Optimization of power coefficient equation for standalone wind energy systems

Regulation of load voltage and frequency is very important in standalone wind energy system under fluctuating wind speeds and changing load conditions. This paper presents vector control strategy for load side inverter in coordination with battery energy storage system for maintaining power balance, voltage and frequency regulation in stand-alone wind-energy system under different operating conditions. The robustness of the proposed control strategy to improve the dynamic performance of standalone PMSG under transient operating conditions is validated using MATLAB/SIMULINK environment.

In this paper, a novel method is proposed and applied to quickly calculate the capacity of energy storage for stand-alone and grid-connected wind energy systems, according to the discrete Fourier transform theory. Based on practical wind resource data and power data, which are derived from the American Wind Energy Technology Center and HOMER software separately, the energy storage capacity of a stand-alone wind energy system is investigated and calculated. Moreover, by applying the practical wind power data from a wind farm in Fujian Province, the energy storage capacity for a grid-connected wind system is discussed in this paper. This method can also be applied to determine the storage capacity of a stand-alone solar energy system with practical photovoltaic power data.

ABSTRACTThe limitation of self-excited induction generator (SEIG) when used in the stand-alone wind energy system (WES) is poor voltage regulation at variable speed. The indirect vector control (IVC) technique is employed for both the generator-side converter (GSC) and load-side converter (LSC) to regulate the variation of SEIG speed, DC link voltage, and electromagnetic torque independently. Further performance of the proposed IVC technique has been analyzed independently with neural network controller (NNC) and fuzzy logic controller (FLC) as its components. The FLC is replaced by an NNC to improve the performance of the proposed system. IVC of SEIG-based WES has been simulated in MATLAB/SIMULINK software, and the prototype model of the proposed WES is developed to experimentally validate the performance using dSPACE DS-1104 R&D controller board.

The goal of this effort is to monitor and manage a hybrid stand-alone photovoltaic (PV) and wind energy system (WES) using the Internet of Things (IoT). The suggested hybrid system uses Incremental Conductance (INC) Maximum Power Point Tracking (MPPT) and Perturb and Observe (P&O)-based Sliding Mode Control (SMC) approaches. The cost-effective Arduino Uno board in Matlab is used to analyze the P&O and INC MPPT methods. Energy from renewable sources is stored in a battery, and the output voltage of each source is monitored using the blynk app and GSM 800c module. Simulation results validate the controller’s operation, and the performance of both MPPT algorithms is compared. Experimental outcomes demonstrate the effectiveness of the IoT-based controller and its characteristic functionalities. Overall, this proposed hybrid PV and WES configuration offers advantages such as reduced human resources, cost-effectiveness, time savings, enhanced reliability, and improved data collection and control capabilities.

Energy storage devices are required for power balance and power quality in stand alone wind energy systems. A Vanadium Redox Flow Battery (VRB) system has many features which make its integration with a stand alone wind energy system attractive. This paper proposes the integration of a VRB system with a typical stand-alone wind energy system during wind speed variation as well as transient performance under variable load. The investigated system consists of a variable speed wind turbine with permanent magnet synchronous generator (PMSG), diode rectifier bridge, buck-boost converter, bidirectional charge controller, transformer, inverter, ac loads and VRB (to store a surplus of wind energy and to supply power during a wind power shortage). The main purpose is to supply domestic appliances through a single phase 230 V, 50 Hz inverter. Simulations are accomplished in order to validate the stability of the supply.

The paper proposes a Fuzzy logic approach for controlling three-level NPC converters in stand alone wind energy systems. A key function of this controller is to maintain constant voltage and frequency for customers while maintaining smooth voltage waveform with less filtering requirements. The principle of the proposed Fuzzy controller is based on a modified PI approach in which the error and its integral are utilized as an input for the controller. The direct and quadrature components are used as control variables for the controller. Due to the integrity of the wind energy systems, a complete system is developed including machine-side converter controller and power balancing controller. The entire system is simulated in MATLAB/SIMULINK environment and tested on several load and wind conditions. A real wind speed measurements were imposed to the wind turbine in the system to ensure some realistic responses of the system.

