Grid Voltage Research Articles

Digital twin technology for enhanced smart grid performance: integrating sustainability, security, and efficiency

This research paper presents the development and analysis of a multifaceted smart grid prototype. It combines various technologies for the smart grid operation. The first technology is environmental analysis of smart grid and solar panel cleaning. Secondly, radio-frequency identification (RFID)-based security and access control system has been integrated for smart grid. The third component is internet of things (IoT)-based energy monitoring and load management. For environmental analysis sensors such as temperature, humidity, light-dependent resistor, and flame sensors are connected to a NodeMCU controller for real time monitoring. Moreover, IoT based solar cleaning system is developed in the form of prototype with the help of Blynk and servo motor. The second component of prototype is smart security system which is developed with the help of Arduino and RFID module to facilitate secure access control. The third part of prototype employs voltage and current sensors with an ESP32 microcontroller and the Blynk application for real-time energy consumption analysis. This setup enables remote monitoring of voltage, power dynamics, and consumption patterns in a smart grid. It also offers an IoT based solution for load management and load shedding within the smart grid. The complete prototype overall demonstrates a comprehensive approach to 1) smart grid management, 2) environmental analysis, 3) security, and 4) energy monitoring.

Real-time V2G simulator for grid system frequency and voltage regulation with fault ride-through capabilities

Electric vehicles (EVs) have become one of the promising power grid ancillary services. They can help reduce the intermittent of renewable energy sources by supporting active power and frequency control services. Additionally, bi-directional chargers included into EV batteries can supply/consume reactive power for voltage regulation. To improve voltage quality, a unique control approach is devised to offer fault ride-through. In this study, real-time charging optimization schemes based on particle swarm optimization are developed to coordinate the EVs charging/discharging power with the grid power dispatches depending on the charging priority and preferential electricity prices. Five different car user profiles including different initial state of charge and plug in state have been depicted. Different optimum issues are carried out with comprehensive simulations employing hardware in the loop via real-time simulation for a modified IEEE 14-bus test system. Where different frequency and voltage controls, management strategies, variant fault scenarios, benefits, and challenges for power system regulation with EVs are illustrated. According to the simulation results, the proposed optimized charging strategies reduce the total expenses of EV parking station by 40 % compared to other cases, hence maximizing EV owner satisfaction. The net load curve is smoothed and reduced by 11 %, particularly during peak period.

Series active filter using seven level packed U cell converter for power quality enhancement

In a low-voltage electrical grid, harmonics can have devastating effects on electrical equipment, leading to premature aging, reduced lifespan, and increased maintenance costs. To mitigate these issues, the control of a PUC-type multi-level converter series active filter is investigated in this study, with the primary objective of improving energy quality and reducing disturbed electrical voltage. The proposed filter utilizes a PUC-type voltage inverter controlled by PWM (Pulse Width Modulation) and employs two methods for identifying disruptive voltages: the instantaneous power (P-Q) method for harmonic compensation and the SRF (Synchronous Reference Frame) method. The simulation models are built using the MATLAB-Simulink software platform, which allows for accurate and efficient modeling of the filter's behavior under various operating conditions. The simulation results demonstrate the effectiveness of the series active filter in mitigating harmonics and voltage disturbances, highlighting its potential for real-world applications. The results show that the filter is able to significantly reduce the total harmonic distortion (THD) of the output voltage, improving the overall power quality. Furthermore, the simulation results also demonstrate the ability of the filter to quickly respond to changes in the grid voltage, making it an effective solution for addressing voltage disturbances. The study's findings suggest that the PUC-type multi-level converter series active filter has great potential for real-world applications in low-voltage electrical grids, particularly in systems that require high-quality power supply and efficient harmonic compensation. The proposed filter's ability to improve power quality and reduce harmonic distortion makes it a promising solution for mitigating the negative effects of harmonics on electrical equipment in low-voltage electrical grids.

Design of a reliable electrical photovoltaic generator based on power converters control

This work proposes a renewable energy generation system that operates with a similar behavior as a synchronous generator in terms of reliability in the power supply and inertial response properties against power changes and grid voltage disturbances. The main contributions of this work are: (1) the renewable energy variability managing by means of a battery energy storage strategy, whose charge and discharge are determined by a forecasted-based power adjustment algorithm, (2) the dynamical modeling of an inverter that includes physical inertia and its corresponding response to power and voltage variations, and (3) the synthesis of a nonlinear optimal control for the inertia-based inverter system where the reactive power injection is regulated. Simulation results for a photovoltaic-based generator are presented to demonstrate the effectiveness of the proposed methodologies.

