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A sliding mode control-based model reference adaptive system (SMC-MRAS) estimator for sensor-less control of doubly fed induction generator (DFIG) systems in wind turbine applications is proposed in this paper. The proposed SMC-MRAS estimator uses the rotor current as a variable of interest. The proposed SMC-MRAS estimator has the advantage of being immune to machine parameter variations. The SMC parameters are designed using the Lyapunov stability criteria. The performance of the proposed SMC-MRAS estimator is validated using simulations in MATLAB/SIMULINK. A comparative study between the proposed SMC-MRAS estimator and the PI-MRAS estimator is also conducted to demonstrate the superiority of the proposed SMC-MRAS estimator. [ABSTRACT FROM AUTHOR]

The fundamental voltage, current, and phase angle are required for a wide variety of power system applications. An algorithm that is capable of calculating or estimating these quantities in real time, in the presence of distorted waveforms, finds application in diverse areas of power systems. Techniques to detect voltage sag include the root mean square (rms), Fourier transform, and peak voltage detection methods. The problem with these methods is that they use a windowing technique and can therefore be too slow when applied to detect voltage sags for mitigation since they use historical data. Recent work in the field of signal processing has led to an algorithm that can extract a single non-stationary sinusoidal signal out of a given multi-component input signal. The algorithm is capable of estimating the amplitude, phase and frequency. In this paper, the algorithm is compared to existing methods of sag detection. [ABSTRACT FROM AUTHOR]

• Renewable obligation policy is used to increase renewable penetration in the grid. • Stochastic multi-objective economic dispatch model is presented. • This model includes renewable obligation and battery storage. • Inactive line constraints are reduced to improve computational complexity. In this paper, a stochastic multi-objective economic dispatch model is presented under renewable obligation policy framework. This proposed model minimises the total operating costs of generators and spinning reserves under renewable obligation while maximising renewable penetration. The intermittent nature of the wind and photovoltaic power plants is incorporated into the renewable obligation model. In order to minimise the cycling costs associated with ramping the thermal generators, the battery energy storage system units are included in the model to assist the system spinning reserves. Dynamic scenarios are created to deal with the intermittency of renewable energy sources. Due to the computational complexity of all possible scenarios, a scenario reduction method is applied to reduce the number of scenarios and solve the proposed stochastic renewable obligation model. A Pareto optimal solution is presented for the renewable obligation, and further decision making is conducted to assess the trade-offs associated with the Pareto front. To show the effectiveness of the proposed stochastic renewable obligation model, two IEEE test systems are used, i.e., the modified IEEE 30-bus and IEEE 118-bus system. In both test systems, the proposed model can attain high renewable penetration while minimising the expected operating cost. In the large IEEE 118-bus test system, the computational efficiency of the renewable obligation model is demonstrated by reducing the line constraints by 87% which minimises the computing time. A comparative study evaluates the impact of the stochastic model to the deterministic one, and it shows that the stochastic model can achieve high renewable penetration. [ABSTRACT FROM AUTHOR]

This study investigates the efficacy of Explainable Artificial Intelligence (XAI) methods, specifically Gradient-weighted Class Activation Mapping (Grad-CAM) and Shapley Additive Explanations (SHAP), in the feature selection process for national demand forecasting. Utilising a multi-headed Convolutional Neural Network (CNN), both XAI methods exhibit capabilities in enhancing forecasting accuracy and model efficiency by identifying and eliminating irrelevant features. Comparative analysis revealed Grad-CAM's exceptional computational efficiency in high-dimensional applications and SHAP's superior ability in revealing features that degrade forecast accuracy. However, limitations are found in both methods, with Grad-CAM including features that decrease model stability, and SHAP inaccurately ranking significant features. Future research should focus on refining these XAI methods to overcome these limitations and further probe into other XAI methods' applicability within the time-series forecasting domain. This study underscores the potential of XAI in improving load forecasting, which can contribute significantly to the development of more interpretative, accurate and efficient forecasting models. • XAI can be effective feature selection tools for high-dimensional time series data • Grad-CAM's speed rivals filter methods, but may sacrifice model accuracy • SHAP selects features that ensures better model accuracy but demands more computation • With array manipulation in model pipeline, SHAP can explain any model architecture [ABSTRACT FROM AUTHOR]

