Dc-link Voltage Research Articles

Enhanced energy storage system efficiency for remote area-based DC microgrid

This article suggests a hybrid storage system-based DC microgrid to supply the needs of remote areas with variable loads demands. This would help solve problems like limited energy storage systems, complicated consumption, and unstable power production from renewable sources. Energy storage is an attractive option for isolated zone; however, a single storage unit may not be sufficient owing to constraints in capacity, power, energy density, and life cycle. consequence, this study is concerned with hybrid energy storage systems battery/supercapacitor, which combine the most advantageous characteristics of various energy storage technologies to attain relevant performance. Furthermore, the supervision energy management technique based decoupling frequency is designed with low pass filter to separate the current to tow elements, low frequency current absorbed by the battery and high frequency current that absorbed by the supercapacitor. Furthermore, PI controllers are employed to control the DC link voltage, and the current of battery and supercapacitor. Energy management control plays an important role to improve the system performance, ensure power allocation among source, storage devices, and load consumption, and to maintain the battery and supercapacitor at their limitation states of charge (SOC), the system must be able to match the load requirements during a shortage and absorb any surplus power provided by wind energy. To confirm the achievement of the objectives of this study, the comparative simulation between battery storage alone and hybrid storage system combined of battery and Supercapacitor. The simulation results show that the hybrid storage battery and supercapacitor allow to increases the stability of DC link voltage with an overshoot less than 1.5% compared to 7.5% when battery alone and fast dynamic response. in addition, reduces the battery stress and increases its lifetime in the case of hybrid storage.

Enhanced grid integration through advanced predictive control of a permanent magnet synchronous generator - Superconducting magnetic energy storage wind energy system

In this study, the use of an Unscented Kalman Filter as an indicator in predictive current control (PCC) for a wind energy conversion system (WECS) that employs a permanent magnetic synchronous generator (PMSG) and a superconducting magnetic energy storage (SMES) system connected to the main power grid is presented. The suggested UKF indication in the hybrid WECS-SMES arrangement is in charge of estimating vital metrics such as stator currents, electromagnetic torque, rotor angle, and rotor angular speed. To optimize control strategies, PCCs use these projected properties rather than direct observations. To control the unpredictable wind energy's nature, SMES must be regulated to minimize fluctuations in the DC-link voltage and power output to the main grid. Fractional order-PI (FOPI) controllers are used in a novel control structure for the SMES system to regulate the output power and DC-link voltage. An artificial bee colony optimization approach is employed to optimize the FOPI controllers. Three commonly utilized indicators, including sliding-mode, EKF, and Luenberger, were evaluated using “MATLAB" to evaluate the performance of the UKF estimate. Assessment criteria such as mean absolute percentage error and root mean squared error were used to gauge the accuracy of the estimates. Simulation findings showed the efficiency of fractional order-PI controllers for SMES and the proposed UKF indication for predictive current control, especially in the presence of measurement noise and over a variety of wind speeds. An improvement in estimation accuracy of up to 99.9 % was demonstrated by the UKF indicator. Moreover, the stability of the suggested UKF-based PCC control for the hybrid WECS-SMES combination was confirmed using Lyapunov stability criteria."

Improved Extended EMF-Based Sensorless Control for IPMSMs With Small DC-Link Capacitor Considering DC-Link Voltage Measurement Error

Improved Extended EMF-Based Sensorless Control for IPMSMs With Small DC-Link Capacitor Considering DC-Link Voltage Measurement Error

IMC based robust and innovative control strategies for higher-order DC-DC converter in DC microgrid applications

The extensive practice of DC-DC converter interfacing circuits to maintain DC link voltage in DC microgrid applications introduces unavoidable voltage regulation problems due to its nonlinearity. These unregulated voltages demean the performance and result in an unstable system. This brief proposes an internal model control (IMC) non-linear approach based robust proportional-integral-lead (PI-Lead) controller design for regulating a practical fifth-order DC-DC boost converter. The main innovation of this paper is the developed procedure for designing controller. The prominent feature of IMC filter coefficient is to fulfil the desired level of gain margin and phase margin to show the trade-off between performance and robustness. The proposed controller's performance is evaluated in the presence of uncertain disruptions and its effectiveness is verified by comparing it with the some conventional proportional-integral (PI) as well as with recently published IMC-proportional-integral-derivative (IMC-PID) and IMC-proportional integral derivative double derivative (IMC-PIDD2) controllers. The applicability of the proposed control methodology has been validated under varying supply and load current levels in presence of parametric uncertainty using a MATLAB/Simulink tool along with a low-cost microcontroller DSP F280379D based laboratory prototype.

