Enhanced control of superconducting magnetic energy storage integrated UPQC for power quality improvement in EV charging station

The recent modification in utilizing Multifunction Power Conditioner (MPC) such as Unified Power Quality Conditioner devices in power systems has led to different degrees of power losses, owing to electronic power impacts. This paper presents a detailed comparison of power loss analysis in various configurations of MPC, that is, the conventional unified power quality conditioner (UPQC) and the UPQC with distributed generation (〖UPQC〗_DG). The independent losses based on inverter design and distributed generation interfacing to the distribution form the basis for each configuration case. The investigation considered conventional UPQC as the base case for power losses, and the study was extended to 〖UPQC〗_DG at steady state operating condition. In all configurations, Switching Losses (SL) and conduction losses were considered using simulation studies carried out in MATLAB/SIMULINK, and the results obtained in all cases were used for comparative studies. Finally, the outcome indicates that the losses in 〖UPQC〗_DG is more than conventional UPQC based on simulation results in all cases.

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Power Loss Analysis with Dispersed Generation in Multifunction Power Conditioner Design to Improve Power Quality

The integration of universal active power filter (UAPF) with standalone hydroelectric system having double stage solar photovoltaic (SPV) and bidirectional battery supported for improvement of the system power quality (PQ), is presented in this work. The power from the self-excited induction generator (SEIG) driven by the hydro turbine is the main source of this standalone system. However, when its operating at variable loads, as well as nonlinear loads, etc. the PQ issues are arisen. So, the PQ indices are improved by integrating a UAPF, which consists of two voltage source converters (VSCs) having a common DC link. The voltage qualities are enhanced using the series compensator of UAPF and maintains the harmonics free constant magnitude voltage across the sensitive loads, regardless of any variation in generator voltage. Moreover, the power indices for instance power factor, current harmonics, reactive power, etc. are improved through the shunt compensator of the UAPF, instantaneously along with voltage quality enhancement. The fundamental components of distorted currents of crucial load are extracted by means of improved lowpass generalized integrator (IL-GI) control algorithm, which are further utilized for estimation of the reference signals and the switching pulses, to ensure the effective and efficient power quality improvement during various conditions. The IEEE-519 standard is being followed by the load voltage and the source current.

Universal Active Filter for Standalone Hydro-Electric System with SPV and Battery Support

The integration of unified power quality conditioner (UPQC) with self-excited induction generator (SEIG) based standalone hydroelectric power generation (HPG) having backup of bidirectional battery and single stage solar photovoltaic (SSSPV) is presented in this paper with the feature of power quality enhancements. When the SEIG is operated at varying loading conditions, or when its frequency varies, the power quality problems arise in this standalone system. Hence, these power qualities issues are mitigated by incorporating a UPQC device, having two separate voltage source converters (VSCs) with same DC points. Irrespective of any variation in voltage generated, the harmonics free with fixed amplitude voltage at the load terminals are regulated by the series connected VSC of UPQC. Furthermore, the current qualities are enhanced by parallel (shunt) connected VSC and improved the source side power factor, harmonics in the source currents, and reactive power, etc., simultaneously with enhancement of voltage quality. An enhanced generalized integrator (EGI) control scheme is used for extraction of fundamental signals for the nonlinear load currents waveform. These fundamentals are further used for generation of the reference and switching pulses for both VSCs. The effectiveness of PQ improvement under a variety of circumstances are analyzed and the source currents and load voltages both adhere to IEEE-519 standard.

PQ Improvement for SEIG Based Standalone Hydroelectric Generation System With UPQC

This paper aims to check the voltage and frequency response of a single-phase solar PV grid inverter with an output of 4 kW in the event of over / under voltage and over/under frequency fluctuations. The inverter voltage and frequency performance are verified against compliance with IS/IEC 61727: 2004 (Indian standard) and the proposed method. The study shows that in the event of an abnormal grid frequency with a deviation of ± 1.5 Hz, the grid-connected inverter trips within limits and meets the requirements of the standard and the proposed method. In contrast to the abnormal frequency condition, the inverter has exceeded the 0.1-second limit during an abnormal voltage condition (under-voltage at 105 V). The proposed method is validated, and the results are provided.

Response of Single-Phase Grid-Tied Solar PV Inverter During Utility Voltage and Frequency Fluctuations

This work presents an enhanced second-order generalized integrator (ESOGI) based control method for the grid integrated unified power quality conditioner (UPQC) with a solar photovoltaic (PV) system. The objective of this work is to improve the power quality (PQ) indices in the grid by eliminating voltage sensors (grid side) in the overall control. Moreover, presented control method effectively eliminates the DC offset from the input signals and estimates the fundamental element (FE), which is processed to compute the reference signals. The UPQC-PV system comprises two voltage source converters, one connected in a parallel at the point of common coupling for load compensation and the other connected in series via an injecting transformer for voltage compensation. The comparative performance is demonstrated in this work to validate the effectiveness of presented control over state-of-art control algorithms. Moreover, the cost analysis of the presented control is also discussed with the traditional controllers. The UPQC-PV system is simulated in Simulink tool of MATLAB and the performances are analyzed at various dynamic scenarios such as load unbalancing; distorted grid voltages; symmetrical and asymmetrical voltages swell and sag; and change in solar insolation, etc. Experimental results illustrate the superior performance under various operating conditions. The harmonics and magnitudes of load side voltages are restricted as per the IEEE standard 1159. The grid currents and load voltages are well sinusoidal with their total harmonic distortions in the permissible range state in the IEEE standard 519.

