Papers by Keyword: Power System

Abstract: Integration of PV systems into the grid is growing rapidly around the world, and PV penetration plays a huge role in minimizing the effect of greenhouse gases in the atmosphere and also contributes to minimizing the impact of load shedding. However, PV systems contribute to grid integration issues such as transients, voltage, and frequency instabilities and reductions in the generator's inertia, respectively; therefore, it is essential to investigate the effect of the PV system on the grid before integrating it. This paper utilized a modified IEEE 9 bus system to investigate the impact of large-scale PV on the power system, and PSCAD software has been used for this study. Four scenarios with different PV penetration levels were considered in this paper. Moreover, for each scenario, the transient stability was assessed based on five parameters, namely: active power, reactive power, rotor angle, rotor speed, and the terminal voltage. Scenario 1 examines the PV systems integrated into a single bus and finds that the optimal PV penetration is 60% of the total power generation. Scenario 2 investigates the effect of integrating PV systems using the optimal PV penetration of 60% distributed into two buses, which was found to be the best for transient stability improvement after a fault condition. Scenario 3 investigates the impact of the power system stabilizer (PSS), using the optimal PV penetration of 60%, and the results reveal that system stability improves when a fault occurs on the bus where the PV system is also connected. Scenario 4 investigates the effectiveness of the fault clearing time on the response of the system with an integrated PV system, using the optimal PV penetration of 60%. The results revealed that a PV system only improves transient stability if the fault-clearing time is below 0.5 seconds; otherwise, the system loses stability. Overall, the study demonstrates that the system’s stability improves up to 60% of the PV penetration level of total generation power.

Abstract: This paper considers an application of Newton's optimal power flow to the solution of the secondary voltage/reactive power control in power system. This procedure is based on the sensitivity theory applied to the determination of zones for the secondary voltage/ reactive power control and corresponding reduced set of regulating sources, whose reactive outputs represent control variables in the optimal power flow program. PSO is applied to solve the OPF problem for optimal power flow the optimal power flow program output becomes a schedule to be used by operators in the process of OPF-PSO (Optimal Power Flow - Particle swarm optimization) PSO applied to optimal reactive power dispatch is evaluated on an IEEE 30-bus power system. The optimization strategy is general and can be used to solve other power system optimization problems as well.

Abstract: Power quality (PQ) has become a more important issue recently due to the use of more sophisticated and sensitive equipment. Medical devices, telecommunication servers and equipment, manufacturing and domestic appliances rely on a good supply of power. This paper presents the review of the power quality in power system. Power quality has always been important for customers, but with increasing applications of electronic loads and controllers sensitive to the power quality, the subject has attracted renewed interest in recent times. Power quality encompasses several aspects: harmonics, over voltage, flicker voltage sags and swells interruptions etc. A major factor contributing to the importance of the quality of power is the deregulation of the power industry. Customers will demand higher levels of power quality to ensure the proper and continued operation of sensitive equipment and processes.

Abstract: This article presents theory of The design of medium sized voltage capacitor in order to improve the Power Factor Value to AC motor. In present, the electrical power system has focus on improving the Power Factor significantly because it is the major key to increase or decrease the applicable expenses. The power system that has low power factor will have a lot of loss to system, especially when electrical voltage is on voltage medium. When power factor has been adjusted, the system can take more loads and electrical power loss is decreased. It also decreases voltage in power line and decreases electrical bills at the same time. This article presents the theory to analyze data from motor that needs to adjust a power factor so that it pass electricity authority standard by considering the efficiency of the motor so that the consumers do not have to pay the penalty of the Power Factor Value differences to the Electricity Authority. Furthermore, it can help decrease the bills of unstandardized electrical power which occurred in the system and enable the system to take more loads at the same time.

Abstract: As small wind turbines are increasingly used, the assessments of power quality may thus become paramount. Unlike the large-scale wind turbines which are optional required to perform power quality measurements during production certification stage; however the power quality measurements are often neglected in small wind turbines since they are not requested on the certain of national grid codes at low-voltage distribution system level. Considering the high penetrations of small wind turbines may be connected to the future urban electric network, the paper performs the power quality on-site measurements of a horizontal axle small wind turbines. The issues may include the discussion of measurement system structure, the description of measurement method, and the analysis of wind turbine power characteristic, voltage/current trends, harmonics and flicker phenomena. The measured data collected in the study will valuable for the further analysis of power systems connected with the small wind turbines.

Abstract: This paper describes a pneumatically powered system based on hydrogen peroxide (H₂O₂) decomposition designed to provide enhanced energy and power density for wearable robotic applications. As one of the energy material, hydrogen peroxide shows good potentials for some applications like jet packs. In particular, the authors establish the pressurization system based on high frequency switch valves which involves a periodic pulsed gas explosion as a result of inspiration from the bombardier beetle. Then numerical simulations of spray force produced by the H₂O₂ based power system are presented. And the power system is used in movement enhanced jet pack in the end. The results show that spray force of the pulsed power system is directly proportional to the flow rate of H₂O₂, while inversely proportional to the volume of catalyst pack. At last the relationship between power system parameters and spray performances are discussed in detail.

Abstract: Dynamic Voltage Restorer (DVR) is a series connected power electronics based custom power device that is used to improve voltage disturbances in low voltage electrical power distribution network. Power quality requirement is one of the most important concerns for power system. The parts of the DVR is made up of voltage source inverter, injection/booster transformer, a harmonic filter, an energy storage device and a bypass switch. The DVR is used to inject three phase voltage in series and in synchronism with the network voltages in order to compensate voltage disturbances with a benefit of active /reactive power control. This paper presents a review of the researches on the dynamic voltage restorer application for power quality improvement in low voltage electrical power distribution networks. It describes power quality issues, principle of operation of DVR, basic components of DVR, DVRs control topologies in distribution network, DVR control strategies and compensation techniques.

Abstract: The paper shows the relevance of the research process protections of power units that reduce or prevent economic damage caused by the accident. For this data, the design methodology for coal-fired units with drum boilers, which allow to define the work on stored energy boiler auxiliary load. The proposed technique reduces the cost of implementing the considered technological protections.

Abstract: The paper is aimed to determine runoff limits of the Vakhsh cascade hydropower plant, which are the main parameters when setting optimum modes of the hydropower plant. It is proposed to increase power generation of the hydropower plant of the Vakhsh cascade by assigning the optimal modes of operation of hydropower plants. The peculiarities of managing the cascades of hydropower plants are described. The description of the Vakhsh cascade hydropower plant and the method of controlling the reservoir of the cascade of the hydropower plants are given.

Abstract: The study sets the objective of overall overrun fuel separation into two components. The first one depends on changes in the electric load of the power unit. The second component is influenced by changes of the power unit controlled parameters. The separation leads to the adjustment of technical and economic performance of the power plant unit. These indicators show both the efficiency of the power unit and the overall plant.