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Author: search.filters.author.Srisuksai, Panu

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    Development and Analysis of a Fast-Charge EV-Charging Station Model for Power Quality Assessment in Distribution Systems
    (2025-09-01)
    Chiradeja, Pathomthat
    ;
    Yoomak, Suntiti
    ;
    Srisuksai, Panu
    ;
    Klomjit, Jittiphong
    ;
    Ngaopitakkul, Atthapol
    With the rapid rise in electric vehicle (EV) adoption, the deployment of EV charging infrastructure—particularly fast-charging stations—has expanded significantly to meet growing energy demands. While fast charging offers the advantage of reduced charging time and improved user convenience, it imposes considerable stress on existing power distribution systems due to its high power and current requirements. This study investigated the impact of EV fast charging on power quality within Thailand’s distribution network, emphasizing compliance with accepted standards such as IEEE Std 519-2014. We developed a control-oriented EV-charging station model in power systems computer-aided design and electromagnetic transients, including DC (PSCAD/EMTDC), which integrates grid-side vector control with DC fast-charging (CC/CV) behavior. Active/reactive power setpoints were mapped onto (Formula presented.) current references via Park’s transformation and regulated by proportional integral (PI) controllers with sinusoidal pulse-width modulation (SPWM) to command the voltage source converter (VSC) switches. The model enabled dynamic studies across battery state-of-charge and staggered charging schedules while monitoring voltage, current, and total harmonic distortion (THD) at both transformer sides, charger AC terminals, and DC adapters. Across all scenarios, the developed control achieved grid-current THDi of <5% and voltage THD of <1.5%, thereby meeting IEEE 519-2014 limits. These quantitative results show that the proposed, implementation-ready approach maintains acceptable power quality under diverse fast-charging patterns and provides actionable guidance for planning and scaling EV fast-charging infrastructure in Thailand’s urban networks.
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    Application of Neutral Grounding Resistor in High Voltage Photovoltaic Solar Substation System
    (2025-01-01)
    Pothosarn, Chaichan
    ;
    Patcharoen, Theerasak
    ;
    Srisuksai, Panu
    ;
    Ngaopitakkul, Atthapol
    ;
    Kunakorn, Anantawat
    Faults in a distribution system with additional renewable energy sources can lead to unnecessary operation of protection devices due to higher detected fault currents compared to conventional systems. In addition, the voltage at the point of interconnection may temporarily drop to a low level, causing inverter-based generators to disconnect from the system. This study, therefore, proposes an investigation into the use of neutral grounding resistors in a 115 kV high-voltage (HV) substation unit located within a solar power generation system. The approach aims to limit ground fault current and reduce temporary voltage sags to maintain the connection status of inverter and ensure compliance with low voltage fault ride-through (LVRT) capability. The case study is modeled after an actual grid network consisting of two feeders, with one feeder connected to a solar power plant. PowerFactory DIgSILENT software is used to simulate the system and analyze the impact of various neutral grounding resistance values. The results of this study can be applied to the selection of neutral grounding resistors for system, helping to reduce fault current, extend relay operating time within the allowable delay range, and minimize unnecessary tripping of overcurrent protection relays in the system.
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    Very Small Power Plant Transformer Without and With Installation of Neutral Ground Resistance on Relay Operation
    (2024-01-01)
    Pothisarn, Chaichan
    ;
    Chiradeja, Pathomthat
    ;
    Yoomak, Suntiti
    ;
    Srisuksai, Panu
    ;
    Ngaopitakkul, Atthapol
    In this study, a double-feeder 22 kV distribution system connected to a very small power plant (VSPP) was simulated in the PowerFactory DIgSILENT program. A neutral ground resistance (NGR) was introduced to reduce a ground fault current from the VSPP, extend the relay operating time to the delay range, and reduce undesired trip of non-faulty feeder that VSPP connected. Thus, the overcurrent protection relay was simulated to analyze working patterns during faults. Three types of VSPP transformer NGR installations were considered: VSPP without NGR, VSPP with a Bisection method approach, and VSPP with the proposed symmetrical component calculation approach. Moreover, this study analyzed the effect of overvoltage on the distribution system with the proposed systematic component calculation approach under fault conditions. The result from the case study indicated that the NGR installation with the proposed approach can reduce the fault current and shift delay time of the protection device to avoid maloperation.
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    Study on Installation of Neutral Ground Resistance in Very Small Power Plant Transformer
    (2022-01-01)
    Chiradeja, Pathomthat
    ;
    Pothisarn, Chaichan
    ;
    Srisuksai, Panu
    ;
    Yoomak, Suntiti
    ;
    Ngaopitakkul, Atthapol
    Faults in the distribution system of the Thai electrical system occur frequently. Such faults directly affect the protective equipment of the distribution system. The protective device disconnects the circuit unnecessarily on many occasions because it detects a higher current than expected. In this study, a 22-kV distribution system and a very small power plant (VSPP) were connected. The system consists of two feeders. Feeder 1 supplies electricity directly to the load; a fault was enforced in this feeder. Feeder 2 supplies electricity directly to the load; the VSPP was connected to this feeder. The fault in Feeder 1 was simulated, and the behavior of the defense system was studied. Unnecessary disconnection of the VSPP circuit took place because the high fault current caused the overcurrent protection relay to operate instantaneously. Therefore, a neutral ground resistance was installed at the VSPP transformer to reduce the fault current, extend the relay operating time to the delay range, and reduce unnecessary disconnections of the overcurrent protection relay of the VSPP. In addition, when a fault occurs in the distribution system, the faulted phase voltage decreases, whereas the non-faulted phase voltage increases. Surge arresters and voltage transformers must be able to withstand an increase in voltage. This is also explained and discussed in this paper.