Control structure for single-phase stand-alone wind-based energy sources

This paper is analyzing the operation of a standalone wind turbine system with variable speed Permanent Magnet Synchronous Generator (PMSG) and a system for storing energy during wind speed and load variations. Energy storage devices are required for power balance and power quality in stand alone wind energy systems. Initially, the holistic model of the entire system is achieved, including the PMSG, the boost converter and the storage system. The power absorbed by the connected loads can be effectively delivered and supplied by the proposed wind turbine and energy storage systems, subject to an appropriate control method. The main purpose is to supply 230 V/50 Hz domestic appliances through a single-phase inverter. The simulation results, validated by experimental testing, show a good prediction of the electrical parameter waveforms. The control system is implemented on a dSPACE DS1103 real-time board. Furthermore, the results confirm the stability of the supply

AMELIORATE DIRECT POWER CONTROL OF STANDALONE WIND ENERGY GENERATION SYSTEM BASED ON PERMANENT MAGNET SYNCHRONOUS GENERATOR BY USING FUZZY LOGIC CONTROL

Purpose. Electricity is a basic energy for life and its consumption increased so we need the discovery of new sources of energy such as wind energy .for this ameliorate the quality of generated wind energy by using the intelligent artificial control, this control is made to optimize the performance of three-phase PWM rectifier working. Methodology. These strategies are based on the direct control of the instantaneous power, namely: the control direct power control (DPC) with classic PI regulator and direct power control with fuzzy logic regulator. The fuzzy characterized by its ability to deal with the imprecise, the uncertain has been exploited to construct a fuzzy voltage regulator. The simulation of these methods was implemented using Matlab/Simulink. Results. A comparison with the results obtained by the classic PI showed the improvement in dynamic performance. This makes the fuzzy controller an acceptable choice for systems requiring quick, precise adjustments and less sensitive to outside disturbances. Originality. The proposed this control strategy using for to obtain a performance adjustment of the DC bus voltage and sinusoidal currents on the network side. Practical value. Fuzzy logic is proven to be effective in terms of reducing the harmonic distortion rate of the currents absorbed, correct adjustment of the active and reactive power and DC voltage and unit power factor operation.Мета. Електроенергія є основною енергією для життя, і її споживання збільшується, тому нам необхідно відкриття нових джерел енергії, таких як енергія вітру. Для поліпшення якості енергії вітру, що генерується за допомогою управління на основі штучного інтелекту, таке управління призначене для оптимізації продуктивності роботи трифазного ШІМ випрямляча. Методологія. Дані стратегії засновані на прямому управлінні миттєвою потужністю, а саме: пряме управління потужністю з класичним ПІ-регулятором і пряме управління потужністю регулятором з нечіткою логікою. Нечіткість, що характеризується її здатністю справлятися з неточністю, невизначеністю, була використана для створення нечіткого регулятора напруги. Моделювання цих методів було реалізовано за допомогою Matlab/Simulink. Отримані результати. Порівняння з результатами, отриманими за допомогою класичного ПІ-регулятора, показало поліпшення динамічних характеристик. Це робить нечіткий контролер прийнятним вибором для систем, що вимагають швидкої і точної настройки і менш чутливих до зовнішніх перешкод. Оригінальність. Запропоновано стратегію управління, що використовує для отримання регулювання продуктивності напруги шини постійного струму і синусоїдальні струми на стороні мережі. Практична цінність. Доведено, що нечітка логіка ефективна з точки зору зниження коефіцієнта гармонійних спотворень поглинаються струмів, коректного регулювання активної і реактивної потужності і постійної напруги, а також коефіцієнта потужності роботи блоку.

SENSORLESS DIRECT POWER CONTROL FOR THREE-PHASE GRID SIDE CONVERTER INTEGRATED INTO WIND TURBINE SYSTEM UNDER DISTURBED GRID VOLTAGES