An efficient power management control strategy for grid-independent hybrid renewable energy systems with hybrid energy storage: Hybrid approach

The increase in renewable energy resource based electricity generation in the past few years can be attributed to dwindling fossil fuels and their negative environmental impact, as well as the exponential expansion of electricity consumption. Furthermore, RERs are environmentally benign and sustainable. This manuscript proposes a hybrid method for managing power in a Hybrid Energy Storage System within a grid-independent Hybrid Renewable Energy System. The proposed hybrid technique combines the Prairie Dog Optimization (PDO) and Multi-scale Attention Convolutional Neural Network, hence named the PDO-MACNN technique. The principal objective of the proposed method is to minimize Total Harmonic Distortion (THD), maintain active power stability among generation and consumption through the charging or discharging of the Hybrid Energy Storage System, and regulate the DC-link voltage within strict bounds. The PDO algorithm is used to optimize the parameters of the three-phase inverter controller, while the MACNN algorithm is used to predict the performance of the hybrid renewable energy systems. The proposed approach is evaluated and compared to other existing methods on the MATLAB platform, demonstrating superior performance to methods like the Whale Optimization Algorithm, Seeker Optimization Algorithm, and Grasshopper Optimization Algorithm. Based on the outcome, it is concluded that the proposed approach achieves a 0.8 % lower THD compared to the existing techniques.

Enhanced supervisory control scheme for hybrid microgrid operation with virtual power plants

Owing to the urgency of energy demand, an enhanced supervisory control scheme (ESCS) is proposed for hybrid microgrids (HMGs) integrating AC and DC grids. This system optimizes energy management within a virtual power plant (VPP) setup, facilitating smart charging stations for electric vehicles (EVs) and enabling vehicle-to-grid (V2G) and grid-to-vehicle (G2V) interactions. The proposed ESCS combines three sub-controllers: a sliding mode approach-based maximum power algorithm (SMA-MPA), active current detection technique (ACDT), and state of charge (SOC) regulation scheme. In this proposed approach, the SMA-MPA method is employed to extract maximum power with necessary stability confirmation. Moreover, ACDT is utilized to mitigate harmonics from nonlinear loads through the DC-AC inverter, thereby improving power quality (PQ). To enhance SOC regulation of the VPP, a detailed flow chart of appropriate converting mode selection associated with SOC controller design is proposed for smoother operation and improved dynamics. The coordination between sub-controllers is achieved by analyzing power demand and supply, DC-link voltage conditions, and SOC states of the VPP. The proposed ESCS approach enhances PQ even during PV shutdown conditions. Through software simulations and real-time Hardware-in-the-Loop (HIL-402) validation, the ESCS's superior power management, PQ, and regulatory compliance are demonstrated against conventional PQ methods. The findings exhibit excellent power management, improved PQ, and better voltage/frequency regulation in accordance with prescribed international IEEE 519 standards.

POWER QUALITY ENHANCEMENT USING GWO OPTIMIZED ANFIS CONTROLLER BASED STATCOM IN MG

In power systems, voltage stability and power quality are major problems. Hence, this work formulated a novel flexible control algorithm for STATCOM in order to mitigate power quality issues in micro grids. Further to improve the performance of the STATCOM, an intelligent optimised ANFIS controller has been incorporated. The suggested technique has two parts; GWO is employed in the first stage to learn the ANFIS parameters. The performance of the suggested ANFIS-GWO approach is assessed in the second stage. Thus, the efficacy of the proposed controller is examined under different case studies using both simulation and experimental results. From the results, it was found that when the system is subjected to load changes, the dynamic performance of the stem is improved and the dc link voltage remains constant. As the proposed controller achieves less fluctuation, it can be considered as suitable controller for micro-grids.

Design and Modeling of a DC-Link Capacitor Droop Controller for a PV System: A Comprehensive Review

This paper presents an in-depth review of the design and modeling of a DC-link capacitor droop controller for photovoltaic (PV) systems. The DC-link capacitor droop controller plays a crucial role in stabilising the DC-link voltage, managing power fluctuations, and ensuring reliable operation of grid-connected PV systems. This review covers the fundamental principles of droop control, the architecture of PV systems, the role of DC-link capacitors, and the detailed design process of the droop controller. Additionally, we explore various control strategies, simulation methods, practical implementations, and future research directions in this field. Keywords: DC-Link Capacitor, Droop Control, PV System, Grid-Connected, Stability, Power Quality, Renewable Energy

