International Journal of Industrial Electronics, Control and OptimizationInternational Journal of Industrial Electronics, Control and Optimization
http://ieco.usb.ac.ir/
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Feed provided by International Journal of Industrial Electronics, Control and Optimization. Click to visit.The Effect of Condition Monitoring of Circuit Breaker on the Reliability and Maintenance Cost ...
http://ieco.usb.ac.ir/article_4462_601.html
Over the recent years, a number of new maintenances methods for high voltage substations have been introduced to reduce the number of substation events. The primary purpose of the present study is to presents a Cost-benefit analysis for Circuit-Breakers (CBS) in a substation equipped with Condition Monitoring (CM) devices. To this end, a mathematical formulation to categorize and model equipment failures based on their severity is developed. By CM, some of severity failures, named major failures, can be detected early, and corrected as the minor failure. This formulation quantifies the effect of CM devices on the outage rate and Predictive Maintenance (PDM) rate of the equipment. The PDM rate is used to modify the Markov maintenance model for the equipment. The proposed modified Markov model quantifies the effect of CM on the maintenance costs and lifetime of CB. The New Markov model is compared with the Preventive Maintenance (PM) model. Expected Energy Not Supply (EENS) and reliability Cost are calculated with and without CM on CBs. Finally, the proposed model is applied on the CBs of 400/132/20KV substation in the Khorasan Regional Electricity Company (KREC) in Iran. The obtained results show that CM on CBs of substations improves the EENS and reliability cost by 82.43 %. Moreover, the maintenance cost of the proposed model shows an improvement of 9.07 % compared to PM model. Finally, the total annual costs show an improvement of 80.67% due to CM on CBs.Sun, 30 Jun 2019 19:30:00 +0100A New Boost DC-DC Converter Based on a Coupled Inductor and Voltage Multiplier Cells
http://ieco.usb.ac.ir/article_4664_0.html
A new non-isolated, coupled-inductor, single-switch boost DC-DC converter for photovoltaic (PV) power application is introduced in this paper. A coupled inductor and voltage multiplier cells is used in the presented converter to obtain a high voltage conversion ratio. Also, a passive clamp circuit is applied in the converter structure to reduce voltage stress of the power switch. This leads to using a power switch with lower on-state resistance in the converter which decreases the conduction loss. In addition, zero current switching (ZCS) condition for the power switch is achieved due to the use of the clamp circuit. Several advantages such as low operating duty cycle, high voltage conversion ratio, reduced voltage stress of semiconductors, low turn ratio for the coupled inductor, leakage inductance reverse recovery and high efficiency operation make the presented converter suitable for renewable energy applications. The steady state operation of the suggested structure in continuous conduction mode (CCM) and discontinuous conduction mode (DCM) is expressed and analyzed. Then, the presented topology is compared with several similar high gain topologies to prove its advantages. Finally, experimental measurement results of a laboratory prototype of the proposed DC-DC converter with about 213W output power and 435V output voltage at 50 kHz switching frequency are presented to corroborate its feasibility and performance.Wed, 22 May 2019 19:30:00 +0100Conformable Fractional Order Sliding Mode Control for a Class of Fractional Order Chaotic Systems
http://ieco.usb.ac.ir/article_4463_601.html
In this paper, a novel conformable fractional order (FO) sliding mode control technique is studied for a class of FO chaotic systems in the presence of uncertainties and disturbances. First, a novel FO nonlinear surface based on conformable FO calculus is proposed to design the FO sliding mode controller. Then, asymptotic stability of the controller is derived by means of the Lyapunov direct method via conformable FO operators. The stability analysis is performed in the sliding and reaching phase. In addition, the realization of reaching phase is guaranteed in finite time and the reaching time is calculated analytically. The proposed control approach has some superiorities. Reduction of the chattering phenomenon, high robustness against the uncertainty and external disturbance, and fast convergence speed are the main advantages of the proposed control scheme. Moreover, it has simple calculations because of using conformable FO operators in the control design. The numerical simulations verify the efficiency of the proposed controller.Sun, 30 Jun 2019 19:30:00 +0100Microgrid optimal scheduling considering normal and emergency operation
