Non-intrusive Load Identification Method based on SAGOA-GMM Algorithm

Non-intrusive Load Identification play an important role in daily life. It can monitor and predict grid load while statistics and analysis of user electricity information. Aiming at the problems of low non-intrusive load decomposition ability and low precision when two electrical appliances are started and stopped at the same time, a new type of clustering and decomposition algorithm is proposed. The algorithm first analyses the measured power and use DBSCAN to filter out the noise of the collected data. Secondly, the remaining power points are clustered using the Adaptive Gaussian Mixture Model (AGMM) to obtain the cluster centres of the electrical appliances, and finally correlate the corresponding current waveform to establish a load characteristic database. In terms of load decomposition, a mathematical model was established for the magnitude of the changing power and current. The Grasshopper optimization algorithm (GOA) is optimized by introducing simulated annealing (SA) to identify and decompose electrical appliances that start and stop at the same time. The result of the decomposition is checked by the current similarity test to determine whether the result of the decomposition is correct, thereby improving the recognition accuracy. Experimental data shows that the combination of DBSCAN and GMM can can identify similar power characteristics. The introduction of SA makes up for the weakness of GOA and gives full play to the advantages of GOA's high identification efficiency. Finally, the test is carried out through the load detection data of the simultaneous start and stop of the two equipment. The test results show that the proposed method can effectively identify the simultaneous start and stop of two loads and can solve the problem of low recognition rate caused by the similar load power, which lays the foundation for the development of non-intrusive load identification in the future.

Lightweight Design of Patch Plate on Car-body B-pillar based on Side Impact Safety

The B-pillar of automobile needs to meet the requirements of vehicle strength and rigidity, and also consider the fuel economy of vehicle. Therefore, the design and development of B-pillar is a difficult point in the field of car body design and manufacturing. Based on the side impact regulations, the safety model ling and simulation analysis of the B-pillar of the vehicle was carried out to obtain the change law of the intrusion amount and the intrusion speed of the five key points in the whole process. According to the analysis results of side impact of B-pillar, a scheme to reduce the material thickness of B-pillar body and increase patch plate for lightweight design was proposed, and a comparative analysis of the safety of side impact was made. In view of the problem that the intrusion of B-pillar of a real vehicle model did not conform to the regulations, the design scheme of adding patch plate was proposed to improve the safety of side impact. According to the actual collision results, the simulation model was modified, and the design scheme was simulated and optimized. The reliability of the design scheme was verified by the real vehicle collision analysis. The results show that: in the side collision of B-pillar, the intrusion of D2 position measurement point is the largest, the intrusion velocity of D3 position measurement point is the largest, and the intrusion amount and intrusion speed of D5 position measurement point are the smallest. Patch plates are added to the inner side of adjacent area of D2 position measurement point. The welding point is welded with B-pillar structure, and other areas of B-pillar keep the same structure, so as to realize lightweight and effective improvement of safety. Under the condition of maintaining the original material and thickness of B-pillar, two patches with thickness of 2 mm and material of B340LA are added in the middle of B-pillar to improve the structural strength. The defect area is set at the wrinkle position of the original B-pillar to guide the deformation mode of the B-pillar. The relative deviation between simulation calculation and test intrusion is less than 20 %, and the car crash simulation model with improved B-pillar structure is more accurate. For this type of car, the optimization and improvement effect of B-pillar structure is ideal, which improves the passenger safety protection ability in side impact.

Reliability and Availability Study of a Gas Turbine based on usual Approaches with a Failure Mode Analysis

The rotating machines like gas turbine types are highly valuable in the gas transportation industry. They are often strategic and have a major impact on the proper operation of gas transport and compression facilities. In this context, the aim of this work is to increase efficiency and production by developing an approach for this kind of installations using real data collected from the operation of the gas turbine. The objective is to provide a database relating to the reliability, availability, and maintenance of gas turbines while using standard reliability approaches. In addition, ensuring maximum availability of this type of rotating machine by preventing its failures and reducing emissions, and by minimizing start-up sequences, which reduces emissions when starting this machine. Also, the proper operation of these gas turbine installations with the reliability approaches developed in this work makes it possible to model the effects of failures in order to predict optimal operating performance and increase the life of their components. This, therefore, ensures a reliable and safe operation of the gas turbine in a compression station for economically profitable gas recovery.

Brushless DC Permanent Magnet Motors State of the Art

The paper presents a study of the permanent magnet brushless DC machine, from two perspectives - from authors’ own experience in designing and manufacturing such motors, as well as from actual published research. Various constructive topologies and how they influence BLDC operation, windings used with emphasis on slot, concentrated windings, are also presented. The following part describes current techniques used for enhancing BLDC limited maximum speed, such as phase advance and dwell control, somewhat similar to flux weakening in AC permanent magnet brushless motors. The paper concludes with presentation of several methods used for sensing BLDC rotor position. Overall, the authors’ intention publishing this paper was to provide an insight regarding current BLDC development, as well as to assist in making documented choices when using BLDC in specific applications.

