Modular Multilevel Converter based Dynamic Performance Improvement of PMSM

Authors:-Venkata Anusha Ongolu, P.Syam kumar

Abstract:-This paper presents improvement of dynamic performance of permanent magnet synchronous machine using modular multilevel converter. This paper proposes a control strategy for the robust dynamic response of MMC even at zero output frequency employing leg offset voltage injection. The leg offset voltage for balancing the arm energy is produced by direct calculation without the circulating current control loop controller. Thanks to the highly dynamic leg offset voltage from direct calculation and not conventional circulating current controller, the dynamic performance of the MMC at low speeds has conspicuously improved. The AC machine has been driven from standstill to rated speed without excessive cell capacitor voltage ripples utilizing this proposed strategy. The simulation results verify that stable operation is guaranteed down to less than 2 % of the rated speed under 40% step load torque disturbance.

Sensor less Speed Control of Induction Motor with Slide Mode Technique

Authors:-Nagalakshmi Chilukoti, P.Syam kumar

Abstract:-A sensorless control scheme is presented for induction motor with core loss and anon linear model is developed in well known (α, β) stationary reference frame, where the core is represented with a resistance in parallel with a magnetization inductance. An optimal rotor flux modulus is calculated by minimizing copper and core loss. This flux modulus is forced to be tracked by the induction motor along with a desired rotor velocity by means of sliding mode observer by using the super twisting algorithm. The rotor velocity is estimated by two methods. The first consist of a super twisting sliding mode observer for rotor fluxes with the purpose of retrieving the back-electromotive force components by means of the equivalent control method. The second method is based on a generalization of the phase – locked loop methodology. PI controller is used in both the technique. The robustness of the system is checked by varying the stator, rotor and core resistances.

Predictive Control for Harmonic and Unbalance Compensation using Active Power Filter

Authors:-Venkata Krishna Medah, P Syam Kumar

Abstract:-An active power filter implemented with a four leg voltage-source inverter using dq-based Current Reference Generator scheme is presented. The use of a four-leg voltage-source inverter allows the compensation of current harmonic components, as well as unbalanced current generated by single-phase nonlinear loads.The grid interfacing can thus be utilized as:1)power converter to inject power generated from rest the grid, and 2)shunt APF to current unbalance, load current harmonics and load reactive power demand. The compensation performance of the proposed active power filter and the associated control scheme under steady state and transient operating conditions is demonstrated through simulations results.

Zeta Converter Based Power Factor Correction using BLDC motor

Authors:-Sri Lakshmi Kurra, M.Sivanageswararao

Abstract:-This paper presents a brushless DC (BLDC) motor drive with power factor correction (PFC) for low power applications. In this work, the speed of the BLDC motor is controlled by adjusting the DC link voltage of the voltage source inverter (VSI) feeding a BLDC motor. Therefore, VSI is used for achieving only an electronic commutation of the BLDC motor and operates in a low frequency switching for reduced switching losses. A PFC based isolated Zeta converter operating in discontinuous conduction mode (DCM) is used for controlling the DC link voltage of the VSI with inherent PFC at AC mains using single voltage sensor. The proposed drive is implemented to achieve a unity power factor at AC mains for a wide range of speed control and supply voltage fluctuations. An improved power quality is achieved with power quality indices within limits of IEC 61000-3-2 standard.

A New Hybrid Multilevel Converter with DC-Fault Blocking Capability using alternate arm converter

Authors:-Y Suresh, Bhukya Ranga Naik

Abstract:-An Alternate Arm Modular Multilevel Converter (AAMMC) is the recently introduced power electronics converter topology suitable for High Voltage DC Transmission (HVDC) system applications. This paper focuses on the operating principle of an Alternate Arm Modular Multilevel Converter. At the beginning the advantages of multilevel converter, basic schematic of converter topology, and its operation is discussed. For the controlling of the converter the simple sorting technique is employed. The AAMMC is a new converter topology which offers several advantages over existing multilevel converter topologies such as scalable and modular structure, low switching losses, DC fault tolerance property which eliminates the need of AC/DC breakers of large size and ratings, lower number of cells as compared to modular multilevel converter. The performance of the 21 level AAMMC without sorting and with sorting technique is verified with MATLAB Simulation.