Impact of large-scale renewable energy integration on the grid voltage stability

Nowadays, the production of renewable energy is increasing rapidly due to its enormous potential and environmental advantages. Still, the addition of renewable energy to the grid has resulted in some volatility in the electrical system. In this work, the national grid of Ethiopia is used as an example to examine the impact of significant wind power integration on grid stability. In particular, issues with voltage stability in both steady-state and emergency scenarios are taken into account for the network. The dynamic modeling of the wind farm is taken into consideration for contingency-based analysis, and the whole nation's power network, including the largest wind farm in the nation, Adama-II, is modeled for base-case analysis using MATLAB's built-in PSAT software. The result indicates that the bus voltages are within an acceptable standard voltage range for the base-case system. Nevertheless, the wind farm will be disconnected from the network in compliance with the global manufacturer's guideline in the case of a three-phase fault at the network point of common coupling (PCC), where the voltage at PCC is equivalent to 0.045 per unit voltage. The results also demonstrate that the voltage profile throughout the whole nation power network is lower when there is a problem at PCC. As a result, as Ethiopia is building several huge wind farms, it is advised that fault detection and control methods be thoroughly designed before connecting the major wind farms to the grid.

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.

Optimal Artificial Intelligence Technique for LVRT Capability Improvement of a Grid-tied Wind Energy Conversion System: A MGOANFIS-PI Methodology

This paper proposes an innovative algorithm-based control model for improving the doubly fed induction generator (DFIG) system’s low-voltage ride-through (LVRT) capabilities. The Mountain Gazelle optimization (MGO) algorithm is combined with an adaptive neuro-fuzzy inference system (ANFIS)-based proportional-integral (PI) regulator, called the MGOANFIS-PI approach. In the proposed method, the data set of an MGO-based PI regulator is used after rectification to train the MGOANFIS controller, so updating the ANFIS technique improves MGO’s searching behavior. The implemented control method ensures LVRT capability on grid-tied wind conversion plants based on DFIG in case of a malfunction or a voltage drop. Multiple metrics relating to LVRT are monitored in the proposed system, comprising current, active, and reactive power and voltages. The objective to be achieved, which is resolved through the cascaded MGOANFIS-based PI scheme, is defined. Based on the collected data, ANFIS performs and anticipates the optimal control signal from converters on the rotor and network sides. The MGOANFIS-PI methodology effectively handles system performance and voltage instability during four fault circumstances. The LVRT functionality of the DFIG system and the power quality are enhanced with the assistance of the proposed methodology. Simulations are carried out using MATLAB/Simulink framework. Two test systems are examined: the IEEE 39 bus and the 9 MW wind power plant (WPP) test systems. The WPP’s ability to withstand grid voltage sags is analyzed as part of an effectiveness assessment. The relevance and efficacy of the proposed MGOANFIS-PI method are evaluated, and proved the better performance of the cascaded MGO-based ANFIS-PI controller when compared to PI controllers optimized by comparing it with other well-known optimization techniques, i.e., Gorilla troop optimizer, particle swarm optimization, and genetic algorithm. In the three-phase IEEE 39 bus system and the 9 MW test scheme, detailed wind power plants could persevere in the face of every fault condition.

A bidirectional power converter connecting electric vehicle battery and DC microgrid

One way to increase electric vehicle (EV) battery utilization is to connect it to a dc microgrid. The EV battery can assume the role of an energy storage from the grid point of view. A bidirectional DC-DC converter will be needed to transfer power between them back and forth. This paper proposes the converter design considering its functional objective, including interleaved phase number determination. Efficiency performance evaluation is presented by power loss analysis with the parasitic-parameters consideration of the components. Finding optimum switching frequency based on power loss analysis is performed independently between input and output sides of the converter. Finally, experiments using a scaled-down prototype are shown to verify the analytical analysis of the converter. The experimental results properly validate the power loss analytic analysis carried out in this paper with a maximum error of 2.04% at 1131-watt, 60 V battery voltage, and 140 V grid voltage. Maximum efficiency 96.97% is obtained at 301-watt, 130 V battery voltage, and 151 V grid voltage. Overall, the converter has a simple structure, capable to be operated in various levels of input and output voltages with a minimum battery side current ripple.