Optimal control scheme for multi-terminal high-voltage direct current system to improve robust grid frequency regulations

This paper proposes an optimal control scheme for robust frequency regulation (FR) in power networks that utilize multi-terminal high-voltage direct current (MT-HVDC) systems to interconnect AC grids. The proposed scheme involves the development of a Linear Quadratic Gaussian (LQG) controller to minimize FR in each grid. A state space model of the MT-HVDC grids is derived to design the controller, considering the DC-link voltage and active power controls at the rectifier and inverter, respectively. Additionally, the model incorporates inertia emulation (IE) and droop controllers. Based on the derived state-space model, an LQG controller is designed to achieve optimal frequency control. The stability of the proposed scheme is analyzed through sensitivity and eigenvalue analysis, with a focus on the influence of grid parameters and control gains. Comparative case studies demonstrate that the proposed scheme outperforms conventional strategies in terms of improving the effectiveness and robustness of real-time FR in MT-HVDC grids. The proposed control scheme involves an LQG controller that considers various factors and demonstrates superior performance compared to conventional methods, as supported by comparative case studies.

Advanced gate driving concepts and switching optimization for SiC semiconductors

Silicon carbide (SiC) MOSFETS are increasingly favoured in power electronics for their improved properties compared to silicon-based counterparts, such as IGBTs. Their ability to operate at higher switching frequencies and execute faster switching transients is notable. However, these features also raise significant concerns with electromagnetic interference (EMI). To exploit the full capabilities of SiC-based technology, meticulous design strategies encompassing the power stage, commutation loop, and gate drive are essential. This paper conducts a comprehensive review of existing gate drive techniques aimed at enhancing the performance of SiC devices. Moreover, this study introduces an innovative approach for optimizing switching processes through the use of active gate drivers (AGD). By pre-mapping the gate-source voltage profiles for different conditions (such as load current, temperature, and DC-link voltage), it is possible to achieve a significantly improved switching trajectory. This optimization process can be applied on a cycle-by-cycle basis in practical scenarios. Herein, pre-mapping and optimization have been experimentally confirmed in a half-bridge configuration. Through simulation, it is demonstrated that optimizing the switching trajectory can lead to a balanced compromise between EMI and switching losses, showcasing the potential for significant performance enhancements in SiC device operation.

Design and investigation of high power quality PV fed DC-DC boost converter

This study presents a new improved voltage gain dc-dc converter architecture to maximize solar photovoltaic (PV) power output. The maximum power point tracking (MPPT) method utilizes particle swarm optimization (PSO)–based artificial neural networks (ANN) to reduce the oscillations of output electrical performance at the maximum power point (MPP). For any solar cell temperature and irradiance, the ANN delivers the electrical current and voltage outputs at the MPP and thus could reach the MPP in minimum instances. A DC-DC converter needs specific characteristics to work with photovoltaic systems. These include higher voltage development to meet increased DC link voltage requirements, the continuous input current to extend the PV system life, common grounding to prevent electromagnetic interference, and reduced electrical stress with fewer components. This paper combines a quasi-switched switch inductor network and extendable diode capacitor modules to achieve the quality mentioned earlier. The converter offers constant input current, high efficiency (95 %) with considerable gain (12 times higher than input), lower voltage stress (almost one-fifth of output voltage), and a common grounding feature. The effectiveness of the proposed MPPT technique is analyzed in terms of higher efficiency, MPP tracking time, gain, and the normalized voltage stress on diodes. The experimental step is developed to validate the simulation (Simulink and Psim) results of the present research work.

Impedance analysis of voltage prediction compensation scheme for DC-link oscillation suppression in cascade drive system

The dc-link voltage oscillation caused by the negative impedance characteristic of the constant power load is a significant issue in the series LC branch-permanent magnet synchronous motor (PMSM) cascade system. To this end, this paper proposes a voltage prediction compensation (VPC) strategy to suppress the dc-link voltage oscillation by adding a voltage stability constraint term to the finite control set model predictive current control (FCS-MPCC). First, the linearized q-axis reference voltage is obtained by taking the derivation of the cost function of the VPC, thereby deriving the input impedance of the inverter-permanent magnet motor system. Then, the impedance matching criterion and Nyquist stability criterion are used to theoretically prove that the proposed strategy can effectively improve system stability, and the robustness of the proposed method to changes in motor parameters is analyzed. Finally, experimental verification was conducted on a 1 kW motor platform. The results show that when the motor is running under rated working conditions, after adding the stability constraint, the dc-link voltage fluctuation drops from 40 V to 7 V; the q-axis current pulsation rate also drops to 3.8 %. Theoretical analysis and experimental results show that the VPC strategy can effectively suppress the dc-link voltage oscillation of the cascade drive system.