Reduced Voltage Sensors Based UPQC Tied Solar PV System Enabling Power Quality Improvement

This article presents a generalised integrator with a band-pass filter frequency locked loop (GI-BPF-FLL) control algorithm for the solar photovoltaic (SPV)-integrated unified power quality conditioner (SPVUPQC) system. This control algorithm extracts fundamental components (FC) of the distorted and deformed input signals, and it has the competence of eliminating DC-offset. The key objective is to decrease the number of sensors used in the control algorithm of the SPVUPQC system while enabling the power quality enhancement features in the distribution grid. The effectiveness of the presented GI-BPF-FLL control algorithm and its performance comparison with the conventional control algorithm are discussed in both the time domain as well as frequency domain analysis. The SPVUPQC system consisting of a distribution static compensator (DSTATCOM) and a dynamic voltage restorer (DVR), to compensate simultaneously both the voltage distortions, sag/swell etc. as well as current harmonics, reactive power and load currents unbalances etc. The model of the SPVUPQC system is developed in the MATLAB/Simulink environment, and its results are presented to demonstrate its capabilities. The system's validation is also done on the hardware prototype, and it performs effectively for the voltage and current power quality enhancement simultaneously. The load side voltages magnitudes, grid side voltages and the grid currents total harmonic distortions are found within the boundaries specified in the IEEE standard 1159 and the IEEE standard 519. 

Multi‐functional control strategy for power quality improvement of three‐phase grid using solar PV fed unified power quality conditioner

The standalone three phase system for power quality (PQ) improvement of both the load side voltages as well as the currents of the machine terminal is presented in this article. This standalone system consists of a three-phase permanent magnet synchronous generator (PMSG) driven by governor-less hydro turbine as a three-phase source feeding the sensitive/nonlinear/linear loads, connected via a unified power quality conditioner (UPQC). The UPQC consists of a back-to-back connected voltage source converters (VSCs) sharing a common dc bus. The series compensator of the UPQC is used to eliminate voltage PQ and to maintain the sinusoidal, balanced, and constant amplitude voltages at load terminals irrespective of any variation in the system. Moreover, the current quality, such as reactive power compensation, and harmonics elimination, are provided by the shunt compensator of the UPQC, simultaneously while improving voltage quality issues. In addition, the efficiency of the overall system is significantly improved by running the generator below its rated voltage and reduces the losses by operating at unity pf. The system frequency and the generated voltage magnitudes are maintained during any load fluctuation or imbalance loading. The model of the UPQC-based hydro turbine driven PMSG system is developed in the Simulink-MATLAB environment, and its results are presented for analysis. The validation of the system is also done on the hardware prototype, and it performs effectively for the voltage and current PQ enhancement simultaneously. It significantly improves the PQs at the generator terminals and ensures to adhere the IEC-61727 and the IEEE-519 standards even with either balanced or unbalanced loads.

Modified Adaptive Filter Based UPQC for Battery Supported Hydro Driven PMSG System

This paper presents improvement of power quality (PQ) in three-phase standalone system using generalized integrator observer (GIO) frequency locked loop (FLL) control algorithm, for three-phase self-excited induction generator (SEIG) driven by hydro turbine as a three-phase source feeding the sensitive/nonlinear/linear loads along a double stage solar PV-battery is integrated at the DC link, connected via a unified power quality conditioner (UPQC). The UPQC consists of two voltage source converters (VSCs) connected back to back at common DC bus. The series VSC of the UPQC is used for compensating voltage power quality and to maintain the harmonic free and constant amplitude voltage at load terminals, irrespective of any variation in the system. Moreover, the power qualities such as reactive power compensation, harmonics elimination, unity power factor corrections are provided by the shunt VSC of the UPQC, simultaneously while voltage power quality is improved. It significantly enhances the power quality at the generator terminals and ensures to adhere the mandate the IEEE-519 and the IEC-61727 standards even with either balanced or unbalanced loads. Moreover, by operating the SEIG below its rated voltage and maintaining the voltage across loads at its desired value, one can minimized the excitation current and hence the core losses.

Modified GIO-FLL for UPQC Based SEIG with Double Stage Solar PV Battery System

The double stage solar photovoltaic (SPV) array integrated four wire unified power quality conditioner (UPQC) system is presented for three phase four wire distribution network. The control of four wire UPQC-PV system is done to eliminate the voltage and current power qualities (PQs) problems like neutral current, harmonics, reactive power, voltage sag, voltage swell, voltage unbalanced, etc. The four wire UPQC-PV system consists of two four legs voltage source inverters (VSIs) connected back to back through common DC- bus. The four wire UPQC-PV system is modelled in the Simulink/MATLAB, and its results are presented for analysis for various instances, unbalancing of load, unbalanced voltage sag and swell, solar irradiation variation, etc. The system performs effectively for such conditions and the current and voltage PQs problems are simultaneously improved. The load side voltages and the grid currents total harmonic distortions (THDs) are within the limits of the IEEE-519 standard.

Chandrakala Devi Sanjenbam

Papers

Reduced Voltage Sensors Based UPQC Tied Solar PV System Enabling Power Quality Improvement

Multi‐functional control strategy for power quality improvement of three‐phase grid using solar PV fed unified power quality conditioner

Modified Adaptive Filter Based UPQC for Battery Supported Hydro Driven PMSG System

Modified GIO-FLL for UPQC Based SEIG with Double Stage Solar PV Battery System

Double Stage Solar PV Array Integrated UPQC for Three Phase Four Wire Distribution System