Nominal Voltage Level Research Articles

Artificial rabbits optimization algorithm based tuning of PID controller parameters for improving voltage profile in AVR system using IoT

The power system is mainly affected by transient situations caused by switching heavy loads. The system may become unstable when transient situations occur. The power system should be able to perform continuous operation to maintain its voltage within acceptable limits. To achieve more stability and increase its speed of response, an Automatic Voltage Regulator (AVR) system requires the inclusion of a controller. The AVR system in the generating station uses the PID controller to adjust the abnormal voltage caused by transient conditions. To maintain the nominal voltage level under all the load conditions in the system, a bio-inspired meta-heuristic algorithm called Artificial Rabbit Optimization (ARO) algorithm is proposed to tune the PID controller gain parameters and obtain the optimal gain, thereby the AVR system adjusts the generator terminal voltage to nominal levels. The ARO algorithm inspires natural survival techniques to improve the AVR performance by reducing errors. To maintain a stable voltage profile in a power system, this research mathematically models survival techniques using the Internet of Things (IoT) to obtain an optimal solution. As a result, all devices connected to the power network receive a stable voltage that ensures their voltage reliability. The effectiveness of the proposed algorithm for the AVR system is verified with the MATLAB R2022a model, and the statistics functions are implemented in the module of Pandas, Scipy and mathematical investigations done in Numpy. The proposed ARO algorithm achieves a better voltage profile with less than 12.63% maximum peak overshoot during the system's transient response. The proposed algorithm provides the fastest response and highest stability comparable to other optimisation algorithms.

Influence of the Supply Voltage Variation on the Conducted Emission in the Frequency Range up to 150 kHz Injected into the Power Grid by CFL and LED Lamps—Case Study

In normal operating conditions, the mains voltage level provided by low-voltage distribution networks follows time-varying patterns within permissible limits. The statistical characterisation of disturbances inserted into the power grid by nonlinear electrical devices is useful since operators are able to establish power quality limits and assess the residual capacity of networks for new smart installations, which may include a multitude of power electronic devices. Existing standards related to emission tests recommend using a power supply source in the measurement circuit with a nominal voltage parameter. However, the range of permissible variations of relevant supply voltage parameters may have an impact on conducted emissions. It can also be considered that the symptoms of supply voltage variations may manifest themselves differently depending on the equipment’s architecture and also the range of frequency observation with reference to harmonics and supraharmonics. The purpose of this study is to measure and analyze non-intentional conducted emissions injected into the power grid by lighting devices, methodically, by numbers of studies under different supply voltage conditions within two frequency bands. The emission is evaluated separately in two ranges: up to 2 kHz and 9-150 kHz. Obtained results show that the level of conducted emission introduced into the low voltage network by modern lighting sources like fluorescent and LED lamps varies with the supply voltage level compared to the emission generated in the nominal voltage level condition. Additionally, in the case of a spectrum of higher frequencies, some trends of shifting of the characteristic frequency bands are recorded. The potential of the obtained results is to complement the knowledge of the emission of modern lighting sources, which can be further used for digital models of these devices and to estimate the impact on the grid under real working conditions.

Performance analysis of voltage profile improvement in AVR system using zebra optimization algorithms based on PID controller

Many problems are associated with dynamic changes in the power system, mainly because the number of switching loads has increased. These loads induce ineffective system behaviour, reduce the system voltage profile, and lead to improper voltage regulation. The proposed Automatic Voltage Regulator (AVR) system is intended to eliminate the above problem and preserve the system voltage at the generator terminal within the allowable range. In this work, Proportional-Integral-Derivative (PID) controllers are applied to enhance the dynamic behaviour of the AVR system. The Zebra Optimization Algorithm (ZOA) and Osprey Optimization Algorithm (OOA) algorithms are implemented to optimize the system's transient response by modifying the gain of PID controller parameters, which include proportional, integral, and derivative parameters, to preserve a stable voltage profile. To achieve an optimal solution, the mathematical model of the proposed system is realized in the Internet of Things (IoT). The connected loads in the system can operate at the nominal voltage level through PID controller tuning using ZOA and OOA. The proposed system's performance is evaluated and verified with MATLAB R2023a. ZOA showed an improvement of 18.5 % with a peak overshoot of 0.01 % during the system-transient condition. Compared to conventional optimization algorithms implemented in AVR systems, ZOA provides faster responsiveness and enhanced system stability.

