Unbalanced Voltage

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Pragasen Pillay - One of the best experts on this subject based on the ideXlab platform.

Jawad Faiz - One of the best experts on this subject based on the ideXlab platform.

Luis Garcia De Vicuna - One of the best experts on this subject based on the ideXlab platform.

  • Voltage support control strategies for static synchronous compensators under Unbalanced Voltage sags
    IEEE Transactions on Industrial Electronics, 2014
    Co-Authors: Miguel Castilla, Jaume Miret, Antonio Camacho, J Matas, Luis Garcia De Vicuna
    Abstract:

    Static synchronous compensators have been broadly employed for the provision of electrical ac network services, which include Voltage regulation, network balance, and stability improvement. Several studies of such compensators have also been conducted to improve the ac network operation during Unbalanced Voltage sags. This paper presents a complete control scheme intended for synchronous compensators operating under these abnormal network conditions. In particular, this control scheme introduces two contributions: a novel reactive current reference generator and a new Voltage support control loop. The current reference generator has as a main feature the capacity to supply the required reactive current even when the Voltage drops in amplitude during the Voltage sag. Thus, a safe system operation is easily guaranteed by fixing the limit required current to the maximum rated current. The Voltage control loop is able to implement several control strategies by setting two Voltage set points. In this paper, three Voltage support control strategies are proposed, and their advantages and limitations are discussed in detail. The two theoretical contributions of this paper have been validated by experimental results. Certainly, the topic of Voltage support is open for further research, and the control scheme proposed in this paper can be viewed as an interesting configuration to devise other control strategies in future works.

  • coordinated reactive power control for static synchronous compensators under Unbalanced Voltage sags
    International Symposium on Industrial Electronics, 2012
    Co-Authors: Miguel Castilla, Jaume Miret, Antonio Camacho, J Matas, Eduardo Alarcongallo, Luis Garcia De Vicuna
    Abstract:

    Unbalanced Voltage sags strongly deteriorate the performance of power converters and electrical machines connected to the distribution network. In particular, a reduction of the power quality is noticed in these equipments, which is caused by a ripple in the output power and an increase of the current harmonic distortion. Several solutions based on reactive power compensation have been introduced to cope with this problem. Among them, static synchronous compensators have confirmed the superior performance due to the possibility of using all rated power exclusively to Voltage support. This paper presents a simple reactive power control algorithm for static synchronous compensators operating under Unbalanced Voltage sags. The main feature of the proposed algorithm is that it allows a fine adjustment of the amount of reactive power injected by the positive- and negative-sequence components. Thus the control algorithm provides Voltage support at the output of the static synchronous compensator. Specifically the proposed control conveniently corrects both the positive- and negative-sequence Voltage. Selected simulation results are provided to validate the proposal.

  • grid fault control scheme for three phase photovoltaic inverters with adjustable power quality characteristics
    IEEE Transactions on Power Electronics, 2010
    Co-Authors: Miguel Castilla, Jaume Miret, J Matas, J L Sosa, Luis Garcia De Vicuna
    Abstract:

    The power quality of a three-phase photovoltaic (PV) inverter drastically deteriorates in the presence of grid faults with Unbalanced Voltages. A ripple in the injected power and an increase in the current harmonic distortion are the main noticeable adverse effects produced by this abnormal grid situation. Several grid-fault control schemes are nowadays available for operating under Unbalanced grid Voltage. These control schemes usually have extreme power quality characteristics. Some of them have been conceived to completely avoid power ripple during Unbalanced Voltage sags, but at an expense of high current harmonic distortion. With other schemes, the harmonic distortion is totally eliminated but at an expense of high ripple in the injected power. This paper further explores the performance of PV inverters under Unbalanced Voltage sags. It has three theoretical contributions: 1) a generalized control scheme, which includes the aforementioned grid-fault controllers as particular cases; 2) a control strategy based on the use of continuous values for the control parameters. This original approach gives adjustable power quality characteristics that cannot be achieved with the previous control schemes; 3) three different control algorithms for calculating the continuous values of the control parameters. These contributions are experimentally validated with a digital signal processor-based laboratory prototype.

