Sensorless Maximum Power Point Tracking Research Articles

A Sensorless MPPT Approach For PV Pumb System Used BLDC Motor

PV irrigation systems have begun to be used intensively today, as energy needs increase. In Partially Shaded Conditions (PSC), the efficiency of the PV system decreases significantly, and traditional Maximum Power Point Tracking (MPPT) algorithms become insufficient. On the other hand, traditional MPPT algorithms require sensors to measure the current and voltage of the PV system. In this study, a sensorless hybrid MPPT algorithm is proposed to reduce system costs and enable operation without the need for PV system data. A simulation study was conducted in the MATLAB/Simulink environment to examine the PV system. The proposed algorithm has been tested under four different PSC scenarios. PV system power, motor speed, and currents were examined under each condition. The high maximum power tracking performance of the proposed algorithm is demonstrated through simulation results. In the steady state, the lowest MPPT efficiency was 95.66%, whereas the highest MPPT efficiency was 99.9%. The MPPT algorithm completed in less than 2 seconds, with the first stage taking 1.3 seconds to reach most of the maximum PV system power. The second stage of the MPPT algorithm was used to achieve maximum power in a narrower area.

Laboratory Tests Assessment of a Mechanical Sensor-less MPPT Control Strategy for Tidal Turbines

The purpose of this study is to demonstrate through towing tank experiments the effectiveness of a novel sensor-less Maximum Power Point Tracking (MPPT) control for Tidal Stream Turbines (TST) under fluctuations of the onset flow. Ocean energies will play a crucial role in the renewable energy sector over the next decades. Instream turbines for tidal currents are a rapidly maturing technology to exploit a highly predictable energy source. However, short-term fluctuations on the inflow velocity caused by waves or turbulence determine fatigue loads that affect system reliability. Power control strategies to maximize the energy yield can be also used to mitigate the effects of transient loading on drivetrain components. Aim of this paper is to present a straightforward and robust MPPT control method based on the linear relationship between the current and voltage squared of the generator's DC outputs. The method requires pre-determined turbine characteristics to establish the control reference that is effective across operating conditions. The proposed MPPT model was derived mathematically through linearization and simplifications of the turbine power conversion system and validated by model tests carried out in the wave-towing tank facility of CNR-INM in Rome, Italy, using the 1.5 m diameter Tidal Turbine Testing (TTT) device developed at the Queen’s University Belfast (QUB). In the study, a conventional TSR control method was also considered in order to perform a comparative analysis of system response to inflow speed fluctuations with time scales comparable to turbine revolution periods. TSR control was tested using two control references: TSR = 5 (design point) and TSR = 6 (over-speed zone) to verify the operation of the turbine under different loading conditions. The tests were conducted in two scenarios: calm water (steady state) and unsteady inflow with a regular (sinusoidal or monochromatic) waveform, with amplitude chosen to simulate an extreme wave case. The power output was measured from the turbine during regular wave conditions and compared to results from steady flow to assess the impact of wave-induced velocity on turbine performance (Fig. 1). Test results showed that by using the proposed MPPT control strategy, the algorithms converged to the maximum power coefficient (Fig. 2), which validates the proposed methodology. Results also demonstrated the capability of the proposed MPPT to significantly reduce mechanical loads fluctuations as compared to the TSR control. In the full-length paper, the proposed MPPT control strategy is outlined, the test methodology, set-up and conditions are described, and main results are presented and discussed.

Climatic sensorless maximum power point tracking based on adaptive neuro-extremum seeking control technique in PV generation systems

Climatic sensorless maximum power point tracking based on adaptive neuro-extremum seeking control technique in PV generation systems

Robust Speed Controller for PMSG Wind System Based on Harris Hawks Optimization via Wind Speed Estimation: A Real Case Study

