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Enhanced Active Power balancing capability of Grid connected Solar PV fed Cascaded H-bridge Converter
摘要： Cascaded H-bridge converter is a promising solution for next generation large scale PV system having both active and reactive power exchange capacity. However, one challenge with this converter is unbalanced power generation among the clusters or cells due to variation in radiation level, temperature, dusting on PV cells etc. In order to inject balanced power to the grid, in this paper, a controlled exchange of reactive power is proposed so that the converter can work with unbalanced power generation within the clusters. Magnitude of reactive power exchange is derived and necessary conditions discussed. Additionally, the magnitude of zero voltage is derived taking into account both active and reactive power exchange with the grid. By exchanging reactive power, the converter can also be used during low voltage ride through (LVRT) condition. This paper introduces a novel representation of unbalanced power generation using barycentric coordinate system which helps to identify regions in the power plane which require the exchange of reactive power. The proposed method is verified through computer simulation and in a laboratory prototype.
关键词： Maximum Power point tracking (MPPT),Active power,Zero sequence voltage,Reactive power,Solar Photovoltaic,Cascaded H-bridge multilevel converter(CHB)
更新于2025-09-23 15:23:52
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[IEEE 2018 International Conference on Intelligent and Innovative Computing Applications (ICONIC) - Mon Tresor, Plaine Magnien, Mauritius (2018.12.6-2018.12.7)] 2018 International Conference on Intelligent and Innovative Computing Applications (ICONIC) - Innovative Method for Power Factor Correction using a Solar Plant as a Source of Reactive Power
摘要： Due to the low power factor of an electrical system there is a high demand of reactive power from the transformers which results in overloading of the transformers. Traditionally, this problem is solved by adding a capacitor in parallel with the load in order to correct the power factor. In this paper a new innovative method which utilizes the solar plant at night when it is idling or during the day when it is not producing real power. During these times a solar plant is used as a source of reactive power, the inverters used in solar plants are capable of being used as a source of reactive power. The case study used to test this innovative method is a food processing plant with multiple transformers. The results show that it is possible to use a solar plant for power factor correction and hence relieve the transformers from overloading issues.
关键词： solar,transformer,overloading,power factor,reactive power
更新于2025-09-23 15:23:52
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An Improved Proposed Single Phase Transformerless Inverter with Leakage Current Elimination and Reactive Power Capability for PV Systems Application
摘要： Single-phase transformerless inverters are broadly studied in literature for residential-scale PV applications due to their great advantages in reducing system weight, cost and elevating system efficiency. The design of transformerless inverters is based on the galvanic isolation method to eliminate the generation of leakage current. Unfortunately, the use of the galvanic isolation method alone cannot achieve constant common mode voltage (CMV). Therefore, a complete elimination of leakage current cannot be achieved. In addition, modulation techniques of single-phase transformerless inverters are designed for the application of the unity power factor. Indeed, next-generation PV systems are required to support reactive power to enable connectivity to the utility grid. In this paper, a proposed single-phase transformerless inverter is modified with the clamping method to achieve constant CMV during all inverter operating modes. Furthermore, the modulation technique is modified by creating a new current path in the negative power region. As a result, a bidirectional current path is created in the negative power region to achieve reactive power generation. The simulation results show that the CMV is completely clamped at half the DC link voltage and the leakage current is almost completely eliminated. Furthermore, a reactive power generation is achieved with the modified modulation techniques. Additionally, the total harmonic distortion (THD) of the grid current with the conventional and a modified modulation technique is analyzed. The efficiency of the system is enhanced by using wide-bandgap (WBG) switching devices such as SiC MOSFET. It is observed that the efficiency of the system decreased with reactive power generation due to the bidirectional current path, which leads to increasing conduction losses.