Adaptive fuzzy integrated LMS based control strategy for voltage power quality enhancement

In this paper, an adaptive Takagi Sugeno (TS) Fuzzy integrated Mixed Order Normalized Least Mean Square/Fourth Algorithm (MONLMS/F) is proposed for the unresolved voltage power quality issues in distribution system. The proposed control utilizes the cost function of mixed order of errors, which are based on second and fourth order and the feature of cost function overcomes the demerit of traditional basic least mean square method, which is based on second-order error. The implemented control technique has two main objectives. Firstly, the fundamental estimation of correct active and reactive signals from polluted grid voltage for computing the reference load voltages and second is the DC link voltage regulation. A correct weight estimation is achieved by Mixed Order Normalized Least Mean Square/Fourth Algorithm (MONLMS/F) and voltage regulation is performed by Takagi Sugeno Fuzzy (TSF) approach. The proposed integrated control enhances the capability of system against voltage deviation from the reference voltage and successfully eliminates the harmonics from polluted grid voltages. A bio-inspired optimizer like Spotted Hyena (SH) is integrated with TSF for self-tuning of the membership functions (MFs) and fuzzy rule to adapt the system variations and regulate fluctuations in the DC link for dynamic conditions. However, auto-tunned TS-Fuzzy have a fast transient response of DC and AC link voltage based on dynamic indicators like settling time (ts=0.12 s), undershoot (Us=3.4 %) and peak overshoot (Mp=5.6 %) are compared to classical PI controller. Nonetheless, the proposed TS-MONLMS/F control strategy outperforms the other classical control with low oscillations at any power quality scenario with improved dynamic response. The significant MATLAB simulation and experimental results are evaluated, and its performance is demonstrated with the dSPACE (DS1202) processor for experimental realization.

A Family of 5-Level Boost-Active Neutral-Point-Clamped (5L-BANPC) Inverters with Full DC-Link Voltage Utilization Designed Using Half-Bridges

A Family of 5-Level Boost-Active Neutral-Point-Clamped (5L-BANPC) Inverters with Full DC-Link Voltage Utilization Designed Using Half-Bridges

A non-isolated PFC bridgeless SEPIC-Cuk converter with adaptive PI controller for induction motor

In general, the induction motor (IM) is extremely nonlinear in nature and frequency dependent. In most cases, the power generated by the IM has a low power factor (PF), which exhibits detrimental effect on the extent to which the whole transmission and distribution system functions. Since there exists more current harmonics as an outcome of minimized PF, the efficiency of the power system suffers due to transmission line heating and voltage distortion characteristics. Therefore, this paper proposes a power factor correction (PFC) method to overcome the aforementioned issues. Here, by the utilization of AC-DC bridgeless SEPIC-Cuk converter, the power quality is improved by reducing reactive power consumption and enabling better control of voltage and current outputs. To maintain the stable DC link voltage with reduced ripples, the adaptive proportional-integral (PI) controller is used in this work. The three-phase voltage source inverter (VSI) transitioning function is controlled by cascaded fuzzy logic (CFL) controller, which is also utilized for regulating the speed of the three-phase IM. Implementing the proposed control strategy improves power quality significantly by reducing total harmonic distortion (THD). The proposed system is simulated in the MATLAB platform and the attained outcomes, it is clear that the proposed system is highly effective.

Performance evaluation of bridgeless isolated SEPIC-Luo converter for EV battery charging using PI and ANN controller

Electric vehicle (EV) rechargeable battery packs that employ traditional power factor correction (PFC) circuit design have performance limitations due to their substantial conductivity loss that ensures at the input of a diode bridge rectifier (DBR). This study suggests a bridgeless (BL) isolated single ended primary inductance converter (SEPIC) - Luo converter to address the problem. As a result, the input current exhibits a power factor operation of unity throughout the charging process. DBR elimination and current conduction through a remarkably small number of circuits both significantly reduce conduction losses. The use of an artificial neural network (ANN) and proportional integral (PI) controller enhances the converter's performance with a stable DC link voltage. The suggested converter overall operation is thoroughly described in terms of variety of operating modes and simulation-based effectiveness. Here, with the assistance of the hysteresis current controller (HCC), the input current disruptions are reduced. Constant current and voltage management is used to successfully charge the EV battery, resulting in improved efficacy and inherent PFC. By utilizing simulation outcomes achieved from MATLAB, the performance of proposed BL isolated SEPIC-Luo in boosting the power quality of EV charger system is examined.

