Dynamic Power Losses Research Articles

Optimizing size and location of UPFC for enhanced system dynamic stability using hybrid approach

This paper proposed a novel hybrid optimization technique, combining the Enhanced Multi-Strategic Sparrow Search Algorithm (EMSA) and White Shark Optimizer (WSO), to determine the optimal location and size of a Unified Power Flow Controller (UPFC) for enhancing power system dynamic stability. The proposed method offers improved search capabilities, reduced randomness, and lower computational complexity compared to existing approaches. Generator faults can significantly impact system dynamic stability constraints, including voltage and power loss. EMSA algorithm is employed to identify optimal location for UPFC placement by selecting bus with minimum power loss. Subsequently, WSO algorithm is used to optimize UPFC's capacity, ensuring that affected system parameters and dynamic stability constraints are restored within safe limits. Optimized UPFC is then installed at identified location, and system's power flow is analyzed. Proposed method is implemented in MATLAB/Simulink environment and tested on both IEEE 30 and IEEE 14 standard benchmark systems. Proposed method's performance is evaluated by comparison with existing methods.

Analytical expressions of the dynamic magnetic power loss under alternating or rotating magnetic field

Analytical methods are recommended for rapid predictions of the magnetic core loss as they require less computational resources and offer straightforward sensitivity analysis. This paper proposes analytical expressions of the dynamic magnetic power loss under an alternating or rotating magnetic field. The formulations rely on fractional derivative analytical expressions of trigonometric functions. The simulation method is validated on extensive experimental data obtained from state-of-the-art setups and gathered in the scientific literature. Five materials are tested for up to at least 1 kHz in both alternating and rotating conditions. The relative Euclidean distance between the simulated and experimentally measured power loss is lower than 5 % for most tested materials and always lower than 10 %. In standard characterization conditions, i.e., sinusoidal flux density, the dynamic power loss contribution under a rotating magnetic field is shown to be precisely two times higher than an alternating one. The knowledge of electrical conductivity reduces the dynamic magnetic power loss contribution to a single parameter (the fractional order). This parameter has the same value for a given material's rotational and alternating contribution. This study confirms the viscoelastic behavior of the magnetization process in ferromagnetic materials and, consequently, the relevance of the fractional derivative operators for their simulation.

A 13.56-MHz 93.5%-Efficiency Optimal On/Off Timing Tracking Active Rectifier with Digital Feedback-Based Adaptive Delay Control.

This paper presents an adaptive active rectifier with digital feedback delay controllers (DFDC) which quickly tracks optimal on/off timing against input voltage and load variations. To efficiently generate the on/off transition, the proposed active rectifier adopts dynamically controlled coarse/fine delay lines rather than using conventional power-hungry static comparators, while removing the risk of unwanted multiple driving pulses to pass transistors. DFDC conducts the dual-loop digital feedback to independently adjust on/off timing with high-speed 13.56-MHz loop bandwidth, improving the voltage conversion ratio (VCR) and power conversion efficiency (PCE). DFDC can enable real-time power-saving mode control that automatically masks clock-toggling to non-essential blocks to minimize dynamic power loss while driving power transistors. To validate the efficacy of the proposed adaptive rectifier during digital feedback and settling procedures, experiments were carried out with 0.25 μm CMOS prototype at the carrier frequency of 13.56-MHz, input voltages between 1.7 and 2.6 V, and load ranges from 0.33 to 2.2 kΩ. The proposed active rectifier employing DFDC achieves a peak PCE of 93.5% and the peak VCR of 96.3% at the output power of 12.52 mW and 2.02 mW, respectively.