The solicitations of the variable speed wind generators need control to operate the wind energy system. Maximum power point algorithm is one of the promising solution to harness maximum energy from the renewable energy source. The study represented in this paper comprises comparative analysis of two MPPT algorithms which is used in standalone wind energy system to extract maximum power from the wind. The comparative analysis is done for Variable current perturbation MPPT algorithm and Variable step P & O MPPT algorithm. The variable current perturbation algorithm and variable step perturbation algorithm is simulated and the performance is studied with the fixed pitch angle and variations in the pitch angle. The electrical parameter like voltage and current is sensed for current perturbation algorithm and angular speed and shaft power is sensed in case of variable step perturbation algorithm. The variable current perturbation algorithm senses MPPT using electrical parameters and the variable step perturbation senses mechanical parameters. The effect of pitch angle for both the algorithms is also introduced to check the power generated from wind energy system.

In this paper, a robust control system is proposed for controlling the input DC voltage and the output AC voltage and frequency of the load-side converters in stand-alone wind energy systems. The proposed controller consists of voltage regulators based on a PI-like fuzzy technique and a current-mode controlled boost converter. The proposed controller is tested on several operation and fault conditions. The performance of the proposed controller is compared with a conventional PI-based controller in terms of the Total Harmonic Distortion of the output voltages.

1 - Overview of stand-alone and hybrid wind energy systems

Due to its high energy generation capability and minimal environmental impact, wind energy is an elegant solution to the growing global energy demand. However, frequent atmospheric changes make it difficult to effectively harness the energy in the wind because maximum power extraction occurs at a different operating point for each wind condition. This paper proposes a parameter-independent intelligent power management controller that consists of a slope-assisted maximum power point tracking (MPPT) algorithm and a power limit search (PLS) algorithm for small standalone wind energy systems with permanent synchronous generators. Unlike the parameter-independent perturb & observe algorithms, the proposed slope-assisted MPPT algorithm preempts logical errors attributed to wind fluctuations by detecting and identifying atmospheric changes. The controller's PLS is able to minimize the production of surplus energy to minimize the heat dissipation requirements of the energy release mechanism by cooperating with the state observer and using the slope parameter to seek the operating points that result in the desired power rather than the maximum power. The functionality of the proposed energy management control scheme for wind energy systems is verified through simulation results and experimental results.

Voltage control of stand-alone wind and solar energy system

Pakistan is an energy deficient country and the current power crisis of Pakistan is hampering its economic development. Pakistan is naturally benefitted with different renewable energy resources; out of which solar and wind energy are the main highlights. This research work will provide an assessment of the renewable energy potential of the Baluchistan region. A comparison of the economic and financial analysis for a centralized hybrid renewable energy system has been simulated by using Homer software. Three cases have been proposed in which centralized standalone solar PV system, centralized standalone wind energy system and a hybrid combination of both centralized standalone solar and wind energy system have been studied. Homer software has been used to devise the most optimal solution. The simulations confirm that the best optimal solution is the hybrid renewable energy system for the rural electrification of the proposed region.

A review on recent size optimization methodologies for standalone solar and wind hybrid renewable energy system

5 - Stand-alone wind energy systems

The author describes a probabilistic method for the computation of the loss of load probability and the expected unserved energy of a stand-alone wind energy system. The system consists of a wind generator and a storage battery supplying the consumer load. The statistics of the surplus generation (excess wind generation over load demand) time series are computed and used for the calculation of the desired reliability indices. It is shown, that in the probability computations, the serial correlation of the surplus generation cannot be ignored. The performance of the developed method is demonstrated with computational results. Some results useful for the design of stand-alone wind energy systems are also presented. >