Journal of Operation and Automation in Power Engineering
Volume:10 Issue: 1, Spring 2022

With day by day increase in electrical energy demand and uneven distribution of sources in nature, there is a need of Integration of power plants. This integration needs a proper scheduling of all connected generating units in accordance with the variation in load demand. An optimum sharing of load is necessary to minimize the generation cost. Emission is also an important issue in a generation. An attempt is also made in this paper to analyze emission dispatch with the Economic Dispatch optimization. Environmental effects tend to involve renewable sources based power generation. Wind and Solar are most popular and highly abundant among all renewable sources. But, the fluctuations of these sources complicate the load dispatch optimization. Also, the conventional thermal generators itself affected by certain constraints and non linearity such as valve-point loading effect. A proper planning should involve consideration of all this issue, which requires advance soft computing technique. Previous approaches need proper tuning of their specific parameters, to remove this ambiguity, a new Jaya Algorithm technique is introduced in this paper.

As a basic tool in power system control and operation, the optimal power flow (OPF) problem searches the optimal operation point via minimizing different objectives and maintaining the control variables within their applicable regions. In recent years, this problem has encountered many challenges due to the presence of renewable energy sources, which has led introducing of a combinatorial type of power networks known as AC/DC hybrid power systems. In this paper, the OPF problem is proposed in an AC/DC hybrid microgrid, including wind power plants. For the first time, the mentioned problem is considered as a multi-objective optimization problem via minimizing fuel cost and emission. The problem is modeled while considering the power flow equations, the voltage limits in AC and DC buses, the AC voltage angle limits, and the firing angle of the converters. Also, due to the uncertain power generated by wind power plants, the probabilistic OPF problem is modeled by the five-point estimation method.  To solve the problem, the "fmincon" function in MATLAB software is used by applying the IP algorithm. The simulation case study on a 13-bus sample MG verifies the effectiveness of the proposed method. The numerical results confirm that increasing the wind farm capacity from 14.54 MW to 113 MW, will be led to increasing the fuel cost from 10% to 61%, in case of including the power losses compared to the condition in which they are neglected. It is also observed that in terms of different weights, the total air pollution including the power losses is 2.30 to 2.40 times higher than the total pollution without electrical losses

The parasitic parameters of an IGBT power module cause various problems, especially for electromagnetic compatibility (EMC) concerns. The high-variations in voltage and current produced by the inductances/capacitances near switches in the transient process are the main sources of high-frequency electromagnetic interference (EMI). To overcome the problems, the parasitic parameters of the module should be accurately characterized. In this paper, a precise detailed model of a commercial half-bridge IGBT module is presented. It includes the parasitic inductances of leads, bond wires, DBC plates, and the parasitic capacitances of the module and IGBTs. The new simplified analytical equations to calculate the partial inductance and parasitic capacitance are proposed and compared with ANSYS Q3D results. To evaluate the accuracy of the model, all the parameters are also derived from a two-port measurement-based parasitic extraction method. The results show an acceptable match between the simulated and experimental values. Finally, the proposed model is implemented by state-space dynamic coupling in ANSYS Simplorer circuit simulator, and a double-pulse test circuit is used to verify the model. By comparing the simulated current and voltage waveforms with experiment, it is proved that the proposed model is applicable to simulate the switching transients for EMC study.

The important role of electricity generation in the power system is evident and is growing more and more with innovative technologies and requirements. Hence, addressing the combined heat and power economic dispatch (CHPED) as one of the relatively new issues in the power system operation and control is more importance. Since the CHPED problem is a non-smooth, highly non-linear, and non-convex one, it is required to solve it so that an optimal global solution can be achieved. In this paper, by applying the piece-wise linearization approach the CHPED problem is solved so that the problem reformulated to a quadratic optimization problem with linear and quadratic constraints. To demonstrate the applicability of the proposed model, four case studies are implemented in the GAMS software environment and the results compared to the literature.

