scholarly journals Consensus Control of Distributed Energy Resources in a Multi-Bus Microgrid for Reactive Power Sharing and Voltage Control

Energies ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2710 ◽  
Author(s):  
Li Yu ◽  
Di Shi ◽  
Guangyue Xu ◽  
Xiaobin Guo ◽  
Zhen Jiang ◽  
...  
Keyword(s):  
Distribution System ◽  
Reactive Power ◽  
Hierarchical Control ◽  
Voltage Control ◽  
Power Sharing ◽  
Consensus Control ◽  
Distributed Generator ◽  
Distributed Generators ◽  
Control Framework ◽  
Major Factors

The hierarchical control architecture, including layers of primary, secondary and tertiary controls, is becoming the standard operating paradigm for microgrids (MGs). Two major factors that limit the adoption of existing hierarchical control in microgrid are the low accuracy in reactive power sharing and the requirement for complex communication infrastructure. This paper addresses this problem by proposing a novel distributed primary and secondary control for distributed generators dispersed in a multi-bus microgrid. The proposed method realizes voltage control and accurate reactive power sharing in a distributed manner using minimum communication. Each distributed generator only needs its own information and minimum information from its neighboring units. Topology of the network can be flexible which supports the plug-and-play feature of microgrids. In a distribution system, high R/X ratio and system imbalance can no longer be neglected and thus the sequence component analysis and virtual impedance are implemented in the proposed control framework. The proposed framework is validated by simulation results on a MG testbed modified from the IEEE 13-bus distribution system.

scholarly journals A novel distributed event-triggered control for reactive power sharing based on hierarchical structure in islanded microgrid

2020 ◽  
pp. 002029402092475
Author(s):  
Yingwen Long ◽  
Yanxiang Zhu ◽  
Wei Zhang
Keyword(s):  
Hierarchical Structure ◽  
Reactive Power ◽  
Hierarchical Control ◽  
Power Sharing ◽  
Control Algorithms ◽  
Centralized Control ◽  
Nonlinear Loads ◽  
Distributed Generator ◽  
Islanded Microgrid ◽  
Event Triggered

Due to line impedance mismatches, nonlinear loads and other reasons, the traditional droop control algorithms have great limitations on the control of reactive power sharing. Distributed control algorithms based on hierarchical structure have become an effective approach for reactive power sharing compared with traditional centralized control methods. In this paper, an event-triggered control algorithm based on stability analysis of Lyapunov method is put forward in order to satisfy the demand of low-bandwidth communication for distributed generator in islanded microgrid. Subsequently, a distributed hierarchical control scheme adopting proposed event-triggered strategy is designed to achieve proportional reactive power sharing in an islanded microgrid. Finally, the feasibility and validity of the proposed algorithm are further verified in MATLAB/Simulink environment.

scholarly journals A Novel Hierarchical Control Strategy for Low-Voltage Islanded Microgrids Based on the Concept of Cyber Physical System

Energies ◽  
2018 ◽  
Vol 11 (7) ◽  
pp. 1835 ◽  
Author(s):  
Qiuxia Yang ◽  
Dongmei Yuan ◽  
Xiaoqiang Guo ◽  
Bo Zhang ◽  
Cheng Zhi
Keyword(s):  
Control Strategy ◽  
Physical System ◽  
Reactive Power ◽  
Low Voltage ◽  
Hierarchical Control ◽  
Physical Layer ◽  
Cyber Physical System ◽  
Droop Control ◽  
Control Effect ◽  
Consensus Control

Based on the concept of cyber physical system (CPS), a novel hierarchical control strategy for islanded microgrids is proposed in this paper. The control structure consists of physical and cyber layers. It’s used to improve the control effect on the output voltages and frequency by droop control of distributed energy resources (DERs), share the reactive power among DERs more reasonably and solve the problem of circumfluence in microgrids. The specific designs are as follows: to improve the control effect on voltages and frequency of DERs, an event-trigger mechanism is designed in the physical layer. When the trigger conditions in the mechanism aren’t met, only the droop control (i.e., primary control) is used in the controlled system. Otherwise, a virtual leader-following consensus control method is used in the cyber layer to accomplish the secondary control on DERs; to share the reactive power reasonably, a method of double virtual impedance is designed in the physical layer to adjust the output reactive power of DERs; to suppress circumfluence, a method combined with consensus control without leader and sliding mode control (SMC) is used in the cyber layer. Finally, the effectiveness of the proposed hierarchical control strategy is confirmed by simulation results.

scholarly journals Coordinated Frequency Control Strategy with the Virtual Battery Model of Inverter Air Conditionings

2019 ◽  
Vol 9 (15) ◽  
pp. 3052
Author(s):  
Jiafu Yin ◽  
Dongmei Zhao
Keyword(s):  
Control Strategy ◽  
Frequency Control ◽  
Hierarchical Control ◽  
Frequency Regulation ◽  
Consensus Protocol ◽  
Consensus Control ◽  
Response Characteristics ◽  
Battery Model ◽  
Control Framework ◽  
Control Scheme

