Power Quality in DC Power Distribution Systems and Microgrids

Whaite, Stephen M.; Grainger, Brandon M.; Kwasinski, Alexis

doi:10.3390/en8054378

Cited by 88 publications

(51 citation statements)

References 64 publications

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“…With the high penetration of direct current (DC) energy sources, storage, and loads, DC micro-grids are becoming more prevalent due to a lower number of power converters compared with an alternating current (AC) micro-grid [1][2][3]. Because of the intermittent nature of renewable energy sources and unpredictable load fluctuations in DC micro-grids, the problem of power imbalance may appear and affect the operation of DC micro-grids.…”

Section: Introductionmentioning

confidence: 99%

Common Grounded H-Type Bidirectional DC-DC Converter with a Wide Voltage Conversion Ratio for a Hybrid Energy Storage System

Wang

2018

Energies

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Hybrid energy storage systems (HESS) play an important role in maintaining the power balance of a direct current (DC) micro-grid. A HESS is mainly composed of high power density super-capacitors (SCs) and high energy density batteries. According to the operational requirements of an SC, a bidirectional DC-DC converter with the characteristics of a good dynamic response and a wide voltage conversion ratio is needed to interface the SC and a high-voltage DC bus. In this paper, a novel common grounded H-type bidirectional converter characterized by a good dynamic response, a low inductor current ripple, and a wide voltage conversion ratio is proposed. In addition, it can avoid the narrow pulse of pulse width modulation (PWM) voltage waveforms when a high voltage conversion ratio is achieved. All of these features are beneficial to the operation of the SC connected to a DC bus. The operating principle and characteristics of the proposed converter are presented in this paper. A 320 W prototype with a wide voltage conversion ranging from 3.3 to 8 in step-up mode and 1/8 to 1/3 in step-down mode has been constructed to validate the feasibility and effectiveness of the proposed converter.

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Section: Introductionmentioning

confidence: 99%

Common Grounded H-Type Bidirectional DC-DC Converter with a Wide Voltage Conversion Ratio for a Hybrid Energy Storage System

Wang

2018

Energies

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“…This is due to the fact that most modern loads require DC power, to supply them with DC power directly rather than with AC power as conventional power systems do. For DC load examples, there are battery energy storage systems (BESSs), electric vehicles, laptops, personnel computers, lightings, televisions, data centers, refrigerators, and air conditioners [4][5][6]. Moreover, since most renewable energy sources (RESs) and energy storage system (ESSs) generate DC power, rectification and inversion power electronic converter stages are eliminable in DC microgrids [7].…”

Section: Introductionmentioning

confidence: 99%

A Decentralized Control Method for Distributed Generations in an Islanded DC Microgrid Considering Voltage Drop Compensation and Durable State of Charge

Hwang

Kim

2016

Energies

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This paper presents a decentralized control method for distributed generations (DGs) in an islanded direct current (DC) microgrid. In most typical DC microgrids, a decentralized control method is based on a voltage droop control method. However, the grid voltage differs from node to node due to line voltage drop, and hence the power sharing ratio among DGs cannot be matched with as desired value. Especially in an islanded DC microgrid including an energy storage system as a voltage source, it is difficult for DGs to maintain the charge state of the ESS in a decentralized way. To overcome this problem, state of charge (SOC)-voltage droop control is applied to the ESS. By using the proposed droop method, the SOC information can be assigned to the grid voltage, and hence the other DGs are able to support the SOC in a decentralized way. For DGs to enhance the accuracy of the SOC estimation, voltage drop is compensated for based on forecasting data and line impedance data. The simulation is modeled and implemented using Power System Computer Aided Design/Electromagnetic Transients for DC (PSCAD/EMTDC, version 4.2, Winnipeg, Manitoba, Canada) and the simulation results show that the capability to maintain SOC as well as the system voltage profile are improved by using the proposed method.

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“…If so, (17) is removed from the constraint set. By applying the cost function (14), equality conditions (8,12,14), and inequality conditions (16,17), the optimization problem is organized as Minimize − 2( * )…”

Section: Optimization Problem For Ess Operationmentioning

confidence: 99%

“…Some studies showed that transferring electricity in DC low-voltage level is more efficient than transferring electricity at an AC high-voltage level to some distance [6], as well as better power quality [7,8]. In developing countries, the DC micro-grid with a small PV system has been applied for rural area electrification [9].…”

Section: Introductionmentioning

confidence: 99%

Power Flow Study of Low-Voltage DC Micro-Grid and Control of Energy Storage System in the Grid

Kim¹

2017

Journal of Electrical Engineering and Technology

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-DC distribution has several differences compared to AC distribution. DC distribution has a higher efficiency than AC distribution when distributing electricity at the same voltage level. Accordingly, power can be transferred further with low-voltage DC. In addition, power flow in a DC grid system is produced by only a voltage difference in magnitude. Owing to these differences, operation of a DC grid system significantly differs from that of an AC system. In this paper, the power flow problem in a bipolar-type DC grid with unbalanced load conditions is organized and solved. Control strategy of energy storage system on a slow time scale with power references obtained by solving an optimization problem regarding the DC grid is then proposed. The proposed strategy is verified with computer simulations.

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Power Quality in DC Power Distribution Systems and Microgrids

Cited by 88 publications

References 64 publications

Common Grounded H-Type Bidirectional DC-DC Converter with a Wide Voltage Conversion Ratio for a Hybrid Energy Storage System

Common Grounded H-Type Bidirectional DC-DC Converter with a Wide Voltage Conversion Ratio for a Hybrid Energy Storage System

A Decentralized Control Method for Distributed Generations in an Islanded DC Microgrid Considering Voltage Drop Compensation and Durable State of Charge

Power Flow Study of Low-Voltage DC Micro-Grid and Control of Energy Storage System in the Grid

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