Aiming at the problems of slow convergence and low accuracy of the traditional sparrow search algorithm (SSA), a multi-strategy improved sparrow search algorithm (ISSA) was proposed. Firstly, the golden sine algorithm was introduced in the location update of producers to improve the global optimization capability of SSA. Secondly, the idea of individual optimality in the particle swarm algorithm was introduced into the position update of investigators to improve the convergence speed. At the same time, a Gaussian disturbance was introduced to the global optimal position to prevent the algorithm from falling into the local optimum. Then, the performance of the ISSA was evaluated on 23 benchmark functions, and the results indicate that the improved algorithm has better global optimization ability and faster convergence. Finally, ISSA was used for the node localization of HWSNs, and the experimental results show that the localization algorithm with ISSA has a smaller average localization error than that of the localization algorithm with other meta-heuristic algorithms.

Modular multilevel converters (MMCs) play an important role in the power electronics industry due to their many advantages, such as modularity and reliability. In the current research, the simulation method is used to study the system. However, with the increasing number of sub-modules (SMs), it is difficult to model and simulate the system. In order to overcome these difficulties, this paper presents a universal mathematical model (UMM) of MMC using half-bridge cells as SMs. The UMM is a full-scale model with switching state, capacitance, inductance, and resistance characteristics. This method can calculate any number of SMs, and it does not need to build a simulation model (SIM) of physical MMC—in particular, parametric design can be realized. Compared with the SIM, the accuracy of the proposed UMM is verified, and the computational efficiency of the UMM is 8.7 times higher than the simulation method. Finally, by utilizing the proposed UMM method, the influence of the parameters of MMCs is studied, including the arm induction, SM capacitance, SM number, and output current/voltage total harmonic distortion (THD) based on the UMM in the paper. The results offer an engineering insight to optimize the design of MMCs.

This study develops a passive fault‐tolerant control (FTC) method with weak conservatism for the discrete parameter system. For the first time, application of (0‐1) and symbolic parameters for describing the discrete parameter system is given. In addition, the relationship between the discrete parameter domain and the control strategy feasible set is discussed. This paper mainly discusses the significance of the intersection set of control strategy feasible sets for passive FTC. Moreover, a suggestion that the intersection set can be constructed in the absence of the intersection set by changing the topology of the controlled object or changing the controller, or combining both options is proposed. Furthermore, the conditions of obtaining a global‐optimal passive FTC strategy and a local‐optimal passive FTC strategy are analyzed, which depend on the size of the control strategy feasible set for optimizing. Finally, the simulation is carried out to show the validity of the proposed passive FTC scheme.

In this paper, a fault detection and diagnosis (FDD) scheme is developed for a class of intensified HEX/reactor, in which faults caused by sensor, actuator, and process are taken into account in the unified framework. By considering overall heat transfer coefficient as a function of fouling and fluid flow rate, a dynamic model which is capable of identifying these two faults simultaneously is derived. Sensor measurements, together with estimation by adaptive high gain observers, are processed, aimed at identifying sensor faults and providing adequate estimation to substitute faulty measurements. Then reliable measurements are fed to several banks of interval filters to generate several banks of residuals; each bank of residuals is sensitive to a particular process parameter/actuator. By evaluating these residuals, process/actuator fault isolation and identification are achieved. The proposed strategy is applied to actual data retrieved from a new intensified heat exchanger reactor. Simulation results confirm the applicability and robustness of the proposed methodology.

To solve the problem of incompatibility and mutual repulsion between a distribution network (DN) and distributed generation (DG), this paper first analyzes the conflicts between current feeder automation (FA) and doubly-fed induction generation (DFIG). Then, a DFIG coordination control strategy compatible with FA is proposed to cause the DFIG operating continuously during fault isolation and power supply recovery. The strategy consists of three aspects: (1) a DFIG islanding active synchronization control technology to support islanding and distant presynchronization control; (2) DFIG senses the status of circuit breakers/tie-switch through generic object oriented substation event (GOOSE) messages to achieve rapid switch of control modes and distant synchronization; (3) tie-switch senses the status of DFIG through GOOSE messages for closing. Finally, the effectiveness of the strategy is validated by multiple sound and detailed time-domain simulation cases. This study indicates future possible development trends and provides a simple and effective strategy for researches in the field of smart grid DN–DG compatibility.