Modern wind power systems have recently tended to focus on achieving fast-tracking wind speeds (WSs), high maximum power point tracking (MPPT) efficacy without mechanical sensors, and high performance under uncertain WS together with an effective control system. Therefore, a sensorless MPPT method is introduced, which calculates the actual WS to save system installation costs and boost performance levels. The implemented MPPT method is based on the approximating of the 3-order polynomial to the aerodynamics torque power coefficient. In this study, three-speed control strategies (SCSs) for a grid-connected permanent magnet synchronous wind generator (PMSWG) are examined and assessed. Harris Hawks’ algorithm (HHA)-based PI controller (HHA-PIC) is used in place of (the conventional proportional-integral controller (CPIC), and adaptive fuzzy logic controller (AFLC)) as a speed controller to overcome their drawbacks. To track the generator speed to the desired speed, the HHA-PIC is used. All the CPIC, AFLC, and HHA-PIC have been carefully thought out and constructed to satisfy the speed control loop’s responsive performance. Additionally, a comparison of SCSs amongst the categories under investigation is done. The effect of HHA on the functionality of SCS is verified using MATLAB/SIMULINK. To ensure the efficacy and supremacy of the HHA-PIC over the CPIC and AFLC, a wide variety of WSs (step change, ramp, and real fluctuations) are applied. The HHA-PIC boosts system efficiency over AFLC and CPIC by 0.81% and 8.48%, respectively. Finally, it can be said that HHA is a crucial remedy for the problems with CPIC and is superior to AFLC.

High-Gain Observer-Based Advanced Nonlinear Control of a Grid-Connected Wind Energy Conversion System with Sensorless Maximum Power Point Tracking

This paper deals with the control development of a wind energy conversion system (WECS) interfaced to a utility grid by using a doubly fed induction generator (DFIG), a back-to-back (B2B) converter and an RL filter for optimal power extraction. The aim was to design a sensorless controller to improve the system reliability and to simultaneously achieve the regulation of the generator speed, reactive power and DC-link voltage. The proposed global control scheme combines: (i) a high-gain observer employed to estimate the generator speed and the mechanical torque, usually regarded as accessible, (ii) a sensorless MPPT block developed to provide optimal generator speed reference, which is designed on the basis of the mechanical observer and a polynomial wind-speed estimator and (iii) a finite-time controller (FTC) applied to the B2B converter to meet the output reference’s tracking objectives in a short predefined finite time by using the backstepping and Lyapunov approaches. The proposed controller performance is formally analysed, and its capabilities are verified by numerical simulations using a 2 MW DFIG wind turbine (WT) under different operating conditions.

Current Sensorless MPPT With a CCM Interleaved Boost Converter for Renewable Energy System

The growing demand for energy and environmental concerns have attracted attention to renewable energy sources. In photovoltaic and fuel cell power generation systems, maximum power point tracking (MPPT) is required to achieve high efficiency. This article proposes an MPPT methodology, exploring the characteristics of an interleaved boost converter with switching cell and switching frequency modulation, enabling the operation without current sensors and with only one voltage sensor. In this converter, the input current is proportional to the input voltage and the switching period, making it a voltage follower, with the advantage of self-balancing current and no output voltage distortion in the input current. This article presents comparisons with other techniques, the mathematical analysis with the nonidealities included, the proposed MPPT principle of operation, and numerous experimental evaluations. The converter is analyzed for both single and combined variations in the irradiance and the temperature, ranging from 0 to 1000 W/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and from 0 to 85 °C, with fabricated and real measured scenarios, resulting in a stable operation, high efficiency, and fast response. The MPPT mean efficiency, when evaluated with measured irradiance and temperature variations representing a complete operational day, is 99.30%. The converter has a maximum efficiency of 97.80%.

Generalized Cost-effective Converter for Solar Street Lighting featuring Averaged State-space Model-based Sensorless MPPT

Decentralized solar street lighting is an economical solution in remote areas. However, non-uniform conditions mandates an efficient maximum power point tracking (MPPT) process. Meanwhile, implementing a less-sophisticated MPPT algorithm on a cost-effective converter is preferable to reduce system cost. In this paper, a current sensorless MPPT approach, based on converter state-space model, is proposed reducing the MPPT controller cost. Moreover, it compromises between tracking accuracy, time and implementation simplicity owing to the applied variable-step perturb and observe algorithm. Regarding the MPPT converter, D1 is selected as it overcomes the discontinuous input current limitation featured by conventional buck/boost converters. Consequently, PV power fluctuations are diminished at minimum converter component-count, enhancing tracking efficiency. Moreover, the large PV output capacitor is eliminated, increasing system reliability. Simulation and experimental results of the developed prototype validate the proposed sensorless approach. Finally, a market-survey verifies the proposed MPPT unit cost-effectiveness when compared to others in literature.

