Avik Bhattacharya

A novel PMSG based WECS for grid integration using DMC

In this paper, direct matrix converter (DMC) based wind energy systems equipped with Permanent Magnet Synchronous Generators (PMSG) is proposed. To extract the maximum available power from the wind, the Matrix Converter (MC) is controlled using the venturini based algorithm together with the voltage oriented vector control (VOC) scheme to regulate active and reactive power (Power Regulation Technique). In this scheme, the maximum extractable power is derived from wind turbine power curves by using Maximum Power Point Tracking (MPPT) is set as reference active power while reference for reactive power is taken as zero. The change in generated power due to change in wind speed are processed through proportional & integral (PI) controllers to regulate the voltage gain of Matrix Converter (MC). In result, the desired regulation of powers is carried out. To evaluate the performances of proposed scheme, Matlab/Simulink based model is tested under varying wind speed. From the simulation results it is confirm that MC with adequate input filters and proposed control scheme is able to extract the maximum power from the wind energy conversion system (WECS) and fed directly to the existing grid at desired output frequency and voltage at nearly unitary input power factor.

Three level Z source inverter based photovoltaic power conversion systems

A Z-source inverter (ZSI) has a unique ability to achieve single stage voltage buck-boost operation for energy conversion. This paper presents a three level ZSI using a single impedance network for photovoltaic (PV) application. A single LC impedance network is used between DC voltage source and neutral-point-clamped (NPC) inverter to achieve the desired stepped-up and stepped-down output voltage level. Alternative phase opposition and disposition (APOD) modulation technique with proper triplen offset and appropriate addition of time delay/advance is used to achieve the required boost in DC link voltage. A traditional MPPT technique is used to introduce a shoot-through interval in switching waveform to extract the maximum power from the PV panel. Traditional MPPT technique does not allow to boost the Z-network capacitor voltage more than the maximum power point (MPP) voltage of the PV array. This paper also presents a unified voltage control technique to track the MPPT and also maintains the desired Z-source capacitor voltage level. The design, implementation and control of single impedance network based multilevel ZSI for photovoltaic application is discussed and their MATLAB/Simulink simulation and results are presented in the later section of the paper to validate proposed control scheme in PV application.

Design, control and simulation of grid connected DC/AC microgrid for residential applications

A basic approach for grid connected DC/AC microgrid modeling using photovoltaic (PV) panels and Energy storage units accessible in this document. The system consists of a two stage power conversion. Solar PV supplies power for both DC and AC loads. Manufacturer datasheet is used for modeling the PV panel that could help to give a suitable way for the researchers to explore the PV generation issues. A battery storage system connected to dc bus via bidirectional converter is used to absorb the excess power whenever generation is more and deliver power to the load when generation is less to keep the bus voltage stable. The system continues to supply the local loads, incase grid discontinuity. Thus it eliminates hazards of islanding. The paper focuses on control and stability of dc bus voltage and energy management scheme. The integration of PV generation, battery storage and utility grid jointly with their linked control system is modeled in Matlab/Simulink and the efficiency of the system is verified by simulation.

A reduced voltage rated unified power quality conditioner for harmonic compensations

“Power Quality (PQ)” is used to describe the electrical phenomenon manifested in terms of variations in current, voltage and/or frequency that produce undesirable effects in the power system. This paper presents a reduced DC-link voltage rated Unified Power Quality Conditioner (UPQC) which eliminates current and voltage harmonics in a distribution network thereby improving the quality of power. Series capacitors have been introduced in series with the coupling inductors on the shunt filter side of the UPQC. The proposed topology helps in reducing the voltage rating of DC-link capacitor without compromising on the harmonic mitigation and thus acts as a cost effective solution in the distribution side. A simulation study of the new topology has been made in a three phase three wire system and is compared with the conventional topology of UPQC. The results are presented in the paper to show the validity of the proposed scheme. State space modelling of the modified UPQC has been implemented and stability analysis is also performed to prove the robustness of the system

PMSG based constant power delivery standalone WECS using SST with bidirectional buck-boost BESS

This paper presents a simplified control algorithm for permanent magnet synchronous generator (PMSG) based wind energy conversion system (WECS) connected to a three phase resistive load through direct matrix converter (DMC) based solid state transformer (SST) with bidirectional buck boost battery energy storage system (BESS) for constant active power delivery to load. The power from WECS is processed through DMC based SST using venturini based control algorithm. In this scheme, Maximum Power Point Tracking (MPPT) algorithm is applied on wind turbine for extracting maximum power from WECS. Moreover, by using DMC based SST, the frequency and amplitude of the output voltage is also maintained constant. The bidirectional buck-boost based BESS is used to absorb the surplus power from WECS during over generating period and delivered this power to the load during a wind power shortage period. During over generation period, battery system comes under charging mode and bidirectional buck boost system operates in buck mode. While in under generation period, battery discharges its store energy to compensate the load demand and bidirectional buck boost system works under boost mode. The control strategy works under variable wind speed variation. To evaluate the performances of proposed scheme, Extensive simulation results have been performed using MATLAB/SIMULINK.

