Modeling of Multiple Master–Slave Control under Island Microgrid and Stability Analysis Based on Control Parameter Configuration

The stable operation of a microgrid is crucial to the integration of renewable energy sources. However, with the expansion of scale in electronic devices applied in the microgrid, the interaction between voltage source converters poses a great threat to system stability. In this paper, the model of a three-source microgrid with a multi master–slave control method in islanded mode is built first of all. Two sources out of three use droop control as the main control source, and another is a subordinate one with constant power control which is also known as real and reactive power (PQ) control. Then, the small signal decoupling control model and its stability discriminant equation are established combined with “virtual impedance”. To delve deeper into the interaction between converters, mutual influence of paralleled converters of two main control micro sources and their effect on system stability is explored from the perspective of control parameters. Finally, simulation and analysis are launched and the study serves as a reference for parameter setting of converters in a microgrid.

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Fault Ride-Through Enhancement of Grid Supporting Inverter-Based Microgrid Using Delayed Signal Cancellation Algorithm Secondary Control

Energies ◽

10.3390/en12203994 ◽

2019 ◽

Vol 12 (20) ◽

pp. 3994 ◽

Cited By ~ 3

Author(s):

Elutunji Buraimoh ◽

Innocent E. Davidson ◽

Fernando Martinez-Rodrigo

Keyword(s):

Reactive Power ◽

Renewable Energy Sources ◽

System Stability ◽

Positive Sequence ◽

Voltage Source ◽

Stable Operation ◽

Droop Control ◽

Secondary Control ◽

Fault Ride Through ◽

Signal Cancellation

The growing level of grid-connected renewable energy sources in the form of microgrids has made it highly imperative for grid-connected microgrids to contribute to the overall system stability. Consequently, secondary services which include the fault ride-through (FRT) capability are expected to be possessed characteristics by inverter-based microgrids. This enhances the stable operation of the main grid and sustained microgrid grid interconnection during grid faults in conformity with the emerging national grid codes. This paper proposes an effective FRT secondary control strategy to coordinate power injection during balanced and unbalanced fault conditions. This complements the primary control to form a two-layer hierarchical control structure in the microgrids. The primary level is comprised of voltage/power and current inner loops fed by a droop control. The droop control coordinates grid power-sharing amongst the voltage source inverters. When a fault occurs, the participating inverters operate to support the grid voltage, by injecting supplementary reactive power based on their droop gains. Similarly, under unbalanced voltage condition due to asymmetrical faults in the grid, the proposed secondary control ensures the positive sequence component compensation and negative and zero sequence components clearance using a delayed signal cancellation (DSC) algorithm and power electronic switched series impedance placed in-between the point of common coupling (PCC) and the main grid. While ensuring that FRT ancillary service is rendered to the main utility, the strategy proposed ensures relatively interrupted quality power is supplied to the microgrid load. Consequently, this strategy ensures the microgrid ride-through the voltage sag and supports the grid utility voltage during the period of the main utility grid fault. Results of the study are presented and discussed.

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Distributed Adaptive Virtual Impedance for Reactive Power Sharing in Microgrid

International Journal for Modern Trends in Science and Technology - RTT2020 ◽

10.46501/ijmtst060824 ◽

2020 ◽

pp. 135-140

Author(s):

Harini M and Dr.S.Chitra

Keyword(s):

Power Quality ◽

Reactive Power ◽

Control Method ◽

Impedance Control ◽

Renewable Energy Sources ◽

Power Sharing ◽

System Stability ◽

Environment Simulation ◽

Control Stability ◽

Virtual Impedance

The concept of microgrid has been developed to realize flexible coordination control among Distributed Generation (DG) units, improve the power quality supplied to customers. The problem such as the power quality and the system stability due to the intermittency of the renewable energy sources and the fluctuating load profile. The reactive power sharing done by droop control method but reactive power is not accurately shared if there is a local load at each DG. In this paper adaptive virtual impedance control is used to improve the power control stability and sharing performance of real and reactive power sharing is compared by using MATLAB/Simulink environment. Simulation results shows the effectiveness of the proposed method is achieving load reactive power sharing and the voltage restoration is settles in less time.