http://ieco.usb.ac.ir/article_4665_0.html
This paper deals with the optimal scheduling of a microgrid (MG) equipped with dispatchable distributed generators (DGs), renewable generators and electrical storages (batteries). A chance-constrained model is developed to handle normal operation and emergency conditions of MG including DG outage and unwanted islanding. Purchasing reserve from the upstream grid is also considered. Moreover, the uncertainties of loads and renewable resources are incorporated into the model. Furthermore, a novel probabilistic formulation is presented to determine the amount of required reserve in different conditions of MG by introducing separate probability distribution functions (PDFs) for each condition. Accordingly, an index named as the probability of reserve sufficiency (PRS) is introduced. The presented model keeps a given value of PRS in normal and emergency conditions of MG operation. In addition, some controllable variables are added to the chance constraints as an innovative technique to reduce the complexity of the model. Finally, a test microgrid is studied in different case studies and the results are evaluated.Wed, 22 May 2019 19:30:00 +0100Control Law Design with Dead-beat Property in Continuous-Time Dynamical Systems
http://ieco.usb.ac.ir/article_4464_601.html
In this paper, an open loop control scheme is developed in order to design a dead-beat control effort in the high order continuous-time systems. The dead-beat control is really a finite-time control law. In this method, the input signal has been manually selected such that the output signal becomes constant in a finite time. In the LTI systems, having known the step response, a control signal could be exactly selected such a way that the control objective would be met in a finite time. For this end, the dead-beat control problem is firstly investigated in a standard first order system. Then a similar problem is studied in the second order systems. Finally a general design framework would be developed to obtain a dead-beat control policy in the high order continuous-time systems. In the proposed method, the control design problem is deliberately converted into the solution of a linear matrix equation. Therefore the control signal would be determined by solving such an algebraic equation. The proposed procedure is applied in some continuous-time LTI systems. The simulation results are shown effectiveness of the suggested methods for designing of a finite-time control law in the continuous-time systems.Sun, 30 Jun 2019 19:30:00 +0100A Z-Source Network Integrated Buck-Boost PFC Rectifier
http://ieco.usb.ac.ir/article_4666_0.html
This paper presents a wide range gain buck-boost type PFC rectifier based on the conventional buck-boost DC-DC converter. This novel rectifier is fed by a buck-type Z-source network at the DC side with the help of an inductor smoothing the AC side input current. The proposed PFC rectifier offers better input and output waveform qualities compared to the conventional buck-boost PFC rectifier. Maintaining near to unity power factor (PF) and low total harmonic distortion (THD) in a wide range of load variations and also the simple single-loop control are the main features of the proposed PFC rectifier. Furthermore, the switching frequency of the proposed rectifier can be chosen very higher than the competitors, since it successfully lets incredibly increase the duty cycle for a same voltage gain compared to the traditional solutions. This leads to reduced size of passive components and volume of the rectifier. A 250 W prototype circuit is designed and simulated considering most practical issues to evaluate the performance of the proposed PFC in both buck and boost modes. The results are compared with some of the well-known conventional PFC rectifiers that confirm the superior performance of the proposed topology.Wed, 22 May 2019 19:30:00 +0100Comparison of Fuzzy and Brain Emotional Learning Based Intelligent Control approaches for a ...