Control and operation of grid-connected solar photovoltaic for DC microgrid application

This paper presented control and operation of grid-connected photovoltaic (PV) for DC microgrid application. The microgrid system consists of solar PV array, energy storage, ac-grid and DC loads. The PV array is connected to a DC bus via a boost converter which extracts maximum power from the PV Array. The ac-grid is interfaced to the microgrid with a boost rectifier and a buck/boost converter which are controlled to keep a constant DC bus voltage. The Energy Storage System (ESS) is connected to the common DC bus through a bidirectional buck-boost converter. Moreover, the stability of the microgrid is preserved by the control action of the energy storage system. Lastly, the proposed DC microgrid system have been analyzed and simulation done using Matlab/Simulink. The simulation study validate utility of proposed system.

3-level Z-source inverter based PV system with bidirectional buck-boost BESS

This paper presents a three-level ZSI for photovoltaic (PV) application to achieve single stage buck-boost (as per the solar variation). A single LC impedance network is used between DC voltage source (including PV array and a bidirectional buck-boost system) and neutral-point clamped (NPC) inverter. Alternative phase opposition and disposition (APOD) modulation technique with proper triplen offset and appropriate addition of time delay/advance is used to achieve the required boost in DC link voltage. Traditional MPPT technique (like Perturbed and Observed (P&O)) does not allow boosting the Z-network capacitor voltage more than the maximum power point (MPP) voltage of the PV array. This paper presents a unified voltage control technique to track the MPPT and also maintains the desired Z-source capacitor voltage level. The design, implementation and control of single impedance network based multilevel ZSI for photovoltaic application with BESS according to generation-demand is discussed. This proposed topology not only tracks MPPT output voltage but also maintained constant output voltage with wide range of variation of insulation (irradiance). To validate the proposed scheme the system is extensively simulated in MATLAB/Simulink.

A noble transformer coupled shunt active hybrid power filter

This paper proposes a reduced voltage transformer based hybrid active power filter topology. It is a combination of two inverters with a split dc link voltage. The dc link voltage of the HFI is reduced by the transformers turn ratio. Both the inverters are connected in shunt with the non linear load. The LFI provides a limited reactive power handling capability due to the high impedance in the shunt path however it provides excellent harmonic compensation at lower cost. MOSFET based switches are used in the HFI while IGBTs are used for the LFI. PWM based controller and hysteresis controller for operating the LFI and HFI respectively are used. The performance of the proposed topology and controller are simulated and observed in MATLAB/SIMULINK. The usefulness of the topology is confirmed by implementing it in an experimental setup.

A novel DMC based SST for voltage and frequency regulation of PMSG based WECS

This paper proposes a novel topology for voltage and frequency regulation of wind energy conversion systems (WECS) equipped with Permanent Magnet Synchronous Generators (PMSG) using Direct Matrix Converter (DMC) based Solid State Transformer (SST). The venturini algorithm along with voltage oriented vector control (VOC) method is applied for regulating the WECS power also known as Power Regulation Technique, which can effectively regulate the generated voltage and frequency at output side of DMC based SST. The variation in generated power with varying voltage & frequency due to the change in wind speed are processed by proportional & integral (PI) controllers to control the voltage gain of DMC, consequently it regulate the desired powers, voltage and frequency. Matlab/Simulink based model is tested for evaluating the performances of proposed scheme. From the simulation results it is confirm that PMSG based WECS under varying wind speed using SST with adequate input filters and proposed control scheme is able to directly fed power to the existing grid or local load at desired output frequency and voltage at nearly unitary input power factor.

Transformerless dual inverter based series injected shunt active power filter

The following paper proposes a topology for reactive power compensation and harmonic reduction for medium voltage three phase three wire systems during unbalanced load conditions. Main three phase inverter produces harmonic compensation. Three single phase inverters connected in series with the three phase inverter for separate compensation of reactive power in three different phases are present. The three phase inverter is a hybrid active power filter which is an HFI (High Frequency Inverter) and uses Hysteresis control. The three single phase inverters are LFIs (Low Frequency Inverters) which also operate using sinusoidal triangular PWM control. The DC bus voltages of the three single phase inverters are common. The topology specifically caters to the need of real-time load which is largely unbalanced and requires both a reduction in harmonic levels as well as reactive power and negative sequence compensation simultaneously. Simulation results are also provided to validate the claims made in this paper regarding the hybrid topology and associated control strategy.