Dr. Nirav Patel, (Ph.D.)

The voltage sourced-inverter (VSI) interfaced photovoltaic (PV) system with classic controller supplies the true power demand of the loads coupled at the Point of Interconnection (PoI). Thus, PV systems assets practically remain dormant at nighttime which reduces the device utilization factor of the VSI. Therefore, to subjugate the underutilization of VSI, this paper presents a synchronously rotating dq-frame and adaptive phase-locked loop (PLL) structure. The proposed system serves the… Show more

The voltage sourced-inverter (VSI) interfaced photovoltaic (PV) system with classic controller supplies the true power demand of the loads coupled at the Point of Interconnection (PoI). Thus, PV systems assets practically remain dormant at nighttime which reduces the device utilization factor of the VSI. Therefore, to subjugate the underutilization of VSI, this paper presents a synchronously rotating dq-frame and adaptive phase-locked loop (PLL) structure. The proposed system serves the following distinctive functions: (i) True power management function which is fundamentally responsible for sharing power requirement of the nonlinear load based on the renewable power accessibility at DC-link; and (ii) Active harmonic filtering (AHF) which is responsible for deliberately producing controlled harmonics in the output current and, in turn confronting the power quality (PQ) challenges. The envisaged control structure can be purposefully employed to transfer the power into the electric grid while providing grid current harmonic mitigation and balancing, reactive power elimination, and unity power factor (UPF) operation. In this respect, it is an inexpensive substitute to existing commercial shunt AHF meant for this job. The most distinctive feature of the presented structure is its computational effectiveness and easy implementation. Furthermore, insights are provided on the operating principle of a DC-link voltage control loop and power balance operation. The proposed PV system employs an incremental conductance (InC)-based technique to ensure optimal power evacuation from the PV arrays. Finally, the MATLAB/Simulink simulation and dSPACE-1104 based experimental results confirm the potential merits of the proposed structure to restrict the grid current distortions within the 5% and thereby complying with THD limit specified in the IEEE-519. Show less

Grid-interfaced solar photovoltaic (GIPV) system requires a robust control algorithm for satisfactory operation under grid voltage disturbances. In this study, an application of Newton's learning rule-based total least-square estimation employing single-layer neural network structure is adopted to interface the photovoltaic unit with the utility grid. In addition, the weight updating mechanism is uniquely integrated with threshold neuron for attaining speedy extraction of fundamental load… Show more

Grid-interfaced solar photovoltaic (GIPV) system requires a robust control algorithm for satisfactory operation under grid voltage disturbances. In this study, an application of Newton's learning rule-based total least-square estimation employing single-layer neural network structure is adopted to interface the photovoltaic unit with the utility grid. In addition, the weight updating mechanism is uniquely integrated with threshold neuron for attaining speedy extraction of fundamental load current component. In particular, the proposed control algorithm has the capability to transfer maximum active power to the utility grid/AC load at unity power factor while operating as distribution static compensator to offer various ancillary services including current harmonics attenuation and reactive current suppression. This will lead to increased device utilisation factor of the overall GIPV system during night time (i.e. in the absence of solar irradiance). Moreover, the proposed control scheme is designed and developed without any complex transformations and derivative terms, which results in less computational intensiveness. The GIPV system with three-phase double-stage configuration is modelled in MATLAB/Simulink software using sim-power system tool. Finally, the adaptability of the proposed control algorithm has been verified and confirmed through 500 W laboratory prototype using low-cost Arm Cortex-M4 microcontroller under various operating conditions. Show less

The electronically interfaced photovoltaic (PV) system and its control approach form an intrinsic part of distributed generation (DG) system. This paper proposes Pseudo Affine Projection (PAP) assisted multitasking control scheme for gridintegrated DG inverter under input grid voltage disturbances. The PAP approach is based on the convergence of active weighted values and is independent of the input signal property, which manifests a discrete characteristic. Additionally, it exhibits a unique… Show more