关键词： leakage current,transformerless inverter,reactive power,wide-bandgap (WBG),silicon carbide (SiC),photovoltaic (PV) power system
更新于2025-09-23 15:23:52
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Cooperative Operation of R-SFCL and Online Current Limitation Strategy of GCPVS under Asymmetrical Faults
摘要： Grid-connected photovoltaic (GCPVS) should remain grid-connected and inject specified reactive current in accordance with fault-ride-through (FRT) requirements. To minimize voltage ripples on the DC link voltage and restrict the maximum phase currents, a modified online current limitation strategy (OCLS) is presented in this paper. Transient performance of GCPVS is enhanced as resistive-type superconducting fault current limiter (R-SFCL) is applied under severe asymmetrical faults. By introducing proper resistance selection process, the cooperative operation of OCLS and SFCL is proved to be effective.
关键词： reactive power control,transient performance,superconducting fault current limiters (FCL),online current limitation strategy (OCLS),photovoltaic systems,Fault ride-through (FRT) capability,symmetrical and asymmetrical faults
更新于2025-09-23 15:22:29
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Impact of Grid Voltage Feed-Forward Filters on Coupling between DC-Link Voltage and AC Voltage Controllers in Smart PV Solar Systems
摘要： This paper presents a novel study of impact of filters of grid voltage feed-forward signals on the coupling between dc-link voltage and ac voltage controllers in smart photovoltaic (PV) solar systems which are used for voltage control in distribution systems. A comprehensive linearized state space model of a PV system including the dynamics of grid voltage feed-forward filters, dc-link voltage and ac voltage controllers is developed for the first time. This model is validated by electromagnetic transients software PSCAD/EMTDC. This model is used to identify the coupling between dc-link voltage and ac voltage controllers by eigenvalue and participation factor analyses. The impact of time constant of feed-forward filters on this coupling is studied by eigenvalue sensitivity analysis for PV systems with Proportional and Proportional Integral type ac voltage controllers. The range of time constants over which the filters interact with controllers and create instability for systems with different strengths and X/R ratios is identified. Insights are provided on the choice of time constants of grid voltage feed-forward filters for stable system design. The developed state-space model can also be used for impact studies of various other parameters e.g. system strength, X/R ratios, types and gains of controllers, on system stability.
关键词： AC Voltage Control,Smart Inverter,Photovoltaic (PV) System,Reactive Power Control,Control Interaction
更新于2025-09-23 15:22:29
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[IEEE 2018 28th International Symposium on Discharges and Electrical Insulation in Vacuum (ISDEIV) - Greifswald, Germany (2018.9.23-2018.9.28)] 2018 28th International Symposium on Discharges and Electrical Insulation in Vacuum (ISDEIV) - Research on Hybrid Reactive Power Compensation Switch Based on Vacuum Switch
摘要： In the field of low and medium voltage reactive power compensation, the switching of capacitor groups based on phase-controlled switching technology is a better way than others. However, the accuracy and reliability of contacts switching point are the key factors affecting the work efficiency. It is technically difficult to meet all the requirements. In recent years, ABB has proposed a phase-choosing model based on the hybrid device composed of semiconductor and mechanical switches, which has a certain effect on suppressing the transient effect of reactive power compensation. Based on the ABB model, this paper presents an optimization model of Y- connection hybrid switching system of vacuum switch and power electronic device, and studies the switching strategy of the model. The simulation and the tests show its effectiveness in suppressing transient problems. Compared with the traditional phase-controlled switch technology, the new scheme will help the switch work in a wide phase range for avoiding transient effect. It is demanded that the new method has more tolerance to the dispersion of the operating mechanism, and more benefit to the realization of the flexible phase -choosing technology.
关键词： semiconductor,hybrid switch,reactive power compensation,DSP
更新于2025-09-23 15:21:21
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LCO-FLL control for single-phase utility integrated single-stage solar PV system
摘要： This study presents a limit cycle oscillator-frequency locked loop (LCO-FLL) control for single-phase utility integrated single-stage photovoltaic (PV) system. The proposed topology increases the utility of the voltage-source converter (VSC), particularly in the absence of PV generation. It has the potential to load harmonics current mitigation. It estimates harmonic free load current accurately with low computational requirement due to the absence of cumbersome mathematical algorithm and transformation techniques. It provides reactive power compensation, both in the absence and the presence of PV generation, improves transient response during dynamics in load and varying irradiance conditions. The total harmonic distortions of utility current and utility voltage, compliance the limit of the IEEE-519 standard. The proportional–integral (PI) regulator regulates the DC-link voltage of VSC input to the reference DC-link voltage. The incremental conductance-based technique derives the reference DC-link voltage. The dynamic behaviour of the LCO-FLL-based control is improved using a feed-forward loop for the PV power sharing. It also reduces loading on the PI controller. Test results demonstrate satisfactory performance of LCO-FLL-based control.
