Siriroj Sirisukprasert

The modeling and control of fuel cell emulators

This paper proposes a prototype of fuel cell emulator used to replace a real fuel cell system during the development stage of a fuel-cell based energy source system. The power stage of this new fuel cell emulator consists of a current source converter (buck rectifier) and a dc-to-dc buck converter. With the collaboration of these two power electronics circuits and a DSPbased controller, the proposed fuel cell emulator provides both emulated V-I fuel cell characteristic and high-quality output voltage and current. This research mainly focuses on emulating the behavior of two well-known fuel cell systems: proton exchange membrane fuel cell and solid oxide fuel cells. The proposed fuel cell emulator can effectively perform in all three operation regions, i.e. activation, ohmic and concentration. Analysis, modeling and control strategy are presented. Finally, both static and dynamic performances of the proposed fuel cell emulator are experimentally verified.

A new mitigation strategy for photovoltaic power fluctuation using the hierarchical simple moving average

A novel mitigation strategy for photovoltaic power fluctuation is presented in this paper. The objective is to adopt the new strategy for optimizing use of the energy storage systems (ESSs). The minimization of storage capacity and the complexity of control strategy are accomplished by introducing of the proposed hierarchical simple moving average (H-SMA). Moreover, the enhance ability to mitigate the problem by allocating the power required by the ESSs is considered. The performance of the proposed technique is verified by a daily power profile collected from the PV power plant. The storage capacities derived by the proposed strategy are compared with those of conventional method. In this paper, the computer simulation is used to carry out the validation results, which points out that it can effectively mitigate the power fluctuation with the minimal-capacity ESSs.

The modeling of AC magnetic contactor for immunity studies and voltage sag assessment

This paper presents the parametric model of AC magnetic contactor to study behavior of contactor during voltage sags. The model derived from contactor structure and its operation so that electrical, magnetic and mechanical equations can be obtained. The model was simulated using electromagnetic transient program. The results show dynamic behavior and immunity of contactor during sag. Additionally, how the sag characteristics, such as point on wave, impact to contactor can study through the model. For voltage sag assessment, the voltage sag ride-through capability curves of AC contactor were constructed and field-test data were also applied. The model reveals that although sag does not cause contactor to disengage, it can cause decreasing in contactor operation lifetime.

Unbalanced voltage sag source location identification based on superimposed quantities and negative sequence

This paper presents a new method to effectively identify the unbalanced sags source location based on negative sequence and superimposed quantities concept. Many previous proposed methods have shown good performance for balanced voltage sag cases. However, their performance reduces for the unbalanced voltage sags, which are the major sag events in power system. The proposed method was derived mathematically and verified by computer simulations and field data from voltage sag survey. The results show the good performance of proposed method. Moreover, the method can locate the sag source in both transmission and radial system.

Distributed Static Compensator with fuel cell for power quality improvement and hybrid power generation

This paper presents analysis and design of Distributed STATic COMpensator (DSTATCOM) with fuel cell utilized for power quality improvement and hybrid power generation. Factors affecting the performance and limitation of active and reactive power compensation are analyzed and presented in this paper. A boost converter circuit is selected to step up and regulate the fuel cell terminal voltage to match the DC link requirement of the voltage source converter. The mathematical model of the DSTATCOM system has been developed and simulated in MATLAB/Simulink. The simulation results indicate that the DSTATCOM with fuel cell can effectively compensate the appropriated amount of reactive power and can be utilized as a hybrid power generation.

The improvement of LVRT criteria for wind generation in PEA transmission grid

This paper presents the improvement of Low Voltage Ride-Through (LVRT) criteria for wind generation interconnection in Provincial Electricity Authority (PEA), Thailand. The existing LVRT is investigated. The intensive studies are carried out by simulations. The results show the existing LVRT should be revised. Finally, LVRT criteria is proposed and the procedures for the future developments are discussed.

An evaluation of voltage variation and flicker severity in micro grid

This paper evaluates the effects of voltage fluctuation in a micro grid. The micro grid is modeled and simulated using the DIgSILENT software. The voltage flicker due to the variation of power productions from renewable sources in microgrid during off-grid and grid-connected mode are presented. The results indicate that the main sources of voltage fluctuation in the studied micro grid are PV and wind generations. The situation becomes worse when the microgrid is operated in off-grid mode. The renewable sources can improve voltage profiles in some cases.

The study of reactive power control strategies of PV plant in PEA distribution system

Due to the significantly increasing of Photovoltaic generations in distribution system, many utilities have reported about the adversely impact of high penetration PV on voltage variations. The various reactive power control strategies have been proposed to solve this issue. The aim of this paper is to study the performance of the implementation of three reactive power control strategies i.e. cosφ, cosφ(P) and Q(U) in Provincial Electricity Authority (PEA) distribution system. The large-scale PV Plant in this study built by DIgSILENT PowerFactory is used to perform simulation. The simulations are shown the voltage improvement and feeder losses on the different reactive power control strategies, by comparing with the base case (PV is generating the maximum active power and not injecting reactive power). The results are expected to use as a guideline for further development of PEA grid code.