• Energy Research
• 2016-2025close

This paper presents the design and implementation of a three-phase buck type unity power factor rectifier used for distribution systems. The AC-DC converter topology considered in this paper is named as SWISS rectifier, consists of front-end three-phase diode bridge rectifier with active current injection circuit and back-end DC-DC buck converter. The characteristics of the AC-DC converter topology, including the principle of operation, modulation schemes, conduction state analysis, and control strategy are discussed in detail. Further, the analytical expression for the loss calculation is performed. Extensive simulation is carried out for the converter system, and the practicability of the converter system is verified by conducting a test on the constructed hardware prototype.

In this paper, a composite control strategy for improved off-grid configuration based on photovoltaic (PV array), a wind turbine (WT), and a diesel engine (DE) generator to achieve high performance while supplying nonlinear loads is investigated. To operate the WT efficiently under variable speed conditions and to obtain accurate and fast convergence to the maximum global operating point without a speed sensor, an iterative interpolation method is integrated with the perturbation and observation (P&O) technique. To ensure the balance of power in the system and to achieve the maximum power from the PV array without using any maximum power point tracking (MPPT) method, and ensuring stable operation during the disturbance, a double-loop control strategy for a two-switches buck-boost converter is developed. Furthermore, to protect the synchronous generator of the diesel generator (DG) from the 5th and 7th order-harmonics created by the connected nonlinear loads and to solve the issue of the filter resonance, the interfacing three-phase inverter is controlled using an improved synchronous-reference frame algorithm (SRF) with virtual impedance active damping. The presented work demonstrates effective and efficient control along with improved performance and cost-effective option as compared to the similar works reported in the literature. The performance of the presented off-grid configuration and its developed composite control strategy are tested using MATLAB/Simulink and validated through small-scale hardware prototyping.

This paper presents a multi-leg variable frequency converter based electric vehicle (EV) charger with improved adaptive current modulation strategy for fast charging operation from a single-phase distribution grid. The multi-leg bridgeless converter provides a higher utilization of input energy with a reduction in electromagnetic interference (EMI). The proposed configuration is more robust towards frequent parameter variation as the high-frequency converter leg reduces the requirement of large passive components. An adaptive sliding mode control (ASMC) has been introduced for faster dynamical control during grid-to-vehicle (G2V) and vehicle-to-grid (V2G) with diverged distribution grid conditions. The ASMC provides a better dynamical response as the tracking error is confined within the pre-defined sliding surface during an abrupt change in adaptive gain variation. The proposed control action virtually eliminates the proportional-integral (PI) controller to address more nonlinearities during the EV charging operation. A MATLAB & SIMULINK model is developed to study the various dynamical response of the converter and proposed control action. A hardware laboratory prototype is also designed for a 3.3 kW EV charger to validate the desired character with the improvement of the source-end power factor during active power exchange in the G2V mode of operation.

This paper presents a control of smart photovoltaic (PV)-distribution static compensator (DSTATCOM) grid tied system using an adaptive reweighted zero attracting control algorithm with perturb and observe maximum power point tracking technique for a three phase system to improve power quality and support the three phase ac grid by supplying power both to the grid and the connected loads. The proposed PV grid tied system is capable of working round the clock. During sunshine conditions, the proposed system performs dual functions of improving power quality by working as DSTATCOM and also transfers power to the load and the grid obtained from PV array. However, during night or cloudy conditions, the proposed system works as DSTATCOM improving power quality and the power is transferred from the grid to the load. The system is termed as a smart as it is able to perform both modes automatically sensing the PV power and is capable of multidirectional power flow. The experimental validation is carried out on a developed prototype in the laboratory under varying modes.

This paper presents an adaptive sliding mode control (ASMC) of an improved power quality standalone single phase microgrid system. The proposed microgrid system integrates a governor-less micro-hydro turbine driven single-phase two winding self-excited induction generator with a wind driven permanent magnet brushless dc generator, solar photo-voltaic (PV) array and a battery energy storage system. These renewable energy sources are integrated using only one single-phase voltage source converter (VSC). The ASMC-based control algorithm is used to estimate the reference source current which controls the single-phase VSC and regulates the voltage and frequency of the microgrid in addition to harmonics current mitigation. The proposed ASMC estimates the reference real and reactive powers of the system, which is adaptive to the fluctuating loads. The sliding mode control is used to estimate the reference real power of the system to maintain the energy balance among wind, micro-hydro, solar PV power, and BESS, which controls the frequency of standalone microgrid. The proposed microgrid is implemented in real time using a digital signal processor controller. Test results of proposed microgrid shows that the grid voltage and frequency are maintained constant while the system is following a sudden change in loads and under intermittent penetration of wind and solar energy sources.

For the quick and accurate dynamic response of a sensorless drive system, proper estimation of position and speed is indispensable. A conventional sliding mode observer (SMO) based sensorless control has several limitations like undesired frequency swing during phase jump, spurious noise speed reversal issue. This paper presents an improved SMO based sensorless control and finite control set model predictive control (FCS-MPC) of permanent magnet synchronous motor (PMSM) EV drive with regenerative braking. An improved phase locked loop (PLL) with a modified control function is utilized to obtain position and speed. It provides a smooth startup and avoids transient in frequency and singularities issues. To avoid cascading linear controllers, a robust FCS-MPC is employed in this paper. It provides switching pulses directly to the switches of voltage source inverter (VSI), which avoids the use of modulators. The proposed sensorless control method for an electric vehicle (EV) application is simulated using Simulink and the effectiveness and compatibility of this control algorithm is verified.