关键词： single-stage solar PV system,LCO-FLL control,proportional–integral (PI) regulator,incremental conductance-based technique,feed-forward loop,reactive power compensation,voltage-source converter (VSC),IEEE-519 standard,single-phase utility
更新于2025-09-23 15:21:21
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[IEEE 2020 IEEE International Conference on Power Electronics, Smart Grid and Renewable Energy (PESGRE) - Cochin, India (2020.1.2-2020.1.4)] 2020 IEEE International Conference on Power Electronics, Smart Grid and Renewable Energy (PESGRE2020) - Analysis of Low Voltage Ride Through Techniques for Grid-Connected Photovoltaic Systems
摘要： This paper presents a comparative analysis of different low voltage ride though strategies proposed for operation of a grid connected two stage photovoltaic system under low voltages. The existing grid codes mandate that, under the presence of low voltages, a distributed energy resource (DER) must stay connected to the grid for a minimum amount of time. This results in abnormally high currents though the inverter of a PV system, which can potentially damage the semiconductor switches. To avoid this, low voltage ride through techniques are proposed in the literature to ensure that the DER stays connected to the grid. Traditionally, the performance of LVRT techniques is evaluated by assuming an ideal voltage dip at the point of common coupling. In this work, comparative evaluation of different LVRT techniques is carried out on the CERTS testbed with an objective to highlight the impact of network transients on their performance.
关键词： active power,reactive power,inverter.,Low voltage ride through,DC-link voltage
更新于2025-09-23 15:21:01
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Improved-efficiency quasi-two-stage current-source-mode SIMO LED driver
摘要： The paper presents a modularized control strategy of doubly fed induction generator (DFIG) system, including the grid-side converter (GSC) and rotor-side converter (RSC), under unbalanced and harmonic grid voltage. The sequence decomposition process and complicated control reference calculation can be avoided in the proposed control strategy. From the perspective of power grid friendly operation, the control targets of DFIG system in this paper are chosen as: 1) smooth active and reactive power injected into the power grid; 2) balanced and sinusoidal current injected into the power grid. The RSC and GSC can work as two independent modules and the communication between RSC and GSC can be removed. Furthermore, the third harmonic current component, dc-link voltage fluctuation, and electromagnetic torque pulsation under the different control targets are theoretically analyzed. Finally, the availability of the proposed modularized control strategy of DFIG system under unbalanced and distorted grid voltage is verified by experiment results.
关键词： unbalanced and harmonic grid voltage,modularized control,doubly fed induction generator (DFIG) system,smooth active and reactive power,Balanced and sinusoidal current
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE 3rd Conference on Energy Internet and Energy System Integration (EI2) - Changsha, China (2019.11.8-2019.11.10)] 2019 IEEE 3rd Conference on Energy Internet and Energy System Integration (EI2) - Harmonic Current Detection and Reactive Power Compensation Method for Photovoltaic System Based on FBD Method
摘要： In order to improve the equipment utilization of distributed photovoltaic power generation system, the harmonic and reactive currents generated by grid-connected photovoltaic can be accurately detected and compensated. A phase-locked loop based on second-order generalized integrator (SOGI-PLL) is introduced into the traditional FBD current detection method to separate the positive and negative sequence components of unbalanced voltage and detect the phase and frequency of reference voltage more accurately. The simulation results show that the algorithm can reduce the computational complexity and increase the detection accuracy and steady-state performance.
关键词： harmonic current detection,reactive power compensation,improved FBD method,grid-connected PV system,SOGI-PLL
更新于2025-09-23 15:21:01