Optimal‐droop voltage‐restorer for zonal dc distribution system with simultaneous consideration of dynamic current balance and power loss reduction

AbstractA dc voltage restorer (dc‐VR) with optimal droop control is developed to reduce the power loss and solve the dynamic current imbalance simultaneously of the zonal dc distribution system integrating multi‐parallel energy storage. Firstly, the power loss model composed of line loss and converter loss is built and it is proved to be a strictly convex function with respect to droop coefficients, which indicates the power loss can be mitigated by optimizing the current distribution. Thus, an image‐based droop optimization method is proposed to search for the optimal droop coefficients. Then, the economy of voltage compensation on power loss reduction is investigated and an ESS‐combined dc‐VR is designed, including an interleaved parallel architecture and a capacitor‐integrated electric spring (C‐ES). Unified virtual inertia is proposed for interleaved parallel bridge arms to make their dynamic performance consistent. And the newly introduced C‐ES can keep the bus voltage at the rated level to reduce the system cost. Therefore, the problem of dynamic currents imbalance is addressed from the points of converter structure (dc‐VR) and control system (unified inertia), and the power loss can be reduced by voltage recovery (C‐ES) and optimizing the current reallocation which is achieved by updating sharing coefficients from the image‐based droop optimization method. Finally, the simulation cases validate the effectiveness of the proposed optimal‐droop dc‐VR on dynamic current balance and power loss reduction, and hardware in the loop experiment results prove the consistent dynamic characteristics of the dc‐VR's arms.

Improving Low-Frequency Digital Control in the Voltage Source Inverter for the UPS System

Today voltage source inverters (VSIs) operate with high switching frequencies (let us assume higher than 50 kHz) owing to the fast Si (Silicon) or SiC (Silicon Carbide) switching transistors. However, there are some applications, e.g., with slower switches (e.g., IGBT—Isolated Gate Bipolar Transistor) or when lower dynamic power losses are required when the switching frequency is low (let us assume about 10 kHz). The resonant frequency of the output filter is usually below 1 kHz. The measurements of Bode plots of the measurement traces of various microprocessor-controlled VSIs show that in this frequency range, the characteristics of these channels can be simply approximated through two or three switching periods delay. For the high switching frequency, it is not noticeable, but for the low frequency it can cause some oscillations in the output voltage. One of the solutions can be to use the predictor of the measured state variables based on the full-state Luenberger observer or the linear Kalman filter. Both solutions will be simulated in MATLAB/Simulink and the chosen one will be tested in the experimental VSI. The research aims to omit delays in the measurement channels for the low switching frequency by using the predictions for the measured state variables and finally increasing the gains of the controller to decrease the output voltage distortions.

A general energy modeling network for serial industrial robots integrating physical mechanism priors

Industrial robots (IRs), as the core equipment of intelligent manufacturing, play increasingly important roles in various industrial scenarios such as assembly, welding, handling, and spraying, significantly improving production efficiency and product quality. The massive popularization and application of IRs have brought about a sharp increase in energy consumption (EC), and the modeling and optimization of EC is becoming imperative. In this paper, a general energy modeling network DM-PLM for serial IRs based on Dynamic Model (DM) and Power Loss Model (PLM) is proposed by integrating the prior knowledge of IR power composition and dynamic mechanism, enabling efficient and accurate modeling of dynamics, power, and EC under multi-load conditions. Considering the force transmission characteristics of serial robots, this paper proposes an improved bidirectional recurrent neural network (BiRNN) to model the joint dynamics. Additionally, a power loss model based on the ResNet convolutional neural network is employed. Experiments are carried out with a KUKA KR210 heavy-duty robot and a UR5 collaborative robot. The results show that the DM-PLM model incorporating the physical mechanism priors achieves 97 %, 98 %, and 99 % modeling accuracy in joint torques, total power, and EC for both robots under multi-load conditions. In addition, the proposed DM-PLM model is applied to the EC optimization of KUKA KR210 through trajectory planning, which achieves over 30 % EC reduction with the genetic algorithm, providing an effective approach to improving the energy efficiency of serial IRs.

Comparison of power consumption in pipelined implementations of the BLAKE3 cipher in FPGA devices

This article analyzes the dynamic power losses generated by various hardware implementations of the BLAKE3 hash function. Estimations of the parameters were based on the results of post-route simulations of designs implemented in Xilinx Spartan-7 FPGAs. The algorithm was tested in various hardware organizations: based on a standard iterative architecture with one round instance in the programmable array, various derived versions with pipeline processing were elaborated, which ultimately led to a set of 6 architectural variants of the cipher, from the iterative case (without pipeline) to one with maximum of 6 pipeline stages. Moreover, the results obtained for the iterative architecture were compared with analogous implementations of the BLAKE2 (direct predecessor) and KECCAK (the foundation of the current SHA-3 standard) algorithms. This case study illustrates the differences (or lack thereof) in the power requirements of these three hash functions when they are implemented on an FPGA platform, and illustrate the significant savings that can be achieved by introducing pipeline to the processing of the BLAKE round.