Recently due to technical, economical, and environmental reasons, penetration of renewable energy resources has increased in the power systems. On the other hand, the utilization of these resources in remote areas and capable regions as isolated microgrids has several advantages. In this paper, a hybrid microgrid, which includes photovoltaic (PV)/wind/energy storage, is investigated. It has been located in Iran-Khalkhal. The purposes of this study are optimal energy management and sizing of the microgrid. Since the magnitude of the harvested renewable energy deals severely and complexly with season and climate issues, planning of the system based on their specific values is an oversimplification. Therefore, in addition to conventional constraints such as environmental and operational ones, estimation of the wind speed at the site is considered. The Monte Carlo method is employed to model and estimate wind behavior. Also, for regulating production and demand in the microgrid the Demand Response (DR) program is conducted to improve the contribution of the renewable energy resources. The planning is constructed as an optimization problem. It is formulated as a Mixed Integer Linear Programming (MILP). By solving it, the size and production magnitude of energy sources, as well as storage conditions, are determined. Finally, the proposed method is simulated by GAMS for all seasons of two scenarios. The results show desirable energy management and cost reduction in the studied grid.

This paper presents a methodology for reactive power scheduling (RPS) of power system in the form of AC optimal power flow (AC-OPF) problem. The objective function is minimization of system total active power losses. The OPF optimally determines reactive power output of generating units and synchronous condensers, tap-changers ratio, shunt capacitor banks and reactors. The effect of tap-changer is modeled in the active and reactive power flow of transformer. The proposed method grantees secure operation of system in normal operating condition and also in contingency of transmission line outage. The validity of proposed method is studied based on IEEE RTS 24-bus. Results show the capability of suggested AC-OPF for RPS of system in base case as well as contingency of single line outage.

Distributed generators (DGs) facilitate minimizing a monetary objective for controlling overload or low-voltage obstacles. In conjunction with controlling such complications, a DG unit can be allocated for maximum reliability or efficiency. This study presents a new method based on a new index for locating and sizing DGs in electricity distribution systems. Stable node voltages which are known as power stability index (PSI) are considered in developing the index. An analytical method is applied in visualizing the effect of DG on losses, voltage profile, and voltage stability of the system. In this study, a new approach using co-evolutionary multi-swarm particle swarm optimization (CMPSO) algorithm is purposed for locating DGs in radial electrical distribution systems considering the uncertainty of solar power as well as load and wind power. In this paper, the optimal locations and sizes of DG units are calculated by considering the active power loss, reliability index, and PSI as objective functions. The presented algorithm is tested on 33-bus and 274-bus real distribution networks. The results of the simulation show the effectiveness of the proposed method.

The Vector Control (VC) of Y-Connected Induction Motor (YCIM) drives is entirely demanding task. Furthermore, YCIM under an Open-Circuit Fault in the Stator Coils (OCFSC) leads to deterioration of the VC. Consequently, the VC of YCIMs under an OCFSC requires a suitable design. This research focuses on an accurate and modified Field-Oriented Control (FOC) strategy for 3-phase YCIM drives under an OCFSC. Most of the recent papers studying VC of YCIMs under an OCFSC ignore the leakage inductance in the VC equations. This paper presents an alternative VC technique, considering the leakage inductance in the VC equations of YCIMs under an OCFSC. In the presented VC system, two asymmetrical Rotating Transformations (RTs) for the stator current and voltage quantities are proposed and employed. In the proposed scheme, the genetic algorithm is used to regulate the parameters of the Proportional-Integral (PI) controllers. The developed VC system provides an accurate control against an OCFSC and can be employed for different industries that need Fault-Tolerant Control (FTC) systems. The effectiveness of the proposed approach is validated through experimentation in the laboratory. The proposed control scheme gives good responses during both steady state and transient sate. In addition, the proposed VC system gives better performances during the post-fault operation compared to previous works in terms of speed and torque ripples.