Wind turbines with permanent magnet synchronous generator (PMSG) are widely used as sources of energy connected to a grid. The studied system is composed of a wind turbine based on PMSG, a bridge rectifier, a boost converter, and a controlled inverter to eliminate low-order harmonics in grid currents under disturbances of grid voltage. Traditionally, the grid side converter is controlled by using the control VFOC (Virtual Flux Oriented Control), which decouple the three-phase currents indirect components (id) and in quadratic (iq) and regulate them separately. However, the VFOC approach is dependent on the parameters of the system. This paper illustrates a new scheme for the grid-connected converter controller. Voltage imbalance and harmonic contents in the three-phase voltage system cause current distortions. Hence, the synchronization with the network is an important feature of controlling the voltage converter. Thus, a robust control method is necessary to maintain the adequate injection of the power during faults and/or a highly distorted grid voltage. The proposed new control strategy is to use the direct power control based virtual flux to eliminate side effects induced by mains disturbances. This control technique lowers remarkably the fluctuations of the active and reactive power and the harmonic distortion rate. The estimated powers used in the proposed control approach is calculated directly by the positive, negative, and harmonic items of the estimated flux and the measured current without line sensor voltage.Ветряные турбины с синхронным генератором на постоянных магнитах (PMSG) широко используются в качестве источников энергии, подключенных к сети. Исследуемая система состоит из ветряной турбины на основе PMSG, мостового выпрямителя, повышающего преобразователя и управляемого инвертора для устранения гармоник низкого порядка в токах сетки при возмущениях напряжения сети. Традиционно преобразователь на стороне сети управляется с помощью виртуального потокоориентированного управления VFOC (Virtual Flux Oriented Control), который разделяет трехфазные токи на косвенные компоненты (id) и на квадратичные компоннеты (iq) и регулирует их отдельно. Однако подход VFOC зависит от параметров системы. Данная статья иллюстрирует новую схему для контроллера преобразователя, подключенного к сети. Дисбаланс напряжения и содержание гармоник в трехфазной системе напряжения вызывают искажения тока. Следовательно, синхронизация с сетью является важной особенностью управления преобразователем напряжения. Таким образом, надежный метод управления необходим для поддержания адекватной подачи энергии во время неисправностей и/или значительно искаженного напряжения сети. Предложенная новая стратегия управления заключается в использовании виртуального потока на основе прямого управления мощностью для устранения побочных эффектов, вызванных помехами в сети. Этот метод управления значительно снижает колебания активной и реактивной мощности и уровень гармонических искажений. Оценочные мощности, используемые в предлагаемом подходе к управлению, рассчитываются непосредственно по положительным, отрицательным и гармоническим элементам оцененного потока и измеренного тока без напряжения линейного датчика

Simulation Methodology for Control of PV- Wind Hybrid System

ABSTRACT:With the increasing power demand the need for generation of useful power is important. Renewable energy generation is one efficient method for producing useful power. With proper power flow control, the efficiency of power transfer increases. This paper provides an efficient power control technique namely the active-reactive power control and dump power control along with auto master-slave control. This paper also provides more efficient control compared to the paper in reference. It can be used in isolated islands as the power line is flexible, so more number of power sources can interconnected in the system there by more power can be generated. KEYWORDS:Hybrid I.INTRODUCTION Natural energy based power generation systems are commonly equipped with storage batteries, to regulate output fluctuations resulting from natural energy variations. Therefore, it is necessary to prevent battery overcharging There aredifferent ways by which the power flow can be controlled; one best method is the active-reactive power control. The active-reactive power control uses phase locked loop (PLL) and parallel operation of inverters for controlling the active and the reactive power of the system. PLL keeps the entire system in a locked state at a single frequency there by controlling the active power of the system. So use of PLL controls the active power efficiently [9]

Real-time testing of energy storage systems in renewable energy applications

Energy storage systems provide a promising solution for the renewable energy sector to facilitate large-scale grid integration. It is thus very important to explore means to validate their control scheme and their behaviour in the intended application before actual commissioning. This paper presents a reduced-scale hardware-in-the-loop simulation for initial testing of the performance of energy storage systems in renewable energy applications. This relieves the need of selecting and tuning a detailed model of the energy storage element. A low-power test rig emulating the storage element and the power converter is interfaced with a real time digital simulator to allow dynamic experimental tests under realistic conditions. Battery energy storage for smoothing the output power of a variable speed wind turbine is considered in this paper; however the proposed test methodology can be easily adapted for other storage elements in renewable energy, distributed generation and smart grid applications. The proposed HIL simulation is detailed and the experimental performance is shown

Selection guidelines for wind energy technologies

The building block of all economies across the world is subject to the medium in which energy is harnessed. Renewable energy is currently one of the recommended substitutes for fossil fuels due to its environmentally friendly nature. Wind energy, which is considered as one of the promising renewable energy forms, has gained lots of attention in the last few decades due to its sustainability as well as viability. This review presents a detailed investigation into this technology as well as factors impeding its commercialization. General selection guidelines for the available wind turbine technologies are presented. Prospects of various components associated with wind energy conversion systems are thoroughly discussed with their limitations equally captured in this report. The need for further optimization techniques in terms of design and materials used for the development of each component is highlighted