Voltage Sag Compensation Through Dynamic Voltage Restorer Under Non-Sinusoidal Electrical Grid Condition

This work presents a method of voltage insertion into the grid with harmonic distortions through a dynamic voltage restorer (DVR) for protection of sensitive loads to short-term voltage sags. The aim is to recover the nominal voltage level at the load by restoring only the fundamental frequency component without compensating the harmonic contents. Corrections carried out in this manner are justified as the DVR is a device dedicated to restore the amplitude of the sensitive load to its rated value, based on rapid variations from the power grid. The correction of distortions is not suitable for this equipment as harmonics are permanent problems and originate from nonlinearities of electrical loads. Therefore, the batteries that supply the DVR do not support the correction of permanent problems, only for rapid variations. Thus, it allows an extension in the lifespan of the batteries (needed in this type of compensator). Collaterally, restoring only the fundamental decreases the total harmonic distortion of the load, thus allowing this method to make a double contribution to improving the system’s power quality. For this purpose, a recursive least-square estimation is developed, suitable for voltages with harmonic content, here called HRLS. The construction of the reference voltage to be produced by the DC–AC converter also considers the synchronism with the fundamental component of the grid, which allows an optimization of the voltage level used on the DC-link. Correction scenarios only inserting the fundamental, as well as with harmonic content, are tested in simulation to compare performance in the use of the compensator power. The same scenarios are also tested on an experimental platform developed in the laboratory to confirm the proposal.

Design and Demonstration of a 540 V/28 V SiC-Based Resonant DC–DC Converter for Auxiliary Power Supply in More Electric Aircraft

Efficient and robust power electronic converters are vital to the success of the electrification of aircraft. Especially, low voltage auxiliary converters, which usually supply high current and low voltage loads, are not readily available industrially and need special attention. In terms of energy density and efficiency, LLC converters are among the most commonly used and efficient topologies for automotive and aerospace applications. In the case of aerospace applications, a fault-tolerant topology is highly desirable to reduce the need for redundant components and weight by removing backup systems. To solve this issue, this study introduces a new 2.0 kW LLC-based converter with a reconfigurable fault-tolerant architecture. With the help of a specially designed secondary side, the proposed converter can reconfigure itself so that even if one of the semiconductor switches fails permanently, the converter can still maintain power at nominal voltage levels, ensuring that the aircraft’s vital functionality is preserved. This paper also describes the basic operation principle, component-design aspects, conduction loss reduction techniques, and control system algorithm. Finally, a 2.0 kW experimental prototype is built to verify and demonstrate the operation of the proposed reconfigurable LLC converter.

Soft-linking of improved spatiotemporal capacity expansion model with a power flow analysis for increased integration of renewable energy sources into interconnected archipelago

This present study offers a novel approach for the improvement of energy planning. This has become increasingly important as higher penetration of variable energy resources and increased interconnection between the different energy sectors require more detailed planning in terms of spatiotemporal modeling in comparison to the presently available approaches. In this study, we present a method that soft-linked the energy planning and power flow models, which enabled fast and reliable solving of optimization problems. A linear continuous optimization model was used for the energy system optimization and the non-linear problem for the power system analysis. The method is used to compare different energy planning scenarios; further, this also offers the possibility for implementation assessment of the proposed scenarios. The method was applied to interconnected islands for five different scenarios. It was determined that the detailed spatial approach resulted in 26.7% higher total system costs, 3.3 times lower battery capacity, and 14.9 MW higher renewable energy generation capacities installed than in the coarser spatial representation. Moreover, the results of the power flow model indicated that the highest voltage deviation was 16% higher than the nominal voltage level. This indicates the need for inclusion of implementation possibility assessments of energy planning scenarios.

Design of combine load frequency and voltage control of power system using optimisation algorithm

Engineers' main concern is the stability of nominal frequency and voltage levels in an electric power system. If these two characteristics deteriorate, the performance and life expectancy of the power system's related equipment would suffer. Because of this, control devices must be set up and installed specifically for a given working environment in order to maintain the frequency and terminal voltage magnitude within acceptable ranges. An effort has been made to develop a fractional-order PID (FOPID) controller for combined frequency and voltage control issues, since the system performance may be enhanced by choosing an appropriate controller. Utilizing moth flame optimization method, this study examines the plan and execution of the FOPID controller for simultaneous load frequency and voltage management of the power system. An AVR-based excitation voltage control system is used in the first portion of the study to illustrate the suggested method for frequency stabilization of isolated power systems. Comparison of dynamic responsiveness of the system with PID controllers improved by other intelligent methods reveals the superiority and efficacy of the suggested methodology. Also included in this project are multi-unit two-area power systems. The algorithm's capacity to be tuned is examined in great detail and compared to other algorithms.