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Microgrids Emergency Control and Protection

International Journal of Energy Optimization and Engineering ◽

10.4018/ijeoe.2013010106 ◽

2013 ◽

Vol 2 (1) ◽

pp. 78-100 ◽

Cited By ~ 1

Author(s):

Hassan Bevrani ◽

Mehrdad Gholami ◽

Neda Hajimohammadi

Keyword(s):

Power Systems ◽

Large Scale ◽

Reactive Power ◽

Renewable Energy Sources ◽

Voltage Regulation ◽

System Stability ◽

Stable Operation ◽

Energy Storage Devices ◽

Control Plan ◽

Emergency Control

Economical harvesting of electrical energy on a large scale considering the environmental issues is a challenge. As a solution, Microgrids (MGs) promise to facilitate the widely penetration of renewable energy sources (RESs) and energy storage devices into the power systems, reduce system losses and greenhouse gas emissions, and increase the reliability of the electricity supply to the customers. Although the concept of MG is already established, the control strategies and energy management systems for MGs which cover power interchange, system stability, frequency and voltage regulation, active and reactive power control, islanding detection, grid synchronization, following contingencies and emergency conditions are still under development. Like a conventional power system, a Micro-grid (MG) needs emergency control and protection schemes to have secure and stable operation. Since MG can operate in both grid-connected and islanded mode, in addition to the control loops and protection schemes, extra issues must be considered. Transition between two operation modes requires an extra control plan to eliminate and stabilize transients due to mode changing. This paper presents an overview of the key issues and new challenges on emergency control and protection plans in the MG systems. The most important emergency control and protection schemes such as load shedding methods that have been presented over the past years are summarized.

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Vector Control of VSC HVDC System under Single Line to Ground Fault Condition

International Journal of Applied Power Engineering (IJAPE) ◽

10.11591/ijape.v7.i1.pp59-64 ◽

2018 ◽

Vol 7 (1) ◽

pp. 59

Author(s):

Prabodha Kumar Rath ◽

Kanhu Charan Bhuyan

Keyword(s):

Vector Control ◽

Reactive Power ◽

Control Method ◽

System Stability ◽

Control Technique ◽

Voltage Source ◽

Voltage Source Converter ◽

Control Loop ◽

Hvdc System ◽

Ground Fault

<span lang="EN-US">This paper proposes a model of a VSC (voltage source converter) based Back to Back HVDC system and its control technique under fault condition. From the mathematical model of the system relationship between the controlling and the controlled variables is determined to control the system parameters. An appropriate vector control technique is used to control active and reactive power and to maintain DC link voltage. The proposed controlling unit consists of outer control loop and inner control loop which effectively damped out the system oscillation and maintains the system stability. The validity of the model and the feasibility of the control method have been proved by the simulation results. In this paper the system performance is studied under fault condition is studied.</span>

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Research on Improved Droop Control Strategy of Microsource Inverter Based on Internet of Things

Security and Communication Networks ◽

10.1155/2021/5043623 ◽

2021 ◽

Vol 2021 ◽

pp. 1-8

Author(s):

Di Bai ◽

Tieyan Zhang ◽

Zheng Yang

Keyword(s):

Control Strategy ◽

Power Supply ◽

Power Distribution ◽

Reactive Power ◽

Control Method ◽

Electronic Devices ◽

Stable Operation ◽

Power Electronic ◽

Distributed Power ◽

Virtual Impedance

Microgrid connects the distributed power supply with the assistance of power electronic devices. Power electronic devices, especially in the inversion link, play a crucial role in the access of distributed power to microgrid. Whether in grid-connected mode or island mode, the control method of inverters is related to the stable operation of distributed power supply and plays an important role in the control strategy of microgrid. In this paper, by adding the drop control of controllable virtual impedance, the power coupling problem caused by resistive line impedance is reduced, and virtual impedance key points such as voltage feedback and frequency compensation are added. By optimizing the power reference value, the parallel operation stability of the control strategy is improved. The experimental results show that the proposed method improves not only the stability of the system and the power quality but also the accuracy of reactive power distribution.