Desenvolvimento e implementação de algoritmos de controlo para turbinas eólicas de baixo custo

O acesso à eletricidade é um requisito básico e indispensável para o desenvolvimento sustentável da humanidade e para o crescimento económico. Em zonas rurais e remotas o acesso à eletricidade ainda é uma irrealidade. O fato de existir um número reduzido de pessoas a habitar nestas zonas, e portanto, um baixo consumo de energia, torna complicada ou mesmo impraticável a utilização das tecnologias tradicionais de fornecimento de energia. Assim, a utilização de turbinas eólicas de pequenas dimensões pode ser uma solução prática para o fornecimento de energia, nestas zonas. Uma vez que é necessário maximizar a energia extraída a partir do vento para que as turbinas eólicas se tornem rentáveis e se apresentem como uma tecnologia eficiente, a utilização de algoritmos de controlo eficazes é extremamente importante. Nesta dissertação, diversos algoritmos de monitorização do ponto de potência máxima (MPPT) foram desenvolvidos e implementados e, após a escolha do algoritmo que melhor satisfazia todos os requisitos exigidos (simplicidade, facilidade de implementação, fiabilidade e custo reduzido), propôs-se um sistema de energia eólica autónomo e de pequenas dimensões para a eletrificação de zonas rurais e remotas. Verificou-se que os algoritmos que melhor satisfaziam os requisitos exigidos eram os algoritmos Perturb & Observe (P&O) pois, ao contrário dos outros, não é necessário um conhecimento prévio das características das turbinas, diminuindo portanto a complexidade e o custo do sistema. Confirmou-se ainda através dos resultados da simulação dinâmica, que o sistema proposto é adequado para a realização de um fornecimento de energia confiável sob variações de carga e da velocidade do vento em locais isolados.Access to electricity is a basic requirement essential to the human sustainable development and for the economic growth. In rural and remote areas, the access to electricity is still an unreality. The existence of a small number of people inhabiting these areas, and therefore their low power consumption, makes the application of traditional technologies for energy supply very difficult or even not feasible. Thus, the use of small scale wind turbines can be a practical solution for the energy supply in these regions. Since it is necessary to maximize the energy extracted from the wind so that the wind turbines are profitable and stand as an efficient technology, the use of effective control algorithms is extremely important. In this dissertation, several maximum power point tracking (MPPT) algorithms were developed and implemented. Once chosen the algorithm that best met all the specified requirements (simplicity, ease of implementation, reliability and reduced cost), it was proposed an autonomous small-scale wind power system for rural and remote area electrification. It was found that the algorithms that best met the requirements were the Perturb & Observe (P&O) algorithms because, unlike the others, a prior knowledge of the turbine characteristics is not necessary, thus reducing system complexity and cost. Dynamic simulation confirmed that the proposed system is suitable for a reliable power supply under load and wind speed variations in isolated locations

Contribution to Wind Energy Conversion Systems in Urban and Remote Areas

Recently, there is a growing interest in the use of wind energy in buildings environment for distributed generation systems. However, the prediction of the wind speed and energy in such environment is difficult, due to the roughness and the frictional effects which reduce the wind speed close to the ground. Moreover, the adjacent buildings affect the wind regime around a specific building in the urban environment. Therefore, a method for appropriate estimating of the wind speed and energy over the buildings’ roofs is required for the initial stages of the wind energy development in the urban environment. This thesis provides a novel method of estimating the wind speed and energy using a wind tunnel. The method has been validated using two case studies, homogeneous and non-homogeneous terrain. The Permanent Magnet Generator (PMG) is preferred in small Wind Energy Conversion System (WECS) for stand-alone and remote areas. A new technique to control the flux of the PMG for WECS applications has been developed and used in this thesis for voltage regulation purposes. By selecting a suitable value of d-axis current, the terminal voltage of the PM generator can be regulated for variable wind speed. Consequently, the terminal voltage across the load is also regulated. No special mechanical techniques or additional electromagnetic coils are used for this purpose. The effect of the PMG flux control on the reactive power compensating capability for a variable inductive load has also been studied for WECS applications. The case study presented in this thesis shows how the reactive power consumed by the load was compensated using the flux control operation of the system. The controller shows highly effective response during steady state and transient. A flux controller of a permanent magnet variable flux machine (PM-VFM) has also been designed and presented in the thesis for voltage regulation purposes. The controller is designed based on injecting d-axis current pulses for short periods of time. These pulses have negligible losses which reduces the machine losses and increases the machine efficiency