Fast dynamics and low power losses of high-speed solenoid valve based on optimized pre-excitation control algorithm

Aiming at the requirements of high precision and reliability of digital hydraulic systems, high-speed solenoid valve (HSSV) needs to satisfy both fast dynamics and low power losses. In this paper, the dynamic performance and power losses of HSSV are studied by combining the coupling relationship between multi-physical fields, and based on the analysis conclusion, a control algorithm for HSSV is optimized based on pre-excitation control algorithm (PECA) to effectively speed up the switching behavior and reduce power losses. The theoretical and experimental results indicate that increasing the pre-opening voltage (POV) and reducing the pre-closing voltage (PCV) can shorten the switching delay time. However, the copper loss increases with the POV, resulting in a lower mechanical energy conversion efficiency. On the other hand, enlarging the opening voltage (OV) and closing voltage (CV) can speed up the switching process of HSSV, but it causes a significant increase in iron and copper losses. The dynamic performance and power losses of the HSSV are dimensionless mapped and the parameter group (POV = 3.6 V, OV = 14 V, PCV = 2.25 V, CV = −24 V) with optimum and well-balanced behaviors is selected with bubble scatter analysis and variation coefficient. The time required for HSSV to open and close was 1.21 ms and 1.71 ms, respectively, and the final temperature rising is optimized at 40.9 ℃. Therefore, the optimized PECA meets the expected requirements.

Dynamic torque coordination control of dual-motor all-wheel drive axles to suppress the longitudinal jerk of the vehicle

The switching of multiple working modes between power sources or axles through an economic torque distribution strategy can cause longitudinal jerk problems in electric vehicles equipped with multiple power sources and multi-axle drive systems. To address this issue, an online real-time dynamic torque distribution strategy was proposed. This strategy can suppress the longitudinal jerks in real-time and minimize the total power loss of the vehicle. In this study, a vehicle dynamics model, which considers a nonlinear system, is developed to reflect the transient process of the torque dynamic response of a vehicle transmission system. The main factors influencing the longitudinal jerk of the vehicle were analyzed. To minimize the total power loss of the vehicle, a dynamic power loss model of the electric drive system is established, and the model accuracy is experimentally verified. Through optimal control theory, this study proposes an online real-time dynamic torque distribution strategy that achieves the lowest total power loss of a vehicle while suppressing the longitudinal jerk. Under WLTC conditions, the longitudinal jerk is reduced by 79.46 % during mode switching, resulting in improved driving comfort, and the effectiveness of this strategy is verified via the experimental bench of the dual-motor four-wheel-drive electric drive system.

Multi-Objective Optimization of Kinetic Characteristics for the LBPRM-EHSPCS System

As the ‘heart’ of energy vehicles, the lithium-ion battery is in desperate need of precision improvement, green production, and cost reduction. To achieve this goal, the electro-hydraulic servo pump control system (EHSPCS) is applied to the lithium-ion battery pole rolling mill (LBPRM). However, this development can lead to limited dynamic performance and large power loss as a result of the EHSPCS unique volume direct-drive control mode. At present, how to solve this conflict has not been studied and how the EHSPCS component parameters influence the dynamic response, power loss, and economic performance is not clear. In this paper, a multi-objective optimization (MOO) model for the LBPRM-EHSPCS is proposed by comprehensively considering the dynamic, efficiency, and economic characteristics. Firstly, the evaluation model of the dynamic response, power loss, and cost is investigated. Then, the NSGA-II algorithm is introduced to address the Pareto front of the MOO model. Finally, the power loss and dynamic response of the LBPRM-EHSPCS before and after optimization are tested to validate the viability of the raised method. Results indicate that power loss is decreased by as much as 7.2% while steady-state precision is greatly improved after optimization. The proposed framework enhances the performance in lithium-ion battery manufacturing and can be applied to other kinds of hydraulic systems.

