Desired Reference Voltage Research Articles

Investigation on the Effect of Parasitic Elements on PID Control of DC-DC Buck Converter

DC-DC converter circuits are used in many electronic devices to adjust the voltage to a certain level such as Electric Vehicle. DC-DC Buck converters, which are the most used type of DC-DC converters, reduce the input voltage and keep the output voltage constant at a desired reference voltage value. In this study, the effect of parasitic elements in Buck DC-DC converters is examined on the PID controllers. Parasitic elements cause a non-linear effect on the Buck converter system model. Studies in the literature generally control the output voltage by designing controllers on the Buck converter model without parasitic elements. Alternatively, linear controllers such as PID are designed according to the linearizing model, taking into account the effect of parasitic elements. In addition, nonlinear controllers are designed on the full model with the effect of parasitic elements. In this study, the effect of parasitic elements on linear controllers, especially PID, is examined.

Distributed consensus control for voltage tracking and current distribution in DC microgrid

DC microgrids are extensively researched because of advancements in power electronics, penetration of DC loads, and the growing demand for DC power. The DC microgrid is also broached as a multi-agent system (MAS) because of its distributed nature. In this paper, a distributed consensus controller for DC microgrids is proposed that has basically two main objects; the first object is to track the desired reference voltage for the distributed generation units while maintaining the voltage stability at the point of common coupling (PCC), whereas the second object is to distribute current proportionally among distributed loads. Furthermore, a linear distributed model is constructed in which the dynamics of the net current for the distributed generation units are established using the directed graph of power lines. Moreover, local information from neighboring agents is utilized to construct a distributed linear controller, and the consensus control problem is solved for voltage tracking and current distribution of the DC microgrid. Furthermore, the control gains for the proposed controller are optimized using closed-loop stability analysis. Finally, simulation results are illustrated for both open-loop and closed-loop systems, and the effects of the directed power line graph and the undirected communication graph are analyzed. The effects of parameter uncertainties on the performance of the proposed controller are investigated through simulations. The results show that the distributed controller efficiently solves the consensus control problem for the MAS.

Design and Control of Two-Stage DC-AC Solid-State Transformer for Remote Area and Microgrid Applications

The critical challenges with integrating renewable energy into the grid are smooth power flow control, isolation between the high-voltage and low-voltage networks, voltage regulation, harmonic isolation, and power quality regulation. This paper considers the design and construction of a two-stage DC-AC solid-state transformer based on wide bandgap (WBG) semiconductor technologies, an optimized medium-frequency transformer, and PI and dq controllers for supplying urban area electric drive systems and microgrid applications. The designed SST consists of a dual active bridge (DAB) DC-DC converter followed by a DC-AC three-phase inverter. Each stage of the SST was simulated with independent controllers. The proposed system was initially developed in MATLAB/Simulink and a laboratory prototype was constructed to verify the results experimentally. Resistive and inductive load were used to test the load disturbance to evaluate the voltage regulation performance. This work has comprehensively provided the performance of a double stage (DC-DC and DC-AC converter) by taking into consideration input voltage, load disturbance, and voltage tracking both in simulation and experiment. The dual active bridge with its controller is able to maintain the desired output reference voltage with minimal voltage ripples under input voltage fluctuations and load variations. Similarly, the three-phase DC-AC converter’s controller exhibits better performance in tracking the desired reference voltage and producing well-regulated AC voltage with low harmonic distortion.

Buck DC-DC 컨버터와 적응 퍼지 제어 시스템을 이용한 태양광 발전 어레이 출력 전압 제어

In solar PV generation, energy conversion efficiency is a very important problem. Hence several important MPPT(Maximum Power Point Tracking) schemes have been proposed and the PV array output voltage is required to track the desired reference voltage determined from the P&O(Perturb and Observation) algorithm of the MPPT cotrol scheme. PV array output voltage dynamic equations are very uncertain and nonlinear under variant atmospheric conditions such as solar radiation and ambient temperature. So the conventional simple control algorithm may not be appropriate to get the good transient performance of the PV array output voltage control. To cope with this problem, an adaptive fuzzy control system for the duty rate control of the Buck DC-DC converter is proposed in this paper and its usefulness is proved by some simulation studies.