The ride through voltage disturbance of an induction motor (IM) reduces the unscheduled shutdown from processes, and the discriminatory protection allows industries to save time, protect machines and to increase the mean time before breakdown. This paper discusses the analyses of the stability performance of an induction motor under disturbance from voltage sags and short interruptions. The work also addresses the challenge associated with the operation of induction motors of power rating from 3 to 100 kW, during voltage dips, brief interruptions, transient overcurrent, and how to select the induction motors protection for a maximum operating time under such circumstances. The study aims to look for the corrected delay time and peak transient of stator current that protection scheme can handle. It is found that the rising stator current during a voltage disturbance (due to voltage sag and short interruption) can reach the per unit value of stator current up to 18 times, and it is recommended that the delay time should be settled between 100 and 200 msec. Therefore, this study is of great significance to the manufacturing industry where IMs are commonly used as it can avoid damage to the motor. [ABSTRACT FROM AUTHOR]

Let-through energy (LTE) refers to the I2t or Joule energy that a conductor is exposed to during a fault on the feeder. This energy is influenced by the magnitude of the fault current and time it takes for the protection system to clear the fault. If the LTE exceeds the conductor thermal energy limit, the conductor will get damaged. This concept of LTE evaluation is applied to the inverse definite minimum time (IDMT) current based back-up protection elements on a multisource high-voltage feeder in a hypothetical and actual network. Another method to calculate the relay operating time for IDMT relays was developed based on an average disk speed of electromechanical over-current relay and the proportionality of its speed to the magnitude of the fault current. This method was incorporated into a software application to generate results. These results allow the user to evaluate the conductor LTE exposure, total fault time exposure, the effect of instantaneous fault clearing and the application of autoreclose cycles. An energy-area evaluation was applied to quantify and evaluate small protection settings changes. The conclusion is that LTE analysis on back-up protection should be considered for high-voltage feeders to ensure that the conductors are protected. [ABSTRACT FROM AUTHOR]

Let‐through energy (LTE) refers to the I2t or Joule energy that a conductor is exposed to during a fault on the feeder. This energy is influenced by the magnitude of the fault current and time it takes for the protection system to clear the fault. If the LTE exceeds the conductor thermal energy limit, the conductor will get damaged. This concept of LTE evaluation is applied to the inverse definite minimum time (IDMT) current based back‐up protection elements on a multisource high‐voltage feeder in a hypothetical and actual network. Another method to calculate the relay operating time for IDMT relays was developed based on an average disk speed of electromechanical over‐current relay and the proportionality of its speed to the magnitude of the fault current. This method was incorporated into a software application to generate results. These results allow the user to evaluate the conductor LTE exposure, total fault time exposure, the effect of instantaneous fault clearing and the application of auto‐reclose cycles. An energy‐area evaluation was applied to quantify and evaluate small protection settings changes. The conclusion is that LTE analysis on back‐up protection should be considered for high‐voltage feeders to ensure that the conductors are protected. [ABSTRACT FROM AUTHOR]

Summary: The addition of photovoltaic (PV)‐based distributed generators introduces several challenges to power system protection and control engineers. In a multi‐source distribution network, power flow becomes bi‐directional, and conventional overcurrent and earth fault protection schemes are threatened. Addition of PV‐based distributed generation could lead to protection blinding, sympathetic tripping, and loss of coordination in conventional overcurrent protection. This paper evaluates the general concerns regarding protection in a PV‐based distributed generation network, by modeling a power system with sequence networks for different types of faults. The power system is simulated with Digsilent PowerFactory. The results show that many of the general concerns can be mitigated by using sequence components to identify faults. A method is presented to adapt conventional overcurrent protection schemes without the need for communication‐assisted protection. [ABSTRACT FROM AUTHOR]

Methods of accurately determining the efficiency of motors in situ without costly plant downtime are required to implement online motor management strategies that can lead to energy and cost savings. An ideal method must perform in practical power system conditions where there is variation in the supply voltage. An improved non-intrusive compensated slip technique utilising vibration signature analysis has been proposed for accurately estimating induction motor efficiency. The performance of this technique is evaluated through experimental data under ideal and non-ideal supply voltage conditions. The proposed method of estimating motor efficiency is found to be accurate and easy to implement. The proposed technique is robust in under-voltage and over-voltage power supply conditions. [ABSTRACT FROM AUTHOR]