Speed sensorless maximum power point tracking technique for SEIG-based wind energy conversion system feeding induction motor pump

Speed sensorless maximum power point tracking technique for SEIG-based wind energy conversion system feeding induction motor pump

Experimental implementation of a novel scheduling algorithm for adaptive and modified P&amp;O MPPT controller using fuzzy logic for WECS

SummaryThis article proposes an adaptive and modified Perturb and Observe (P&amp;O) maximum power point tracking (MPPT) algorithm, using fuzzy logic step size controller, for a wind energy conversion system (WECS) based on wound rotor synchronous generator. The modified P&amp;O controller uses additional current information of the dc‐link, to decrease power oscillation around MPP, and choose the correct direction of the perturbation, while wind speed increase condition, depending on the sign of dc‐link current change. So, in this contribution, a modified drift‐free P&amp;O algorithm was chosen because it gives better results, but the duty cycle step size in the proposed MPPT controller has been varied adaptively, using a fuzzy logic inference system based on the variation of the rectifier output power and the previous change of the duty cycle to get fast convergence until the MPP is reached in increasing and decreasing wind speed conditions. Performances and robustness of the proposed speed sensorless MPPT controller are evaluated in an experiment implementation, using a WECS emulator and dSpace DS1104 controller board, where experimental results show that the proposed method guarantees fast convergence with better energy quality and high robustness against speed or load change conditions.

MPPT of Permanent Magnet Synchronous Generator in Tidal Energy Systems Using Support Vector Regression

In this paper, an improved Maximum Power Point Tracking (MPPT) algorithm for a tidal power generation system using a Support Vector Regression (SVR) is proposed. To perform this MPPT, a tidal current speed sensor is needed to track the maximum power. The use of these sensors has a lack of reliability, requires maintenance, and has a disadvantage in terms of price. Therefore, there is a need for a sensorless MPPT control algorithm that does not require information on tidal current speed and rotation speed that improves these shortcomings. Sensorless MPPT control methods, such as SVR, enables the maximum power to be output by comparing the relationship between the output power and the rotational speed of the generator. The performance of the SVR is influenced by the selection of its parameters which is optimized during the offline training stage. SVR has a strength and better response than the neural network since it ensures the global minimum and avoids being stuck at local minima. This paper proposes a high-efficiency grid-connected tidal current generation system with a permanent magnet synchronous generator back-to-back converter. The proposed algorithm is verified experimentally and the results confirm the excellent control characteristics of the proposed algorithm.

Second-Order Fast Terminal Sliding Mode Control for MPPT of PMSG-based Wind Energy Conversion System

This article proposes a new maximum power point tracking (MPPT) controller based on voltage-mode Second-Order Fast Terminal Sliding Mode Control (SO-FTSMC) to obtain better performance in the power extraction from Permanent Magnet Synchronous Generator (PMSG)-based Wind Energy Conversion System (WECS). The major objective of the study is the design of SO-FTSMC that can ensure the operation of the system in maximum power reference with higher efficiency, less steady-state error, and voltage fluctuation. Maximum power references are determined by mechanical sensorless MPPT approach. The small-scale WECS configuration incorporates wind turbine, PMSG, uncontrolled rectifier, boost converter, and MPPT controller. SO-FTSMC method has not been performed before as a voltage regulator in such a topology. The proposed controller has been validated for two different wind speed test scenarios in simulation environment, which can be applied effectively to PMSG-based WECS. Moreover, Conventional SMC (C-SMC) is created and then performance of controllers is compared in these wind speed scenarios according to maximum extracted average power, output voltage fluctuation, and voltage error in steady-state, MPPT efficiency, and performance indices. Obtained results indicate that proposed SO-FTSMC-based MPPT controller achieves superior performance.

