Trin Saengsuwan

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.

Diversity control approach to ant colony optimization for unit commitment problem

This paper presents a new method to solve the constrained unit commitment problem by applying ant colony optimization (ACO) based on the diversity control approach. The pheromone updating rule is modified to control the diversification by adopting a simple mechanism for random selection in ACO. The proposed method is tested on the 10-unit test system with a scheduling time horizon of 24 hours. The numerical results show an economical saving in the total operating cost when compared to the previous literature results. Moreover, two types of the proposed diversity control technique have the features of easy implementation and a better convergence rate superior to a standard ACO.

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.

Three zones adaptive characteristic of the mho distance relay by KU method

This paper presents the three zones adaptive characteristic of the mho distance relay for compensate of the phase to phase fault with fault resistance by KU method. Generally, the characteristic of mho distance relay is suitable for the phase fault protection and in the case of a low fault resistance. But, the fault in case of the phase to phase fault with fault resistance are a trajectory of impedance outside the protection zone of the R-X diagram and the circuit breaker does not trip. In this paper, we present an analysis of the three zones adaptive characteristic of R-X diagram of the mho distance relay for compensate of the phase to phase fault with fault resistance in the radial transmission line. The KU method has been shown an extent protection zone for the compensation of phase to phase fault with fault resistance. The algorithm of proposed system is verified by simulation and results.

Database development for power quality in PEA’s distribution system

At present, Provincial Electricity Authority (PEA) has two SQL database systems for power quality (PQ) monitoring system. They are ION7650 of Power Measurement and U902 of Unipower. The complexity to analysis PQ data comes from the different format of those two types of database system and therefore, PEA has to analyze PQ data from ION7650 and 1902 separately. In the future, the PEA may have many types of database systems, and that would cause more complexity to analyze the PQ data. To analyze several types of database system, any database system should be set identically as minimum requirement for PQ monitoring system comply with EN50160 standard. This paper presents tools namely PEA ASSESSMENT, to organize and merge two different types of database system from the PQ data result for future of the PEA PQ Data Centre.

Evaluation of DVR Capability Enhancement-Zero Active Power Tracking Technique

This paper presents a utilization technique for enhancing the capabilities of dynamic voltage restorers (DVRs). This paper aims to enhance the abilities of DVRs to maintain acceptable voltages and last longer during compensation. Both the magnitude and phase displacement angle of the synthesized DVR voltage are precisely adjusted to achieve lower power utilization. The real and reactive powers are calculated in real time in the tracking loop to achieve better conditions. This technique results in less energy being taken out of the dc-link capacitor, resulting in smaller size requirements. The results from both the simulation and experimental tests illustrate that the proposed technique clearly achieved superior performance. The DVR’s active action period was considerably longer, with nearly five times the energy left in the dc-link capacitor for further compensation compared with the traditional technique. This technical merit demonstrates that DVRs could cover a wider range of voltage sags; the practicality of this idea for better utilization is better than that of existing installed DVRs.

The voltage sags correlations between transmission and distribution system of PEA region 1

This paper presents the correlations of voltage sags between the transmission system and the distribution system. The studies included the effect of the transformer connections. Rotchana substation of Provincial Electricity Authority (PEA) has been selected as the case study. It receives power from 115 kV transmission systems and distribute to customers in 22 kV distribution systems. The studied network is simulated by PSCAD/EMTDC program and also the voltage sags data recorded by the power quality meters are used in the analysis. Finally, the results are proposed and discussed.

The studies of a transmission system and distribution system voltage sags correlations

This paper presents the correlation of voltage sags between two sides of difference types of transformer winding connections. We study the propagation of voltage sag down to low voltage and reverse up to high voltage. This study performs on network of provincial electricity authority (PEA), a utility in Thailand. The network is modeled using PSCAD/EMTDC. The faults are applied on this network to generate voltage sags. The types of transformer winding connection are varied to study its influence on voltage sag. Finally, the results are discussed.

Modelling of the high voltage direct current transmission system links between Thailand-Malaysia using EMTP/ATP program

The ac systems of Thailand and Malaysia have been linked together by the 300/600 MW HVDC interconnection project. The dc connection allows both countries fully bi-direct control the interchange power, improving reliability and operating in asynchronous mode constantly. In the stage of system design, EMTDC program was used to establish the control model and protection system. With this program, the suitable parameters can be evaluated and review the system response. This paper also presents the study of the EGAT-TNB HVDC interconnection project with digital computer program establishing by ATP program. The study cases are the deblocking system, control power transfer and fault in case of DC line to ground. Also, the results from ATP program are compared with the real recording data from the field-testing.