Энергоэффективный конденсаторный DC-DC преобразователь для автономной системы электроснабжения

The main requirement for autonomous power supply systems is improved weight-size and energy parameters. A promising way to solve this problem is to use DC-DC converters based on resonant structures with switched capacitors. Improvement of energy indicators of the converter is achieved due to soft-switching mode of semiconductor elements providing reduction of dynamic power losses and increasing the level of the primary source. Improvement of weight-size parameters of the converter is provided due to the following: multi-cycle principle of the design providing a significant increase of frequency conversion up to several hundred kHz due to multiple reduction of installed capacity of semiconductor elements; high specific energy indicators of modern multilayer ceramic capacitors, more than two orders of magnitude higher than similar indicators of reactors and transformers; optimization of parameters of semiconductor and reactive elements, which also contributes to significant reduction of weight and volume of power supply systems. The authors have conducted the analysis of weight-size parameters of the step-up DC-DC converter and the value of its efficiency under the assumption of proportionality of weight and volume of reactive converter elements to the maximum accumulated energy and proportionality of weight and volume of semiconductor elements to their installed capacity. The authors have proposed and studied the circuit of multipolar DC-DC converter based on structures with switched capacitors, which has the space symmetry. The space symmetry provides a significant improvement of weight-size parameters due to two-fold reduction of the total installed capacity of semiconductor elements. The volume and energy indicators of the converter under study as a part of power supply system have been evaluated. A method to design a power circuit of a capacitor converter with improved energy and weight-size parameters as a part of an autonomous power supply system is proposed. The authors have established the most effective ways to improve the weight-size and energy indicators of DC voltage converters. The improvement of weight-size parameters is achieved due to a twofold reduction of the installed capacity of semiconductor elements and optimization of the parameters of reactive elements. Improvement of energy indicators is achieved due to increasing the input voltage level of the converter and soft switching of its semiconductor elements.

An Analytical Model of Dynamic Power Losses in eGaN HEMT Power Devices.

In this work, we present an analytical model of dynamic power losses for enhancement-mode AlGaN/GaN high-electron-mobility transistor power devices (eGaN HEMTs). To build this new model, the dynamic on-resistance (Rdson) is first accurately extracted via our extraction circuit based on a double-diode isolation (DDI) method using a high operating frequency of up to 1 MHz and a large drain voltage of up to 600 V; thus, the unique problem of an increase in the dynamic Rdson is presented. Then, the impact of the current operation mode on the on/off transition time is evaluated via a dual-pulse-current-mode test (DPCT), including a discontinuous conduction mode (DCM) and a continuous conduction mode (CCM); thus, the transition time is revised for different current modes. Afterward, the discrepancy between the drain current and the real channel current is qualitative investigated using an external shunt capacitance (ESC) method; thus, the losses due to device parasitic capacitance are also taken into account. After these improvements, the dynamic model will be more compatible for eGaN HEMTs. Finally, the dynamic power losses calculated via this model are found to be in good agreement with the experimental results. Based on this model, we propose a superior solution with a quasi-resonant mode (QRM) to achieve lossless switching and accelerated switching speeds.

An Event-Triggered Deadbeat Control Considering Dynamic Power Loss Compensation for Hybrid Energy Storage System

Hnybrid energy storage system (HESS) in microgrids is used to achieve the power balance between the load and generation sides. This paper proposed an event-triggered deadbeat control for HESS to regulate the the bus voltage of microgrids efficiently. The charging and discharging behaviours of HESS are controlled by the deadbeat-based controller, and the turn-on resistance of the circuit is considered in the system modeling, to eliminate the steady-state error caused by the conduction losses. Under the control of the event-triggered mechanism, the switching actions for DC-DC converters would be triggered only if the variation of state variables exceed the safe range, which can reduce switching losses to reach the better performance of regulation, and the computational burden can be reduced. The performance of the proposed method is conducted by simulation and hardware experiments.