Nonlinear Control of Wind Energy Conversion System Based on DFIG with a Mechanical Torque Observer

In this paper, an advanced nonlinear backstepping control approach is developed and applied to the whole nonlinear system including the AC/DC/AC converters combined with the doubly-fed induction generator(DFIG). A high gain observer is synthesized, in order to provide an estimated value of the mechanical torque whereas, a wind speed estimation block is designed based on roots polynomial method; followed by sensorless maximum power point tracking (MPPT). The control objectives are fourfold: (i) Forcing the generator speed to track the reference signal given by the MPPT block, (ii) adjusting the stator reactive power injected into the grid to be null, (iii) Regulating the DC-link voltage between the rotor side and the grid side converters at the desired level, (iv) assuring a unitary power factor in the grid side. The achievement of these control objectives leans on a multi-loop regulator which shows a satisfying performance as far as it concerns the simulation results.

An Adaptive Model Predictive Controller for Current Sensorless MPPT in PV Systems

Finite control set model predictive control (MPC) is a model-based control method that can include multi-objective optimization, constrained control, adaptive control, and online auto-tuning of weighting factors all in a single controller that exhibits fast dynamic tracking. This paper utilizes the model-based framework of MPC to develop a sensorless current maximum power point tracking (MPPT) algorithm. Eliminating the current sensor can reduce the cost and improve the reliability of the photovoltaic system. This paper also utilizes constrained control and online auto-tuning of MPC to develop an adaptive perturbation MPPT to reduce steady-state oscillation and improve dynamic performance. This paper builds in a single framework the different layers of the MPPT problem: control, estimation, and MPPT. The proposed adaptive perturbation sensorless current mode MPPT (ASC-MPPT) technique performance is compared to the well-known incremental conductance (InCon) MPPT technique. The EN50530 European industrial test standards were used to demonstrate performance.

Discrete‐time integral terminal sliding mode based maximum power point controller for the PMSG‐based wind energy system

This study proposes a discrete-time integral terminal sliding mode controller (DITSMC) integrated with a sensorless maximum power point tracking (MPPT) method for a permanent magnet synchronous generator (PMSG)-based wind energy conversion system (WECS). The effects of the parameters of the proposed DITSMC on the convergence-time and the error-bound are investigated by the simulation studies. The dynamic performance of the DITSMC has been evaluated experimentally on a test bench for step-type wind changes. The optimum coefficient between the output voltage of the generator and the extracted power from the WECS is determined only for a wind speed by offline studies. Then, the MPPT can be provided using this coefficient for all wind speeds in the operating range of the WECS without any mechanical sensor. Additionally, the experimental studies show that DITSMC has better performance than the PI controller in terms of the settling time and thus the efficiency of the WECS.

A Control Scheme without Sensors at the PV Source for Cost and Size Reduction in Two-Stage Grid Connected Inverters

In order to reduce the cost of PV facilities, the market requires low cost and highly reliable PV inverters, which must comply with several regulations. Some research has focused on decreasing the distortion of the current injected into the grid, reducing the size of the DC-link capacitors and removing sensors, while keeping a good performance of the maximum power point tracking (MPPT) algorithms. Although those objectives are different, all of them are linked to the inverter DC-link voltage control loop. Both the reduction of the DC-link capacitance and the use of sensorless MPPT algorithms require a voltage control loop faster than that of conventional implementations in order to perform properly, but the distortion of the current injected into the grid might rise as a result. This research studies a complete solution for two-stage grid-connected PV inverters, based on the features of second-order generalized integrators. The experimental tests show that the proposed implementation has a performance similar to that of the conventional control of two-stage PV inverters but at a much lower cost.

Drift-free current sensorless MPPT algorithm in photovoltaic systems

High system cost and reduced output power due to the changing weather conditions such as the irradiance or temperature are two major concerns for a practical photovoltaic (PV) system design. This paper presents a current sensorless (CS) maximum power point tracking (MPPT) algorithm that uses only one single-input-voltage sensor (SIVS) and totally eliminates the expensive current sensors, which can significantly reduce the system cost and retain the advantages of the widely used MPPT algorithms such as incremental conductance (INC). To further eliminate the drift effect, which is a severe phenomenon due to the incorrect decision in duty cycle for fast irradiation change, drift-free technique is adopted in the presented algorithm by incorporating the information of change in duty cycle (Δ D) and change in input voltage (Δ V). A mathematical expression is given to define the drift-free criterion and the threshold is determined by the Lambert W function with respect to the dynamic EN50530 test standard. Experimental results under different scenarios are presented to validate the advantages of the presented method in terms of the tracking efficiency and drift-free characteristic.

