Wind-diesel System Research Articles

The SVC Additional Adaptive Voltage Controller of Isolated Wind-Diesel Power System Based on Double Sliding-Mode Optimal Strategy

Due to the voltage fluctuation resulting from variable wind energy and reactive load change in an isolated wind-diesel hybrid system, an additional adaptive voltage compensation controller for static var compensator (SVC) by using double sliding-mode (SM) optimal strategy is proposed to maintain the system bus voltage stability. Considering the uncertainties of SVC model parameters and unobservable state variables, the SM algorithm is used to design the robust state observer and SVC adaptive voltage controller. The mathematical state model of isolated wind-diesel hybrid power system together with SVC is established, and then, the SM robust observer is constructed to estimate the SVC state variables. In order to improve the system bus voltage stability, an additional robust adaptive voltage controller is designed for SVC by selecting appropriate switching surface and adaptive reaching condition. The proposed control strategy is shown to be effective through opal-RT OP5600 simulator together with TIF28335 DSP for the isolated wind-diesel system under different operation point.

Improved frequency control of a micro-grid with a genetically tuned fuzzy controlled super-capacitor system

In this paper, genetically tuned fuzzy controlled super-capacitor energy storage system (SCESS) is employed to improve the frequency control of a hybrid wind-diesel system. Super-capacitor is interfaced with the system through voltage source converter and bidirectional DC-DC buck-boost converter. The fuzzy logic controller for SCESS is designed in such a way that the effect of load disturbance is continuously mitigated while considering the operational constraints of SCESS. The membership functions of fuzzy controller are tuned by employing genetic algorithm (GA) for optimal performance. Optimised membership functions are reached out by introducing a regulated variable based on supercapacitor voltage and frequency deviation of the system. To validate the proposed scheme, detailed model is developed and tested in MATLAB/Simulink environment.

Modelling and performance assessment of a standalone hybrid wind-diesel-superconducting magnetic energy storage system using four-quadrant operation of superconducting magnetic energy storage

In this article, a comprehensive model for power quality assessment of a standalone wind-diesel-superconducting magnetic energy storage system is developed using firing angle control scheme of superconducting magnetic energy storage unit. A four-quadrant operation of superconducting magnetic energy storage unit is proposed where firing angle of superconducting magnetic energy storage converter is controlled depending upon active and reactive power demand of wind-diesel system, under various disturbances. Superconducting magnetic energy storage is designed as a controllable current source capable of reducing both frequency and voltage deviations simultaneously. For continuous control of superconducting magnetic energy storage unit, a regulating variable is formulated which forces the superconducting magnetic energy storage current to return to its nominal value after handling a disturbance in order to handle a new disturbance. Frequency of the system is estimated using the concept of centre of inertia. System performance is assessed for disturbances of higher magnitudes. Complete modelling is carried out in MATLAB/Simulink environment, and simulation results demonstrate that the scheme gives expected results under load disturbance and wind perturbations.

MATLAB/Simulink-based modelling and performance assessment of wind–diesel energy storage system

In this article, a comprehensive model is developed to study the performance of a hybrid wind–diesel energy storage system. Energy storage system exchanges both real and reactive power with the wind–diesel system to improve both frequency and voltage. For obtaining pre-disturbance steady-state scenario of the system, a modified load flow algorithm is proposed which calculates induction machine slip and other initial conditions, in addition to the results obtained with conventional load flow. A compact model is developed by integrating network model, energy storage system and machine equations along with the associated control systems. For frequency estimation concept, centre of inertia is utilised. Energy storage system is modelled as a controllable current source. Complete modelling is carried out in MATLAB/Simulink environment. Simulations are carried out for load disturbance as well as wind perturbations to demonstrate the efficacy of the proposed scheme.