RESEARCH THE ACCURACY OF MODELING POWER LOSSES IN POWER DIODES AND TRANSISTORS

The methodology for modeling static and dynamic power losses in power IGBT and MOSFET transistors in the Matlab and Multisim software environments is given. It is shown that when modeling switching processes in power transistors, Matlab / Simulink does not allow determining the dynamic components of power losses, namely, the energy of turning on the transistor, the energy of turning off the transistor, as well as the recovery energy of power diodes. At the same time, the simulation of static power losses of power diodes and transistors in Matlab/Simulink is carried out with a significant error due to incorrect representation of the current-voltage characteristics. It is shown that for a more correct and accurate simulation of the operation of power transistors, including power losses in power switches, it is more appropriate to conduct simulations in the Multisim software environment, which takes into account more than 47 parameters during simulation, including temperature characteristics, parasitic input and output capacitances and inductances, nonlinearities of current-voltage characteristics and others. In Multisim, a circuit of a half-bridge inverter with power MOSFETs controlled by the IR2104PBF driver has been developed. It is shown that the switching of power transistors is significantly influenced by the parameters of the driver microcircuit, namely the size of the storage capacitor of the driver, as well as the value of the active resistance of the gate resistor. It is shown that the simulation in Multisim correctly displays the transient processes of turning on and off power transistors and reverse recovery of diodes, which allows determining the dynamic losses of power transistors and power diodes.

A Cooperative Game-Based Sizing and Configuration of Community-Shared Energy Storage

Sizing and configuring community-shared energy storage according to the actual demand of community users is important for the development of user-side energy storage. To solve this problem, this paper first proposes a community energy storage cooperative sharing mode containing multiple transaction types and then establishes a sizing and configuration model of community-shared energy storage based on a cooperative game among community users and energy storage operators, in which the loss caused by the capacity decay of energy storage is quantified by a dynamic power loss cost factor. To improve the solving efficiency, a distributed and cooperating solving method based on ADMM is used to solve the sizing and configuration model. On this basis, the bilateral Shapley method is used to allocate the total annual cost according to the marginal expected cost brought by each user. Compared with existing strategies, this paper calculates the economic benefits of community-shared energy storage based on several typical days of each year and quantifies the capacity decay of energy storage by a dynamic power loss cost factor which increases year by year to be closer to the real situation. Finally, the simulation verifies that the model proposed in this paper can be used for the sizing and configuration of community-shared energy storage. Compared with the original annual cost, the total annual cost of the community is reduced by 3.92%, and the annual operation cost of the community which equals annual electricity purchasing cost minus annual electricity selling income plus annual power loss cost is reduced by 25.6%.

Dual-Converter Active Power Filter with Reduced Dynamic Losses: Control Synthesis and Modelin

Nowadays, active power filters represent one of the most efficient means to reduce inactive power components which provides proper quality of electricity at common network connectivity points. Dynamic power losses in the valves that have a significant impact on the efficiency of the converter and, accordingly, determine the feasibility of using these filters in each specific situation, are among their key parameters. Along with the solution of the problem of ensuring the proper quality of electricity at common network connectivity points, the task of reducing dynamic losses in the valves becomes especially relevant. The purpose of the study is to increase the efficiency of active filtration in terms of reducing dynamic losses in the valves while ensuring high-quality voltages at common network connectivity points and currents consumed from the network. To achieve the goal, it is proposed to jointly use a dual-converter active power filter operating in a mode with different conversion frequencies and rated converter capacities, and an interface LCL-filter. Synthesis of converter control is performed. As a control method, the sliding mode control has been used. The efficiency of the proposed system was assessed by modeling in the MATLAB-Simulink application software package. The simulation results confirm the possibility of organizing a mode of operation in which the conversion frequencies and rated capacities of the converters of active power filters are different. In such a case, the currents and voltages consumed from the network at common network connectivity points have an almost perfect harmonic shape; and the phase shift of the network currents relative to the corresponding voltages has a negligible value. It is shown that the organization of the operating mode of converters with different conversion frequencies and rated capacities can significantly reduce the dynamic losses in the switches of active power filters.