Due to the potential of thermal storage being similar to that of the conventional battery, air conditioning (AC) has gained great popularity for its potential to provide ancillary services and emergency reserves. In order to integrate numerous inverter ACs into secondary frequency control, a hierarchical distributed control framework which incorporates a virtual battery model of inverter AC is developed. A comprehensive derivation of a second-order virtual battery model has been strictly posed to formulate the frequency response characteristics of inverter AC. In the hierarchical control scheme, a modified control performance index is utilized to evaluate the available capacity of traditional regulation generators. A coordinated frequency control strategy is derived to exploit the complementary and advantageous characteristics of regulation generators and aggregated AC. A distributed consensus control strategy is developed to guarantee the fair participation of heterogeneous AC in frequency regulation. The finite-time consensus protocol is introduced to ensure the fast convergence of power tracking and the state-of-charge (SOC) consistency of numerous ACs. The effectiveness of the proposed control strategy is validated by a variety of illustrative examples.

scholarly journals Consensus Control for Reactive Power Sharing Using an Adaptive Virtual Impedance Approach

Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 2026 ◽  
Author(s):  
Ahmed S. Alsafran ◽  
Malcolm W. Daniels
Keyword(s):  
Rate Of Convergence ◽  
Reactive Power ◽  
Impedance Control ◽  
Power Sharing ◽  
Control Methods ◽  
Triangle Mesh ◽  
Secondary Control ◽  
Consensus Control ◽  
Communication Topology ◽  
Virtual Impedance

Reactive power sharing among distributed generators (DGs) in islanded microgrids (MGs) presents control challenges, particularly in the mismatched feeder line condition. Improved droop control methods independently struggle to resolve this issue and centralized secondary control methods exhibit a high risk of collapse for the entire MG system under any failure in the central control. Distributed secondary control methods have been recently proposed to mitigate the reactive power error evident in the presence of mismatched feeder lines. This paper details a mathematical model of an adaptive virtual impedance control that is based on both leaderless and leader-followers consensus controls with a novel triangle mesh communication topology to ensure accurate active and reactive power sharing. The approach balances an enhanced rate of convergence with the anticipated implementation cost. A MATLAB/Simulink model with six DG units validates the proposed control performance under three different communication structures: namely, ring, complete, and triangle mesh topologies. The results suggest that leaderless consensus control is a reliable option with large DG systems, while the leader-followers consensus control is suitable for the small systems. The triangle mesh communication topology provides a compromise approach balancing the rate of convergence and the expected cost. The extensibility and scalability are advantages of this topology over the alternate ring and complete topologies.

Effect of Capacitors on Frequency of OLTC Tap Changes in the Presence of Wind Generation

2015 ◽  
Vol 16 (4) ◽  
pp. 385-395 ◽  
Author(s):  
Neelakanteshwar Rao Battu ◽  
Nilanjan Senroy ◽  
A. R. Abhyankar
Keyword(s):  
Mathematical Model ◽  
Distribution System ◽  
Reactive Power ◽  
Wind Generation ◽  
Voltage Sensitivity ◽  
Distributed Generator ◽  
System A ◽  
Wear And Tear ◽  
Tap Changer ◽  
Load Tap Changer

Abstract Installation of a wind power distributed generator in a distribution system alters the reactive power drawn by the system. This affects the load bus voltages. Any deviation in load bus voltages from their limits is sensed by an on load tap changer of a transformer and it responds to maintain the bus voltages within their limits. The reactive power requirements of a wind generator vary due to the intermittent behaviour of wind, which will in turn vary the bus voltages. This has an affect on number of tap changings of a transformer. Frequent tap changing of a transformer increases wear and tear of it and ultimately reduces the life of it. A mathematical model is developed to analyze the voltage sensitivity at a load bus to the tap change of a transformer under different scenarios and conditions in the distribution system. A possible solution to reduce the number of tap changings is presented in this paper.

scholarly journals Control Strategy to Regulate Voltage and Share Reactive Power Using Variable Virtual Impedance for a Microgrid

2019 ◽  
Vol 9 (22) ◽  
pp. 4876 ◽  
Author(s):  
Eder Molina ◽  
John E. Candelo-Becerra ◽  
Fredy E. Hoyos
Keyword(s):  
Power Control ◽  
Electric Vehicles ◽  
Control Strategy ◽  
Reactive Power ◽  
Control Variable ◽  
Control Voltage ◽  
Primary Control ◽  
Distributed Generator ◽  
Distributed Generators ◽  
Virtual Impedance

This paper presents a control strategy to regulate voltage and share reactive power from distributed generators in a microgrid when electric vehicles (EVs) are connected and disconnected at different nodes and times. The control strategy considers fixed and variable virtual impedances created in the microgrid (MG) when loads change (EVs are connected or disconnected). Fixed virtual impedance is related to the distance from each house to the power inverter and is used as an input of the primary control. Variable virtual impedance is associated with the distance from each EV to the power inverter and is also used as an input of the primary control. Thus, the control of the inverter seeks to regulate the voltage where the EVs create variations in the network. The results show that the control strategy regulates well the voltage of different nodes, and the reactive power is distributed to renewable generators based on the distance from the loads to the inverters. By considering the fixed and variable virtual impedances in the primary control, voltage can be regulated, assuming various consumptions of EVs in the network. This result is promising for reactive power control and sharing for each distributed generator (DG) in a microgrid where a great number of EVs affect the operation.

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