Performance evaluation of solar-PV integrated hybrid fuzzy-logic controlled multi-functional UPQC for enhancing PQ features

To improve distribution system voltage and current quality, a newly built solar-PV system connected multi-functional universal power quality compensator (MFUPQC) has been extensively used. The proposed MFUPQC mitigates both load and source-side concerns in a three-phase distribution system. Furthermore, as part of the distributed generation scheme, active power from solar PV is injected into the grid or source when solar PV is available. In this context, the proposed MFUPQC was tested in both PQ enhancement and DG integration modes using a feasible control scheme. The proportional-integral controller is used for shunt- voltage-source inverter (VSI) DC-link control, which is not suitable for regulating DC-link voltage at the desired level due to incorrect gain value selection. In this work, an intelligent hybrid-fuzzy-logic DC-link control of MFUPQC evidences the intelligent knowledge base for better regulation of power-quality issues. The suggested hybrid fuzzy-logic controlled MFUPQC device's performance for both power quality (PQ) improvement and DG integration is validated using the MATLAB/Simulink software tool, and simulation results are provided with an appealing comparison analysis.

A novel hybrid-fuzzy logic based UVC technique for solar-PV/grid integrated water-pumping system

The continual depletion of fossil fuels and increased green-house emissions are persuading the consumers to install micro-renewable energy sources-based water pumping system. Among numerous energy sources, the solar-PV plays a significant role in water pumping application due to its virtuous, environment friendly, noise-free and abundant nature, so on. Along with solar-PV, the grid integrated system enables the continuous operation of water pumping system during varying temperature and irradiance conditions, and also delivers available solar-PV energy to grid during non-functional of pumping system. The above operations are carried by using bidirectional inverter which is controlled by using unit-vector control (UVC) technique. It consists of proportional-integral controller, which is not suited for regulation of DC-link voltage at desired level because of improper selection of gain values. In this work, an intelligent hybrid-fuzzy logic based UVC technique evidences the intelligent knowledge base for better regulation of DC-link voltage and power-flow of bidirectional inverter. The performance and operation of proposed hybrid-fuzzy logic control UVC technique for solar-PV/Grid integrated water-pumping system is evaluated under various operating cases by using MATLAB/Simulink tool; simulated results are conferred with superlative comparisons.

An optimal regulation of grid-connected doubly-fed induction generator angular speed and the DC-link voltage

In this work, a linear quadratic regulator controller is utilized to optimize the gains of the machine-side converter and grid-side converter controllers. The DC-link voltage and the rotational speed of the doubly-fed induction generator are optimally regulated by these controls. Additionally, the small-signal stability of the proposed system has been evaluated using the linearized model of the system. The small-signal stability analysis of the designed system has been accomplished through the application of the eigenvalues and participation factors technique. The suggested controller has been tested in a variety of operating conditions under small disturbances. MATLAB/SIMULINK simulation simulations have been used to evaluate the efficacy of the suggested optimal control system. Additionally, the generator-angular speed and DC-link voltage dynamic performances demonstrate the efficacy of the proposed controller. Finally, the robustness of the proposed controller has also been tested and validated using OPAL-RT technology under large perturbations at stator terminal voltage.

A fuzzy integrated non-linear backstepping control of a grid connected PMSG wind farm

In this paper a grid connected PMSG wind farm is controlled by non-linear backstepping control. The PMSG power is delivered to grid through two back-to-back connected IGBT based VSCs. The VSCs are controlled by individual Sin PWM techniques for which the reference signals are generated non-linear backstepping controller. A capacitor is connected at the common DC link of the back-to-back VSCs for voltage stability. The backstepping controller designed for the control of PMSG has the capability to extract maximum power from the wind farm. The machine side connected VSC operates in synchronization to the rotor angle and the grid side connected VSC operates in synchronization with the grid voltages. The DC voltage regulator of the grid side converter control should be optimum for better stability of the system. Therefore, the conventional PI controller of the voltage regulator is replaced by a 49-rule base FLC which reduces the ripple and settling time of the DC link voltage. A 2MG PMSG wind farm is considered for performance analysis with PI and FLC in the non-linear backstepping control structure. The comparative analysis is carried out in MATLAB software with Simulink block sets utilized to design the wind farm connected to grid. The graphs are compared to determine the performance of the controller with different operating conditions.