Design and Implementation of ANFIS Based Controller on Variable Speed Isolated Wind-Diesel Hybrid System for Better Performance

In this paper, a transient study on Isolated Wind-Diesel Hybrid System (IWDHS) of 200 kW has been carried out in MATLAB/SIMULINK environment. The detailed model of synchronous generator coupled to diesel engine, self-excited induction generator and load is studied and considered for analyzing the dynamic behavior of IWDHS. It has been taken into consideration that most of the time; the energy is to be provided by wind turbine in comparison to diesel generator. Instead of a fixed wind speed, the IWDHS is being supplied by variable wind speeds. that are more than its nominal value (10 m/s). This function is accomplished by using a conventional PI controller which regulates the pitch angle of the wind turbine blades during incoming varying gusts of wind. Further the system performance is improved by implementing an ANFIS controller. A controller design process is identified; it consists of generating input-output data pairs to identify the control variables range and initial fuzzy memberships, and then to tune or adapt them using an ANFIS network structure. The control objective was to extract maximum power at varying wind speeds and to limit the power as well as improve settling time at rated value at high wind speeds. The simulations have shown how advantageous an ANFIS based controller is over a conventional PI controller.

Firefly Optimization Algorithm for the Reactive Power Control of an Isolated Wind-Diesel System

This paper investigates the application of firefly optimization algorithm to design an optimal control for voltage stability of a stand-alone hybrid renewable generation unit based on reactive power control. The studied renewable generation unit mainly consists of a permanent magnet induction generator driven by wind turbine and a synchronous generator driven by diesel engine. A STATCOM is used to stabilize the terminal load bus voltage via compensating of reactive power. The main control objective aims to stabilize the terminal load voltage against any disturbances in load reactive power and/or input wind power by adjusting the total system reactive power. This is accomplished by controlling STATCOM phase angle and hence to control the load bus voltage and also by controlling the excitation voltage of the synchronous generator. The proposed renewable energy power system based on the proposed optimal controller has been tested through step change in input wind power and load reactive power. The system performance based on the proposed control is compared with model predictive control, a robust H∞ control, and a classical PI control.

Techno-Economic and Environmental Analysis of Wind-Diesel Power System

Techno-Economic and Environmental Analysis of Wind-Diesel Power System

Hybrid diesel-wind system with battery storage operating in standalone mode: Control and energy management – Experimental investigation

In this work, an experimental Hybrid diesel-wind system with battery storage operating in standalone mode, is presented. The system is comprised of a small scale wind turbine based on 1 kW PMSG, storage batteries, a charge controller, an inverter, a diesel generator, a weather station, a data logger, an electrical load prototype realized and developed such as to simulate a typical house consumption, the controller and the current and voltage sensor.The main task of the proposed scheme was confirmed under three considered scenarios corresponding respectively to low wind speed and high state of charge of batteries, high wind speed and moderate state of charge of batteries and moderate wind speed and low state of charge of batteries while the extensive measurement results demonstrate the system ability to run as expected each of these modes. On the other hand, the data logger via the realized current and voltage sensor as well as the different software and computer tools used and exploited in the present experimental study allowed the permanent supervision and follow-up of the whole system which enabled also to intervene at any time in order to improve the behavior of the whole system.

Analysis and investigation on direct and cross coupling effect of small isolated and interconnected wind diesel power generating system

This study presents the analysed result of wind–diesel system with the consideration of real power-frequency control, reactive power-voltage control as well as cross-coupling between reactive power-frequency and real power-voltage control. The system under study uses synchronous generator (SG) for diesel generator and induction generator (IG) for wind generation systems. The mathematical model of the system with both direct and cross-coupling effect is derived to simulate the behaviour of the wind–diesel system. The classical control technique and eigenvalue, participation factor matrix is used to study the strength of the direct and cross-coupling effect, in the studied system. The simulated responses of the system under various types of disturbances are presented to show the cross-coupling effect in the wind–diesel system. System performances under interconnected mode of operation is also studied.