Adaptive Resilient Secondary Control for Microgrids With Communication Faults.

In this article, we consider the resilience problem in the presence of communication faults encountered in distributed secondary voltage and frequency control of an islanded alternating current microgrid. Such faults include the partial failure of communication links and some classes of data manipulation attacks. This practical and important yet challenging issue has been taken into limited consideration by existing approaches, which commonly assume that the measurement or communication between the distributed generations (DGs) is ideal or satisfies some restrictive assumptions. To achieve communication resilience, a novel adaptive observer is first proposed for each individual DG to estimate the desired reference voltage and frequency under unknown communication faults. Then, to guarantee the stability of the closed-loop system, voltage and frequency restoration, and accurate power sharing regardless of unknown communication faults, sufficient conditions are derived. Some simulation results are presented to verify the effectiveness of the proposed secondary control approach.

IMPLEMENTION OF A DSPACE CONTROL SYSTEM FOR A NON-ISOLATED DC-DC BOOST CONVERTER

This paper presents the use of the dSPACE rapid control prototype (RCP) control system to implement a feedback control system for a conventional Boost DC-DC converter hardware to validate the converter's operation and performance during the research and development stage. The proposed system was implemented and tested using a conventional Boost DC-DC converter and a dSPACE (RCP) based control strategy. The advantage of employing this control platform for the converter is that it allows for the identification of design errors in the development process without the requirement for complicated control coding. Details of the DC-DC boost converter operations, the converter feedback dSPACE control system experimental setup and experimental test results are all presented in the paper. The results show that the system can conform to any set desired reference voltage.

Voltage Oriented Control and Direct Power Control Strategies in solving under and overvoltage conditions for heavy load application on Malaysian Distribution Representative Network

This paper proposed two PWM control scheme which is the Voltage Oriented Control (VOC) and Direct Power Control (DPC) on a heavy loaded LV-distribution network with photovoltaic (PV) integration in Malaysia. The surge in demand of power supply is overcome by deploying more PV to fulfil the load demand. However, this could give rise to power quality issues that can affect the stability of the grid. The focus in this work is to solve voltage dynamic concern which results in over and undervoltage problems within the distribution network and at the same time to evaluate on the performance of both control schemes under a heavy loaded condition. A 33 kV Malaysian LV-Distribution model integrated with PV is constructed to serve as a base model in this paper. From the base model, a load flow analysis is conducted in order to locate the weakest bus. The two proposed control schemes are introduced into the weakest bus in the grid system, and its performance of the controller will be evaluated based on three aspects such as compensation margin, voltage and current total harmonics distortion (vTHD and iTHD) and lastly the compensated voltage levels. It is shown that VOC control scheme has outperformed DPC due to a wider compensation margin and its ability to achieve the desired reference voltage with a faster settling time under heavy loaded condition. Therefore, the proposed PWM control scheme of both VOC and DPC under a heavy load scenario could be set as a benchmark to provide impactful insights and findings towards an actual implementation of the application within a distribution network or distributed generation.

Direct Torque Neuro-Fuzzy Control of An Induction Motor (Dept.E)

In this article a direct torque of the induction motor drive controlled by Neuro-Fuzzy systet. The proposed control scheme uses the stator flux amplitude and the electromagnetic torque errors through an adaptive Neuro_fazzy inference system (ANFIS) to act on both the amplitude and the angle of the desired reference voltage. Simulation results by using ANFIS are compared with those of the conventional direct torque control (DTC). The comparison results of Direct torque Neuro-fuzzy controller (DTNFC), illustrate the reduction in the torque and stator flux ripples. The validity of the proposed method is confirmed by the simulative results

Fuzzy logic-based tuning of PID controller for zeta converter regulation

In renewable energy, the DC-DC converter plays important roles to convert the electric variables, such as voltage and current. Zeta converter is considered to be widely applied in various applications, includes: power factor correction, photovoltaic generation, and so on. However, the characteristics of the open loop response output voltage from the Zeta converter has quite high overshoot and long settling time. In addition, the input voltage and load variations will affect the Zeta converter’s voltage regulation. To encounter these issues, PID controller based on fuzzy logic tuning is implemented to regulate the output voltage of Zeta converter such that the output voltage can follow the desired voltage. According to simulation results the output voltage with fuzzy-PID controlled is able to track the desired reference voltage. Compared to PID controller, the output voltage controlled with fuzzy-PID controller has a smaller voltage deviation and recovery time. At a significant input voltage change the PID controller output response becomes unstable, while the fuzzy-PID controller still produces a good output response.