Improve the voltage profile of the grid-integrated induction motor with a fuzzy-based voltage source converter

This article suggests installing a series compensator on grid-connected induction motors that allows for the ride-through of unbalanced voltage sag. Fuzzy logic controls the motor voltages in a standard three-phase voltage source inverter or voltage source inverter (VSI). An open-ended three-phase machine and the grid form a series connection for the VSI. The proposed system is well suited for uses where frequency variation is unnecessary, such as with large pumps or fans. There is no requirement for a direct current (DC) source or injection transformer when conducting an electric mutual coupling The severity of the sag in the grid voltage that will prevent EMC from shutting down is proportional to the load on the motors. An increase in the voltage of the DC link may be necessary if the voltage is not balanced. A 1.5 hp four-pole induction motor was used alongside grid voltage disturbances to test the proposed compensator's ride-through capability. Grid's current analysis demonstrates that the proposed system does not require the addition of a passive filter to achieve low levels of total harmonic distortion (THD). Additionally, the control strategy, component ratings, and analysis of the converter's output voltage operating principle and pulse width modulation technique are covered. The system's viability is shown via simulation and experimental results.

Enhancing Low Voltage Ride-Through Resilience using Empowering Solar Energy Strategies

The rapid advancement of Low Voltage Ride-Through (LVRT) technology has been highlighted by the exponential rise of photovoltaic (PV) generation systems. An extensive analysis of LVRT methods specifically designed for PV generating systems is presented in this research. Important topics like main causes, current control schemes, power balance and overall solutions are the main focus of the review. Moreover, it provides comprehensive insights and elaborates on integrated solutions intended for large-scale PV systems. The objective of this research is to improve the resilience and reliability of renewable energy sources, especially solar photovoltaic systems, against grid disruptions and voltage changes by investigating LVRT approaches in solar power systems. Enhancing the integration of solar power systems into current electrical grids, reducing downtime, and optimizing system performance are the objectives in order to accelerate the shift to a more resilient and sustainable energy infrastructure.

Research on optimization and improvement method of new energy access grid stability based on transient stability margin index

Abstract This paper focuses on the potential local voltage stability risks and transient stability margin decline in the power grid after the large-scale integration of new energy. Based on the transient stability margin index of the power grid, a method for evaluating and optimizing the transient stability margin after the integration of wind power into the power grid is proposed. This paper provides guidance for the grid connection points and voltage level determination of the wind power access system during the planning phase, as well as the configuration of reactive power compensation devices such as SVGs.

Fast synchronization with enhanced switching control for grid-tied single-phase square wave inverter using FPGA

Research on grid synchronization has been conducted worldwide by researchers in conjunction with the development of innovative technologies, such as dedicated short-range communication (DSRC) and cellular vehicle-to-everything (C-V2X). However, grid-connected inverters face several challenges, mainly the mismatch in voltage amplitude, frequency, and phase angle, as well as grid voltage disturbance and grid faults. Thus, the control algorithm of this research mainly focused on a half-cycle algorithm to design an enhanced digital switching control for fast synchronization using an FPGA. The control algorithm was developed based on zero-crossing detection (ZCD) and digital phase-locked loop (PLL) modeling techniques using the hardware description language (HDL) and a combination of digital logic blocks in Quartus II software, where the proposed switching was applied using the square-wave switching technique through a 300-watt full-bridge experimental prototype. The performance of the proposed technique was studied, where the total harmonic distortion (THD) for voltage and current resulted in a percentage reduction of 89.29% and 78.05% for voltage and current, respectively, after filter implementation. Also, the resulting signal synchronized in every half cycle and matched the voltage amplitude, frequency, and phase angle of the grid signal in 10 ms.