The electronically interfaced photovoltaic (PV) system and its control approach form an intrinsic part of distributed generation (DG) system. This paper proposes Pseudo Affine Projection (PAP) assisted multitasking control scheme for gridintegrated DG inverter under input grid voltage disturbances. The PAP approach is based on the convergence of active weighted values and is independent of the input signal property, which manifests a discrete characteristic. Additionally, it exhibits a unique capability of updating weight based on multiple, delayed input signal vectors. The fundamental distinguishing feature of proposed PAP is its intrinsic learning behaviour and therefore it provides an optimal solution to the ingrained paradox between steady-state misadjustment and convergence speed compared to its conventional counterpart affine projection (AP). The PAP assisted algorithm practically enables DG inverter to perform multiple tasks including suppression of source current harmonics, unbalancing, and neutral current. It also provides load reactive current support with unity power factor (UPF) operation while transferring the maximum active power into the utility grid. The practicality of the proposed PAP algorithm is investigated through MATLAB/Simulink software. Finally, the experimental results recorded with dSPACE-1104 based real-time control platform shows good to excellent agreement with simulations in the steady-state, as well as transient phenomena. Show less

This paper presents photovoltaic (PV) system control as distributed static compensator (DSTATCOM), termed as PV-DSTATCOM, operated with active current control (ACC) and feed-forward control loop (FFCL). Besides active power injection into the utility grid, the proposed PV system autonomously transforms into a DSTATCOM to provide various ancillary services including source current harmonic suppression, load reactive current compensation, zero sequences component mitigation, and power factor… Show more

This paper presents photovoltaic (PV) system control as distributed static compensator (DSTATCOM), termed as PV-DSTATCOM, operated with active current control (ACC) and feed-forward control loop (FFCL). Besides active power injection into the utility grid, the proposed PV system autonomously transforms into a DSTATCOM to provide various ancillary services including source current harmonic suppression, load reactive current compensation, zero sequences component mitigation, and power factor correction. Since PV-DSTATCOM operates with ACC, it precisely extracts the fundamental in-phase and quadrature components of current. It introduces high-gain at the third-order harmonic and thereby alleviates stationary errors in the current control loop of PV inverter. The proposed ACC+FFCL structure is computationally efficient and unconditionally stable. Practically, FFCL addresses the challenges emerged due to nonlinearity introduced by the PV unit and ensure a rapid power balance between the PV unit and electric grid. Further, a simplified perturb and observe based maximum power point tracker has been employed to evacuate the maximum power from the PV array. The proficiency of the developed ACC+FFCL structure is investigated through a comprehensive set of transient studies using MATLAB/Simulink software. Finally, a laboratory setup has been developed using the dSPACE-1104 platform and experimental results are recorded with detailed comparative evaluation. Show less

The grid-tied solar photovoltaic system requires a multiobjective control approach for performing the dual operation of active power transfer at unity power factor and harmonic filtering. In this context, this study proposes an improved robust-mixed-norm (RMN) filter-based multiobjective control strategy for integrating the solar photovoltaic system with the utility grid. The standard RMN filtering control exhibits slow convergence, requires large sampling time and involves high computational… Show more

The grid-tied solar photovoltaic system requires a multiobjective control approach for performing the dual operation of active power transfer at unity power factor and harmonic filtering. In this context, this study proposes an improved robust-mixed-norm (RMN) filter-based multiobjective control strategy for integrating the solar photovoltaic system with the utility grid. The standard RMN filtering control exhibits slow convergence, requires large sampling time and involves high computational cost. Therefore, a switching parameter is designed to toggle between least mean square and least absolute deviation for extracting the benefits of both filtering techniques as per requirement. The switching parameter will also help in minimising the computational intensiveness during hardware implementation and successfully confronts the conflict between convergence speed and steady-state misadjustment in the presence of outliers. The proposed control is implemented with the help of multiple delayed input vectors to extract the fundamental weight component from the non-sinusoidal load current. In addition, the effects of grid voltage distortion and imbalance have been detached by using complex vector filter-based synchronisation technique. The practicality of the proposed multiobjective approach has been verified under different operating conditions of supply and load through both MATLAB/Simulink tool and low-cost microcontroller-STM32F407VGT6-based laboratory prototype. Show less

