KMITL

Permanent URI for this communityhttps://dspace.kmitl.ac.th/handle/123456789/1

Browse

Settings

Subject: search.filters.subject.Distributed generation (DG)

Search Results

Now showing 1 - 4 of 4
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    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.
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    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.
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    Hierarchical control strategies in AC microgrids
    (2015-08-17)
    Khongkhachat, Somkiart
    ;
    Khomfoi, Surin
    Hierarchical ac microgrid control strategies are presented in this paper. All operating modes of ac microgrid are also discussed and ranked. There are two operating mode in an ac microgrid: grid-connected mode and islanding mode. Grid-connected mode is operated under utility grid connected with the ac microgrid whereas islanding mode is operated without the utility grid. Normally, energy conversion devices such as a dc-dc converter, an ac-ac converter and an inverter have a local control. For instance, a solar inverter will have a MPPT control mode; however, if the ancillary service for reactive power compensation due to over voltage is required, this inverter control mode will change from MPPT mode to constant voltage mode. Meanwhile, other devices can reduce supplied power to the grid to stabilize grid voltage. Therefore, hierarchical control strategy of ac microgrid is necessary to control and stabilize voltage and frequency in the microgrid. Hierarchical control can also offer high efficiency and more degree of freedom energy management in ac microgrid. Hierarchical control proposed in this paper consists of four ranks: current and voltage loop control for regulating voltage and power in each distributed generation (DG), primary droop control, secondary droop control and energy management and power flow control between ac microgrid and utility grid. The proposed hierarchical ac microgrid control can explain the relationship and interaction among control ranks. This can lead to a better understanding and design for ac microgrid applications.
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    PEA guidelines for impact study and operation of DG for islanding operation
    (2008-10-13)
    Fuangfoo, Pradit
    ;
    Meenual, Thongchai
    ;
    Lee, Wei Jen
    ;
    Chompoo-Inwai, Chow
    Intentional islanding operation of distributed generation (DG) can increase system reliability and reduce customer outage costs. Guidelines for the impact study and operation of DG for islanding operation should be implemented. The Provincial Electricity Authority (PEA) plays more attention to intentional islanding operation. To perform islanding operation, PEA has established islanding operation and impact study guidelines for DG. This paper presents the development of these guidelines. A case study was conducted to demonstrate the results of both steady-state and dynamic analyses. Operational issues are also taken into account in this paper. © 2008 IEEE.