Performance Comparison of Reactive Power Controllers in Autonomous Wind-Diesel System

Performance Comparison of Reactive Power Controllers in Autonomous Wind-Diesel System

Calculating Size of Pump-Hydro Combined Energy Storage System in Wind-Diesel Systems Based on PHCES Dynamic Model

This paper will propose an approach to calculate and evaluate the reserve capacity and energy size of Pumping-Hydro Combined Energy Storage (PHCES) when wind power is integrated to power grid while considering the scheme of generation capacity allocation and operation of PHCES. This approach will use Monte Carlo Method to simulate large amount of samples to obtain the minimum value of capacity and energy size that could satisfy the requirement of system reliability. Finally this approach will apply in a RBTS system to assess the project feasibility.

Optimal controllers designs for automatic reactive power control in an isolated wind-diesel hybrid power system

The paper presents the bacterial foraging optimization algorithm (BFOA) and particle swarm optimization (PSO) algorithm based robust controllers for voltage deviations due to the variation of reactive power in an isolated wind-diesel hybrid power system. The isolated wind-diesel system consists of wind energy conversion system (WECS) utilizing a permanent magnet induction generator (PMIG). Further, a synchronous generator (SG) is used with the diesel engine set for power generation. The mismatch between generated and consumed reactive power in the system causes voltage fluctuations, which will occur at generator terminals. These oscillations further causes reduction in the stability and quality of the power supply. The static synchronous compensator (STATCOM) and an automatic voltage regulator (AVR) are used to suppress voltage fluctuations in an isolated wind-diesel hybrid power system. The STATCOM is used as a reactive power compensator and the AVR is used to keep the terminal voltage constant for the synchronous generator. Both STATCOM and AVR are having proportional and integral (PI) controllers with single input. In modeling for the system, a normalized co-prime factorization is applied to show the possible unstructured uncertainties in the power system such as variation of system parameters and generating and loading conditions. The performance and robust stability conditions of the control system are formulated as the optimization problem, which is based on the Hα loop shaping. BFOA and PSO algorithms are implemented to solve this optimization problem and to achieve PI control parameters of STATCOM and AVR simultaneously. In order to show the efficiency of the proposed controllers, the performance of the proposed controllers is compared with the performance of the conventional controller and genetic algorithm (GA) based PI controllers for the same wind-diesel system. The dynamic responses of the system for four different small-disturbance case studies has been carried out in MATLAB environment.

Frequency regulation in a wind–diesel powered microgrid using flywheels and fuel cells

This study presents a control strategy for the frequency regulation in a wind–diesel powered microgrid. With wind as a major energy resource, ensuring reliability and quality of power supplied in the system is a great challenge. To reduce the adverse effects caused by wind's variability, intermittency and uncertainty on the system frequency and improve the performance of diesel generator (DG), a solution is explored that involves the use of two different energy storage technologies. A test system is proposed consisting of a wind farm and a DG, supplemented by hydrogen storage with fuel cell (FC) as a long-term and a flywheel (FW) as a short-term energy storage. During low demand or high wind periods, the surplus energy generated is stored as kinetic energy in the FW and as hydrogen gas after water electrolysis. During periods of low wind speed or increased demand, the FW supplies energy by shedding its rotor speed and hydrogen is converted into electricity through the FC. The effectiveness of adding a short-term and a long-term energy storage in enhancing the robustness of wind–diesel system is demonstrated in this study.

Optimal design of battery energy storage system for a wind–diesel off‐grid power system in a remote Canadian community

This study focuses on the design issue of battery energy storage system (BESS) for a wind–diesel off-grid power system located in the Whapmagoostui community in Quebec, Canada. The local range of wind speed is from 0 to 24.8417 m/s, and the total yearly load demand in 2013 was 11,176 MWh. An optimal planning model is proposed in this study with the objectives of maximising the economic, environmental benefits, and reliability of the system. The battery energy capacity and the rated capacity of converter are selected as the optimal variables. In order to consider the impacts of renewable energy randomness, the uncertainty of component failures, and the power flow constraints on planning results, quasi-steady state simulation is adopted to calculate the indices for each design scheme of BESS. The proposed optimal planning model of BESS is implemented and verified in the Whapmagoostui community. Also, a detailed analysis of several scenarios is presented. A base scenario with three diesel generators and four wind turbines is investigated, and its optimal BESS integration reduces fuel consumption by 4% and improves the average annual profit by 19%. The optimal designing of BESS enhances the economic, environmental benefits, and reliability of the wind–diesel system with high fuel prices in the Whapmagoostui community.

