Decentralized Control of DC Microgrid Based on Droop and Voltage Controls with Electricity Price Consideration (original) (raw)
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DC microgrids are gaining popularity due to high efficiency, high reliability and easy interconnection of renewable sources as compared to ac system. Control objectives of dc microgrid are: (i) ensure equal load sharing (in per unit) among sources and (ii) maintain low voltage regulation of the system. Conventional droop controllers are not effective in achieving both the aforementioned objectives simultaneously. Reasons for this are identified to be the error in nominal voltages and load distribution. Though centralized controller achieves these objectives, it requires high speed communication and offers less reliability due to single point of failure. To address these limitations, this paper proposes a new decentralized controller for dc microgrid. Key advantages are high reliability, low voltage regulation and equal load sharing, utilizing low bandwidth communication. To evaluate the dynamic performance, mathematical model of the scheme is derived. Stability of the system is evaluated by eigenvalue analysis. The effectiveness of the scheme is verified through detailed simulation study. To confirm the viability of the scheme, experimental studies are carried out on a laboratory prototype developed for this purpose. Controller Area Network (CAN)
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This paper proposes a new algorithm for power flow analysis in droop controlled DC microgrids. By considering the droop control in the power flow analysis for the DC microgrid, when compared with traditional methods, more accurate analysis results can be obtained. The algorithm verification is carried out by comparing the calculation results with detailed time domain simulation results. With the droop parameters as variables in the power flow analysis, their effects on power sharing and secondary voltage regulation can now be analytically studied, and specialized optimization in the upper level control can also be made accordingly. Case studies on power sharing and secondary voltage regulation are carried out using proposed power flow analysis. Index Terms-DC microgrid, droop control, power flow, power sharing, secondary control.
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This paper proposes a decentralized control technique to minimize the total operation cost of a DC microgrid in both grid-connected and islanded modes. In this study, a cost-based droop control scheme based on the hourly bids of all participant distributed generators (DGs) and the hourly energy price of the utility is presented. An economic power sharing technique among various types of DG units is adopted to appropriately minimize the daily total operation cost of DC microgrid without a microgrid central controller. The DC microgrid may include non-dispatchable DG units (such as photovoltaic systems) and dispatchable generation units. Unlike other energy management techniques, the proposed method suffers neither from forecasting errors for both load demand and renewable energy power prediction modules, nor from complicated optimization techniques. In the proposed method, all DGs and the utility are classified in a sorting rule based on their hourly bids and open market price, and t...
International Journal of Advanced Research in Electrical, Electronics and Instrumentation Engineering, 2016
The increasing trends of the usage of renewable sources faces challenges in the reliable operation and control. The main issues related with parallel connected dc-dc converters in DC microgrid are load current sharing and circulating current. Droop control method is common technique used for load current sharing and the drawbacks of conventional droop method are poor current sharing and drop in dc grid voltage. This paper describes a figure of merit called Droop Index(DI) which is used to improve the performance of dc microgrid, which is a function of normalized current sharing difference and losses in the output side of the converters. By using an instantaneous virtual resistance R droop , minimizes the circulating current and current sharing difference between the converters. The MATLAB/Simulink model of control strategy using droop index is developed and compare with conventional droop control method and validate its theoretical results.
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