A multi-modular second life hybrid battery energy storage system for utility grid applications

The modern grid system or the smart grid is likely to be populated with multiple distributed energy sources, e.g. wind power, PV power, Plug-in Electric Vehicle (PEV). It will also include a variety of linear and nonlinear loads. The intermittent nature of renewable energies like PV, wind turbine and increased penetration of Electric Vehicle (EV) makes the stable operation of utility grid system challenging. In order to ensure a stable operation of the utility grid system and to support smart grid functionalities such as, fault ride-through, frequency response, reactive power support, and mitigation of power quality issues, an energy storage system (ESS) could play an important role. A fast acting bidirectional energy storage system which can rapidly provide and absorb power and/or VARs for a sufficient time is a potentially valuable tool to support this functionality. Battery energy storage systems (BESS) are one of a range suitable energy storage system because it can provide and absorb power for sufficient time as well as able to respond reasonably fast. Conventional BESS already exist on the grid system are made up primarily of new batteries. The cost of these batteries can be high which makes most BESS an expensive solution. In order to assist moving towards a low carbon economy and to reduce battery cost this work aims to research the opportunities for the re-use of batteries after their primary use in low and ultra-low carbon vehicles (EV/HEV) on the electricity grid system. This research aims to develop a new generation of second life battery energy storage systems (SLBESS) which could interface to the low/medium voltage network to provide necessary grid support in a reliable and in cost-effective manner. The reliability/performance of these batteries is not clear, but is almost certainly worse than a new battery. Manufacturers indicate that a mixture of gradual degradation and sudden failure are both possible and failure mechanisms are likely to be related to how hard the batteries were driven inside the vehicle. There are several figures from a number of sources including the DECC (Department of Energy and Climate Control) and Arup and Cenex reports indicate anything from 70,000 to 2.6 million electric and hybrid vehicles on the road by 2020. Once the vehicle battery has degraded to around 70-80% of its capacity it is considered to be at the end of its first life application. This leaves capacity available for a second life at a much cheaper cost than a new BESS Assuming a battery capability of around 5-18kWhr (MHEV 5kWh - BEV 18kWh battery) and approximate 10 year life span, this equates to a projection of battery storage capability available for second life of >1GWhrs by 2025. Moreover, each vehicle manufacturer has different specifications for battery chemistry, number and arrangement of battery cells, capacity, voltage, size etc. To enable research and investment in this area and to maximize the remaining life of these batteries, one of the design challenges is to combine these hybrid batteries into a grid-tie converter where their different performance characteristics, and parameter variation can be catered for and a hot swapping mechanism is available so that as a battery ends it second life, it can be replaced without affecting the overall system operation. This integration of either single types of batteries with vastly different performance capability or a hybrid battery system to a grid-tie 3 energy storage system is different to currently existing work on battery energy storage systems (BESS) which deals with a single type of battery with common characteristics. This thesis addresses and solves the power electronic design challenges in integrating second life hybrid batteries into a grid-tie energy storage unit for the first time. This study details a suitable multi-modular power electronic converter and its various switching strategies which can integrate widely different batteries to a grid-tie inverter irrespective of their characteristics, voltage levels and reliability. The proposed converter provides a high efficiency, enhanced control flexibility and has the capability to operate in different operational modes from the input to output. Designing an appropriate control system for this kind of hybrid battery storage system is also important because of the variation of battery types, differences in characteristics and different levels of degradations. This thesis proposes a generalised distributed power sharing strategy based on weighting function aims to optimally use a set of hybrid batteries according to their relative characteristics while providing the necessary grid support by distributing the power between the batteries. The strategy is adaptive in nature and varies as the individual battery characteristics change in real time as a result of degradation for example. A suitable bidirectional distributed control strategy or a module independent control technique has been developed corresponding to each mode of operation of the proposed modular converter. Stability is an important consideration in control of all power converters and as such this thesis investigates the control stability of the multi-modular converter in detailed. Many controllers use PI/PID based techniques with fixed control parameters. However, this is not found to be suitable from a stability point-of-view. Issues of control stability using this controller type under one of the operating modes has led to the development of an alternative adaptive and nonlinear Lyapunov based control for the modular power converter. Finally, a detailed simulation and experimental validation of the proposed power converter operation, power sharing strategy, proposed control structures and control stability issue have been undertaken using a grid connected laboratory based multi-modular hybrid battery energy storage system prototype. The experimental validation has demonstrated the feasibility of this new energy storage system operation for use in future grid applications