http://ieco.usb.ac.ir/article_4581_601.html
In this paper, the Brain Emotional Learning Based Intelligent Controller (BELBIC) and fuzzy controller were used to control output voltage of the full bridge DC-DC converter. The converter is presented by its state space averaged model assuming that it operates in the continuous conduction mode (CCM). A comparison was also made between the results. The effectiveness of control approaches are demonstrated by the uncertainty of system parameters and acceptable load variations. The performance of the BEBLIC and fuzzy controller in controlling the output voltage of the full bridge DC-DC converter was satisfactory. Since these controllers are not designed to reduce error to zero, it is not possible to claim that the error rate is precisely zero. Compared to the fuzzy controller, the BELBIC shows negligible overshoots and fluctuations. Both controllers reach stabilization almost at once. It is, therefore, concluded that the BELBIC acts better than the fuzzy controller. Considering the uncertainty of system parameters (including inductance, capacitance, and input voltage and acceptable variations of load), BELBIC acts better than the fuzzy controller.Sun, 30 Jun 2019 19:30:00 +0100Robot Action Space of Tractable Subsumption Architecture
http://ieco.usb.ac.ir/article_4667_0.html
Abstractâ€”In this article, a new hybrid feedback system is introduced, which integrates the behavior- based planning by reactive agent-based control scheme through subsumption architecture. At first, subsumption protocol studies the interactions of robot with its environment which cover problems including translating of agent action into an outcome, interactions with the environment, and cooperative actions. Second considers deliberative behavior given the prevailing protocol. It determines the best and quickest response for each agent and tunes the actions based on an objective function obtained by a leader agent. More specifically, tasks are arranged as a hierarchy, where the high-level task is obstacle avoidance. Conflicting lower level tasks are removed by the leader agent decisions. Indeed, the leader agent can adjust the priority of all action to provide an optimal behavior. In other words, our new agent-based method optimizes the subsumption architecture by producing an approximating objective function that made not only behaviors but also optimization done in incremental procedure. We also define an emergency avoidance factor that made higher speed still stable and better interaction of robot in the presence of obstacles. For obstacles avoidance, the leader agent projects a plane to investigate the space ahead and continues. Finally, the leader agent makes a basic stand by task sharing behaviors in decentralized manner using subsumption architecture to draw an optimal path. Simulation results show that although the proposed apporach has little knowledge about the unexpected and adhoc situation in the robotâ€™s environment, it is able to provide suitable performance.Wed, 22 May 2019 19:30:00 +0100A Single-Phase Extendable Topology for Multilevel Inverters
http://ieco.usb.ac.ir/article_4599_601.html
This paper presents a single-phase topology for multilevel inverters with minimum number of switching devices. The proposed topology significantly reduces the number of DC voltage sources, switches, and power diodes as the number of output voltage levels increases. The proposed multilevel inverter is constructed using series-connection of multilevel strings. Suggested multilevel string is composed of multiple basic switching units. The proposed multilevel inverter has extendable configuration that increases the number of output voltage levels more and more by adding more stages. The proposed multilevel inverter would be implemented in both symmetric and asymmetric configurations. Two different algorithms are introduced for determination of magnitude of DC voltage sources to reach the maximum number of output voltage levels with minimum number of semiconductor devices. Important characteristics of both symmetric and asymmetric configurations are extracted and compared with similar multilevel inverter topologies. Finally, a prototype of the proposed multilevel inverter is simulated and implemented experimentally to verify operation of the proposed multilevel inverter.Sun, 30 Jun 2019 19:30:00 +0100Secondary Voltage Control in a Hybrid Microgrid
http://ieco.usb.ac.ir/article_4603_601.html
Compared to individual DC or AC microgrids, the Hybrid microgrids (HMGs) are more efficient and inexpensive due to eliminating of multiple DC-AC-DC conversions. In HMGs, where AC loads are supplied by DC link, load demand disturbance has direct negative effects on the DC link voltage. In this study, primary and secondary controllers are applied to realize suitable operation conditions and control the microgrid converters. Each converter has primary controller to compensate the demand power fluctuations. The secondary controller is also designed for extra demand varieties and sends the proper control signals for primary controllers. The expressed capability of primary controllers can be obtained by designing a simple and robust secondary controller. Hence, the effects of demand fluctuations are eliminated and the system is stabilized. The overall state space model of system is conducted for stability analysis. To demonstrate the proposed controller efficiency, a prototype HMG is modeled and simulated. The stability analysis reveals that the system is stable when the secondary controller tracks the error signal of DC link. Simulation results show that the proposed method could efficiently manage the AC side voltage under load fluctuations.Sun, 30 Jun 2019 19:30:00 +0100A numerical scheme for constrained optimal control problems
