Development of voltage control system for multi-terminal low-voltage DC distribution system

Hai, Trinh Phi; Cho, Hector; Chung, Ilyong; Cho, Jintae; Kim, Ju–Yong

doi:10.1109/isgt.2017.8086018

Cited by 6 publications

(7 citation statements)

References 10 publications

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“…Based on the VSF, the total voltage compensation for the undervoltage problem from total EV discharging must be higher than or equal to the voltage deviation at the kth bus, while the total voltage reduction for the overvoltage problem from overall EV charging must be higher or equal to the voltage deviation at the h-th bus, which can be respectively defined as follows:  is the VSF defined as the effect of the power-variation control of the DERs at the i-th bus on the voltage compensation of the k-th specific bus at time step j. The authors in [18,19] suggested that the VSF can be obtained from the Jacobian matrix of the LVDC distribution system as follows:…”

Section: Voltage Regulation Constraintsmentioning

confidence: 99%

“…Many researchers have focused on voltage regulation in a DC distribution system. The authors in [18,19] proposed a voltagecontrol algorithm by coordinating the main AC/DC converter and DER scattering in a distribution system. They calculated voltage sensitivity factors (VSFs) based on the solution of load-flow analysis to calculate the relevant power injection or absorption to compensate for the voltage problems.…”

Section: Introductionmentioning

confidence: 99%

“…Section 4 comprises an explanation of the optimal DER control scheme. Last, in Section 5, we report the experimental results of various simulation studies to verify the effectiveness of the proposed optimal strategy method compared to conventional methods [18,19].…”

Section: Introductionmentioning

confidence: 99%

“…The power flow is calculated in each interval time using the predicted load and PV power to determine the voltage profiles in the overall distribution system. The constraints for voltage regulation and EV charging/discharging operations from Equations (8) to (9) and (13) to (19), respectively, are added into the optimization process based on the operation modes to restrict the EV charging and discharging under the aforementioned voltage problems. Depending on which, the operation modes are divided into three principal modes (Figure 4):  Normal operation.…”

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confidence: 99%

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Optimal Control Strategy for Distributed Energy Resources in a DC Microgrid for Energy Cost Reduction and Voltage Regulation

Trinh

Chung

2021

Energies

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Distributed energy resources (DERs), including renewable energy resources (RESs) and electric vehicles (EVs), have a significant impact on distribution systems because they can cause bi-directional power flow in the distribution lines. Thus, the voltage regulation and thermal limits of the distribution system to mitigate from the excessive power generation or consumption should be considered. The focus of this study is on a control strategy for DERs in low-voltage DC microgrids to minimize the operating costs and maintain the distribution voltage within the normal range based on intelligent scheduling of the charging and discharging of EVs, and to take advantage of RESs such as photovoltaic (PV) plants. By considering the time-of-use electricity rates, we also propose a 24-h sliding window to mitigate uncertainties in loads and PV plants in which the output is time-varied and the EV arrival cannot be predicted. After obtaining a request from the EV owner, the proposed optimal DER control method satisfies the state-of-charge level for their next journey. We applied the voltage sensitivity factor obtained from a load-flow analysis to effectively maintain voltage profiles for the overall DC distribution system. The performance of the proposed optimal DER control method was evaluated with case studies and by comparison with conventional methods.

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Section: Voltage Regulation Constraintsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Optimal Control Strategy for Distributed Energy Resources in a DC Microgrid for Energy Cost Reduction and Voltage Regulation

Trinh

Chung

2021

Energies

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“…Calculated output adjustment value is transferred to the corresponding distributed energy resource as a command, the output is adjusted accordingly, and then the voltage violation in the power system is cleared. Figure 8 shows the entire flow chart of the voltage control algorithm [31][32][33][34][35]. Figure 9 is the configuration diagram of the demonstration site for DC distribution at the Gochang Power Testing Center of KEPCO.…”

Section: Of 23mentioning

confidence: 99%

Demonstration Study of Voltage Control of DC Grid Using Energy Management System Based DC Applications

Kim

Cho

et al. 2020

Energies

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This paper is about the development of the real-time direct current (DC) network analysis applications for the operation of DC power systems. The applications are located in the central energy management system (EMS) and provide the operator with the optimal solution for operation in real time. Developed DC applications are not limited by voltage level. Applications can be used at all DC voltage levels such as low voltage, medium voltage and high voltage. A program configuration and sequence for analyzing the DC distribution system are suggested. Algorithms of each program are presented and the differences when compared with the processes of the applications of the existing alternating current (AC) systems are analyzed. The DC grid demonstration site at the Korea Electric Power Corporation (KEPCO) power testing center is introduced. The details of EMS and applications installation are described. The developed DC applications were installed in the EMS of the demonstration site and verification tests have been carried out. The configuration of the test scenario for testing the voltage control of the DC network is described. The voltage control result is analyzed and the measured data and the results of the applications are verified for compatibility by comparing them with the results of an off-line simulation tool. Finally, the future direction of the development of technology for the operation of the DC grid is introduced.

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Multilevel LVDC Distribution System With Voltage Unbalancing and Disturbance Rejection Control Topology

et al. 2020

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With the emergence of power electronic technology and advancements in highly efficient electric power converters, DC-DC converters play a significant role in DC networks and DC distribution systems. Not being fully understood, nevertheless, the stability, protection and safety of DC systems present an open challenge for the research community. In this study, a high quality low voltage DC distribution system has been proposed, which provides a constant power in the event of voltage disturbance (sag), fluctuations, and fault. A three wire line system is adopted: +375 V line, neutral and −375 V line. Furthermore, the required DC power is transformed from DC or AC voltages by using load side converters, and these power converters do not need any transformers to adopt the proper DC voltage. In this research work double-closedloop control strategy, the outer voltage control loop and inner current loop (decoupled without the exact value of boost inductance) are proposed. If short circuit or any fault occurs on the load side, the proposed strategy prevents the effect of remaining load. Also, the grid reconnection and disconnection is very smooth. Furthermore, a voltage balancer is proposed near to low voltage side. To confirm the effectiveness of the suggested control topology, simulations are performed in Matlab/Simulink and PSCAD software. The results obtained from simulation show that the suggested control system topology can provide excellent power in various conditions.INDEX TERMS DC distribution, micro-grid, voltage disturbance, double-closed-loop control.

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Development of voltage control system for multi-terminal low-voltage DC distribution system

Cited by 6 publications

References 10 publications

Optimal Control Strategy for Distributed Energy Resources in a DC Microgrid for Energy Cost Reduction and Voltage Regulation

Optimal Control Strategy for Distributed Energy Resources in a DC Microgrid for Energy Cost Reduction and Voltage Regulation

Demonstration Study of Voltage Control of DC Grid Using Energy Management System Based DC Applications

Multilevel LVDC Distribution System With Voltage Unbalancing and Disturbance Rejection Control Topology

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