Seamless transfer control strategy for three-phase inverter in microgrid

Chen, Yandong; Wang, Zili; Zhou, Xiaoping; Zhou, Leming; Chen, Zhiyong; Luo, An; Wang, Mingyue

doi:10.1109/ipemc.2016.7512560

Cited by 9 publications

(4 citation statements)

References 8 publications

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“…is process is presynchronization [13,[33][34][35][36][37]. Presynchronization is the operational process that the converter regulates its output voltage (including amplitude, frequency, and phase) constantly as a controlled voltage source after the utility is restored normally, which is totally controllable and predictable.…”

Section: Modementioning

confidence: 99%

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Compulsory Islanding Transition Strategy Based on Fuzzy Logic Control for a Renewable Microgrid System

Wan

Wang

2021

Mathematical Problems in Engineering

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Advantages of microgrid integrated with a renewable energy system have been acknowledged in more and more applications. Operating steadily during different modes is of great significance, and different modes transferring must be transient, seamless, and reliable to maintain the continuous electricity supply for loads, especially sensitive ones. As a semicontrolled switch that is unable to shut instantly until the zero point of its current, thyristors should be forced to be turned off by certain strategies to minimise the influence brought by the delay of modes transferring. In this paper, a compulsory turn-off strategy based on fuzzy logic control of converter output voltage is proposed. With the strategy, an alterable reverse voltage is applied across the conducting thyristor by dynamically adjusting the output voltage reference instruction and closed-loop control parameters depending on the changing rate rather than detecting the polarity of voltage or current. Constraints from acquisition of analog data and error of digital calculation will be eliminated. Finally, simulation and experimental results verify the effectiveness of the proposed strategy.

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Section: Modementioning

confidence: 99%

“…Compensation strategies are introduced in [33,34] that the injecting current of the inverter is regulated to follow the instantaneous value of load when the off-grid transfer signal starts up; then, the current of thyristors can be reduced to zero and enter the blocking state quickly. But, the deficiencies are also obvious.…”

Section: Introductionmentioning

confidence: 99%

Compulsory Islanding Transition Strategy Based on Fuzzy Logic Control for a Renewable Microgrid System

Wan

Wang

2021

Mathematical Problems in Engineering

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“…This is a modification for the virtual impedance loop mentioned before as part of the power sharing control (specifically to improve the reactive power and harmonic current sharing). Therefore as the control structure is already equipped with a virtual impedance loop it is just required to include the soft starter [94,99,118,119]. The implementation of the soft starter is done by the following Equation (8):…”

Section: Soft Startmentioning

confidence: 99%

Smart Inverters for Microgrid Applications: A Review

et al. 2019

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In a microgrid, with several distributed generators (DGs), energy storage units and loads, one of the most important considerations is the control of power converters. These converters implement interfaces between the DGs and the microgrid bus. In order to achieve higher functionality, efficiency and reliability, in addition to improving the control algorithms it is beneficial to equip the inverters with “smart” features. One interpretation of “smartness” refers to minimizing the requirement of communication and therefore switching from centralized to decentralized control. At the same time, being equipped with efficient and state of the art communication protocols also indicates “smartness” since the requirement of communication cannot be completely omitted. A “smart inverter” should offer some features such as plug and play, self-awareness, adaptability, autonomy and cooperativeness. These features are introduced and comprehensively explained in this article. One contribution discussed here is the possibility of achieving long-range wireless communication between inverters to empower various control schemes. Although current efforts aim to modify and improve power converters in a way that they can operate communication free, if a suitable and functional communication protocol is available, it will improve the accuracy, speed and robustness of them.

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“…Therefore, instead of voltage and current, virtual‐impedance schemes have progressively surfaced as popular schemes for mitigating switching impulses during the mode transfer. One example is the soft‐start virtual‐impedance scheme introduced in [21], which nonetheless requires a high sampling rate and very accurate measurement of the grid frequency.…”

Section: Introductionmentioning

confidence: 99%

Seamless transfer scheme for parallel PV inverter system

Zhang

Liu

Wang

et al. 2020

IET Power Electronics

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Most grid-connected inverters can operate in both grid-connected and islanded modes with usually different control schemes adopted in each mode. The control schemes, if noticeably complex and different, can result in inrush currents and voltage distortions at instants of mode transfer. An existing grid-connected form of droop control has hence been developed from the usual islanded droop control to better streamline the transfer. However, the grid-connected droop control does not regulate the grid current directly, causing it to distort by grid voltage harmonics and respond slower during a transient. The motivation here is thus to propose another highly unified droop control scheme that can regulate the grid current directly with a transfer dynamic lasting only two fundamental cycles. This is in addition to the usual targets of seamless transfer and proper power sharing among the islanded inverters. The hypothetical approach followed is to reformulate the grid-connected and islanded control schemes, so that mode transfer can simply be treated as a normal change of voltage reference, rather than an inner change of control structure. The final unified scheme has been tested in simulation and experiments with results apparently confirming its precise grid-current regulation, islanded voltage regulation and seamless mode transfer within two fundamental cycles.

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Seamless transfer control strategy for three-phase inverter in microgrid

Cited by 9 publications

References 8 publications

Compulsory Islanding Transition Strategy Based on Fuzzy Logic Control for a Renewable Microgrid System

Compulsory Islanding Transition Strategy Based on Fuzzy Logic Control for a Renewable Microgrid System

Smart Inverters for Microgrid Applications: A Review

Seamless transfer scheme for parallel PV inverter system

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