http://ieco.usb.ac.ir/article_4604_601.html
In this paper, a numerical technique is proposed to solve optimal control problems (OPCs) of Volterra integral equations (VIEs). We apply the linear B-spline polynomials to solve OPCs by VIEs. The B-spline function divides the interval into sub-intervals and then built a different approximating polynomial on each sub-interval. In this method, optimal trajectory and control functions are expanded in terms of B-spline functions. The linear B-spline operational matrix of integration and multiplication are utilized in the proposed method.The main characteristic this method is that by using the suggested numerical technique and the related operational matrices, optimal control problem governed by Volterra integral equations is converted to a system of equations. Suffice it to say that this scheme simplifies The main problems and also makes to obtain a good approximate solution for them. In the end, there are two illustrative examples which numerical results show the validity and applicability of our method.Sun, 30 Jun 2019 19:30:00 +0100Stability Analysis of Discrete-time Switched Linear Systems with Parametric Uncertainties
http://ieco.usb.ac.ir/article_4605_601.html
This paper considers the stability problem of discrete-time switched linear systems in the presence of parametric uncertainties. Parametric uncertainty is sometimes called structured uncertainty because of the structure of the model is known, but some of the parameters are uncertain. From the practical viewpoint, it is important to investigate the robust stability conditions of uncertain switched systems. Therefore, under the assumption of knowing the structure of the uncertainty matrix and based on the common Lyapunov function for the nominal switched system, sufficient conditions for robust exponential stability of the discrete-time uncertain switched system (under any switching signal) are derived. Sufficient conditions are formulated in terms of matrix inequalities for fixed values of some parameters which may be solved via LMI techniques based on numerical methods. Moreover, a procedure is proposed to determine the maximum admissible bounds of the uncertain parameters which characterize the exponential stability of the uncertain switched system. Finally, numerical examples are provided to verify the theoretical results.Sun, 30 Jun 2019 19:30:00 +0100Reliability Assessment and Thermal Consideration of a Step-down DC/DC Converter
http://ieco.usb.ac.ir/article_4607_601.html
Reliability consideration is always important among the manufacturers of power modules and converters. Before using of power electronic converters into the related application, it is necessary to predict its reliability over time. In the meanwhile, the power loss and heat generated within the power semiconductors play a key role in the lifespan of the whole system. In this paper, a method for assessing the reliability of a step-down DC-DC converter is employed based on the thermal modeling of power semiconductors. As is evident from the used reliability approach, the junction temperature of power semiconductors – diodes and insulated-gate bipolar transistors (IGBTs) – is the most influential factor on the lifetime of power converters. Therefore, the simultaneous influence of switching frequency and duty cycle is analyzed at the same time as a factor for evaluating reliability. A cut-off of 150°C is considered for the maximum allowable junction temperature for the examined IGBT power module. The results show that a failure can be expected after 46,000 hours of operation of the considered power converter. Additionally, 3D curves are presented to illustrate the influence of duty cycle and switching frequency on the reliability of circuit’s components and the overall system. The obtained results confirmed that an increase in switching frequency from 1 kHz to 10 kHz can decrease the circuit’s lifetime almost 22%.Sun, 30 Jun 2019 19:30:00 +0100Reconfigurable CT QDSM with mismatch shaping dedicated to multi-mode low-IF receivers
http://ieco.usb.ac.ir/article_4610_601.html
A reconfigurable third-order multi-bit continuous-time quadrature delta-sigma modulator (CT-QDSM) with mismatch error correction is reported in this paper. This modulator is designed for a tri-mode WLAN/WCDMA/GSM Low-IF (Intermediate Frequency) receiver. A three-bit quantizer is utilized to achieve the bandwidth (BW) and signal to noise ratio (SNR) required in WLAN/WCDMA standards. In this modulator, the adders are eliminated to optimize the power consumption. The excess loop delay of modulator compensated by half of the sampling period of quantizer. The reconfigurable dynamic element matching (DEM) is proposed to eliminate the mismatch error. Therefore, the I and Q mismatch error are alleviated by designing the data weighted average (DWA) and homogeneous block (HB) circuits for WCDMA/WLAN modes respectively. In addition, the complex_digital to analog converter (C_DAC) is designed to eliminate the mismatch between I and Q paths. Implemented in 180 nm CMOS, achieves 53.6/74.2/81.63 dB SNR and figure-of-merits (FoM) of 0.863/0.495/1.63 pJ/ (conversion step) with a 20/2/0.2 MHz BW for WLAN/WCDMA/GSM operational mode.Sun, 30 Jun 2019 19:30:00 +0100