An Initiative Towards Efficient and Sustainable V2G Technology Fed STATCOM for Grid connected Wind Energy System

The proliferation of renewable energy sources, particularly wind energy, has significantly contributed to the diversification of the global energy mix and the mitigation of greenhouse gas emissions. However, the intermittent nature of wind power generation poses challenges to the stability and reliability of the power grid. This paper explores the integration of Vehicle-to-Grid (V2G) technology with Static Synchronous Compensator (STATCOM) for grid-connected wind energy systems. Novelty. Vehicle-to-Grid (V2G) technology enables bidirectional energy flow between electric vehicles (EVs) and the power grid, allowing EV batteries to serve as energy storage devices. This capability can be leveraged to support grid stability and reliability by utilizing EV batteries to store surplus wind energy during periods of high generation and release it back to the grid during periods of low generation or high demand. Purpose. This effectively mitigates the intermittency and variability of wind power, smoothing out fluctuations and improving grid stability. Methods. By employing V2G technology and leveraging the dual-purpose battery solution can compensate the grid voltage fluctuations and improve power factors in grid-connected wind energy systems, enhancing overall system stability and reliability. Results. The Hystersis current controller (HCC) scheme is used for controlling STATCOM to enhance the dynamic performance. Practical value. The system is simulated in its entirety using the matrix laboratory (MATLAB) . The proposed sustainable model will pave the way for maintaining the true power supply under varying wind conditions.

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.

A Stabilization Control Strategy for Wind Energy Storage Microgrid Based on Improved Virtual Synchronous Generator

In high-penetration renewable-energy grid systems, conventional virtual synchronous generator (VSG) control faces a number of challenges, especially the difficulty of maintaining synchronization during grid voltage drops. This difficulty may lead to current overloads and equipment disconnections, and it has an impact on the security and reliability of the system, as well as limiting the dynamic reactive power support capability of the system. To solve this problem, in this study, a wind–solar hybrid power generation system is designed with a battery energy storage device connected on the DC side, and proposes a low voltage ride-through (LVRT) control strategy for the grid-connected inverter based on an improved VSG. The control strategy employs an integrated current limiting technique combining virtual impedance and vector current limiting to ensure that the VSG exhibits good dynamic power support characteristics during symmetrical faults by adjusting the setpoint value of reactive power. At the same time, it maintains the synchronization and power angle stability of the VSG itself to achieve the goal of LVRT. Simulation results show that the proposed control strategy can effectively suppress the renewable power fluctuations (about 30% reduction in fluctuations compared to the conventional strategy) and ensure the safe and reliable operation of the renewable energy sources and VSGs during grid-side faults. In addition, it provides a given reactive power support and stable grid voltage control (voltage dips reduced by about 20%), which significantly enhances the LVRT capability of the hybrid wind–solar-storage generation system.

Power Harmonic Suppression based direct vector control for robust DFIG operation during grid voltage distortions

AbstractThis paper proposes a Power Harmonic Suppression (Damping) (PHS) based reference current generation scheme, which focuses on simultaneous mitigation of harmonic pulsations in electromagnetic torque, stator real and reactive powers, and DC‐link voltage while retaining sinusoidal stator and grid currents and unity power factor at grid side. The crux of this PHS method lies in its ability to eliminate the harmonic powers developed in the DFIG stator and grid at 100Hz, 200Hz, 300Hz, 400Hz, and 600 Hz owing to second, fifth, and seventh harmonic grid voltages. This is achieved as a result of the elimination of natural fluxes developed in the DFIG air gap due to second, fifth, and seventh harmonic distortions in grid voltage. For this, a single concurrent reference current generation technique is developed for RSC and GSC to mitigate the oscillations of electromagnetic torque, stator real and reactive powers, and ripples in DC‐link voltage. Further, the reference rotor currents (positive, negative, fifth, and seventh sequence) are compared with the actual rotor currents using a PI controller to retain sinusoidal stator and grid currents. The proposed scheme's efficacy is validated with PSCAD/EMTDC simulations and using OPAL‐RT OP4510 real‐time simulator, on a 2.3 kVA DFIG.