A new wind energy conversion system (WECS), with a position sensor-less synchronous reluctance generator (SynRG), integrated to the grid is proposed in this paper. Simple, brushless, compact structure of SynRG along with a full-scale converter makes it suitable for wind power applications. SynRG offers a fast dynamic response due to the absence of permanent magnets and windings in the rotor thus eliminating rotor losses completely. The torque pulsation from wind turbine (WT) are prevented from being transmitted to the grid by making use of a back-to-back (BTB) connected full-scale converters. The WECS and the grid are sharing a common DC-link through their respective voltage source converters (VSCs). The VSC connected to the machine side provides the required reactive power to the SynRG and operates it at a speed decided by the maximum power point (MPP) algorithm. A rotor position/speed sensor-less field-oriented control is implemented for controlling the SynRG. A fast, accurate, and oscillation-less adaptive observer based algorithm is introduced for the grid integration of WECS. MATLAB®/Simulink platform is used for the modeling and simulation of the system and a laboratory prototype is used for its experimental validation.

Une nouvelle stratégie de contrôle pour un micro-réseau éolien-BES (stockage d'énergie par batterie) est présentée, qui contrôle le transfert de puissance et le mode de fonctionnement de manière transparente d'un mode îlot (IM) au mode connecté au réseau (GCM) et vice versa. Dans GCM, la régulation de la tension de liaison CC, la compensation de la puissance réactive de charge et l'atténuation du courant harmonique sont effectuées par le convertisseur de source de tension côté charge (LVSC) à l'aide d'un algorithme de commande basé sur un intégrateur de signal sinusoïdal double (DSSI). La puissance maximale de la production éolienne est extraite en faisant fonctionner le convertisseur de source de tension côté générateur (GSC). Au défaut de réseau ou aux perturbations de réseau, ce micro-réseau fonctionne en IM et LVSC est contrôlé en mode de contrôle de tension. Un contrôleur de synchronisation est utilisé pour contrôler le fonctionnement de la synchronisation. Les distorsions de tension du courant du réseau et du point de couplage commun (PCC) sont maintenues dans la limite des normes IEEE-519-2014 et IEEE-1547. Le fonctionnement du système est démontré par des résultats d'essais dans plusieurs conditions telles que des vitesses de vent changeantes, des charges variables et une transition transparente. Se presenta una nueva estrategia de control para una microrred Wind-BES (almacenamiento de energía de batería), que controla la transferencia de energía y el modo de operación sin problemas desde un modo aislado (IM) al modo conectado a la red (GCM) y viceversa. En GCM, la regulación de voltaje de enlace de CC, la compensación de potencia reactiva de carga y la mitigación de corriente de armónicos son realizadas por el convertidor de fuente de voltaje del lado de carga (LVSC) utilizando un algoritmo de control basado en integrador de señal sinusoidal doble (DSSI). La potencia máxima de la generación eólica se extrae haciendo funcionar el convertidor de fuente de tensión (GSC) del lado del generador. En la falla de la red o las perturbaciones de la red, esta microrred funciona en IM y LVSC se controla en el modo de control de voltaje. Se utiliza un controlador de sincronización para controlar el funcionamiento de la sincronización. La corriente de red y las distorsiones de voltaje del punto de acoplamiento común (PCC) se mantienen dentro del límite según las normas IEEE-519-2014 y IEEE-1547. El funcionamiento del sistema se demuestra a través de los resultados de las pruebas en varias condiciones, como el cambio de la velocidad del viento, la variación de las cargas y la transición sin problemas. A new control strategy for a wind-BES (battery energy storage) microgrid is presented, which controls the power transfer and the mode of operation seamlessly from an islanded mode (IM) to the grid connected mode (GCM) and vice versa. In GCM, the DC link voltage regulation, the load reactive power compensation and harmonics current mitigation are performed by the load side voltage source converter (LVSC) using a double sinusoidal signal integrator (DSSI) based control algorithm. The maximum power from the wind generation is extracted by operating the generator side voltage source converter (GSC). At the grid fault or grid disturbances, this microgrid operates in IM and LVSC is controlled in the voltage control mode. A synchronizing controller is utilized to control the operation of synchronization. The grid current and point of common coupling (PCC) voltage distortions are kept within the limit as per the IEEE-519-2014 and the IEEE-1547 standards. The system operation is demonstrated through test results at several conditions such as, changing wind speeds, varying loads and seamless transition. يتم تقديم استراتيجية تحكم جديدة لشبكة الرياح الصغيرة (تخزين طاقة البطارية)، والتي تتحكم في نقل الطاقة ووضع التشغيل بسلاسة من الوضع الجزري (IM) إلى وضع توصيل الشبكة (GCM) والعكس صحيح. في GCM، يتم تنفيذ تنظيم جهد وصلة التيار المستمر، وتعويض القدرة التفاعلية للحمل وتخفيف التيار التوافقي بواسطة محول مصدر جهد جانب الحمل (LVSC) باستخدام خوارزمية تحكم قائمة على مدمج إشارة جيبية مزدوجة (DSSI). يتم استخراج الطاقة القصوى من توليد الرياح عن طريق تشغيل محول مصدر الجهد الجانبي للمولد (GSC). عند حدوث عطل في الشبكة أو اضطرابات في الشبكة، تعمل هذه الشبكة الصغيرة في IM ويتم التحكم في LVSC في وضع التحكم في الجهد. يتم استخدام وحدة تحكم مزامنة للتحكم في تشغيل المزامنة. يتم الاحتفاظ بتيار الشبكة ونقطة تشوهات جهد الاقتران المشترك ضمن الحد وفقًا لمعايير IEEE -519-2014 و IEEE -1547. يتم توضيح تشغيل النظام من خلال نتائج الاختبار في عدة ظروف مثل تغيير سرعات الرياح والأحمال المتغيرة والانتقال السلس.