A Hybrid Model of Photovoltaic Power Stations for Model Ling Tasks of Large Power Systems

Renewable energy sources are being actively penetrated in the global energy sector, with the main growth being achieved by new photovoltaic power stations. At the same time, the influence of photovoltaic power stations on the operation of power systems is known. This is primarily due to the inconstancy of the weather, which leads to a decrease in the output of each specific photovoltaic panel and power station as a whole. To study the effect of partial shading of photovoltaic panels on the parameters of its operation, various models of the current-voltage characteristics of photovoltaic cells are used in the world, while detailed two-diode models show the best results. The use of detailed models allows to get complete information about the processes in a variety of photovoltaic panels of a power station, as well as other elements of it, such as a voltage converter. This makes it possible to assess the impact of these processes on the external power system. However, for detailed modelling of large photovoltaic power stations as part of power systems, it is necessary to use powerful software and hardware systems. Such systems include the Hybrid real-time power system simulator. This simulator is a multiprocessor installation that provides a solution to the aggregate model of the power system through the use of three approaches to modelling: digital, analogue and physical. The article presents the results of experimental studies of software and hardware tools for modelling a photovoltaic power station, developed on the basis of a hybrid approach to modelling electric power systems.

Artificial Intelligence Enhancements in the field of Functional Verification

Functional Verification is one of the main processes in the Research and Development of new System-on-Chip. As chips are becoming more and more complex, this step becomes an extensive bottleneck which can vastly delay the chip mass production. It is a mandatory step as the design needs to not contain any faults, to ensure proper functioning. If this step is bypassed, large major financial losses and customer dissatisfaction can happen later in the process. Additionally, if the verification process is prolonging for a long period of time, to achieve a higher quality product, it will also cause a financial impact. Therefore, the solution is to find ways to optimize this activity. This paper contains a review on how Artificial Intelligence can reduce this blockage, taking into consideration the time spent on implementing the verification environment and the time of attaining the aimed coverage percentage. The engineer will take a decision on which causes of time-consuming processes presented in the paper will be reduced, depending on project specifics and his or her experience. A candidate for optimizing the training of the Neural Network is the Nvidia’s Computer Unified Device Architecture (CUDA). CUDA is parallel computing platform that make use of the GPU, peculiarly of the CUDA cores located inside Nvidia GPUs.

Power Quality Enhancement in Four-Wire Systems under different distributed Energy Resource Penetrations

Reactive and harmonic currents that are being injected into the power supply by nonlinear loads, cause an increasing deterioration of the power system voltages and currents, whereas active power filter (APF) has been widely used to overcome this problem and to improve the power quality delivered by the power supply. In this paper, a three-level four-legged active power filter based on a neutral-point-clamped (NPC) inverter is presented. To fulfil the requirement of the active power filtering function under balanced, unbalanced, and distorted (including 3rd and 5th harmonics) power supply voltages, a control method based on the instantaneous power theory has been used and discussed. On the other side, the inverter switching state control has been achieved based on PWM current controller. The performance of the proposed topology under the control approach has been finally discussed through the obtained simulation results.

Weight Coefficient Setting of Current Predictive Control for Permanent Magnet Synchronous Machine using HPSO

Aiming at the problem of multi-objective weight coefficient setting of model predictive control (MPC) for permanent magnet synchronous motor (PMSM), a hybrid particle swarm optimization (HPSO) algorithm with low computational complexity of fitness value is proposed to realize the self-setting of weight coefficient of cost function. In the proposed strategy, good particles update velocity and position through particle swarm optimization (PSO) algorithm, while bad particles not only do the same but generate the offspring by cross and mutation, and then the worse offspring will be replaced by their extremum individuals. It is faster that the adaptive cross and mutation rate makes the offspring get closer to the good particles, and it increases the diversity of particles without destroying the good particles. Experimental results show that compared with other optimization algorithms, the proposed algorithm. Firstly, is more inclined to escape from the local optimum. Secondly, it has higher search accuracy and faster convergence speed. Moreover, with setting weight coefficient, the system speed regulation time is shortened, the current total harmonic distortion (THD) is reduced significantly, and the switching frequency is effectively reduced without affecting the output power quality.

Analysis and Design of Oil Cooling Structure in Motor Shaft of New Energy Vehicle

Due to the small volume and high-power density of new energy vehicle motor, a large number of losses in the working process are converted into heat accumulation, resulting in temperature rise, which affects its efficient operation. Based on the heat conduction mechanism, four kinds of shaft oil cooling models with different structures are designed, which are comprehensively analysed by using the thermal-fluid-structure coupling analysis method, and the most effective cooling shaft oil cooling model is solved. The simulation is based on Ansoft Maxwell, and the loss results of each component of the motor are obtained, and the loss data is imported into the Fluent software for fluid-structure coupling analysis. By keeping the other variables consistent, the oil flow rate, pressure drop, and temperature rise of four kinds of in shaft oil cooling structures are analysed and compared. The experimental results show that the rectangle around type is the optimal oil cooling structure. In addition, based on the rectangle around oil duct model , the thermal-fluid-structure coupling analysis of the whole motor is carried out, and compared with the motor without cooling system. The temperature rise cloud diagram of the two motors shows that the former has more obvious heat dissipation effect than the latter, and effectively reduces the temperature rise of the motor, especially the rotor and permanent magnet parts, which verifies the rationality of the shaft cooling structure design.

Status and Trends of Power Devices

Advances in power semiconductor technology have improved the efficiency, size, weight, and cost of power electronic systems. Power integrated circuits have been developed for the use of power converters for portable, automotive and aerospace applications. New materials (SiC and GaN) have been introduced for advanced applications. They increase the output power density per area or per volume, reduce the consumption of natural resources, and increase the efficiency of electric systems. Especially the effects of SiC devices are dramatic. The paper reviews the state of these devices in terms of higher voltages, higher power density, and better switching performance.