Mitra Mirhosseini - One of the best experts on this subject based on the ideXlab platform.

  • individual phase current control with the capability to avoid overVoltage in grid connected photovoltaic power plants under Unbalanced Voltage sags
    IEEE Transactions on Power Electronics, 2015
    Co-Authors: Mitra Mirhosseini, Josep Pou, Vassilios G Agelidis
    Abstract:

    Independent current control of each phase of a three-phase Voltage source inverter under Unbalanced Voltage sags is proposed to effectively meet grid code requirements for grid-connected photovoltaic power plants (GCPPPs). Under current grid codes, GCPPPs should support grid Voltages by injecting reactive currents during Voltage sags. Such injection must not allow the grid Voltages of the nonfaulty phases to exceed 110% of their nominal value. However, grid overVoltages can occur in the nonfaulty phases, especially if the currents injected into the grid by the GCPPP are balanced. Based on a new requirement of the European network of transmission system operators published in 2012, a transmission system operator is allowed to introduce a requirement for Unbalanced current injection. In this letter, this grid code is addressed by controlling individual phases and injecting Unbalanced currents into the grid during Voltage sags. Experimental results from a 2.8-kV $\cdot$ A inverter are presented, confirming the effectiveness of the proposed control method.

  • a three phase frequency adaptive phase locked loop for independent single phase operation
    IEEE Transactions on Power Electronics, 2014
    Co-Authors: Mitra Mirhosseini, Josep Pou, Vassilios G Agelidis, Eider Robles, Salvador Ceballos
    Abstract:

    This letter proposes a phase-locked loop (PLL) able to operate as an independent single-phase PLL in the context of three-phase systems. Its key advantage is that the extracted information allows the independent control of both the active and reactive powers for each phase. The proposed PLL utilizes moving average filters and, hence, remains robust under Unbalanced and highly distorted Voltages. A frequency estimator is also presented and incorporated in the PLL angle detector path to make it frequency adaptive. The performance of the proposed PLL is verified experimentally and results for frequency change, phase-angle jump, and Unbalanced Voltage sag are reported as a confirmation of its potential.

  • a three phase frequency adaptive phase locked loop for independent single phase operation
    IEEE Transactions on Power Electronics, 2014
    Co-Authors: Mitra Mirhosseini, Vassilios G Agelidis, Eider Robles, Salvador Ceballos
    Abstract:

    This letter proposes a phase-locked loop (PLL) able to operate as an independent single-phase PLL in the context of three-phase systems. Its key advantage is that the extracted information allows the independent control of both the active and reactive powers for each phase. The proposed PLL utilizes moving average filters and, hence, remains robust under Unbalanced and highly distorted Voltages. A frequency estimator is also presented and incorporated in the PLL angle detector path to make it frequency adaptive. The performance of the proposed PLL is verified experimentally and results for frequency change, phase-angle jump, and Unbalanced Voltage sag are reported as a confirmation of its potential. © 2014 IEEE.

  • positive and negative sequence control of grid connected photovoltaic systems under Unbalanced Voltage conditions
    Australasian Universities Power Engineering Conference, 2013
    Co-Authors: Mitra Mirhosseini, Josep Pou, B Karanayil, Vassilios G Agelidis
    Abstract:

    This paper discusses the control of the positive- and negative-sequence components of a large-scale grid-connected photovoltaic system (GCPS) under Unbalanced Voltage sag conditions in the grid. Some issues regarding stability and dynamic performance of the system occur when applying PI controllers in the current control loops. The reason is the delay that the filtering method imposes when extracting the current/Voltage sequences. Because of such a delay, the dynamic response of the system becomes slower compared with the case when no filtering technique is needed. Furthermore, there is a strong restriction on choosing suitable parameters for the current/Voltage loop controllers without compromising system stability. All these issues are discussed in this paper on a 1-MVA GCPV system using MATLAB/Simulink software.

