Volume 16, Issue 2 -

A current source inverter fed from photovoltaic cells is proposed to power an autonomous load when operating under either power regulation or voltage and frequency drooping modes. Input–output linearization technique is applied to the overall nonlinear system to achieve a globally stable system under feasible operating conditions. After obtaining the steady-state model that demarcates the modes of operation, computer Simulation results for variations in irradiance and the load power of the controlled system are generated in which an acceptable dynamic response of the power generator system under the two modes of operation is observed.

This paper deals with computer application procedures for the evaluation of the causal consistency between anomalous phenomena manifested in electrical networks, along with the physical damage associated with electrical equipment and possible reimbursement requests. The focus is on the development of an air conditioner appliance model of the type known as split founded upon a representation, in the time domain, in accordance with the Alternative Transients Program (ATP) simulator requirements. This approach permits investigations concerning the performance of the product when submitted to ideal and non-ideal supply conditions. Once the equipment model is implemented in the program, a set of investigative studies are carried out to show the device performance under specific energy quality disturbance conditions. In addition, there are still the results for the validation of the process established through the correlation between computational performance of the air conditioner with corresponding studies carried out experimentally, which are presented herein. Moreover, once the effectiveness of the developed model is verified, it is implemented into the Requests for Reimbursement Software. Investigations related to the correlation between disturbances and the levels of thermal and dielectric tolerance are then performed aiming at illustrating the use of the research results for the reimbursement analyzes purposes.

A blackout can take place in entire power system or a part of the system due to extreme voltage instability (voltage collapse) that can appear abruptly. Instability prediction and continuous monitoring of the power system performance is, therefore, known exigent. This paper is conducted with a broad overview of the voltage stability indices, which are previously studied in the literature, and have the same foundation during their formulation. Afterward, an improved voltage stability indicator is introduced as a result of the multi-criteria integration and enhancement of the original indices by employing linear algebra methods. It is found that the proposed algorithm can overcome on the probable limitations from calculating point view. Then comparative analysis of the indices is presented in order to reach a unique consensus about the typical techniques of modal analysis (sensitivity, eigenvalue, right eigenvectors, and bus participation factor) as a precise algorithm. Finally, the IEEE 14-bus, and 30-bus test systems are selected to verify the algorithm, and compare the performance of the improved indicator approach with the existing indices.

This paper presents a new distributed agent-based scheme to enhance the transient stability of power systems by maintaining phase angle cohesiveness of interconnected generators through proper relay coordination with critical clearing time (CCT) information. In this distributed multi-agent infrastructure, intelligent agents represent various physical device models to provide dynamic information and energy flow among different physical processes of power systems. The agents can communicate with each other in a distributed manner with a final aim to control circuit breakers (CBs) with CCT information as this is the key issue for maintaining and enhancing the transient stability of power systems. The performance of the proposed scheme is evaluated on a standard IEEE 39-bus New England benchmark system under different large disturbances such as three-phase short-circuit faults and changes in loads within the systems. From the simulation results, it is found that the proposed scheme significantly enhances the transient stability of power systems as compared to a conventional scheme of static CB operation.

High-voltage infrastructure upgrade is expending due to the growth in populations. To save on easement cost and to reduce the environmental impact of these projects, HV transmission lines occupy the same easement as pipelines in many cases. This joint easement introduces the AC interference between transmission lines and pipelines. The induced voltage can reach a limit which will jeopardize the human safety. The cited research studies the induced voltage under the presence of the overhead earth wire (OHEW) using the shielding factor. The work in this paper studies the induced voltage using the OHEW section current along with the superposition theorem. The simulations are compared to the existing research methods. The case study along with the theoretical study discusses the advance accuracy of the proposed method over the existing shield factor used in the presence research. Furthermore, they introduce the effective length along with the effective shielding factor, which aids in computing the additional effect that the OHEW has on the induced voltage.

The problem of voltage control and reactive power management plays a crucial role on power system’s operations. Particularly, detecting the most effective control actions to reduce the system loss and enhance the voltage profile is of major interest. This paper deals with system voltage inadequacy detection. To address this problem, artificial immune system is employed considering its negative selection mechanism. Its purpose is to monitor system operation data entry and check if the voltage level is within its operating values. In this sense, the user may define the range of control, so the proposed methodology may be useful for normal and emergency operating conditions. Corrective actions are undertaken if necessary. The IEEE 34 nodes distribution system is used to test the proposed methodology.

The electrical vehicles (EVs) can be connected to the grid for power transaction. The vehicle-to-grid (V2G) supports the grid requirements and helps in maintaining the load demands. The grid control center (GCC), aggregator and EV are three key entities in V2G communication. The GCC sends the information about power requirements to the aggregator. The aggregator after receiving the information from the GCC sends the information to the EVs. Based on the information, the interested EV owners participate in power transaction with the grid. The aggregator facilitates the EVs by providing the parking and charging slot. In this paper the queuing model for EVs connected to the grid and development of wireless infrastructure for the EV to Smart Meter communication is proposed. The queuing model is developed and simulated. The path loss models for WiMAX are analyzed and compared. Also, the physical layer of WiMAX protocol is modeled and simulated for the EV to Smart Meter communication in V2G.

The aim of this paper is to present a multipurpose converter, appropriate for non-grid-connected microsystems, which are prone to harmonic distortion. The converter suppresses harmonics by injecting mirror harmonics in the modulation stage. An important property is that it continuously monitors and significantly reduces the harmonic content without the use of active or passive low-frequency filters. This is under constant switching frequency, no matter if the harmonics are mainly created by the source, the loads or even its own operation. The converter is regulating output voltage using typical fuzzy control. The two types of control (harmonic and voltage) do not seem to affect each other during operation. Furthermore, it can supply either dc or ac loads from a dc source. The versatility of the converter is a useful property for remote or mobile micropower systems, where neither sources nor loads are of a single type. The converter has been tested successfully for a combination of harmonic-injecting electric appliances and various load step changes.

This paper presents the analysis, design and implementation of a power factor corrected Arc Welding Power Supply (AWPS) with a boost converter at the front end and three full-bridge (FB) converters connected in parallel at the load end. The modular arrangement of the FB converters offers several meritorious features like usage of power devices with comparatively lower voltage and current ratings, ease of power expandability, easy maintenance, etc. The boost converter operates in continuous conduction mode minimizing the input current ripple and leading to the lowest RMS current thereby improving the input power quality. Individual control loops are designed for each power stage. A dual loop control scheme is employed to incorporate over-current limit on the proposed AWPS which ensures excellent weld bead quality. The proposed AWPS is implemented to validate its performance over a wide range of line/load variations. Test results confirm its fast parametrical response to load and source voltage variations and over-current protection leading to improved welding performance and weld bead quality. The system is found to perform extremely well with very low input current THD and unity power factor, adhering to international power quality norms.

This paper presents a new multi-objective day-ahead market clearing (DAMC) mechanism with demand-side reserves/demand response (DR) offers, considering realistic voltage-dependent load modeling. The paper proposes objectives such as social welfare maximization (SWM) including demand-side reserves, and load served error (LSE) minimization. In this paper, energy and demand-side reserves are cleared simultaneously through co-optimization process. The paper clearly brings out the unsuitability of conventional SWM for DAMC in the presence of voltage-dependent loads, due to reduction of load served (LS). Under such circumstances multi-objective DAMC with DR offers is essential. Multi-objective Strength Pareto Evolutionary Algorithm 2+ (SPEA 2+) has been used to solve the optimization problem. The effectiveness of the proposed scheme is confirmed with results obtained from IEEE 30 bus system.