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Reactive Power Control Method for Enhancing the Transient Stability Total Transfer Capability of Transmission Lines for a System with Large-Scale Renewable Energy Sources

Energies ◽

10.3390/en13123154 ◽

2020 ◽

Vol 13 (12) ◽

pp. 3154

Author(s):

Yuwei Zhang ◽

Wenying Liu ◽

Fangyu Wang ◽

Yaoxiang Zhang ◽

Yalou Li

Keyword(s):

Power Control ◽

Transmission Lines ◽

Reactive Power ◽

Control Method ◽

Renewable Energy Sources ◽

Voltage Source ◽

Reactive Power Control ◽

Total Transfer Capability ◽

Transfer Capability ◽

Thevenin Equivalent

With the increased proportion of intermittent renewable energy sources (RES) integrated into the sending-end, the total transfer capability of transmission lines is not sufficient during the peak periods of renewable primary energy (e.g., the wind force), causing severe RES power curtailment. The total transfer capability of transmission lines is generally restricted by the transient stability total transfer capability (TSTTC). This paper presents a reactive power control method to enhance the TSTTC of transmission lines. The key is to obtain the sensitivity between TSTTC and reactive power, while the Thevenin equivalent voltage is the link connecting TSTTC and reactive power. The Thevenin theorem states that an active circuit between two load terminals can be considered as an individual voltage source. The voltage of this source would be open-circuit voltage across the terminals, and the internal impedance of the source is the equivalent impedance of the circuit across the terminals. The Thevenin voltage used in Thevenin’s theorem is an ideal voltage source equal to the open-circuit voltage at the terminals. Thus, the sensitivities between TSTTC and the Thevenin equivalent voltages of the sending-end and receiving-end were firstly derived using the equal area criterion. Secondly, the sensitivity between the Thevenin equivalent voltage and reactive power was derived using the total differentiation method. By connecting the above sensitivities together with the relevant parameters calculated from Thevenin equivalent parameter identification and power flow equation, the sensitivity between TSTTC and reactive power was obtained, which was used as the control priority in the proposed reactive power control method. At last, the method was applied to the Gansu Province Power Grid in China to demonstrate its effectiveness, and the accuracy of the sensitivity between TSTTC and reactive power was verified.

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Voltage Stability of Power Systems with Renewable-Energy Inverter-Based Generators: A Review

Electronics ◽

10.3390/electronics10020115 ◽

2021 ◽

Vol 10 (2) ◽

pp. 115

Author(s):

Nasser Hosseinzadeh ◽

Asma Aziz ◽

Apel Mahmud ◽

Ameen Gargoom ◽

Mahbub Rabbani

Keyword(s):

Renewable Energy ◽

Power Systems ◽

Voltage Stability ◽

Reactive Power ◽

Power Grid ◽

Renewable Energy Sources ◽

Electrical Power ◽

System Stability ◽

Special Issue ◽

Synchronous Generators

The main purpose of developing microgrids (MGs) is to facilitate the integration of renewable energy sources (RESs) into the power grid. RESs are normally connected to the grid via power electronic inverters. As various types of RESs are increasingly being connected to the electrical power grid, power systems of the near future will have more inverter-based generators (IBGs) instead of synchronous machines. Since IBGs have significant differences in their characteristics compared to synchronous generators (SGs), particularly concerning their inertia and capability to provide reactive power, their impacts on the system dynamics are different compared to SGs. In particular, system stability analysis will require new approaches. As such, research is currently being conducted on the stability of power systems with the inclusion of IBGs. This review article is intended to be a preface to the Special Issue on Voltage Stability of Microgrids in Power Systems. It presents a comprehensive review of the literature on voltage stability of power systems with a relatively high percentage of IBGs in the generation mix of the system. As the research is developing rapidly in this field, it is understood that by the time that this article is published, and further in the future, there will be many more new developments in this area. Certainly, other articles in this special issue will highlight some other important aspects of the voltage stability of microgrids.

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A Novel Adaptive Control Approach Based on Available Headroom of the VSC-HVDC for Enhancement of the AC Voltage Stability

Energies ◽

10.3390/en14113222 ◽

2021 ◽

Vol 14 (11) ◽

pp. 3222

Author(s):

Duc Nguyen Huu

Keyword(s):