Robust Nonlinear Sensorless MPPT Control with Unity Power Factor for Grid Connected DFIG Wind Turbines

This paper focuses on the sensorless maximum power point tracking (MPPT) and unity power factor operation of a grid connected wind energy conversion system based on the doubly fed induction generator (DFIG). The proposed investigation is based on the nonlinear mathematical models of the wind turbine, the DFIG and the inverters. Based on the synchronized state-space model of DFIG and using stator field oriented vector control, an effective control of stator power is proposed. In this method, rotor speed, stator flux, and rotor resistance are estimated on-line. Field synchronization is provided by a three-phase PLL (Phase-Locked Loop). Unity power factor injection is achieved by controlling the power injected by the rotor and the closed-loop stability is ensured by Lyapunov analysis. Simulation results realized in MATLAB/SIMULINK environment, under different wind speeds, are presented and discussed. These results confirm the validity and effectiveness of the proposed controller.

Application of finite-time control Lyapunov function in low-power PMSG wind energy conversion systems for sensorless MPPT

This paper discusses the problem of observer-based finite-time control (FTC) of a grid-connected wind turbine and a low-power permanent magnet synchronous generator (PMSG). An adaptive nonlinear observer is employed to estimate the mechanical variables. Maximum power point tracking (MPPT) is obtained using the estimation of rotor speed and torque from the adaptive observer, and excluding the wind speed sensor. Improvement of the MPPT technique through the designed FTC is investigated. The proposed controller stabilizes the WECS and tracks the reference trajectories in a short pre-known time alternative to common nonlinear controllers with large settling time. The suggested controller is also robust against uncertainties in WECS parameters. Parameters’ variations are compensated by robust control design. Finite time stability and robustness of the proposed WECS controller is mathematically proved. Moreover, the advanced performance of the suggested FTC is demonstrated by simulation and is compared to a conventional asymptotic convergent controller (ACC). The proposed FTC provides fast and robust rotor speed regulation and thus enhances the sensorless MPPT. The proposed FTC improves the WECS performance for tracking of ramp references and robustness against parameter uncertainties. Furthermore, advanced control of the grid-side converter yields improved resiliency and reliability.

Modelling and Control Design for Energy Management of Grid Connected Hybrid PV-wind System

&lt;p class="MsoNormal" style="margin-right: -14.15pt; text-align: justify; text-justify: inter-ideograph;"&gt;This paper deals with the control of hybrid PV-WIND power conversion structure. This paper develops a very important contribution which is the use of a single DC to DC converter, linearization of control of the three- level boost converter (TLBC) considering the imperfections of the passive components. The (TLBC) control provides balancing of capacitor voltages and maximum power operation of PV generator. For reasons of simplicity, a linearization based on the dynamic compensation of the disturbance is proposed. A sensorless maximum power point tracking (MPPT) algorithm is used to maximize a power extracted of the wind generator. The proportional relation between the rotational speed and the output voltage of the rectifier allows to use a voltage sensor to estimate the DC bus voltage reference instead of a mechanical speed sensor. The control of the three-phase inverter allows a transfer of the active power, the power factor close to the unit and thus a limitation of the reactive power injected into the grid. The external control loop performs the regulation of the common DC bus voltage while the internal control loop regulates the dq components of the currents injected into the grid. The simulation results showed the validity of the control approach. The proposed power conversion structure based on a single static converter has shown very good performance in terms of efficiency, the quality of the energy produced, complementarity between the two renewable sources and reliability. The paper ends with conclusions.&lt;/p&gt;

Sensorless double integral sliding mode MPPT control for the WECS

In this paper, a double integrator sliding mode controller (DISMC) via the mechanical sensorless maximum power point tracking (MPPT) method is suggested to extract maximum power from a wind energy conversion system (WECS). The controller is required to bring the system to the maximum power point reference generated by the MPPT method. However, the controller design for the WECS operated in a wide wind speed range is a challenging task due to its highly nonlinear behavior. In this study, to enhance the performance of the WECS, a voltage mode DISMC, which is not used before for the WECS, is offered. The dynamic performance of the proposed method, considering the different wind speed scenarios, is proved with the simulation studies. Additionally, the performance of the DISMC is compared with that of the conventional sliding mode controller for the same wind speed scenarios.