Control and grid integration of MW-range wind and solar energy conversion systems

Solar-based energy generation has increased by more than ten times over the same period. In total, worldwide electrical energy consumption increased by approximately 6340 TWh from 2003 to 2013. To meet the challenges created by intermittent energy generation sources, grid operators have increasingly demanded more stringent technical requirements for the connection and operation of grid-connected intermittent energy systems, for instance concerning fault ride through capability, voltage and frequency support, and inertia emulation. Ongoing developments include new or improved high-voltage converters, power converters with higher power density, control systems to provide ride-through capability, implementation of redundancy schemes to provide more reliable generation systems, and the use of high-voltage direct current (HVdc) links for the connection of large off-shore intermittent energy systems

Analisis Simulasi Inverter Multilevel Kaskade dengan Teknik Selective Harmonic Elimination Pulse Width Modulation

Salah satu teknik pengendalian saklar-saklar semikonduktor daya dari inverter multilevel adalah menggunakan Pulse Width Modulation (PWM). Dari berbagai teknik PWM, Selective Harmonic Elimination Pulse Width Modulation (SHEPWM) merupakan teknik yang andal dalam mengeliminasi harmonisa-harmonisa tingkat rendah. Tujuan dari makalah ini adalah menjabarkan proses perhitungan, perancangan dan simulasi inverter multilevel kaskade dengan menggunakan teknik SHEPWM. Pulsa-pulsa pensaklaran setiap saklar semikonduktor daya inverter dibangun berdasarkan sudut-sudut pensaklaran optimum agar komponen harmonisa tertentu dapat tereliminasi. Demikian pula gelombang tegangan AC yang dihasilkan dapat diprediksi bentuknya berdasarkan hasil rancangan. Selanjutnya simulasi komputer dilakukan dengan perantara perangkat lunak PSPICE. Analisis hasil simulasi terhadap inverter 9-level menunjukkan komponen harmonisa ke-3, 5 dan 7 tereliminasi sama sekali. Hasil ini sesuai dengan perhitungan dan perancangan secara teoritis

A novel five-level switched capacitor type inverter topology for grid-tied photovoltaic application

This paper presents a novel five-level inverter topology and associated control scheme. The proposed structure consists of a capacitor and eight active switching elements. It requires only one dc source and is capable of generating five voltage levels with double voltage boosting gain. On the other hand, it does not require any control scheme to balance the capacitor in the DC-bus due to inherent voltage balancing capability. As a result, the control complexity reduces a lot. Brief analysis followed by simulation and measurement results of a proposed 5-level inverter using the finite control set model predictive control (FCS-MPC) algorithm is presented. Detail of the analysis with more measurement result and comparison will be presented in the final paper

Wind Farm Grid Integration Architecture using Unified Expandable Power Converter

IEEE This paper proposes a novel unified expandable low switch power electronic converter architecture for grid integration of direct drive variable speed wind turbine (VSWT) system using permanent magnet synchronous generator (PMSG). The proposed unified expandable power converter (UEPC) can interface two or more bidirectional output ports such as wind generators, energy storages and grid. The size of the power converter is compact because of low number of power electronic switches and protection devices and its architecture is easily expandable to accommodate more outputs, i.e., in this case, the wind turbines. A generalized sequential space vector modulation technique is developed based on the operational principle of the proposed converter to control of the outputs autonomously in order to track maximum power point for individual VSWTSs driven PMSG's. It is expected that the proposed approach will reduce the cost of power electronic converters in a wind farm compared to both AC- and DC-link based topologies, which are available for the momen

Flexible cascaded multilevel inverter with multiple operation modes

In this paper, a flexible cascaded multilevel inverter is proposed with a wide operational range. The inverter can change its topology structure to operate in three modes by a bidirectional switch unit. The nine-level or five-level mode of the inverter is adopted to optimize the output waveform when the input power is low. To decrease power losses, the three-level mode of the inverter is adopted to reduce the number of active switch devices when the input power is high. The topology and modulation strategy of the proposed inverter are presented and analyzed. The total losses and current THD of the inverter are calculated. In addition, simulations and experiments are conducted. The obtained simulation and experimental results indicate the correctness and feasibility of the proposed inverter and its modulation strategy

Algorimto Mppt Mediante Variación de Fase de Amplitud en Inversor Fotovoltaico Multinivel Conectado a la Red

