Power sharing strategy using H∞ controller between two distributed generation sources in islanded mode
This project addresses the problem of the primary controller of parallel-connected inverters in AC microgrid, which is operated in islanded mode. Voltage and frequency power sharing controller techniques are commonly used for sharing loads. However, this non-communication power sharing control...
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Main Author: | |
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Format: | Thesis |
Language: | English English English |
Published: |
2020
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Subjects: | |
Online Access: | http://eprints.uthm.edu.my/901/1/24p%20ERUM.pdf http://eprints.uthm.edu.my/901/2/ERUM%20COPYRIGHT%20DECLARATION.pdf http://eprints.uthm.edu.my/901/3/ERUM%20WATERMARK.pdf |
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Summary: | This project addresses the problem of the primary controller of parallel-connected
inverters in AC microgrid, which is operated in islanded mode. Voltage and
frequency power sharing controller techniques are commonly used for sharing loads.
However, this non-communication power sharing control technique has a
disadvantage, where the frequency and voltage deviations are severe during a sudden
load change. Currently, it can be fixed by using the communication-based secondary
level. Therefore, the concept of non-communication network is needed for the DGs
with fast restoration of voltage and frequency in order to maintain the stability and
sensitivity of the islanded system. This project aims to develop a robust distributed
H
∞
power sharing strategy to overcome the problem of restoration. The new
controller would be able to enhance the performance and give a more reliable
performance for power sharing, voltage and frequency restoration. Moreover, this
project mainly focuses on the mathematical modelling of parallel-connected
inverters, where the eigenvalues technique of the electric network is used to predict
the stability of the islanded condition by applying eigenvalue technique. The
proposed H
∞
power sharing control has established a condition for power sharing
among the DGs and restores the voltage and frequency. This controller has shown
the robustness effect in order to restore voltage and frequency and to satisfy the
system performance. Finally, this H
∞
controller with robust and dynamic response is
tested in islanded mode configuration, which has two DGs with identical power
ratings connected to several local loads at the point of common coupling. The
proposed robust controller’s theoretical concept is validated by using MATLAB
Simulink, and it is compared with the conventional and existing secondary power
sharing strategies that are also applied at the same electrical system. As result, the
proposed controller can achieve better steady state performance and fast restored
frequency within 0.002 s with rise time 0.05s while compared to 0.13 s rise time for
existing secondary controller. Maximum overshoot is also reduced during the suddenvi
load changed and good tracking performance efficiency by 95% as compared to the
90% efficiency of existing secondary controller and 85% conventional controller.
Thus, it is able to restore voltage and frequency to nominal values and enhances
power sharing according to inverter rating. |
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