Модель распределения электрического напряжения и изменения электрического тока в сети с наличием неучтённого потребления электрической энергии

The aim of the study is control of commercial losses in electrical grids, especially in low voltage grids, which is one of the priority lines of activities conducted by electric network companies. The complexity of solving this problem is stemming from the difficulty of exactly locating the commercial loss occurrence place under the conditions of extensively branched low and medium voltage electrical networks. Various methods are currently used to determine the commercial loss occurrence places. However, no effective methods have been created for determining the fact and place of unaccounted electricity consumption in networks under the conditions of performing remote analysis of networks based on the data from modern electricity meters used in the automated fiscal electricity metering system. These difficulties can be overcome by developing a model of voltage distribution and change of current in distribution networks of the 0.4--35 kV nominal voltage levels. A model of voltage distribution and changes of current for a network containing unaccounted electricity consumption is proposed. The effectiveness of using the proposed model has been theoretically substantiated; its applicability limits are defined, and the accuracy of the obtained results is estimated. Graphical representation of the proposed model, which is one of the electrical network digital imaging forms, can be used to analyze electrical networks for revealing if there is unaccounted electricity consumption in them. By using the proposed model of voltage distribution and change of current in the network, it is possible to represent the electrical network as a set of electrical parameters to analyze electrical networks for the presence of commercial losses.

A composite power management strategy for congregated-storage based multiple voltage-level DC network

This paper proposes a composite power management strategy for a novel multiple voltage-level dc network topology. To realize convenient power management, all storages are congregated to form a storage subsystem which is connected to a common bus. DC network with various nominal voltage levels immensely improves the efficiency and performance of the whole dc system. To realize better dc network operations, the composite power management strategy is necessary. First, with the consideration of trade-off between voltage regulation and power sharing, an adaptive droop control strategy is proposed for storage subsystem to realize voltage recovery and improve power sharing accuracy without any need of common bus voltage variation detection scheme. Besides, the lifetime of storage is extended due to the reduced frequent charging/discharging cycles. Second, a distributed coordinated power control strategy is applied to dc subgrids supported by their neighbors. Third, a dc subgrid with higher share of critical loads or weight factor should sustain small power deviations, for which a coordinated coefficient is applied to the proposed distributed coordinated power control strategy. Finally, hardware-in-loop (HIL) platform is built up to validate the effectiveness of the proposed control strategy.

Analysis and Implementation of a Phase-Shift Pulse-Width Modulation Converter with Auxiliary Winding Turns

A phase-shift pulse-width modulation converter is studied and investigated for railway vehicle or solar cell power converter applications with wide voltage operation. For railway vehicle applications, input voltage range of dc converters is requested to have 30–40% voltage variation of the nominal input voltage. The nominal input voltages of dc converters on railway vehicles applications may be 37.5 V, 48 V, 72 V, 96 V and 110 V. Therefore, a new dc converter with wide input voltage operation from 25 to 150 V is presented to withstand different nominal input voltage levels such as 37.5–110 V on railway power units. To realize wide input voltage operation, an auxiliary switch and auxiliary transformer windings are used on output side of conventional full-bridge converter to have different voltage gains under different input voltage values. Phase-shift pulse-width modulation is adopted in the developed dc converter to accomplish soft switching operation on power switches. To confirm and validate the practicability of the presented converter, experiments based on a 300 W prototype were provided in this paper.

Combined load frequency and terminal voltage control of power systems using moth flame optimization algorithm

Stability of nominal frequency and voltage level in an electric power system is the primary control issue of practicing engineers. Any deterioration in these two parameters will affect the performance and life expectancy of the associated machinery to the power system. Hence, controllers are installed and set for a specific working situation and deal with small variations in load demand to keep the frequency and terminal voltage magnitude within the permissible limits. As the system performance can be improved with selecting suitable controller, an attempt has been made to design fractional-order PID (FOPID) controller for combined frequency and voltage control problems. This paper presents plan and execution examination of FOPID controller for simultaneous load frequency and voltage control of power system using recently developed nature-motivated powerful optimization technique, i.e., moth flame optimization algorithm. The first part of the present work demonstrates the implementation of the proposed technique on frequency stabilization of isolated power system with AVR for excitation voltage control. The superiority and effectiveness of the proposed approach are tested by comparing the dynamic response of the system with PID controllers optimized by other intelligent techniques. Then the present work is extended to multi-unit two-area power system. The tuning ability of the algorithm is extensively and comparatively investigated.

