Recent Advances in Electrical & Electronic Engineering - Volume 11, Issue 1, 2018

Background: Existing power systems normally operate at heavily loaded conditions and often face a surge in load demand. In spite of the implementation of the state of the art preventive measures, blackout prompted interruption in the energy supply is an enduring issue. Typically, the voltage collapse is evaded by severing a critically loaded line, which has severe repercussions including oscillatory transients and stability hindrances, which can eventually lead to a voltage collapse. Methods: This work presents a viable solution for the on-line alleviation of voltage stability constrained transmission corridors to avoid the blackout without interrupting or severing any load line. The proposed method is implemented by the insertion of a resistive impedance in the most affected and critical line to damp out power oscillations and to avoid repetitive operation and cascaded effects leading to the system collapse. Result: This work aims to develop a methodical transmission network analysis and to establish the effectiveness of the proposed augment scheme followed by a demonstration of the proposed methodology through the simulation results of the IEEE 24 bus test power system model. Conclusion: Further, experimental verification is performed on hardware in the loop test bench with a 220 KV artificial transmission line to demonstrate the capability in practical systems, to address the challenge of voltage collapse and blackouts in smart power systems.

Background: In this paper, fuzzy pole placement control approach is proposed to control the speed of D.C motor. In this method, state feedback gain is tuned by fuzzy logic. Methods: In conventional pole placement control, constant gain is considered to insert the poles of system in the desired place. Therefore, unnecessary effort is appliedto the system, and the system implementation becomes costly. In contrast, in fuzzy pole placement control, poles of system alter gradually based on the performance of system and are settled in desired point causing the system to display apposite performance. In other words, in conventional pole placement, a determined pair of poles exists, whereas in fuzzy pole placement method, an area, in which a pair of poles is relocated is obtained. Pair of poles changes its place based on the recent behavior of the system to have more appropriate manner. Results: As a result, state feedback gain changes intelligently according to the on-line performance of system eventuating in acceptable outcomes. Results show that this approach is effectual and sound.

Background: In this study, a new model-based fault detection and isolation (FDI) strategy of IGBTs open circuit faults detection and diagnosis in voltage source inverter (VSI) is proposed for space vector modulation direct torque control (SVM DTC) permanent magnet synchronous motors drives. Methods: The method is based on the bridge leg pole voltage, when with an additional simple circuit, the diagnostic method detected and effectively identified single and multiple open-circuit faults of inverter IGBTs. Also, a fault compensation strategy is suggested by using the information of the modelbased FDI stage composed of a four-leg inverter in which the fourth inverter leg is used as hardware redundancy. Results: The simulation results of fault detection, identification and compensation methods are included to prove that the proposal leads to good results.

Background: Due to the influence of core breaking, the traditional iron core linear motor has the end-effect of lateral and vertical side, which makes the output of the thrust line fluctuating greatly. The ironless permanent magnet synchronous linear motor has the advantages of zero slot effect, simple structure and flexible control. Methods: The study was based on the analysis of air gap magnetic field of ironless permanent magnet synchronous linear motor problems using two kinds of analytical methods, namely equivalent magnetic potential method and the equivalent magnetizing current method, and the finite element analysis of the magnetic field using the finite element method. Result: The analytical method for magnetic field analysis is verified to be accurate. Conclusion: By changing the motor parameters, the optimization design is achieved, which provides the reference for the design and analysis of same kind of motors.

Background: Pedestrians are the major road users in transportation system. They are more vulnerable than other road users when traffic accidents occurr, which has attracted much concerns from researchers around the world by developing corresponding countermeasures. Pedestrians are not easy to be tracked accurately because of the changes in illumination conditions and the occlusion of human body using traditional tracking algorithms. Method: To improve the effectiveness of pedestrian tracking, particle filter (PF) is utilized to track the pedestrian, which is detected using the histograms of oriented gradient (HOG) features. Then scale invariant feature transform (SIFT) features are employed to represent the region of interest for sequence images. Result: The representative vector utilized to describe the pedestrian is renewed after comparing the object model and the characteristic variables during the tracking process. This method takes advantage of color histogram and adopts PF to predict the position of the pedestrian. Conclusion: Experiments were conducted to compare the proposed method with traditional PF tracking method. Results verify the accuracy and efficiency of the proposed method.

Background: This work describes the methodology and the basic procedure developed by the patent entitled DC-DC Converter with Bipolar Output and its Use for Connection of a Distributed Generation System to a Bipolar DC Grid. Methods: The invention relates to a DC-DC converter capable of generating bipolar voltage with a suitable novel topology for distributed generation connection to a DC bipolar grid. The proposed topology uses only a power switch, unlike other DC-DC converters which employ two or four switches. Thus the complexity of the converter is reduced. The DC-DC converter with bipolar output has an input for connection to a monopolar DC source and a bipolar output voltage with a positive terminal and a negative terminal. The DC-DC converter can be applied to bipolar DC grids because it allows the connection of a monopolar DC source to such networks. The present invention is especially applicable in the industrial sector and renewable energies. In the first case, because this network type is an alternative to classic electric system, currently of interest special in the industry. In this sector, the proposed converter can control the voltage level and possible unbalances of the DC voltage network. On the other hand, in the renewable energy sector, the proposed scheme enables the connection of generation and storage systems to a bipolar DC network in a way reliably. Result: The proposed topology is a solution for these applications with sufficient guarantees of reliability, quality and performance. Conclusion: An experimental prototype based on a combination of SEPIC (Single Ended Primary Converter) and Cuk converter has been implemented to validate the patented system.

