scholarly journals Distributed Economic Control for AC/DC Hybrid Microgrid

Electronics ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 13
Author(s):  
Hongjun Wang ◽  
Wanfeng Li ◽  
Youjun Yue ◽  
Hui Zhao
Keyword(s):  
Power Distribution ◽  
Cost Effective ◽  
Control Mode ◽  
Frequency Regulation ◽  
Dc Microgrid ◽  
Dc Microgrids ◽  
Hybrid Microgrid ◽  
Economic Operation ◽  
Optimal Power ◽  
Effective Operation

In this paper, a new double-layer droop control mode for island AC/DC microgrids is proposed to realize autonomous and cost-effective operation. The optimal power reference iterative algorithm is used to realize the internal active power distribution in the subnet. On this basis, secondary frequency and voltage adjustments are introduced to realize the economic operation, autonomy and stability of the subnet. At the microgrid level, the local control strategy of cost micro increment deviation is designed to optimize the exchange power between subnets. The cooperation of the two can realize the global economic operation of the microgrid, as well as voltage following and frequency regulation in the subnet. Based on the hybrid AC/DC microgrid simulation model, the effectiveness of the proposed method is verified.

scholarly journals Real-Time Economic Frequency Regulation for Partitioned Microgrids Based on Cost-Driven Droop Function

2020 ◽  
Author(s):  
Qian Hu ◽  
Siqi Bu
Keyword(s):  
Real Time ◽  
Cost Effective ◽  
Power Sharing ◽  
Consensus Algorithm ◽  
Total Power ◽  
Frequency Regulation ◽  
Distributed Energy ◽  
Economic Operation ◽  
Proposed Regulation ◽  
And Control

With the increase of the number and geographic dispersion of distributed energy resources (DERs), the microgrid (MG) has become scattered along with the higher complexity of control and communication. This paper proposes a two-level regulation strategy to achieve the local objective of frequency regulation and power sharing as well as the global objective of economic operation in the real time for the scattered MG. Firstly, the MG integrated with multiple DERs is partitioned into several<i> </i>nanogrids (NGs) such that DERs connecting on the same feeder are grouped in the same NG for the efficient and cost-effective communication and control. Then<i> </i>in the NG level, the total power mismatch of the entire MG can be learned and an optimal incremental cost can be agreed by each NG through the fastest distributed linear averaging (FDLA) and discrete-consensus algorithm, respectively. In the DER level, a cost-driven droop gain is developed to indicate the willingness of each DER in the NG to participate into the frequency regulation service. The pinning-based protocol is formulated to regulate the frequency and meanwhile enable the proportional power sharing among DERs based on the economic droop function. Case studies satisfactorily demonstrate the effectiveness of the proposed regulation strategy for the economic frequency regulation in the tested MG.

scholarly journals Real-Time Economic Frequency Regulation for Partitioned Microgrids Based on Cost-Driven Droop Function

2020 ◽  
Author(s):  
Qian Hu ◽  
Siqi Bu
Keyword(s):  
Real Time ◽  
Cost Effective ◽  
Power Sharing ◽  
Consensus Algorithm ◽  
Total Power ◽  
Frequency Regulation ◽  
Distributed Energy ◽  
Economic Operation ◽  
Proposed Regulation ◽  
And Control

With the increase of the number and geographic dispersion of distributed energy resources (DERs), the microgrid (MG) has become scattered along with the higher complexity of control and communication. This paper proposes a two-level regulation strategy to achieve the local objective of frequency regulation and power sharing as well as the global objective of economic operation in the real time for the scattered MG. Firstly, the MG integrated with multiple DERs is partitioned into several<i> </i>nanogrids (NGs) such that DERs connecting on the same feeder are grouped in the same NG for the efficient and cost-effective communication and control. Then<i> </i>in the NG level, the total power mismatch of the entire MG can be learned and an optimal incremental cost can be agreed by each NG through the fastest distributed linear averaging (FDLA) and discrete-consensus algorithm, respectively. In the DER level, a cost-driven droop gain is developed to indicate the willingness of each DER in the NG to participate into the frequency regulation service. The pinning-based protocol is formulated to regulate the frequency and meanwhile enable the proportional power sharing among DERs based on the economic droop function. Case studies satisfactorily demonstrate the effectiveness of the proposed regulation strategy for the economic frequency regulation in the tested MG.

scholarly journals A Hierarchical Control Approach for Power Loss Minimization and Optimal Power Flow within a Meshed DC Microgrid

Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4846
Author(s):  
Igyso Zafeiratou ◽  
Ionela Prodan ◽  
Laurent Lefévre
Keyword(s):  
Power Distribution ◽  
Power Loss ◽  
Optimal Power Flow ◽  
Cost Minimization ◽  
Loss Minimization ◽  
Dc Microgrid ◽  
Control Approach ◽  
Power Loss Minimization ◽  
Optimal Power ◽  
The Cost

This work considers the DC part of a hybrid AC/DC microgrid with a meshed topology. We address cost minimization, battery scheduling and the power loss minimization within the power distribution network through constrained optimization. The novelty comes from applying differential flatness properties to the microgrid components and formulating the cost and constraints in terms of the associated B-splines parametrization of the flat outputs (the voltages and currents of the system). This allows us to obtain optimal power profiles to minimize the power dissipation and the cost of the electricity purchase from the external grid. These profiles are tracked by a model predictive controller at the higher level, while at a a lower level a controller deals with the operation of the switches within the DC/DC converters. Extensive simulations under nominal and fault-affected scenarios using realistic data validate the proposed approach.

scholarly journals Research on the Optimal Operation Method of DC Microgrid Base on the New DC Power Distribution Management System

Electronics ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 9
Author(s):  
Qingwen Peng ◽  
Zhichang Yuan ◽  
Bin Ouyang ◽  
Peiqian Guo ◽  
Lu Qu
Keyword(s):  
Power Distribution ◽  
Distribution System ◽  
Management System ◽  
Distribution Network ◽  
Dc Microgrid ◽  
Distribution Management ◽  
Power Distribution System ◽  
Dc Microgrids ◽  
Dc Power ◽  
Distribution Management System

The grid-connected operation of the distributed generation (DG) via the direct current (DC) microgrid is the operation mode of the DC power distribution system in the future. Considering the grid-connected operation of multiple DC microgrids, we have proposed a new type of DC power distribution management system aiming at the lowest operating cost of the entire DC power distribution system. Our proposed DC power distribution management system can be used to carry out the optimized dispatching for the connected DC microgrids, thereby achieving the economic, safe, and stable operation of DC power distribution management systems. At the same time, through the different nodes where the modular multilevel converter (MMC) is connected to the alternating current (AC) distribution network, a DC power distribution management system can control the active and reactive power generated by the MMC, achieving the control of the load flow of the upper-stage AC grids in real time. The example simulation shows that the method proposed in this paper has a great role in reducing the transmission losses of the power distribution network, achieving electric power peak-load shifting, and utilizing renewable energy. Thus, it can not only maximize the use of distributed renewable resources, but also enable mutual support and optimal scheduling between a DC power distribution system and multiple microgrids.

scholarly journals A Cost-Effective Decentralized Control for AC-Stacked Photovoltaic Inverters

Energies ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 2262 ◽  
Author(s):  
Hua Han ◽  
Chao Luo ◽  
Xiaochao Hou ◽  
Mei Su ◽  
Wenbin Yuan ◽  
...  
Keyword(s):  
Decentralized Control ◽  
Cost Effective ◽  
Current Control ◽  
Control Mode ◽  
Communication Link ◽  
Grid Voltage ◽  
Point Tracking ◽  
Pv Inverter ◽  
Communication Links ◽  
Voltage Phase

For an AC-stacked photovoltaic (PV) inverter system with N cascaded inverters, existing control methods require at least N communication links to acquire the grid synchronization signal. In this paper, a novel decentralized control is proposed. For N inverters, only one inverter nearest the point of common coupling (PCC) needs a communication link to acquire the grid voltage phase and all other N − 1 inverters use only local measured information to achieved fully decentralized local control. Specifically, one inverter with a communication link utilizes the grid voltage phase and adopts current control mode to achieve a required power factor (PF). All other inverters need only local information without communication links and adopt voltage control mode to achieve maximum power point tracking (MPPT) and self-synchronization with grid voltage. Compared with existing methods, the communication link and complexity is greatly reduced, thus improved reliability and reduced communication costs are achieved. The effectiveness of the proposed control is verified by simulation tests.

scholarly journals A Bus-Sectionalized Hybrid AC/DC Microgrid: Concept, Control Paradigm, and Implementation

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3508
Author(s):  
Jing Li ◽  
Hongda Cai ◽  
Pengcheng Yang ◽  
Wei Wei
Keyword(s):  
Hierarchical Control ◽  
Mode Switching ◽  
Stable Operation ◽  
Service Reliability ◽  
Test Results ◽  
Dc Microgrid ◽  
Dc Microgrids ◽  
Operation Modes ◽  
Control Paradigm ◽  
Operational Data