A 192-pW Voltage Reference Generating Bandgap–$V_{\text{th}}$ With Process and Temperature Dependence Compensation

This article presents a methodology to design a circuit to compensate for process skew by exploiting an inherent dimension-dependent effect of process skew on change in the threshold voltage. We design a voltage reference circuit with a hybrid architecture of bandgap reference (BGR) and CMOS reference, which generates a nominal voltage level of (bandgap - threshold). By compensating the process skew of the threshold term with the proposed dimension-induced effect as well as the temperature dependence, the circuit achieves the simultaneous benefits of BGR and CMOS references. For verification, the circuit was fabricated in three wafers of a 0.18- $\mu \text{m}$ CMOS including extreme slow and fast corners. With an active area of 0.0045 mm2, it consumes 192 pW at room temperature. Measurement from 45 chips (15 chips per wafer) shows untrimmed process/voltage/temperature variations of 0.53%, 0.020%/V, and 33 ppm/°C, respectively.

Introducing Voltage-Level Dependent Parameters to Synthetic Grid Electrical Topology

Building synthetic power system test cases for testing, demonstrating, and cross-validating new innovations in smart grid applications is of great importance. In this paper, we propose a new two-phase methodology to enhance our random-topology synthetic grid modeling, called RT- nestedSmallWorld , by introducing voltage-level dependent parameters. Unlike the original per unit format of electrical topology in the model, the voltage-level dependent parameters will distinguish between transmission lines and transformers as we found different characteristics for them in terms of per unit and actual impedances. This could also help integrate relative geographical information to our synthetic grid model in the form of approximate line length and dependence on nominal voltage level. The interdependence of parameters and variables on the nominal voltage level is observed from actual power system data in North America. Next, the interdependence is mathematically formulated and verified using grid physical constraints derived from Kirchhoff’s and Ohm’s laws to serve in the building of random-topology transmission network for synthetic grids.

A Low-Power and High-Speed Voltage Level Shifter Based on a Regulated Cross-Coupled Pull-Up Network

In this brief, a fast and very low power voltage level shifter (LS) is presented. By using a new regulated cross-coupled (RCC) pull-up network, the switching speed is boosted and the dynamic power consumption is highly reduced. The proposed LS has the ability to convert input signals with voltage levels much lower than the threshold voltage of an MOS device to higher nominal supply voltage levels. The presented LS occupies a small silicon area owing to its very low number of elements and is ultra-low-power, making it suitable for low-power applications such as implantable medical devices and wireless sensor networks. Results of the post-layout simulation in a standard 0.18- ${\mu }\text{m}$ CMOS technology show that the proposed circuit can convert up input voltage levels as low as 80 mV. The power dissipation and propagation delay of the proposed LS for a low/high supply voltages of 0.4/1.8 V and input frequency of 1 MHz are 123.1 nW and 23.7 ns, respectively.

Local voltage control of an inverter-based power distribution network with a class of slope-restricted droop controllers

Motivated by the environmental and economical benefits of using renewable energy, we consider the problem of regulating the voltage of a power distribution network in a line configuration where each customer is equipped with an inverter. The substation at the head of the line determines the nominal voltage level which is communicated to each customer in the distribution line. The voltage level of each customer is regulated by an inverter which generates reactive power according to our class of droop controllers satisfying the slope-restriction property. This paper provides a sufficient condition for regulating the customers’ voltage level within a desired band, which depends on the properties of the distribution line (line impedances) and the droop controller employed. This is achieved when only the upper bound of all the customers’ net power usage is known, thereby preserving the privacy of each customer. Simulation studies are performed on a benchmark model for a distribution system with renewable sources.

О применении номинального напряжения 20 кВ в воздушных электрических сетях

Matters concerned with advisability of shifting from the existing 10(6) kV voltage level to the 20 kV voltage level are analyzed. The structure and parameters of the 10 kV electric networks operated by one of the country’s large electric network companies are considered. Their integral characteristics used as input data and boundary conditions are identified. The necessary feasibility assessments are carried out, including those involving the use, as an optimization technique, the Lagrange multiplier method. The advisability of predominantly using the 20 kV nominal voltage level for the country’s overhead electric networks is investigated. A feasibility study of its application fields is carried out based on the network integral parameters. It is shown that, owing to a tendency toward making the technical-economic parameters of the 10 and 20 kV equipment close to each other, the 20 kV networks have more substantial advantages over the conventional 10 kV installations.