Adaptive Control ◽

Voltage Stability ◽

Reactive Power ◽

Control Method ◽

Offshore Wind ◽

Voltage Source ◽

Long Distance ◽

Control Approach ◽

Hvdc System ◽

Voltage Support

Increasing offshore wind farms are rapidly installed and planned. However, this will pose a bottle neck challenge for long-distance transmission as well as inherent variation of their generating power outputs to the existing AC grid. VSC-HVDC links could be an effective and flexible method for this issue. With the growing use of voltage source converter high-voltage direct current (VSC-HVDC) technology, the hybrid VSC-HVDC and AC system will be a next-generation transmission network. This paper analyzes the contribution of the multi VSC-HVDC system on the AC voltage stability of the hybrid system. A key contribution of this research is proposing a novel adaptive control approach of the VSC-HVDC as a so-called dynamic reactive power booster to enhance the voltage stability of the AC system. The core idea is that the novel control system is automatically providing a reactive current based on dynamic frequency of the AC system to maximal AC voltage support. Based on the analysis, an adaptive control method applied to the multi VSC-HVDC system is proposed to realize maximum capacity of VSC for reactive power according to the change of the system frequency during severe faults of the AC grid. A representative hybrid AC-DC network based on Germany is developed. Detailed modeling of the hybrid AC-DC network and its proposed control is derived in PSCAD software. PSCAD simulation results and analysis verify the effective performance of this novel adaptive control of VSC-HVDC for voltage support. Thanks to this control scheme, the hybrid AC-DC network can avoid circumstances that lead to voltage instability.

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Analysing integration issues of the microgrid system with utility grid network

International Journal of Emerging Electric Power Systems ◽

10.1515/ijeeps-2020-0170 ◽

2021 ◽

Vol 22 (1) ◽

pp. 113-127

Author(s):

Mulualem Tesfaye ◽

Baseem Khan ◽

Om Prakash Mahela ◽

Hassan Haes Alhelou ◽

Neeraj Gupta ◽

...

Keyword(s):

Renewable Energy ◽

Distribution System ◽

Reactive Power ◽

Renewable Energy Sources ◽

Operating Conditions ◽

Control Mode ◽

Voltage Source ◽

Modulation Scheme ◽

Main Challenge ◽

Utility Grid

Abstract Generation of renewable energy sources and their interfacing to the main system has turn out to be most fascinating challenge. Renewable energy generation requires stable and reliable incorporation of energy to the low or medium voltage networks. This paper presents the microgrid modeling as an alternative and feasible power supply for Institute of Technology, Hawassa University, Ethiopia. This microgrid consists of a 60 kW photo voltaic (PV) and a 20 kW wind turbine (WT) system; that is linked to the electrical distribution system of the campus by a 3-phase pulse width modulation scheme based voltage source inverters (VSI) and supplying power to the university buildings. The main challenge in this work is related to the interconnection of microgrid with utility grid, using 3-phase VSI controller. The PV and WT of the microgrid are controlled in active and reactive power (PQ) control mode during grid connected operation and in voltage/frequency (V/F) control mode, when the microgrid is switched to the stand-alone operation. To demonstrate the feasibility of proposed microgrid model, MATLAB/Simulink software has been employed. The performance of fully functioning microgrid is analyzed and simulated for a number of operating conditions. Simulation results supported the usefulness of developed microgrid in both mode of operation.

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Contribution of Voltage Support Function to Virtual Inertia Control Performance of Inverter-Based Resource in Frequency Stability

Energies ◽

10.3390/en14144220 ◽

2021 ◽

Vol 14 (14) ◽

pp. 4220

Author(s):

Dai Orihara ◽

Hiroshi Kikusato ◽

Jun Hashimoto ◽

Kenji Otani ◽

Takahiro Takamatsu ◽

...

Keyword(s):

Reactive Power ◽

Control Function ◽

Current Source ◽

Voltage Control ◽

Frequency Stability ◽

Voltage Regulation ◽

System Stability ◽

Voltage Source ◽

Apparent Difference ◽

Virtual Inertia

Inertia reduction due to inverter-based resource (IBR) penetration deteriorates power system stability, which can be addressed using virtual inertia (VI) control. There are two types of implementation methods for VI control: grid-following (GFL) and grid-forming (GFM). There is an apparent difference among them for the voltage regulation capability, because the GFM controls IBR to act as a voltage source and GFL controls it to act as a current source. The difference affects the performance of the VI control function, because stable voltage conditions help the inertial response to contribute to system stability. However, GFL can provide the voltage control function with reactive power controllability, and it can be activated simultaneously with the VI control function. This study analyzes the performance of GFL-type VI control with a voltage control function for frequency stability improvement. The results show that the voltage control function decreases the voltage variation caused by the fault, improving the responsivity of the VI function. In addition, it is found that the voltage control is effective in suppressing the power swing among synchronous generators. The clarification of the contribution of the voltage control function to the performance of the VI control is novelty of this paper.

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