Recent Advances in Electrical & Electronic Engineering - Volume 15, Issue 2, 2022

The development in the field of electrical energy has been growing increasingly due to the need for this energy in daily life. The reliability and safety of electrical power systems and equipment represent complex problems that are difficult to solve by conventional methods such as Fuzzy Logic and Artificial Neural Networks. Bayesian network is recently used to overcome some limitations in conventional methods. This paper represents a bibliographic review about the use of Bayesian networks in the field of electric systems. This paper seeks to answer the following questions: (i) What are the areas of interest? (ii) What are the most active countries in this field?? (iii) Who are the most participating authors in this field? (iv) which year witnessed the largest number of publications? (v) What is the most widespread field related to this research? (vi) What is the most used system in terms of application? This field witnesses a slight increase in the number of publications in the last two decades (1999-2021), with a note of a sharp increase in publishing in the last two years. It is observed that reliability assessment and fault diagnosis are the most common fields. Furthermore, it is found that China and USA are the active countries in this field. Electric Power and Energy Systems Journal and IEEE Transactions on Power Systems Journal are the lead source documents, and most of the documents used electric power systems as an application. This paper will help researchers to know the versability features of BN and to identify the gaps in the use of BN in electric domains.

Background: Surface permanent magnet motors (SPMVM) and dual permanent magnet motors (DPMVM) have broad prospects in direct drive systems, but some problems occur with large magnetic leakage, large torque ripple and large amount of permanent magnets (PMs). Objective: In order to reduce the torque ripple and magnetic flux leakage of SPMVM and DPMVM, and improve the torque density, a dual permanent magnet vernier machine with Halbach PM array (DHPMVM) is proposed. Methods: By air gap permeance method, flux density analysis of three kinds of motors was analyzed, and the main harmonics of SPMVM and DHPMVM are investigated with structure parameters. Electromagnetic characteristics of three motors such as no-load back, electromotive force (EMF), torque, and inductance are compared and analyzed by finite element method (FEM). Results: The study found that under the same size, winding distribution, electrical load and speed conditions, DHPMVM uses Halbach PM array and consequent pole structures to reduce magnetic flux leakage and torque ripple, increase torque density, PM utilization and torque per unit PM volume. Compared with SPMVM and DPMVM, the DHPMVM proposed in this paper has better electromagnetic performance. Conclusion: The DHPMVM topology is the better choice in terms of torque density, torque ripple, and magnet usage among the investigated topologies.

Background: With the continuous development of big data, artificial intelligence, the Internet of things, and blockchain technology, distributed interactive systems have gradually become the mainstream of computing technologies and applications with the help of real-time interaction platforms. The real-time interaction platforms provide a data communication bridge for distributed applications, not only meeting the timeliness and correctness of data interaction but also providing a unified interface for application development. It realizes the plug and play of different functional modules in the distributed system and improves development efficiency for system developers. Objective: According to the characteristics of the large scale, wide range, and complex running environment of distributed interaction systems, this paper analyzes the function and performance requirements of the distributed interactive platform and designs and implements a real-time interactive platform named NetDDS based on a publish-subscribe mechanism. Methods: Concerning the idea of a layered design, the real-time interactive platform is constructed from three aspects: distribution service layer, QoS guarantee layer, and data transmission layer. The platform provides a data synchronization function based on publish/ subscribe mechanism, a configurable QoS guarantee mechanism, and a multi-protocol data transmission mechanism based on Ethernet, ensuring the real-time correctness and reliability of data transmission. Results: Experimental results show that the interactive platform exhibits less delay in message update. Conclusion: This paper proposes a hierarchical architecture, designs and implements a real-time interaction platform based on publish/subscribe mechanism, and provides a topic- based publish/subscribe model to the application layer. The publisher and subscriber directly publish and subscribe with data as the center to meet the real-time requirements of distributed real-time applications.