This review paper is focused on common protection challenges related to the integration of distributed generation (DG) into medium voltage (MV) distribution power systems. Protection challenges, as indicated by the general scientific community, are explained and discussed. Based on these challenges, several alternative centralized and decentralized protection alternatives are explained and critically evaluated. Photovoltaic (PV) based distributed generators are connected to the utility grid through inverters, which are able to control active and reactive parts of their output and also limit their fault current contribution. Research is proposed to quantify the risks to protection in conventional power systems with increasing presence of distributed generation. Since the positive, negative and zero sequence current output from PV inverters can be controlled, conventional overcurrent protection using negative and zero sequence current is proposed to increase the protection reliability and maintain coordination in the presence of distributed generators. [ABSTRACT FROM AUTHOR]

The battery pack performance and expected lifespan are crucial in electric vehicle applications. Balancing the charge on a battery pack connected in series and parallel is crucial due to manufacturing discrepancies and distinct performance of each cell in a standard battery pack. In this paper, a switched-resistor passive balancing-based method is proposed for balancing cells in a battery management system (BMS). The value of the available voltage at the battery cell terminals is balanced using resistors in an electrical circuit, and the excess voltage is eliminated. The cell balancing outcome demonstrates that the electrical circuit can maintain an even voltage across each cell. The procedure of balancing involves individually adjusting each cell's level of charge. Passive balancing releases energy as heat by draining charge from cells that have too much charge. A passive cell balancer is a cost-effective solution and easy to install, but due to thermal loss from a resistor, it has a low energy efficiency for cell balancing and necessitates a lengthy balancing process. This passive cell balancer is an effective and reliable method for low-power devices and portable applications such as electrical vehicles. The power limits during charging and discharging are estimated using the bisection method. [ABSTRACT FROM AUTHOR]

This paper presents a new single-source switched capacitor- (SC-) based multilevel inverter (MLI) design with a boosting potential of three times the supply voltage. To produce a waveform with seven output voltage levels, the suggested switching capacitor inverter consists of eight switches, single diode, and two capacitors. Because capacitors are inherently balanced, there is no need for a balancing circuit or sensor. The structure can be expanded using the provided generalized equations. In addition, the technique for switching control and loss analyses is explored. A fair comparison with the most recent SCMLI topologies has been conducted to demonstrate the merits of the proposed work. Furthermore, the proposed topology is evaluated using the MATLAB/SIMULINK tool, and experiments under both transient and steady-state situations are performed to demonstrate its feasibility. At dynamic-loaded situations, the performance of the proposed SCMLI with dynamic modulation index and switching frequency is tested. [ABSTRACT FROM AUTHOR]

This work presents the two space vector pulse width modulation (SVPWM-I and SVPWM-II) strategies for eleven-level (11L) asymmetric cascaded H-bridge (CHB) multilevel inverter (MLI). Depending on the isolated structure and nonappearance of capacitor voltage balancing issues, the CHB MLI structure is favoured. These days, the SVPWM control method is accomplished superior consideration among the diverse PWM methods. In common, the SVPWM strategy is realized based on deteriorating higher-level hexagons into a lower level hexagon (2-level). Compared to the classical SVPWM strategy, the proposed SVPWM-I strategy decreases the memory and mathematical burden necessity included within the demonstration of eleven-level SVPWM devoid of losing the inverter output voltage (AC) contour by diminution the number of two-level hexagons. Also, the SVPWM-II strategy is presented, which incredibly diminishes the mathematical endeavours. The presented two SVPWM methods performed on an eleven-level asymmetric CHB multilevel inverter (MLI) by utilizing SIMULINK/MATLAB program tool and are compared with conventional sinusoidal PWM and Third harmonic injection (THI) PWM methods to confirm the proposed SVPWM methods. The proposed SVPWM methods give higher AC RMS voltage and lower harmonic distortion when compared to SPWM and THIPWM methods. To validate the presented two SVPWM control schemes, hardware results are taken on asymmetric eleven-level CHB MLI. [ABSTRACT FROM AUTHOR]