Modeling Push–Pull Converter for Efficiency Improvement

In this paper, we model and analyze the power losses of push–pull converters. The proposed model considers conduction and dynamic power losses, as well as transformer and inductor losses. Transformer and inductor models include skin and proximity effects, as well as power losses in the core. Moreover, the model includes the diode recovery time losses. We derived the equations for both continuous and discontinuous current operating modes. All model parameters can be obtained either from the datasheets of the used components or by simple measurement techniques. The model is verified experimentally by measuring the efficiency of the 500 W push–pull converter prototype. Simulations and experimental validation are conducted using the assumption that the converter is used in a permanent magnet (PM) wind turbine generator.

Energy Efficiency Evaluation and Revenue Distribution of DC Power Distribution Systems in Nearly Zero Energy Buildings

With the advantage of integrating distributed energy, storage and DC load with high efficiency, the DC distribution network recently attracted wide attention in the field of nearly zero energy buildings. Considering the large number of buildings and the enormous energy-saving potential, the distribution form and the revenue distribution are key factors affecting energy efficiency and operational economy. Aiming at the characteristics of AC and DC distribution topologies in nearly zero energy buildings, an energy efficiency evaluation method is proposed based on time-sequential power flow simulation, where the piecewise linear efficiency function of converters and dynamic line power loss model are established. Based on a DC distribution demonstration project, an AC power distribution system with the same boundary conditions is designed. The results show that the efficiency of DC distribution topology is about 6% higher than the AC system, while the efficiency advantage in office, hotel, commercial, educational and residential buildings in Beijing, Shenzhen and Shanghai varies from 0.6–4.96%, which shows a high correlation with the proportion of a high-power load, with Pearson correlation coefficient of 0.794. With the increase of DC load ratio and distributed power supply access capacity, the efficiency of the system will be improved accordingly. On the basis of this, a method to equalize DC distribution income in the nearly zero energy buildings power market is proposed. In addition, 15 typical scenarios of different cities were selected to evaluate efficiency and influencing factors. Finally, assessing the multi-stakeholder impact of DC retrofitting to balance the revenue generated by the DC distribution model suggests that transport costs should be raised by 8.2–13.1% to balance revenue with the equipment prices decreased by about 0.1 yuan/W.

Model Predictive Control Based Dynamic Power Loss Prediction for Hybrid Energy Storage System in DC Microgrids

In islanding microgrids, supercapacitors (SCs) are used to compensate the transient power fluctuation caused by sudden variations of load demand and generation power to keep the output voltage stable and reduce the stress in batteries. However, SC current in dynamic response leads to transient power loss on power electronic converters, and it would cause an additional voltage ripple. To smoothen the voltage fluctuation, a dual-layer model predictive control (MPC) method is proposed in this article to control the charging/discharging behaviors efficiently. The dynamic power loss can be predicted by the predicted current and duty ratio in the primary layer MPC. The predicted dynamic power loss is one of the state variables in the secondary layer MPC to generate the more optimal power reference for the primary layer MPC, which can compensate the voltage ripple caused by the dynamic power loss and reduce the dynamic error and settling time. The proposed method is validated by simulation and hardware experimental results, demonstrating significant improvements than other methods.

The Effect of Replacing Si-MOSFETs with WBG Transistors on the Control Loop of Voltage Source Inverters

The operation of a voltage source inverter (VSI) depends on its output LC filter and the PWM modulator delay. The VSI model includes serial equivalent resistance based on the resistances of the active inverter bridge transistors, the filter coil winding, and additional PCB elements, such as traces and connectors, in addition to the large equivalent resistances that result from power losses in the coil core and switches. These dynamic power losses depend on the switching frequency and the inverter load. This paper investigates the change in equivalent serial resistance that occurs if the standard Si-MOSFET switches are replaced with wide bandgap (WBG) transistors with correspondingly lower equivalent serial resistance. The paper further investigates how such a change influences the design of the controller, given that replacement of the switches shifts the roots of the closed-loop characteristic equation. Theoretical analyses of the influence of equivalent serial resistance for a multi-input single-output passivity-based controller and a single-input single-output coefficient diagram method are also presented. These analyses are applied to both types of switches. Two methods are used to measure the serial equivalent resistance for a given VSI using Si and WBG switches. The possibility of replacing switches with WBG technology in existing inverters was assessed, and the corresponding controller adjustment that would be required. The theoretical analysis is verified via the use of an experimental VSI.