Measurement of voltage instabilities caused by inverters in weak grids

The research presented in this study shows that the stability of pulse-width modulation inverters is strongly related to the short-circuit power, and especially to the frequency-dependent grid impedance (fGI) at the point of common coupling. Based on two different cases, it is shown that inverters can lead to unstable behaviour in a weak grid, independent of the nominal voltage level. With a set of field measurements, it is shown that the fGI is highly influenced by the number and type of connected inverters. It is discussed that commercial, power-grid simulation tools are not able to predict this kind of instability. Finally, some recommendations are made to ensure a stable operation of distribution grids with a large number of inverter-based grid elements.

A New State-of-Charge Control Derivation Method for Hybrid Battery Type Integration

The hybrid of ex-transportation and conventional new battery system integration has started gaining interests within energy storage systems as number of electric vehicle on-road increases. Each module within such a system may consist of batteries with different charging/discharging rates, characteristics and also different nominal voltage levels. Control of these hybrid batteries within the same system is more challenging compared to conventional battery management systems, which mainly deal with the homogeneous battery system. One of the key issues is how to control the state-of-charge trajectory of the hybrid modules to maximize the investment on the new hybrid battery system. To cater this problem, this paper brings a new rigorous derivation method of state-of-charge control based on converter sample time. The proposed method generates desired current reference in each time step to distribute the power among hybrid modules such that their discharging or charging trajectories finish at the same time. This technique makes sure that the energy delivered/absorbed from each cell in a uniform manner maximizing the overall lifespan. Detailed derivation of the current sharing method and suitable module based adaptive bidirectional control architecture has also been presented. Modeling, analysis, and experimental validations are performed on a three-module-based grid-tie hybrid battery energy storage system prototype to validate analysis.

Understanding Reduced-Voltage Operation in Modern DRAM Devices

The energy consumption of DRAM is a critical concern in modern computing systems. Improvements in manufacturing process technology have allowed DRAM vendors to lower the DRAM supply voltage conservatively, which reduces some of the DRAM energy consumption. We would like to reduce the DRAM supply voltage more aggressively, to further reduce energy. Aggressive supply voltage reduction requires a thorough understanding of the effect voltage scaling has on DRAM access latency and DRAM reliability. In this paper, we take a comprehensive approach to understanding and exploiting the latency and reliability characteristics of modern DRAM when the supply voltage is lowered below the nominal voltage level specified by DRAM standards. Using an FPGA-based testing platform, we perform an experimental study of 124 real DDR3L (low-voltage) DRAM chips manufactured recently by three major DRAM vendors. We find that reducing the supply voltage below a certain point introduces bit errors in the data, and we comprehensively characterize the behavior of these errors. We discover that these errors can be avoided by increasing the latency of three major DRAM operations (activation, restoration, and precharge). We perform detailed DRAM circuit simulations to validate and explain our experimental findings. We also characterize the various relationships between reduced supply voltage and error locations, stored data patterns, DRAM temperature, and data retention. Based on our observations, we propose a new DRAM energy reduction mechanism, called Voltron. The key idea of Voltron is to use a performance model to determine by how much we can reduce the supply voltage without introducing errors and without exceeding a user-specified threshold for performance loss. Our evaluations show that Voltron reduces the average DRAM and system energy consumption by 10.5% and 7.3%, respectively, while limiting the average system performance loss to only 1.8%, for a variety of memory-intensive quad-core workloads. We also show that Voltron significantly outperforms prior dynamic voltage and frequency scaling mechanisms for DRAM.

Understanding Reduced-Voltage Operation in Modern DRAM Devices

The energy consumption of DRAM is a critical concern in modern computing systems. Improvements in manufacturing process technology have allowed DRAM vendors to lower the DRAM supply voltage conservatively, which reduces some of the DRAM energy consumption. We would like to reduce the DRAM supply voltage more aggressively, to further reduce energy. Aggressive supply voltage reduction requires a thorough understanding of the effect voltage scaling has on DRAM access latency and DRAM reliability. In this paper, we take a comprehensive approach to understanding and exploiting the latency and reliability characteristics of modern DRAM when the supply voltage is lowered below the nominal voltage level specified by manufacturers.