scholarly journals Capacity Limitation Control of Multiple Bi-directional DC-DC Converters for Micro Grid Application

2015 ◽  
Vol 2 (1) ◽  
pp. 61 ◽  
Author(s):  
S. J. Chiang ◽  
Yu-Min Liao ◽  
Ke-Chih Liu
Keyword(s):  
Power Management ◽  
Control Method ◽  
Droop Control ◽  
Control Methods ◽  
Power Capacity ◽  
Capacity Limitation ◽  
Current Sharing ◽  
Parallel Control ◽  
Micro Grid ◽  
Bus Voltage

The micro grid system requires battery for energy storage and power management. In which, the bi-directional DC to DC converter is the key component for maintaining the DC bus voltage and controlling the charge and discharge of the battery with or without grid support. Parallel control of multiple DC to DC converters is a critical technique to enlarge the power capacity. This paper presents two capacity limitation control methods that multiple DC to DC converters can be paralleled with distributed battery banks. The first method is the capacity limitation control with cascaded load current sense needing no control interconnection. The second method is the capacity limitation control with master-slave and cascaded current command limitation. Two methods are presented to solve the limitation of droop control method and active current sharing method respectively, and can be extended without converter number limitation theoretically. Three prototype 240W bidirectional half-bridge DC to DC converters are built and paralleled in this paper. The proposed method is confirmed with some measured results.

scholarly journals The Hierarchical Control Algorithm for DC Microgrid Based on the Improved Droop Control of Fuzzy Logic

Energies ◽  
2019 ◽  
Vol 12 (15) ◽  
pp. 2995 ◽  
Author(s):  
Liang Zhang ◽  
Kang Chen ◽  
Shengbin Chi ◽  
Ling Lyu ◽  
Guowei Cai
Keyword(s):  
Fuzzy Logic ◽  
Control Algorithm ◽  
Voltage Drop ◽  
Hierarchical Control ◽  
Voltage Regulation ◽  
Droop Control ◽  
Dc Microgrid ◽  
Current Sharing ◽  
The Difference ◽  
Bus Voltage

In the direct current (DC) microgrid composed of multiple distributed generations, due to the different distances between various converters and the DC bus in the system, the difference of the line resistance will reduce the current sharing accuracy of the system. The droop control was widely used in the operation control of the DC microgrid. It was necessary to select a large droop coefficient to improve the current sharing accuracy, but a too large droop coefficient will lead to a serious bus voltage drop and affect the power quality. In view of the contradiction between the voltage regulation and load current sharing in the traditional droop control, a hierarchical control algorithm based on the improved droop control of the fuzzy logic was proposed in this paper. By improving the droop curve, the problems of voltage regulation and current sharing were solved simultaneously. The effectiveness of the algorithm was verified by simulation.

scholarly journals Droop Control in DQ Coordinates for Fixed Frequency Inverter-Based AC Microgrids

Electronics ◽  
2019 ◽  
Vol 8 (10) ◽  
pp. 1168 ◽  
Author(s):  
Mohamed Toub ◽  
Mehrzad M. Bijaieh ◽  
Wayne W. Weaver ◽  
Rush D. Robinett III ◽  
Mohamed Maaroufi ◽  
...  
Keyword(s):  
Reactive Power ◽  
Control Technique ◽  
Droop Control ◽  
Control Methods ◽  
Fixed Frequency ◽  
Active And Reactive Power ◽  
Bus Voltage ◽  
High Level ◽  
System Frequency ◽  
Frequency Inverter

This paper presents a proof-of-concept for a novel dq droop control technique that applies DC droop control methods to fixed frequency inverter-based AC microgrids using the dq0 transformation. Microgrids are usually composed of distributed generation units (DGUs) that are electronically coupled to each other through power converters. An inherent property of inverter-based microgrids is that, unlike microgrids with spinning machines, the frequency of the parallel-connected DGUs is a global variable independent from the output power since the inverters can control the output waveform frequency with a high level of precision. Therefore, conventional droop control methods that distort the system frequency are not suitable for microgrids operating at a fixed frequency. It is shown that the proposed distributed droop control allows accurate sharing of the active and reactive power without altering the microgrid frequency. The simulation and hardware-in-the-loop (HIL) results are presented to demonstrate the efficacy of the proposed droop control. Indeed, following a load change, the dq droop controller was able to share both active and reactive power between the DGUs, whereas maintaining the microgrid frequency deviation at 0% and the bus voltage deviations below 6% of their respective nominal values.

scholarly journals Power Management in Hybrid Microgrid

2020 ◽  
Vol 9 (5) ◽  
pp. 1964-1969
Keyword(s):  
Power Management ◽  
Management Strategy ◽  
Load Sharing ◽  
Control Technique ◽  
Droop Control ◽  
Hybrid Microgrid ◽  
Management Algorithm ◽  
Power Management Strategy ◽  
Maximum Power Tracking ◽  
Bus Voltage

This paper is representing power management in a hybrid microgrid. The hybrid microgrid consists of PV, wind, battery, and grid. The power management strategy is mentioned in islanding and grid-connected mode. In a grid-connected system, the grid converter has to monitor and manage the power to flow between microgrid and grid. The voltage shifting based droop control technique is used in DG for proper load sharing when two sources are connected in parallel. DG units in hybrid microgrid have two switching modes including droop control and maximum power tracking (MPPT). The operation of a hybrid microgrid is operated in different thee mode. The bus voltage is the main carrier to switching the mode of a hybrid microgrid. The power management algorithm for hybrid microgrid described here. This renewable-based hybrid microgrid model can be used for different aspects like small residential and commercial buildings. The feasibility and effectiveness of this strategy for hybrid microgrid running in various modes verified by simulation result.

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