This paper presents a two-stage, common-source, single-phase, cascade, H-bridge, multilevel photovoltaic inverter that adopts a maximum power point tracking algorithm that at the same time enables synchronization and grid monitoring. the 2-stage common source cascade H-bridge converter allows that the entire device works with a single source, provided by the array of photovoltaic generator, and allows the maximum number of levels in the voltage waveform, for this case it would be 9. For the algorithm, a PLL is used as a synchronization technique and the proposed control strategy allows to regulate the active and reactive power in a simplified way by changing the phase angle and amplitude of the modulated sinusoidal signal that controls the inverter. To the maximum power point tracking, the phase angle is controlled and to regulate the supply of reactive power the amplitude of the modulated wave is modified. The article describes the operating principles of both the inverter and the proposed technique, in the same way the modelling of the system is presented in the specialized software Matlab Simulink and it is tested in different irradiance, temperature and load scenarios in order to verify the response of the proposed device faces changes that allow validating the correct operation of the control and the inverter  En este artículo se presenta un inversor fotovoltaico multinivel monofásico de puente H en cascada, de fuente común de dos etapas, que adopta un algoritmo de seguimiento de máximo punto de potencia que al mismo tiempo permite realizar la sincronización y monitoreo de la red, se utiliza el convertidor de puentes H en cascada de fuente común de 2 etapas con el fin de que el dispositivo completo funcione con una única fuente, proporcionada por el arreglo de paneles fotovoltaicos, y permita tener el máximo número de niveles en la onda de tensión que para este caso sería de 9. Para el algoritmo se utiliza un PLL como técnica de sincronización y la estrategia de control propuesta permite regular la potencia activa y reactiva de una manera simplificada mediante el cambio del ángulo de fase y amplitud de la señal sinusoidal modulada que controla el inversor. Para obtener el máximo punto de potencia se controla el ángulo de fase y para regular el aporte de reactivos se varía la amplitud de la onda modulada. En el artículo se describe los principios de funcionamiento tanto del inversor como de la técnica propuesta, de igual forma se presenta el modelado del sistema en el software especializado Simulink de Matlab y se prueba frente a diferentes escenarios de irradiancia, temperatura y carga con el fin de verificar la respuesta del dispositivo propuesto frente a cambios que permitan validar el correcto funcionamiento del control y el inversor

Performance assessment of grid-interactive solar photovoltaic projects under India’s national solar mission

Lack of long-term global solar radiation data has often been a significant challenge to the solar power sector development primarily in developing countries. The choice of a solar radiation database is projected to have a considerable impact on the predicted performance of a solar power project and consequently on its techno-commercial viability. Therefore, use of reliable and well- characterized solar radiation data source is important for bankability of solar power projects. This study presents the technical and economic performance evaluation of grid-interactive solar photovoltaic (PV) projects implemented under the first phase of India’s national solar mission. For performance assessment, we compare annual energy yield predictions using several solar radiation databases and monitored data of 39 solar PV power plants located across the country. Technical simulations have been carried out for each project location using static and dynamic solar irradiance data obtained from various databases available in the Indian context. PVSYST software has been used for energy yield assessment of solar PV projects after taking into account the key design and technical parameters and associated energy losses during solar energy conversion. The inter-comparability of capacity utilization factor and levelized cost of electricity of operational solar PV projects have also been analyzed with the estimates obtained through different solar radiation databases. Mutual deviation for the techno-economic performance of solar PV projects varied from −12% to 31% for the projects under the first phase of India’s solar mission. Our study indicates that the long-term measured or high-resolution time series databases should be preferred for the bankability of solar power projects. Further, solar power policies of the country must provide clear guidelines for selection of solar radiation databases to enhance their bankability

Multilevel Inverter Topology for Renewable Energy Grid Integration

International audienceIn this paper, a novel three-phase parallel grid connected multilevel inverter (MLI) topology with a novel switching strategy are proposed. This Inverter is intended to feed a microgrid from renewable energy sources (RES) to overcome the problem of the polluted sinusoidal output in classical inverters and to reduce component count, particularly for generating a multilevel waveform with a large number of levels. The proposed power converter consists of n two-level (n + 1) phase inverters connected in parallel, where n is the number of RES. The more the number RES, the more the number of voltage levels, the more faithful is the output sinusoidal wave form. In the proposed topology, both voltage pulse width and height are modulated and pre-calculated by using a pulse width and height modulation (PWHM) so as to reduce the number of switching states (i.e. switching losses) and the total harmonic distortion (THD). The topology is investigated through simulations and validated experimentally with a laboratory prototype. Compliance with the IEEE 519-1992 and IEC 61000-3-12 standards is presented and an exhaustive comparison of the proposed topology is made against the classical cascaded H-bridge topology