The effectiveness of phase over-current protection cannot be evaluated by using time-current graphs alone. This article develops a method to evaluate and optimize the phase over-current protection on a radial medium-voltage distribution feeder, which can reduce the risk at the point of fault and improves the overall reliability of the feeder. The method is based on the evaluation of protection operating time, let-through energy, pickup sensitivity, and extent of the voltage dips experienced at the point of common coupling due to network faults under high- and low-source impedance conditions. A Microsoft Excel-based software application (Microsoft, Redmond, WA, USA) is developed that incorporates the four evaluation measures under user-definable network criteria. The application illustrates the results in unique, special forms across the analyzed path and allows the benefits of small changes in protection settings to be quantified. The method and software applications are applied in two case studies on an actual distribution network. The results confirm that it is possible to evaluate the effectiveness of the phase over-current protection philosophy using the aforementioned criteria. [ABSTRACT FROM PUBLISHER]

This paper presents a combined economic dispatch and demand response optimisation model under renewable obligation. Real data from a large-scale demand response programme are used in the proposed model. The model uses renewable obligation policy and direct load control to find an optimal energy and reserve strategy that minimises generation costs and maximising renewable penetration. The real data from the South African large-scale demand response programme are used in which the system operator can directly control the participation of electric water heaters at the substation level. The actual load before and after demand reduction are used to assist the system operator in making optimal decisions on whether a substation should participate on the demand response programme. The application of real data to the proposed model avoids the traditional approaches which assume arbitrary controllability of flexible demand. The effectiveness of the model is tested using the modified IEEE 30 and 118-bus systems. The results show that the proposed model can achieve significant demand reduction as high as 830 MW for the IEEE 30-bus system and shift up to 401 MW. Moreover, a total cost reduction of 21.56% can be achieved using the IEEE 118-bus system. • Economic dispatch and demand response models are combined for renewable obligation. • Real data from a large-scale direct load control programme are applied. • Cost reductions are 21.57% and 15.81%, respectively, for two testing systems. [ABSTRACT FROM AUTHOR]

Smart grid technologies are a catalyst for the modernisation of the electrical system whilst satisfying all electrical power stakeholders. The application of intelligent systems results in more flexibility and reliability. This paper presents a dynamic energy management system for a microgrid connected to a grid for residential application. The system models a smart metering system to collect data from different components of the electrical system. A grid-tied photovoltaic and energy storage system model is optimally designed. The model uses the framework of a smart grid based on demand response and energy pricing to coordinate the energy flow of a home. Three optimal control scenarios are formulated, where the opportunity energy is considered to be injected to the main grid. These scenarios are two linear methods (open and closed-loop models) and a quadratic approach based on model predictive control. It was observed that the energy storage system plays an essential role in the context of energy-saving and gain from the demand side. The models provide benefits in terms of energy-saving and energy cost. The performance of dynamic modelling is validated with the experimental data from the smart metering system. • Formulates linear and quadratic model of smart home energy coordination for the intelligent microgrid application. • Designs optimal energy flow control strategies by the use of a smart metering system based on wireless communication. • Compares the dynamic performance of the energy management schemes based on demand response. • Provides the consumer with an opportunity of selling the energy to the utility for a microgrid connected to the main grid. • Applies system analysis on the energy components of a residential home. [ABSTRACT FROM AUTHOR]

Summary: The existence of midpoint series flexible alternating current transmission system (FACTS) devices leads to degrade the performance of mho relay, leading in erroneous estimation of fault location, ie, overreach or underreach for wide variation in network parameters. This research article proposes a novel mho relay algorithm to improve the performance of distance relay in presence of FACTS device using phasor measurement unit (PMU). First, the complete model of transmission system employing static synchronous series compensator (SSSC) and its control strategy is described analytically, where the error introduced in measurement of impedance due to SSSC on the performance of distance relay. Second, a novel mho relay procedure is developed based on PMU to protect the first zone of double‐circuit transmission line for single line‐to‐ground (SLG) fault. The proposed work is analysed and simulated with 48‐pulse SSSC carried out with Bergeron model of transmission line using power system computer‐aided design (PSCAD) computer simulation. Finally, the simulation results represent that the suggested adaptive scheme is truthful, reliable, and secure with change in compensation level of SSSC. [ABSTRACT FROM AUTHOR]