A State Equation Model of a Single-Phase Grid-Connected Inverter Using a Droop Control Scheme With Extra Phase Shift Control Action

Avelar, Henrique José; Parreira, Wanderley Alves; Vieira, J.B.; Freitas, Luiz Carlos Gomes de; Coelho, E.A.A.

doi:10.1109/tie.2011.2163372

Cited by 95 publications

(69 citation statements)

References 14 publications

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“…Several modifications to droop control have been proposed [13], [14], where the stability problem is either ignored or simplified by dealing with a linear model. While droop control provides a satisfactory performance in terms of power sharing, it has been observed that droop control can result in poorly damped or even unstable systems [6], [8], [15], [16]. Recently, conditions for proportional power sharing and synchronization of a microgrid under frequency droop control have been derived in [17] by applying results of the theory of coupled oscillators.…”

Section: Introductionmentioning

confidence: 99%

On power sharing and stability in autonomous inverter-based microgrids

Schiffer

Anta

Trung

et al. 2012

2012 IEEE 51st IEEE Conference on Decision and Control (CDC)

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Abstract-We consider the problem of voltage and frequency stability for an autonomous inverter-based microgrid. An LMIbased decentralized feedback control design is derived that stabilizes the system under the consideration of droop-like controllers aiming to achieve power sharing among the different generation units. We provide a design procedure that accounts for uncertainties in line impedances and loads while guaranteeing zero steady-state frequency deviation.

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Section: Introductionmentioning

confidence: 99%

On power sharing and stability in autonomous inverter-based microgrids

Schiffer

Anta

Trung

et al. 2012

2012 IEEE 51st IEEE Conference on Decision and Control (CDC)

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“…This is due to the fact that the angular velocityφ depends on w q from (14), since if the states try to reach the horizontal axis, then w q → 0 andφ → 0 independently from the term K e (E * −V c )−n(P −P set ). This forces the controller states to slow down and remain on the upper semi-ellipse of W 0 , avoiding a continuous oscillation around W 0 .…”

Section: B Controller Designmentioning

confidence: 99%

“…Since w and w q start from point (w m , 1), they travel on the ellipse W 0 and can reach the point (w min , 0) at the limit of the current after a settling time t s , then by considering the worst case scenario where the controller states travel on the arc of W 0 with central angle π 2 rad and with a maximum angular velocity π 2ts rad/s, one can calculate a minimum value of c w . Since tight voltage regulation can be achieved for the capacitor voltage (V c ≈ E * ) and w q ≤ 1, assuming the real power starts from zero and reaches the maximum real power P set = S n , then from (14) it yieldsφ max = π 2t s = c w nS n ∆w m , which finally gives…”

Section: E Selection Of the Controller Parametersmentioning

confidence: 99%

“…Droop control has been extensively studied in the literature for both grid-connected and islanded operation of inverters [1], [11]- [13]. Several control methods have been developed to improve the droop control performance, such as the addition of an extra phase shift term [14], adapting the controller parameters using a grid-impedance estimator [15], or changing the output impedance of the inverter [3], [16], [17]. Among these methods, the robust droop controller reported in [16] not only can achieve the desired droop functions but can also guarantee tight output voltage regulation near the rated value independently from parameter variations or external disturbances.…”

mentioning

confidence: 99%

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Current-Limiting Droop Control of Grid-Connected Inverters

Zhong

Konstantopoulos

2017

IEEE Trans. Ind. Electron.

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Abstract-A current-limiting droop controller is proposed for single-phase grid-connected inverters with an LCL filter that can operate under both normal and faulty grid conditions. The controller introduces bounded nonlinear dynamics and, by using nonlinear input-to-state stability theory, the current-limiting property of the inverter is analytically proven. The proposed controller can be operated in the set mode to accurately send the desired power to the grid or in the droop mode to take part in the grid regulation, while maintaining the inverter current below a given value at all times. Opposed to the existing current-limiting approaches, the current limitation is achieved without external limiters, additional switches or monitoring devices and the controller remains a continuous-time system guaranteeing system stability. Furthermore, this is achieved independently from grid voltage and frequency variations, maintaining the desired control performance under grid faults as well. Extensive experimental results are presented to verify the droop function of the proposed controller and its current-limiting capability under normal and faulty grid conditions.

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“…This increases the cost and decreases both the reliability and plug and play ability. Therefore, droop control, which mimics the behavior of synchronous generators [7]- [12], has been introduced to enable inverters to operate in parallel without any communication mechanism. However, the traditional droop control is known for its poor performance in reactive power sharing.…”

Section: Introductionmentioning

confidence: 99%

Improved Reactive Power Sharing for Parallel-operated Inverters in Islanded Microgrids

Issa¹,

Sharkh²,

Mallick³

et al. 2016

Journal of Power Electronics

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The unequal impedances of the interconnecting cables between paralleled inverters in the island mode of microgrids cause inaccurate reactive power sharing when the traditional droop control is used. Many studies in the literature adopt low speed communications between the inverters and the central control unit to overcome this problem. However, the losses of this communication link can be very detrimental to the performance of the controller. This paper proposes an improved reactive power-sharing control method. It employs infrequent measurements of the voltage at the point of common coupling (PCC) to estimate the output impedance between the inverters and the PCC and then readjust the voltage droop controller gains accordingly. The controller then reverts to being a traditional droop controller using the newly calculated gains. This increases the immunity of the controller against any losses in the communication links between the central control unit and the inverters. The capability of the proposed control method has been demonstrated by simulation and experimental results using a laboratory scale microgrid.

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A State Equation Model of a Single-Phase Grid-Connected Inverter Using a Droop Control Scheme With Extra Phase Shift Control Action

Cited by 95 publications

References 14 publications

On power sharing and stability in autonomous inverter-based microgrids

On power sharing and stability in autonomous inverter-based microgrids

Current-Limiting Droop Control of Grid-Connected Inverters

Improved Reactive Power Sharing for Parallel-operated Inverters in Islanded Microgrids

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