An Economic Assessment of Hybrid Renewable Energy for a Remote Area Electrification in Iran

The utilization of renewable resources is growing, in part due to the environmental impacts caused by fossil fuels. The largest sources of renewable energy are wind and solar and many predict that these energy sources will be increasingly used for distributed generation. In this paper, the feasibility is examined of a grid-independent system applied for a remote area electrification in Binalood, Iran. Traditional power systems for remote or rural areas are based on fossil fuels. After addition of renewable energy resources, solar energy applications have become popular in remote energy systems. The recent study and research works show that adding other possible renewable energy resources such as wind, hydro and biomass could make a hybrid system more cost-effective and environmentally friendly. Hence, in the present study, an overview of applied hybrid renewable energy system (HRES) for worldwide villages with special attention on Iran has been proposed to help present and future works for better achievement in this field. Furthermore sensitivity analyses are performed to determine the impact on performance of several key parameters: wind speed and fuel costs. HOMER was used to evaluate the feasibility of various hybrid systems. The results of a comprehensive feasibility data analysis along with its economic evaluation indicate that the wind-diesel hybrid system with battery storage is most efficient energy system for supplying this remote area's electrical energy demands.

Influence of Natural and Cost Factors on the Choice of Optimal Wind Power Plant Capacity as Part of a Wind-Diesel System in the East of Russia

The paper presents the results of testing the methods for determining optimal capacity of wind power plant for offgrid consumers. Analysis of hydrometeorological data on yearly variation in long-term average wind speed in the eastern regions of Russia allows us to identify three characteristic groups of annual distribution of this parameter depending on territory. For each of the groups the relationships between the ratio of an optimal wind power plant capacity to a maximum off-grid consumer load and wind resource indices and annual distribution are presented. The research substantiates that capital investment of the wind power plant construction project and prices of replaced diesel fuel do not affect the value of optimal wind power plant capacity but make a considerable impact on the costeffectiveness of the projects.

Potential Evaluation of Hybrid Wind-Diesel System Island Area in Thailand

Some communities in Thailand located on Island with high wind velocities but an unreliable utility supply, will typically install diesel powered generators and wind generators to form a microgrid. Microgrid projects have been developed in many parts of the world, and commercial solutions have started to appear. Such systems face specific design issues, especially when the wind penetration is high enough to affect the operation of the diesel plant. The dynamic behavior of a medium penetration hybrid microgrid is investigated. It consists of a diesel generator set, a wind power generator and several loads. The diesel engine drives a 3x2,000 kW synchronous generator with excitation control. The wind turbine drives a 6x800 kW (full power converter) synchronous generator. The total load of the microgrid is about 4 MW which varies during the day. The excitation controller and speed controller for the diesel’s synchronous generator are designed, as well as the power control of the wind turbine. The system is modeled and simulated using software DIgSILENT PowerFactory. The study evaluates how the power generation is shared between the diesel generator set and the wind generator, the voltage regulation during load connections, and discusses the need of battery energy storage, the system ride-through-fault capability and frequency control. The results of several case studies are presented. The results have shown that the systems are stable under various ratio of PWIND / PLOAD from 10% to 100%, except ratio of PWIND / PLOAD from 110%.