This paper aims to propose an optimized and robust current controller for the transformerless grid-integrated photovoltaic inverter. Challenge of ensuring improved power quality while minimizing the DC component under non-ideal grid condition is at forefront in the grid-integrated photovoltaic system. In this context, in the proposed work, an advanced current controller is designed and developed in a stationary reference frame with a proportional-integral (PI) plus four-vector (4VPI) PI… Show more

This paper aims to propose an optimized and robust current controller for the transformerless grid-integrated photovoltaic inverter. Challenge of ensuring improved power quality while minimizing the DC component under non-ideal grid condition is at forefront in the grid-integrated photovoltaic system. In this context, in the proposed work, an advanced current controller is designed and developed in a stationary reference frame with a proportional-integral (PI) plus four-vector (4VPI) PI controllers. The PI controller modulates the shape of fundamental current to follow its reference induced from outer DC-link loop. Meanwhile, 4VPI controllers are tuned at the multiple of grid frequencies including third-(𝟑𝝎𝟎), fifth-(𝟓𝝎𝟎), seventh-(𝟕𝝎𝟎), and ninth-(𝟗𝝎𝟎) to introduce infinite gain, and thereby alleviating stationary errors in the current loop of a photovoltaic inverter. The most distinguishing feature of the proposed controller is its inherent control robustness, and therefore, it operates satisfactorily against control delay time and frequency excursion. Traditionally, cumbersome trial-and error techniques have been largely employed to adjust the PI-VPI controller gains. Nonetheless, tuning of these parameters has made many practitioners switch-off from employing the proposed controller. Given this, the Particle Swarm Optimization algorithm is proposed. Finally, the practicality of the proposed controller is validated through a comprehensive set of simulation and experimental tests conducted on a laboratory-developed prototype using dSPACE-1104. Show less

Conventional variable perturbation–size maximum power point (MPP) tracking methods use a constant multiplying factor to enable fast convergence process. However, it potentially leads to the sluggish dynamic response. In this context, a novel autoscaling variable perturbation–size MPP tracking algorithm is proposed to precisely recognize the MPP under an abrupt change in solar irradiance. Initially, a new perturbation size scaling function of the duty cycle is defined, which typically modulates… Show more

Conventional variable perturbation–size maximum power point (MPP) tracking methods use a constant multiplying factor to enable fast convergence process. However, it potentially leads to the sluggish dynamic response. In this context, a novel autoscaling variable perturbation–size MPP tracking algorithm is proposed to precisely recognize the MPP under an abrupt change in solar irradiance. Initially, a new perturbation size scaling function of the duty cycle is defined, which typically modulates the DC‐DC boost converter output. The principle objective of employing this algorithm is to enable the fast dynamic response while harvesting steady‐state power with nearly zero sustained power oscillations around the MPP. In a second step, a method is proposed to improve the decision‐making system during a sudden change in irradiance. The proposed MPP technique optimally achieves 99.72% tracking efficiency without much computational intensiveness, which is better compared with previous MPP tracking methods. The adaptability of the proposed technique is validated through a comprehensive set of MATLAB/Simulink software simulation studies followed by a low‐cost STM32F407VGT6‐based microcontroller‐based experimental setup. Furthermore, the reliability of the proposed algorithm is also investigated. The result implies that the proposed MPP tracker operates satisfactorily under sudden changes in irradiance. Show less

Distributed generation (DG) is an important technology for increasing penetration of renewable energy sources (RES) and thereby reducing oil use and coal‐related emission. In addition, there has been recent renewed interest in multifunctional photovoltaic inverter due to its uniqueness to provide ancillary services while increasing device utilization factor. In this context, a combined active power‐sharing and grid current distortion enhancement‐based approach is proposed in this paper for… Show more