Nonlinear observer based PI sliding surface of adaptive sliding mode control for boost converter in PV system

In photovoltaic system, solar energy is not able to be directly utilized to the grid. This is because the the generated output voltage from solar array are fluctuating depends on the environmental condition, such as the intensity of solar irradiance and temperature. Any changes from those variables will affect the generated output voltage. Boost converter is one type of power converter that is able to regulate the output voltage of solar array to dc grid. However, the dynamics of boost converter is nonlinear and non-minimum phase. Therefore, it requires an appropriate control method that can force the output voltage follows the desired reference voltage, by considering the fluctuation of environmental conditions and loads. To reduce the number of sensors and cost investment, nonlinear observer technique is employed to estimate the input voltage and load variations. By considering this problem, this paper is aimed at designing nonlinear observer based on adaptive sliding mode control with PI sliding surface for boost converter. The stability of proposed system is investigated through analytical and simulation proof. As comparison with PID controller, the performance of proposed system has produced Integral Absolute Error (IAE) about 7 times smaller than PID controller when it is tested under various conditions.

Nonlinear observer based PI sliding surface of adaptive sliding mode control for boost converter in PV system

In photovoltaic system, solar energy is not able to be directly utilized to the grid. This is because the the generated output voltage from solar array are fluctuating depends on the environmental condition, such as the intensity of solar irradiance and temperature. Any changes from those variables will affect the generated output voltage. Boost converter is one type of power converter that is able to regulate the output voltage of solar array to dc grid. However, the dynamics of boost converter is nonlinear and non-minimum phase. Therefore, it requires an appropriate control method that can force the output voltage follows the desired reference voltage, by considering the fluctuation of environmental conditions and loads. To reduce the number of sensors and cost investment, nonlinear observer technique is employed to estimate the input voltage and load variations. By considering this problem, this paper is aimed at designing nonlinear observer based on adaptive sliding mode control with PI sliding surface for boost converter. The stability of proposed system is investigated through analytical and simulation proof. As comparison with PID controller, the performance of proposed system has produced Integral Absolute Error (IAE) about 7 times smaller than PID controller when it is tested under various conditions.

Current Sharing Control for Parallel DC–DC Buck Converters Based on Finite-Time Control Technique

The problem of current sharing controller for parallel dc–dc buck converter system is investigated in this paper. Specifically, to achieve the goal of sharing control and improve the systems dynamic performance, a new finite-time current sharing control algorithm is designed and employed. Under the proposed control algorithm, rigorous proofs show that not only the output voltage of the converter system can reach the desired reference voltage in a finite time, but also the objective of current sharing can be achieved within almost the same time. In addition, when the external load is time-varying and unknown, a finite-time load estimator is given to handle the load variation, and an adaptive finite-time current sharing control algorithm is subsequently developed. Experimental results are presented to verify the effectiveness of the proposed method, and to show its advantages over some traditional control algorithms. It is shown that a faster convergence rate and a better load disturbance rejection performance can be yielded by the present algorithm. Finally, it is shown that the main results can be extended to the case of $n$ parallel dc–dc buck converters.

Second-Order Sliding-Mode Controller Design and Its Implementation for Buck Converters

A second-order sliding-mode (SOSM) control method is developed for the regulation problem of a dc–dc buck converter. By taking into account the model uncertainties and external disturbances in the mathematical model, a sliding variable with relative of degree 2 is first constructed. Then, a new SOSM controller is developed such that the output voltage will well track the desired reference voltage. Theoretical analysis shows that the resulting closed-loop system is globally finite-time stable, while similar SOSM control results only give the proof for finite-time convergence. The way on how to implement the proposed SOSM algorithm is also presented. The theoretical findings are verified by extensive simulations and experiments.