Background: Many multiprocessor systems have interconnection networks as underlying topologies and an interconnection network is usually represented by a graph where nodes represent processors and links represent communication links between processors. Methods: The diagnosability of the system plays an important role in measuring the fault tolerance of the interconnection network. The n -alternating group graph has many favorable properties such as vertex and edge symmetry, recursive structure, high connectivity, small diameter and average distance, etc., which make it favorable as a network topology for the system. Results: The diagnosability of an interconnection network G is less than or equal to the minimum degree of G . G has the strong local diagnosaility property if the local diagnosability of every vertex equals to its degree in G . In this paper, we prove that the n -alternating group graph has the strong local diagnosability property even if there exist (2n - 7) missing edges in it under the MM* model. Conclusion: In this paper, we studied the diagnosis of an n -dimensional alternating group graph n AG under the MM* model. We proved that n AG has the strong local diagnosability property, and keeps this strong property even if there exists up to (2n - 7) missing edges in it. As a result, the diagnosability of n AG with arbitrary missing links can be obtained as the minimum value among the remaining degree of every processor, provided that the cardinality of the set of missing links does not exceed 2n - 7 .

Background: The increasing concern of global climate change, the promotion of renewable energy sources, primarily wind generation, reduces the power generation from conventional plants that lead to the reduction in pollutant emission. The exploitation of wind power generation is rising throughout the world. The objective of Unit Commitment (UC) is to identify the optimal generation scheme of the committed units such that the overall generation cost is reduced, when subjected to a variety of constraints at each time interval. The optimum generation planning in electrical power system is difficult, since UC Problem has many variables and system and unit constraints of thermal generating units. Nowadays, it is essential to include reliability analysis of the power system in operation strategy of the generating units. Here, the generator failure and malfunction are considered in UC problem formulation. Methods: This paper presents a meta-heuristic algorithm based approach to determine the thermal generation schedule with consideration of wind energy system. A novel evolutionary algorithm known as Grey Wolf Optimization (GWO) algorithm is applied to solve the UC problem. Results: The potential of the GWO algorithm is validated by the standard test systems. Besides, the ramp rate limits are also incorporated in the mathematical problem formulation. In order to validate the applicability of the GWO, the standard test system is used for demonstration. Conclusion: The GWO algorithm is applied for the first time to solve wind integrated thermal UC problem considering generator forced outage rates. The simulation results reveal that the GWO algorithm has the capability of obtaining economical resolutions with good solution quality. The implementation of algorithm for solving the chosen problem is simple and robust which indicates that the GWO is a promising alternative for solving wind integrated thermal UC problems.

Background: Single-channel observed signal analysis based on independent component analysis (ICA) model belongs to the extremely underdetermined blind source separation (BBS) problem. Method: In order to extract the fault feature hidden in the single-channel measured signal from multi-stage gearbox, a joint approach of fault feature extraction based on ensemble empirical mode decomposition (EEMD) and constrained independent component analysis (CICA) is proposed. The single-channel vibration fault signal is decomposed into several intrinsic mode functions (IMFs) by EEMD, which can overcome the shortcomings of classical empirical mode decomposition (EMD). By computing the kurtosis and correlation coefficients of each IMF, we can select some suitable IMFs to construct a newly observed vector combined with the original signal, which meets the requirement of CICA algorithm. Finally, the suitable reference signal including faulty gear meshing frequency is generated, and the desired gear low frequency slight feature is extracted by CICA combined with envelope analysis. Conclusion: Through the experiment analysis of fault feature extraction with a missing tooth on the low speed gear pairs, the effectiveness and applicability of the proposed method are verified.

Background: This paper presents the design and implementation of an ultra-wideband transition from double-sided micro-strip to parallel-strip line which is usually used as balanced antenna feed. Methods: This transmission is composed of a near-optimum taper of metal on top layer and exponential taper of ground on bottom layer. The transmissions were simulated and optimized by CST Microwave Studio and then they are fabricated. Finally, the results of simulations and measurements are compared. Results: The measured results show that the performance of two back-to-back near-optimum taper transmission possesses a return loss of better than 10 dB and insert loss of one transition less than 1 dB over a bandwidth from 1.20 to 5.75 GHz (1:4.8). For a wider bandwidth, an insert loss of one transition less than 3 dB and return loss better than 10 dB can be achieved from 1.20 to 9.68 GHz (1:8.1). With 100 ohm resistor loading, the return loss of near-optimum taper transmission better than 10 dB can be received from 0.86 to 11 GHz (1:12.8).

Background: In view of the lack of centralized control of traditional home appliances, this paper implements an intelligent gateway based on the Linux embedded operating system as the software platform and the ARM9 processor S3C2440 as the hardware development platform to solve this problem. Methods: The intelligent gateway is equipped with Wi-Fi, CC1101, Ethernet card and other functional modules, and based on the 433MHz radio-frequency protocol stack and the Linux operating system kernel. We establish the platform of the remote control through the cloud server, so the users can log on the client to achieve smart home remote monitoring. Result: This paper introduces the hardware and software development process of intelligent gateway, which involves the realization of the 433MHz radio-frequency protocol stack, the software design of the 433MHz radio-frequency module, and the design and implementation of the smart home client and so on. Conclusion: The test results show that the intelligent gateway has the characteristics of low-cost, low-power consumption, high reliability.