Distributed generation (DG) is an important technology for increasing penetration of renewable energy sources (RES) and thereby reducing oil use and coal‐related emission. In addition, there has been recent renewed interest in multifunctional photovoltaic inverter due to its uniqueness to provide ancillary services while increasing device utilization factor. In this context, a combined active power‐sharing and grid current distortion enhancement‐based approach is proposed in this paper for three‐phase four‐wire (3P4W) grid‐connected solar photovoltaic (SPV) system. The DG is uniquely controlled by multifunctional photovoltaic inverter to autonomously acquire the following multifunctionalities: (a) active power‐sharing feature to govern the power flow between the SPV unit and utility grid based on the availability of active power at direct current (DC)–bus terminal; (b) shunt active power filter (SAPF) with functionalities of source current harmonic attenuation, load reactive current compensation, and zero sequences harmonic component mitigation, in addition to unity power factor (UPF) operation; and (c) to supply constant power to the electrical loads during solar intermittency. The proposed control systems of the DG mainly consist of the fundamental load current decomposition (FLCD) loop, active and reactive power components extractor, and source current balancing compensator. By adopting the proposed FLCD‐based approach, the fundamental load current is precisely detected while diminishing the computational intensiveness. In this study, an incremental conductance (INC)–based maximum power point (MPP) tracker has been realized using an Arm Cortex M4 microcontroller (STM32F407VGT). The multifunctionalities are demonstrated through exhaustive MATLAB/Simulink simulation results and are also validated by developing a laboratory prototype using dSPACE 1104 control platform. Show less

In this paper, a detailed documentation revealing the design, development, and implementation aspects of grid-connected solar photovoltaic (SPV) power conversion system is presented. Since the inverter is considered as a key constituent of an SPV system, a laboratory developed three-phase four-legged (3P4L) inverter is employed to diminish the overall cost of the SPV system considerably. The multifunctional inverter controlled SPV system proposed in this work not only injects active power into… Show more

In this paper, a detailed documentation revealing the design, development, and implementation aspects of grid-connected solar photovoltaic (SPV) power conversion system is presented. Since the inverter is considered as a key constituent of an SPV system, a laboratory developed three-phase four-legged (3P4L) inverter is employed to diminish the overall cost of the SPV system considerably. The multifunctional inverter controlled SPV system proposed in this work not only injects active power into the electric grid, but it also serves as an active power filter (APF) to provide various power quality (PQ) solutions. This typically includes source current harmonic attenuation, load reactive current mitigation, neutral current elimination, source current balancing, in addition to ensure unity power factor operation. A various hardware circuits including signal sensing circuit, signal conditioning circuit, pulse amplification and isolation circuit, and blanking circuit are fabricated and assembled to develop a complete laboratory prototype model. In addition, the voltage and current controllers, the synchronize reference frame theory (SRFT)-based approach, and the phaselocked loop (PLL) control algorithms are embedded in dSPACE 1104 control platform. Furthermore, an STM32F407VGT microcontroller is employed to implement the incremental conductance based maximum power point (MPP) tracking algorithm. The effectiveness of the developed SPV system is first simulated in MATLAB/Simulink software. In the second step, the efficacy of the proposed configuration is investigated under balanced and unbalanced nonlinear loads on a laboratory developed prototype. Show less

The multifunctional grid-connected inverter (MFGCI's) has drawn a significant attention among researchers because of its ancillary services including active power injection into utility grid while also serving as an active power quality conditioner (APLC) to enhance the power quality (PQ). It should be noted that the application of a multifunctional inverter is specifically increased to integrate renewable and sustainable energy sources like solar photovoltaic (SPV) and wind turbine (WT) in… Show more

The multifunctional grid-connected inverter (MFGCI's) has drawn a significant attention among researchers because of its ancillary services including active power injection into utility grid while also serving as an active power quality conditioner (APLC) to enhance the power quality (PQ). It should be noted that the application of a multifunctional inverter is specifically increased to integrate renewable and sustainable energy sources like solar photovoltaic (SPV) and wind turbine (WT) in distributed energy resources (DERs) and microgrid (MGs), where the aim is to diminish the transmission and distribution losses considerably by generating power at one place and serving the load requirement of nearby localities. In view of this, various configurations used in MFGCI's are presented along with their detailed comparative study. Furthermore, control strategies employed in single and three-phase MFGCI's are comprehensively reviewed. Additionally, an in-depth explanation, comparison and discussion on MFGCIs are accomplished. Beside this, the author has also made an attempt to provide a detailed explanation on future scopes of MFGCIs in DERs and MGs. Show less