In the last several years, the coordination control of hybrid AC/DC microgrids (HMGs) has been gaining increasingly more attention. However, most of these discussions are focused on single-bus HMGs whose AC or DC bus is not sectionalized by AC or DC breakers. Compared with these single-bus HMGs, the bus-sectionalized HMG has more flexible topologies, more diverse operation modes, and consequently higher service reliability. However, meanwhile, these benefits also bring challenges to the stable operation of bus-sectionalized HMGs, particularly for mode switching. Relying on the national HMG demonstrative project in Shaoxing, China, this paper makes efforts to present the hierarchical control paradigm of a typical bus-sectionalized HMG toward standardization. The test results demonstrate that the proposed system provides seamless switching and uninterrupted power supply without controller reconfiguration among different operation modes. The operational data are also brought forth and analyzed to provide significant and useful experiences for designing and developing similar HMGs in the future.

scholarly journals Optimization of Two-Stage IPD-(1+I) Controllers for Frequency Regulation of Sustainable Energy Based Hybrid Microgrid Network

Electronics ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 919
Author(s):  
Abdul Latif ◽  
S. M. Suhail Hussain ◽  
Dulal Chandra Das ◽  
Taha Selim Ustun
Keyword(s):  
Sustainable Energy ◽  
Research Field ◽  
Optimization Techniques ◽  
Frequency Regulation ◽  
Water Heater ◽  
Two Stage ◽  
Domain Specific ◽  
Hybrid Microgrid ◽  
Main Challenge ◽  
Algorithmic Technique

Sustainable energy based hybrid microgrids are advantageous in meeting constantly increasing energy demands. Conversely, the intermittent nature of renewable sources represents the main challenge to achieving a reliable supply. Hence, load frequency regulation by adjusting the amount of power shared between subsystems is considered as a promising research field. Therefore, this paper presents a new stratagem for frequency regulation by developing a novel two stage integral-proportional-derivative with one plus integral (IPD-(1+I)) controller for multi sources islanded microgrid system (MS-IμGS). The proposed stratagem has been tested in an MS-IμGS comprising of a wind turbine, parabolic trough, biodiesel generators, solid-oxide fuel cell, and electric water heater. The proposed model under different scenarios is simulated in MATLAB environment considering the real-time recorded wind data. A recently developed sine-cosine algorithmic technique (SCA) has been leveraged for optimal regulation of frequency in the considered microgrid. To identify the supremacy of the proposed technique, comparative studies with other classical controllers with different optimization techniques have been performed. From the comparison, it is clearly evident that, SCA-(IPD-(1+I)) controller gives better performance over other considered stratagems in terms of various time domain specific parameters, such as peak deviations (overshoot, undershoot) and settling time. Finally, the robustness of the proposed stratagem is evaluated by conducting sensitivity analysis under ±30% parametric variations and +30% load demand. The lab tests results validate the operation of the proposed system and show that it can be used to regulate the frequency in stand-alone microgrids with a high penetration of renewable energy.

scholarly journals Bidirectional Power Flow Control in AC/DC Hybrid System under AC and DC Fault Conditions

2019 ◽  
Vol 3 (2) ◽  
Author(s):  
Wai Wai Hnin
Keyword(s):  
Power Flow ◽  
Storage System ◽  
Control Technique ◽  
Diesel Generator ◽  
Dc Microgrid ◽  
Photovoltaic Array ◽  
Hybrid Microgrid ◽  
Dc Bus ◽  
Bidirectional Power Flow ◽  
Ac Microgrid

This paper presents a hybrid AC-DC microgrid to reduce the process of multiple conversions in an individual AC microgrid or DC microgrid. The proposed hybrid microgrid compose of both AC microgrid and DC microgrid connected together by bidirectional interlink converter (BIC). Utility grid, 150kVA diesel generator (DG) and 100kW AC load are connected in AC microgrid. DC microgrid is composed of 100 kW photovoltaic array (PV), 20kW battery energy storage system (BESS) and 20kW DC load. The droop control technique is applied to control the system for power sharing within the sources in AC/DC hybrid microgrid in proportion to the power rating. When the faults occur at AC bus, protection signal applied to breaker for isolating the healthy and faults system. DC faults occur at DC bus, DC breaker isolate the AC and DC bus. The system performance for power flow sharing on hybrid AC-DC microgrid is demonstrated by using MATLAB/SIMULINK.

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