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SummaryAlong with expansion in using of Internet and computer networks, the privacy, integrity, and access to digital resources have been faced with permanent risks. Due to the unpredictable behavior of network, the nonlinear nature of intrusion attempts, and the vast number of features in the problem environment, intrusion detection system (IDS) is regarded as the main problem in the security of computer networks. A feature selection technique helps to reduce complexity in terms of both the executive load and the storage by selecting the optimal subset of features. The purpose of this study is to identify important and key features in building an IDS. To improve the performance of IDS, this paper proposes an IDS that its features are optimally selected using a new hybrid method based on fruit fly algorithm (FFA) and ant lion optimizer (ALO) algorithm. The simulation results on the dataset KDD Cup99, NSL‐KDD, and UNSW‐NB15 have shown that the FFA–ALO has an acceptable performance according to the evaluation criteria such as accuracy and sensitivity than previous approaches.

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This paper proposes a novel resonance suppression scheme for a single-phase grid inverter with the LLCL filters. In the structure of the LLCL filters, a small inductor is added in series with the capacitor in the conventional LCL filters to make zero impedance at the switching frequency, by which the grid-side inductor filter can be reduced remarkably. However, a resonance phenomenon is still a critical issue in this system. So, an active damping method based on the proportional and resonant controllers is proposed to suppress the resonance. In addition, the stability is analyzed for the feasibility of the proposed algorithm. Finally, the simulation and experimental results have verified the control algorithm for a single-phase grid inverter.

This paper proposes an analytical method for optimal allocation and sizing of Distributed Generation (DG) units in order to minimize losses and to improve the voltage profile in distribution systems. The evaluation of losses and voltage profile is based on a power flow method for radial networks. The approach, which is based on the calculation of losses sensitivity factor, has been applied to IEEE 13 and 37 bus distribution test systems. The proposed method has better results than the results obtained from other methods.

In this paper, an active damping control scheme for LLCL filters based on the PR (proportional-resonant) regulator is proposed for grid-connected three-level T-type PWM converter systems. The PR controller gives an infinite gain at the resonance frequency. As a result, the oscillation can be suppressed at that frequency. In order to improve the stability of the system in the case of grid impedance variations, online grid impedance estimation is applied. Simulation and experimental results have verified the effectiveness of the proposed scheme for three-phase T-type AC/DC PWM converters.

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