Adaptive neuro-fuzzy control of an induction motor

In this article a direct torque of the induction motor drive controlled by neuro-fuzzy system is proposed. The proposed control scheme uses the stator flux amplitude and the electromagnetic torque errors through an adaptive neuro-fuzzy inference system (ANFIS) to act on both the amplitude and the angle of the desired reference voltage. Simulation results by using ANFIS are compared with those of the conventional direct torque control (DTC). The comparison results of direct torque neuro-fuzzy controller (DTNFC), illustrate the reduction in the torque and stator flux ripples and the validity of the proposed method is confirmed by the simulation results.

NEURO-FUZZY CONTROLLER IMPLEMENTATION FOR AN ADAPTIVE CATHODIC PROTECTION ON IRAQ-TURKEY CRUDE OIL PIPELINE

Impressed current cathodic protection is widely used to prevent corrosion of structural steels, especially, those used in a crude oil pipeline. The potential required for cathodic protection depends upon the steel being protected from the environment. Since corrosion rate depends on current flow to or from the steel and the adjacent medium, the corrosion activity of the steel in soil normally increases as soil resistivity decreases. The major constituents are resistivity, chlorides, sulfates, and the acidity (pH) of the soil. Output voltage, depending on desired reference voltage, needs to be controlled and tuned by transformer rectifier (TR) units. Proportional–integral (PI) and proportional–integral–derivative (PID) controllers have been used recently in tuning the output voltage, but overshoot and oscillation occurred in the outputs. In order to overcome these problems, a new approach based on a neuro-fuzzy controller for tuning the output voltage of TR units is presented in this study. The neuro-fuzzy classification based on a fuzzy logic controller was implemented in a microcontroller. The controller helps to compensate for the variations and the dynamic changes in the TR units on the Iraq-Turkey crude oil pipeline. The experimental results achieved from two stations have shown that the proposed neuro-fuzzy controller is simple, does not require any derivative function, and has no overshoot and oscillation.

Application of Fuzzy Logic Controlled Cathodic Protection on Iraq-Turkey Crude Oil Pipeline

Impressed current cathodic protection is widely used to prevent corrosion of structural steels. The major constituents, which accelerate corrosion, are resistivity, chlorides, sulfatesand the acidity (pH) of the soil. Because of these variations, the transformer-rectifier units must control and tune the output voltage depending on desired reference voltage steadily. Usually, classical controls such as PI and PID, have been widely used with their gains manually tuned based on the desired reference voltage. But, classical controls require different gains at the lower and higher end of the output voltage range to avoid overshoot and oscillation. In this study, a closed loop control system incorporating fuzzy logic has been developed for tuning output voltage of the transformer-rectifier units. The algorithm based on fuzzy logic was implemented on a modern microcontroller (PIC16F877) allowing great flexibility for various real time applications. The desired reference voltage has been given by using keypad and output values have been displayed on an LCD. It is achieved by implementing an adaptation mechanism based on fuzzy logic controller to compensate for the variations and the dynamic changes in the environment. The proposed fuzzy logic controller was applied to two different areas on Iraq-Turkey crude oil pipeline. When the performance of the proposed fuzzy logic controller was observed, it has been seen that the output voltage of transformer-rectifier unit controlled by fuzzy logic controller has no overshoot and oscillation in the both areas.

Genetic algorithm‐based self‐learning fuzzy PI controller for buck converter

AbstractThis paper presents a self‐learning fuzzy proportional‐integral (PI) controller design for a buck converter. Although a triangle type of membership functions is used, their parameters for fuzzy subsets are deemed unnecessary in the fuzzy control rules design. Knowledge of both the normalization factor in the fuzzification phase and feedback gain of the PI controller is also not required. In addition, a genetic algorithm (GA) optimization technique is proposed to tune the parameters of normalization factors, membership functions and the gain of PI‐like controller. The proposed GA‐based fuzzy controller is then applied to a buck converter. Simulation results indicate that the output voltage of the closed‐loop system can be regulated to a desired reference voltage regardless of the variations in input voltage and of changes in output load.