Aim: Improving the frequency regulation in a Low Voltage (LV) microgrid during grid mode transition using Grid Forming Grid Support (GFGS) converters with inertia emulation. Background: The ever-increasing demand for energy and the depleting fossil fuels has increased the proliferation of converter-fed Renewable Sources (RES) in the conventional grid. The reduced system inertia results in frequency regulation issues which are further aggravated by the unpredictable nature of RES and dynamic switching of loads. This scenario results in blackouts, unwanted load shedding, power quality issues, and discrepancies in protection schemes. Objective: A control scheme is presented on the principle of swing equation-based synchronization to regulate the active power output of a grid-tied voltage-source converter operating in a grid forming grid supporting mode in a low voltage PV-based microgrid. The Virtual Synchronous Machine control (VSM) is implemented for controlling the active power output, which follows the grid frequency deviations, ensuring the safe State of Charge (SoC) limits of the Battery Energy Storage System (BESS). Methods: The stability issues due to the absence of inertia in an inverter-fed LV microgrid are staved off by giving auxiliary grid support by implementing VSM control in a BESS inverter in the grid forming mode. The LV microgrid model with all the converters in the GFGS converter is developed in the MATLAB/Simulink environment. Particle Swarm Optimization (PSO) is used to fine- tune the control parameters. The effectiveness of the control strategy has been investigated for unintentional islanding events. Results: The droop control-based GFGS grid-tied converters with power balance equation-based VSM control gave frequency regulation within the range stipulated by the grid codes during the islanding events. Conclusion: The work demonstrates the effectiveness of VSM control in providing the auxiliary grid support for droop-based grid forming converters in an LV microgrid.

Background: Static Synchronous Compensator plays an essential role in governing the reactive power and harmonics of power systems. The accuracy and real-time performance of reactive power and harmonic detection are necessary to ensure balancing compensation effectiveness. The traditional dq current detection method can only extract positive sequence components in the positive sequence rotational reference frame and extract negative sequence components in the negative sequence rotational reference frame. Objective: This paper aims to give a practical and straightforward current detection solution to enhance the compensator performance and simplify the control system by extracting the positive sequence, negative sequence, and harmonics in the positive sequence rotational reference frame. Methods: Firstly, a grid-connected four-quadrant converter with an Inductance-Capacitance- Inductance (LCL) filter balancing compensation topology is constructed. Then an improved current detection algorithm is proposed to extract the positive sequence, negative sequence, and harmonics in the positive rotational reference frame separately. Finally, the Direct Current (DC) side voltage design method is discussed to avoid the overmodulation effects. Results: Matlab simulation and a prototype 500kVA Static Synchronous Compensator (STATCOM) experiment are implemented to demonstrate the proposed method. Conclusion: The proposed strategy can effectively improve the compensation accuracy, and the system structure is simplified while the stability and reliability of the whole system are ensured.

With the increase in the number of Electric Vehicles (EVs), more power will be needed from the grid. An increase in the load demand, losses, and grid operational costs will occur. Furthermore, with the increasing number of EVs, there comes a possibility of user dissatisfaction which can further lower the popularity of EVs. Objective: This article focuses on EV battery charging and discharging control optimization, i.e., optimizing load demand to minimize power grid system losses and reduce charging costs. It also aids in the vehicle to grid (V2G) process while considering the "User Decision Variable" for each prospective EV. Methods: As a load minimization problem, the optimal power flow model has been formulated first, then the problem has been formulated for each EV. The operational cost of the charging station is an objective function. Results: Further investigation of the load minimization of the IEEE33-bus system has been carried out, and Particle Swarm Optimization (PSO) algorithm is proposed. Conclusion: MATLAB results show that the proposed strategy to charge and discharge can decrease losses from the power grid, reduce the running operational cost while considering battery life and the user's sense of security.

Background: With the development of technologies such as the Internet of Things (IoT) and cloud/edge computing, a large number of edge devices in the smart grid accomplish information interconnection and generate massive amounts of data. On the one hand, smart grids need to obtain a large amount of grid data from edge terminal devices. On the other hand, edge computing also brings some security threats. Therefore, edge data security faces major challenges. Objective: In order to ensure the security of data in the edge computing environment of the smart grid, we propose an edge data storage scheme (BlockSE) for the smart grid edge computing environment. Methods: BlockSE combines permissioned blockchain and smart contract technology to achieve secure storage of data on edge. We adapted ring signature technology to achieve privacy preserving of participating nodes. To allocate the storage resources of edge servers fairly and transparently, we designed a storage resource allocation algorithm based on the smart contract, whereby edge devices can obtain storage resources fairly according to demand. Results: Simulation experiments were performed; the results show the effectiveness of the proposed BlockSE scheme. Conclusion: This paper focused on data security in the smart grid's edge computing environment and proposed a secure storage scheme for edge data based on permissioned blockchain. The evaluation shows the safety, effectiveness, and practicability of the proposed BlockSE scheme.