Dynamic Performance of Photovoltaic Source Simulator in both Steady and Transient State Conditions

Authors:-T.Mahesh, Shaik Mabhu Jani

Abstract:-Photovoltaic (PV) source simulators serve as a convenient tool for the dynamic evaluation of solar power conditioning systems and maximum power point tracking algorithms. High efficiency and fast transient response time are essential features of any PV source simulator. This paper proposes a new type of PV source simulator that incorporates the advantages of both analog and digital-based simulators. The proposed system includes a three-phase ac–dc dual boost rectifier cascaded with a three phase dc–dc interleaved buck converter. The selected power stage topology is highly reliable and efficient. Moreover, the multiphase converter helps improve system transient response though producing low output ripple which makes it adequate for PV source simulators. The simulator circuitry emulates precisely the static and the dynamic characteristics of actual PV generators under different load and environmental conditions. Additionally, the system allows the creation of the partial shading and bypass diodes effect on PV characteristics. The paper investigates the dynamic performance of a commercial solar power inverter using the proposed PV source simulator in steady-state and transient conditions. Closed-loop output impedance of the proposed PV source simulator has been measured and verified at different operating regions. The impedance profile—magnitude and phase—matches the output impedance of actual PV generators. Mathematical modeling and experimental validation of the proposed system is thoroughly presented based on a 2.0 kW hardware prototype. The proposed simulator efficiency, including the active-front-end rectifier and the converter stages, peaks at 96.7%.

Power Control and Management of Distributed Generation with Unified Control Strategy

Authors:-Venkata Subba Rao Kanniganti, M.Sivanageswararao

Abstract:-This project presents a unified control strategy that enables both islanded and grid-tied operations of three-phase inverter in distributed generation, with no need for switching between two corresponding controllers or critical islanding detection. The proposed control strategy composes of an inner inductor current loop, and a novel voltage loop in the synchronous reference frame. The inverter is regulated as a current source just by the inner inductor current loop in grid-tied operation, and the voltage controller is automatically activated to regulate the load voltage upon the occurrence of islanding. Furthermore, the waveforms of the grid current in the grid-tied mode and the load voltage in the islanding mode are distorted under nonlinear local load with the conventional strategy. Finally, the effectiveness of the proposed control strategy is validated by the simulation and experimental results.

Integration of Offshore Wind Farms using L-C HVDC for Mitigating Harmonics

Authors:-SK Fayaz, SHAIK MABHU JANI

Abstract:-Experimental validation in addition to detailed modeling and simulation of a new transformer-less series compensator for line-commutated HVDC rectifier terminal is presented. The compensator employs very small capacitors compared to those in conventional shunt compensators or fixed series capacitors for reactive power compensation of such links. The proposed device demonstrates fundamental-frequency reactive power and harmonic-current compensation.

Power Quality Improvement using VSC based DSTATCOM

Authors:-SK.Saleem, BHUKYA RANGA NAIK

Abstract:-This project proposes a new algorithm to generate reference voltage for a distribution static compensator (DSTATCOM) operating in voltage-control mode. The proposed scheme exhibits several advantages compared to traditional voltage-controlled DSTATCOM where the reference voltage is arbitrarily taken as1.0 p.u. The proposed scheme ensures that unity power factor (UPF) is achieved at the load terminal during nominal operation, which is not possible in the traditional method. Also, the compensator injects lower currents and, therefore, reduces losses in the feeder and voltage-source inverter. Further, a saving in the rating of DSTATCOM is achieved which increases its capacity to mitigate voltage sag. Nearly UPF is maintained, while regulating voltage at the load terminal, during load change. The state-space model of DSTATCOM is incorporated with the deadbeat predictive controller for fast load voltage regulation during voltage disturbances. With these features, this scheme allows DSTATCOM to tackle power-quality issues by providing power factor correction, harmonic elimination, load balancing, and voltage regulation based on the load requirement. Simulation and experimental results are presented to demonstrate the efficacy of the proposed algorithm.

Line Commutated HVDC based Offshore Wind Power Integration for Harmonic Compensation

Authors:-Naga Padma Doddipati, Y.SambasivaRao

Abstract:-Experimental validation in addition to detailed modeling and simulation of a new transformer-less series compensator for line-commutated HVDC rectifier terminal is presented. The compensator employs very small capacitors compared to those in conventional shunt compensators or fixed series capacitors for reactive power compensation of such links. The proposed device demonstrates fundamental-frequency reactive power and harmonic-current compensation.