An improved droop control strategy of three-phase inverter for grid voltage unbalance compensation

Liu, Hongpeng; Jiajie, Zhou; Li, Pengfei; Wang, Wei

doi:10.1109/ifeec.2017.7992427

Cited by 6 publications

(7 citation statements)

References 17 publications

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“…In [100], the injection of both active and reactive current is based on the severity of voltage sags so that the inverter rating is not exceeded. In [101], the voltage unbalance factor is minimized by employing droop control. The scheme injects the positive and negative sequence components of active and reactive powers to ensure that the PCC voltage remains within specified limits.…”

Section: ) Optimal Voltage Support Strategy (Ovss) [99]mentioning

confidence: 99%

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A Comprehensive Review of Control Strategies to Overcome Challenges During LVRT in PV Systems

Joshi¹,

Swami

Jately

et al. 2021

IEEE Access

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Due to the high penetration of grid-connected photovoltaic (GCPV) systems, the network operators are regularly updating the grid codes to ensure that the operation of GCPV systems will assist in maintaining grid stability. Among these, low-voltage-ride-through (LVRT) is an important attribute of PV inverters that allows them to remain connected with the grid during short-term disturbances in the grid voltage. Hence, PV inverters are equipped with control strategies that secure their smooth operation through this ride-through period as per the specified grid code. During the injection of reactive power under LVRT condition, various challenges have been observed, such as inverter overcurrent, unbalance phase voltages at the point of common coupling (PCC), overvoltage in healthy phases, oscillations in active, reactive power and dc-link voltage, distortion in injected currents and poor dynamic response of the system. Several strategies are found in the literature to overcome these challenges associated with LVRT. This paper provides a critical review on the recent challenges and the associated strategies under LVRT conditions in GCPV inverters. The drawbacks associated with the conventional current control strategies are investigated in MATLAB/Simulink environment and each category of the advanced LVRT control strategy is analyzed under different types of grid faults. Moreover, this work categorizes different state-of-the-art LVRT techniques on the basis of synchronization methods, current injection techniques and dc-link voltage control strategies. It is found that the state-of-the-art control strategies like OVSS/OCCIDGS provides improved voltage support and current limitation which results in smooth LVRT operation by injecting currents of enhanced power quality.

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Section: ) Optimal Voltage Support Strategy (Ovss) [99]mentioning

confidence: 99%

“…where, the nominal power is denoted by S, V base is the base voltage and it is equal to the RMS value of line-line grid voltage, = + 2 + + 2 and = − 2 + − 2 . Based on the per-unit depth in voltage sag, the reactive power is calculated as per the Chinese grid code as in (101).…”

Section: ) Sinusoidal Current Injection Strategy (Scis) [115]mentioning

confidence: 99%

A Comprehensive Review of Control Strategies to Overcome Challenges During LVRT in PV Systems

Joshi¹,

Swami

Jately

et al. 2021

IEEE Access

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“…As the penetration of the distributed generation (DG) into the distribution networks continues to increase, the DGs are required to participate in the grid stability control [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. One of the requirements is the low voltage ride through [1][2][3][4][5].…”

Section: Introductionmentioning

confidence: 99%

Performance Improvement of Dual-Buck Inverter With Mitigating Reverse Recovery Characteristics and Supporting Reactive Power

Han

Cho

2022

IEEE Access

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This paper proposes a three-level dual-buck inverter (DBI) that reduces reverse recovery current and compensates reactive power. To reduce the reverse recovery problem of main switching diodes in the DBI, the auxiliary circuit consisting of diodes and coupled inductors is adapted. The auxiliary circuit enables zero-current turn-off of the diodes. The coupled inductor design is also conducted considering not only for unity power factor (PF) but also non-unity PF operations. By utilizing the auxiliary circuit, the reverse recovery and the shoot-through problems in silicon devices can be significantly mitigated so that the efficiency and the reliability of the DBI are much improved. Meanwhile, the pulse-width modulation scheme is also proposed to supply reactive power with the DBI which is a unidirectional inverter. In the proposed modulation method, the duty offset is simply added according to the required PF and the operating region of the DBI. By doing so, traditional current control concepts for bidirectional inverters can be directly applied to the DBI without any modification. By utilizing the proposed techniques, the reliability, efficiency, and utilization of the DBI can be significantly improved. The experimental results with a 3 kVA DBI prototype demonstrate the effectiveness of the proposed DBI.

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“…[2,3]. Power conversion systems use an DC-to-AC power converter interfaced with a grid system, also known as a grid-connected inverter (GCI) [4][5][6]. Maintaining grid current control in a GCI is important to ensure the stability and resilience of DG and MG systems.…”

Section: Introductionmentioning

confidence: 99%

A Current Control Algorithm to Improve Command Tracking Performance and Resilience of a Grid-Connected Inverter

2020

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This paper presents a stationary reference frame grid current control algorithm for a grid-connected inverter (GCI) to improve command tracking performance and resilience in response to disturbances, i.e., a grid voltage incident in a GCI current control system. In the proposed algorithm, disturbance rejection is applied to reduce the overcurrent at the GCI in response to a grid fault. Disturbances to the GCI current control system are estimated using a grid current observer, and the estimate applied to the grid current controller to activate the disturbance rejection. The stationary reference frame current of a GCI system is also controlled to avoid cross-coupling issues at a synchronous reference frame model, reference transformation and dependency to phase locked loop (PLL) performance. However, the phase lead or lag and steady-state response error, which are drawbacks of AC signal control based on stationary reference frame proportional-integral (PI) controller, must be eliminated in order to secure competition with the synchronous reference PI (SRFPI) controller that was mainly used in the GCI system. Hence, to compensate for command tracking the AC current, such as steady-state response error and phase lead or lag, command feedforward control is applied in the proposed control system. The theory behind the proposed GCI current control algorithm is analyzed, and the proposed algorithm is tested via simulation and experimentation.

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An improved droop control strategy of three-phase inverter for grid voltage unbalance compensation

Cited by 6 publications

References 17 publications

A Comprehensive Review of Control Strategies to Overcome Challenges During LVRT in PV Systems

A Comprehensive Review of Control Strategies to Overcome Challenges During LVRT in PV Systems

Performance Improvement of Dual-Buck Inverter With Mitigating Reverse Recovery Characteristics and Supporting Reactive Power

A Current Control Algorithm to Improve Command Tracking Performance and Resilience of a Grid-Connected Inverter

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