Optimal management of compressed air energy storage in a hybrid wind-pneumatic-diesel system for remote area's power generation

Electricity in Canadian remote areas is, historically, produced using Diesel generators. Its total production cost is very high not only due to inherent cost of fuel but also due to transportation and maintenance costs. Moreover, the use of fossil fuels is a significant source of greenhouse gas emissions. Hybrid systems that combine wind turbines and diesel generators reduce fuel consumption, operational cost and pollution. Adding a storage element to this hybrid system increases the penetration level of renewable sources, i.e. the percentage of renewable energy in the overall production, and further improves fuel savings. Among all energy storage techniques, CAES (compressed air energy storage) has several advantages to be combined with hybrid WDS (wind-diesel systems), due to its low cost, high power density and reliability. In a previous work, we have exposed and have evaluated a new technique to transform the existing Diesel engine to a HPCE (hybrid pneumatic combustion engine), able to operate as a bi-source engine (compressed air and fuel). Based on ideal cycle modeling, we provided a first estimation of the annual fuel economy obtained with this multi-hybrid system (WDS–HPCE). As a continuity to this work, we will compare, in this article, several strategies of management of the CAES. We will demonstrate that one of these strategies that uses an algorithm based on wind speed forecast, is the most efficient. We will, also, provide an evaluation of the fuel economy generated by the WDS–HPCE, as a function of the wind power penetration ratio, the air-storage capacity, and the average wind speed on site.

Analytical Comparison of Static and Dynamic Reactive Power Compensation in Isolated Wind–Diesel System Using Dynamic Load Interaction Model

This article presents static and dynamic reactive power compensators together for a self-excited induction generator and synchronous generator based isolated hybrid power system. Reactive power is required for excitation of the induction machine and for load under steady-state and transient state operations in an isolated hybrid power system. For small perturbation of load reactive power and input wind power, the use of a dynamic compensator alone may give better voltage stability but at a high cost; in contrast, the static compensator reduces the cost on compromising with the voltage stability. The proper rating selection of both compensators used may give the optimum solution between the voltage stability as system performance and cost of compensation. The fixed costs and voltage profiles are compared for the different participations of the fixed capacitor bank and STATCOM. The interaction of the dynamic load model is also introduced to make the system more reliable and hence a new power balance equation is derived. A 10% step disturbance in the dynamic load model as well as wind power input is considered for the system study. Four different cases designed for unique participation of static and dynamic reactive power compensators are presented. The analytical comparison is based on cost, rating selection, and voltage stability under transient condition.

Economic perspective of hybrid wind-diesel technology for commercial loads of Dhahran Saudi Arabia: A step towards sustainable future

The governments world-wide are deliberating to promote renewable energy sources such as wind to mitigate increasing demand of energy and to overcome effects of pollution due to to use of fossil fuels. Integration of wind turbine generators (WTG) with the diesel plants is pursued widely to reduce dependence on fossil-fuels and to reduce carbon emissions. Literature indicates that commercial/residential buildings in the Kingdom of Saudi Arabia (K.S.A) consume an estimated 10 - 40% of the total electric energy generated. The aim of this study is to analyze wind-speed data of Dhahran (East-Coast, K.S.A.) to assess the economic feasibility of utilizing hybrid wind-diesel power systems to meet the load requirements of a typical commercial building (with annual electrical energy demand of 620,000 kWh). The monthly average wind speeds range from 3.3 to 5.6 m/s. The hybrid systems simulated consist of different combinations of 100 kW commercial WTG supplemented with diesel generators. NREL?s (HOMER Energy?s) HOMER software has been employed to perform the techno-economic analysis. The simulation results indicate that for a hybrid system comprising of 100 kW wind capacity together with 175 kW diesel system, the wind penetration (at 37 m hub-height, with 0% annual capacity shortage) is 25%. The cost of generating energy (COE, $/kWh) from this hybrid wind-diesel system has been found to be 0.121 $/kWh (assuming diesel fuel price of 0.1$/liter). The study exhibits that for a given hybrid configuration, the number of operational hours of diesel gensets decreases with increase in wind farm capacity. Emphasis has also been placed on wind penetration, un-met load, energy production and COE, excess electricity generation, percentage fuel savings and reduction in carbon emissions (relative to diesel-only situation) of different hybrid systems, cost break-down of wind-diesel systems, COE of different hybrid systems, etc.