Vassilios G Agelidis - One of the best experts on this subject based on the ideXlab platform.

  • individual phase current control with the capability to avoid overVoltage in grid connected photovoltaic power plants under Unbalanced Voltage sags
    IEEE Transactions on Power Electronics, 2015
    Co-Authors: Mitra Mirhosseini, Josep Pou, Vassilios G Agelidis
    Abstract:

    Independent current control of each phase of a three-phase Voltage source inverter under Unbalanced Voltage sags is proposed to effectively meet grid code requirements for grid-connected photovoltaic power plants (GCPPPs). Under current grid codes, GCPPPs should support grid Voltages by injecting reactive currents during Voltage sags. Such injection must not allow the grid Voltages of the nonfaulty phases to exceed 110% of their nominal value. However, grid overVoltages can occur in the nonfaulty phases, especially if the currents injected into the grid by the GCPPP are balanced. Based on a new requirement of the European network of transmission system operators published in 2012, a transmission system operator is allowed to introduce a requirement for Unbalanced current injection. In this letter, this grid code is addressed by controlling individual phases and injecting Unbalanced currents into the grid during Voltage sags. Experimental results from a 2.8-kV $\cdot$ A inverter are presented, confirming the effectiveness of the proposed control method.

  • a three phase frequency adaptive phase locked loop for independent single phase operation
    IEEE Transactions on Power Electronics, 2014
    Co-Authors: Mitra Mirhosseini, Josep Pou, Vassilios G Agelidis, Eider Robles, Salvador Ceballos
    Abstract:

    This letter proposes a phase-locked loop (PLL) able to operate as an independent single-phase PLL in the context of three-phase systems. Its key advantage is that the extracted information allows the independent control of both the active and reactive powers for each phase. The proposed PLL utilizes moving average filters and, hence, remains robust under Unbalanced and highly distorted Voltages. A frequency estimator is also presented and incorporated in the PLL angle detector path to make it frequency adaptive. The performance of the proposed PLL is verified experimentally and results for frequency change, phase-angle jump, and Unbalanced Voltage sag are reported as a confirmation of its potential.

  • a three phase frequency adaptive phase locked loop for independent single phase operation
    IEEE Transactions on Power Electronics, 2014
    Co-Authors: Mitra Mirhosseini, Vassilios G Agelidis, Eider Robles, Salvador Ceballos
    Abstract:

    This letter proposes a phase-locked loop (PLL) able to operate as an independent single-phase PLL in the context of three-phase systems. Its key advantage is that the extracted information allows the independent control of both the active and reactive powers for each phase. The proposed PLL utilizes moving average filters and, hence, remains robust under Unbalanced and highly distorted Voltages. A frequency estimator is also presented and incorporated in the PLL angle detector path to make it frequency adaptive. The performance of the proposed PLL is verified experimentally and results for frequency change, phase-angle jump, and Unbalanced Voltage sag are reported as a confirmation of its potential. © 2014 IEEE.

  • positive and negative sequence control of grid connected photovoltaic systems under Unbalanced Voltage conditions
    Australasian Universities Power Engineering Conference, 2013
    Co-Authors: Mitra Mirhosseini, Josep Pou, B Karanayil, Vassilios G Agelidis
    Abstract:

    This paper discusses the control of the positive- and negative-sequence components of a large-scale grid-connected photovoltaic system (GCPS) under Unbalanced Voltage sag conditions in the grid. Some issues regarding stability and dynamic performance of the system occur when applying PI controllers in the current control loops. The reason is the delay that the filtering method imposes when extracting the current/Voltage sequences. Because of such a delay, the dynamic response of the system becomes slower compared with the case when no filtering technique is needed. Furthermore, there is a strong restriction on choosing suitable parameters for the current/Voltage loop controllers without compromising system stability. All these issues are discussed in this paper on a 1-MVA GCPV system using MATLAB/Simulink software.

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