Predictive power control strategy without grid voltage sensors of the Vienna rectifier

AbstractThis paper proposes a predictive power control strategy for the three‐phase, six‐switch Vienna rectifier without grid voltage sensors to reduce the hardware cost and complexity of a high‐power PWM rectifier system. Firstly, an algorithm for calculating the AC‐side voltage in the αβ coordinate system is derived according to the operating principle of the Vienna rectifier, and a voltage observer is constructed by combining a second‐order low‐pass filter to estimate the grid voltage. Secondly, a soft start method is designed to solve the problem that the rectifier is prone to inrush current when it is started. Furthermore, the control method of grid voltage sensorless is combined with predictive power control with good dynamic characteristics and simple parameter settings to form the control strategy proposed in this paper. Finally, simulation analysis and experimental verification are carried out on the proposed control strategy. Simulation and experimental results show that the grid voltage estimation has high accuracy, a good surge current suppression effect, unit power factor operation, low input current harmonic content, and good dynamic and steady‐state performance. Therefore, the correctness and effectiveness of the strategy proposed in this paper are verified.

Low voltage ride through enhancement of a permanent magnet synchronous generator based wind energy conversion system in an islanded microgrid: A dynamic matrix controlled virtual DC machine

In an isolated microgrid, the wind energy conversion system based on direct-drive permanent magnet synchronous generator may experience fluctuations in the DC bus voltage due to wind variations and grid voltage drop, thereby compromising system reliability. To address this issue, the scheme of the supercapacitor energy storage system is proposed. The existing double closed-loop PID control, which cannot provide inertia support, has shortcomings such as difficult parameter setting and slow dynamic response. To solve this problem, the dynamic-matrix-control based predictive control for a virtual DC machine method is proposed. Firstly, the concept of virtual DC machine control is firstly introduced in supercapacitor energy storage system. Secondly, according to the unit step response of virtual DC machine, the prediction model of virtual DC machine is established. Finally, the desired torque increment reference of virtual DC machine is calculated by the dynamic-matrix-control controller to change the input torque reference. Hardware-in-the-loop experiment verifies the effectiveness of the proposed method: Compared with traditional double closed-loop PID control, the maximum voltage fluctuation is reduced by 67.9 % under random wind fluctuation and the inhibition effect on DC voltage surge and plunge when fault occurs in the power grid is increased by 61.4 % and 57.9 %.© 2017 Elsevier Inc. All rights reserved.

Seamless transfer of virtual synchronous generator using virtual synchronizing torque controller

AbstractInverter‐dependent renewable energy sources are being integrated into the grid, raising several stability‐related difficulties. This is because these renewable sources have less inertia than synchronous generators. Since the power grid's overall inertia has improved, the introduction of virtual synchronous generators (VSG) has gained much attention. A robust microgrid system requires an effortless transition from grid‐connected to autonomous mode. This can be easily achieved with the help of VSGs. The angle, frequency, and magnitude of the grid voltage needed for synchronization have traditionally been determined by phase‐locked‐loop (PLL). The virtual synchronizing torque and voltage‐based synchronization controller for simple switching between islanding and grid‐connected modes are presented in this study. The proposed method requires no additional controller to identify the unwanted islanding situations because the operating mode can be identified with the help of synchronizing torque. The proposed method does not need to shift to different control algorithms while changing between grid connection and stand‐alone modes. The effectiveness of the suggested controller is established by comparing the experimental prototype of the VSG incorporating the proposed controller to the existing synchronization methods.

Reviewing Control Paradigms and Emerging Trends of Grid-Forming Inverters—A Comparative Study

Grid-forming inverters (GFMs) have emerged as crucial components in modern power systems, facilitating the integration of renewable energy sources and enhancing grid stability. The significance of GFMs lies in their ability to autonomously establish grid voltage and frequency, enabling grids to form and improve system flexibility. Discussing control methods for grid-forming inverters is paramount due to their crucial role in shaping grid dynamics and ensuring reliable power delivery. This paper explores the fundamental and advanced control methods employed by GFMs, explaining their operational principles and performance characteristics. Basic control methods typically involve droop control, voltage and frequency regulation, and power-balancing techniques to maintain grid stability under varying operating conditions. Advanced control strategies encompass predictive control, model predictive control (MPC), and adaptive control, which influence advanced algorithms and real-time data for enhanced system responsiveness and efficiency. A detailed analysis and performance comparison of different control methods for GFM is presented, highlighting their strengths, limitations, and suitability for diverse grid environments. Through comprehensive studies, this research interprets the ability of various control strategies to mitigate grid disturbances, optimize power flow, and enhance overall system stability.