system is taken to compensate the effect of the excitation saturation. Then, the sliding mode control (SMC) and the predefined-time stability theory are taken to devise the DPTSMC to make the power system stable in a predefined time, which has an upper limit and is directly equivalent to an adjustable parameter, thus satisfying the high requirement of the power system for expected convergence time. Meanwhile, the estimated upper bound convergence time of the power system under the proposed DPTSMC is less conservative than some existing fixed-time control strategies. Moreover, the distributed control is taken to devise the DPTSMC and the controller can receive the real-time information from the phasor measurement units (PMU). Hence, the central controller is not required and the communication network is simple, thus releasing the pressure in complicated calculation and communication, and gaining rapid and coordinated response capacity. Next, the stabilization of the power system under the DPTSMC within a predefined upper limited time is proved through the Lyapunov function. Finally, the exceptional performance of the proposed DPTSMC than the existing control methods is verified through the simulation in the IEEE 39-bus 10-machine New England power system under different operation scenarios. [ABSTRACT FROM AUTHOR]