Load Control Method Research Articles

High Overload Power Supply System and Its Energy Synchronization Control Method for Short-Term High-Energy Pulse Load

High Overload Power Supply System and Its Energy Synchronization Control Method for Short-Term High-Energy Pulse Load

Research on flexible smart home appliance load participating in demand side response based on power direct control technology

More and more flexible smart home appliance loads are participating in the demand-side response of the power system, which leads the complexity of power system load regulation is gradually increasing. In order to accurately regulate and control the flexible smart home appliance loads, this paper constructs a regulation architecture according to the load control method which is based on the load aggregator. And then, combined with the regulation architecture, this paper further establishes the value indicator of flexible smart home appliance loads. By analyzing the air-conditioner load proportion of smart homes on basis of the load value indicators, this paper effectively calculates the adjustable potential of the single fixed frequency air-conditioner and inverter air-conditioner load. Finally, through the simulation study, the demand response capability ΔPt and continuously controlled time Δtlast of air-conditioners are accurately calculated. Meanwhile, the adjustable potential of the air-conditioner load in smart home during the demand response period is obtained.

Comparison of different load-following control strategies of a sCO2 Brayton cycle under full load range

The supercritical CO2 Brayton cycle has been regarded as a promising next-generation power conversion system owing to its flexibility and high efficiency. Dynamic performance and control strategy are essential research topics when systems are subjected to various load demands. Inventory control has been proven as a very effective load control method and valve controls have the potential to meet wider load demands. While few studies have focused on the differences in efficiency and system performance under different control strategies. In this study, a dynamic model of recompression supercritical CO2 Brayton cycle is proposed, and its components are carefully validated. Moreover, an inventory and anti-surge coupled control strategy is proposed to achieve better control performance. Under the premise of considering system security, various control strategies meeting 0%–100% load range are compared. The primary objective of this study is to reveal the differences in efficiency and dynamic performance of various control strategies in the full load range, to provide a basis for the selection of control strategies in off-design conditions. The results demonstrate that inventory and anti-surge coupled control allow safe tracking loads as low as 0%, and it provided an absolute advantage in terms of efficiency compared to valve controls.

Multiobjective Metaheuristic Load Control Algorithm for Interaction between Smart Home and Humans

Technology has boosted electric power consumption both locally and worldwide, resulting in a substantial increase in demand for electric power. A multiobjective smart house human-computer interaction load control method is suggested to meet the goal of lowering power usage and pricing in smart home load control. It presents a model that includes marginal costs and establishes an electricity price model that takes the load rate into account. It identifies switch appliances and temperature control appliances and gathers human activities, indoor and outdoor temperature, and light intensity using intelligent equipment to create a multiparameter comfort model. It creates a multiobjective model of comfort and electricity price with the purpose of reducing electricity price and multiparameter comfort, and it improves particle swarm performance by using a distance ratio based on fitness value. The optimization algorithm solves the model, determines the best smart home human-computer interaction load control scheme, creates the smart home remote control system’s functional modules, and optimizes the multiobjective smart home human-computer interaction load control algorithm using a frequency-duration parameter tracking learning model. The testing findings suggest that the proposed algorithm can cut power prices in a reasonable manner, as well as regulating 40% reduced electricity usage and load in smart homes.

A minimum transmitted load control method for shock isolation mounts with magnetorheological energy absorbers

This paper proposed a minimum transmitted load (MTL) control method for drop-induced shock isolation mounts (SIM) with magnetorheological energy absorbers (MREAs). MTL control method consists of two parts of maximum damping force (MDF) control and one part of constant acceleration (CA) control, which can make the payload stop after fully utilize MREA stroke (soft landing) with minimum transmitted load. The control algorithm of MTL control method is derived in a single-degree-of-freedom (SDOF) system. The relationship between the controllable velocity range of MTL control method and parameters of shock isolation mounts is also derived. An optimal control method selection criterion between Bingham number (BN) control method and MTL control method is developed. The performance of MTL control method and selection criterion are shown by applying to the SIM system with variable drop velocities and system parameters. Results shows that MTL control method has the minimum transmitted load and the selection criterion is feasible.

Combined Method of Flow-Reduced Dump Load for Frequency Control of an Autonomous Micro-Hydropower in AC Microgrids

Nowadays, microgrids (MGs) play a crucial role in modern power systems due to possibility of integrating renewable energies into grid-connected or islanded power systems. The Load Frequency Control (LFC) is an issue of paramount importance to ensure MGs reliable and safe operation. Specifically, in AC MGs, primary frequency control of each energy source can be guaranteed in order to integrate other energy sources. This paper proposes a micro-hydro frequency control scheme, combining the control of a reduced dump load and the nozzle flow control of Pelton turbines operating in autonomous regime. Some works have reported the integration of dump load and flow control methods, but they did not reduce the dump load value and adjust the nozzle flow linearly to the power value demanded by users, causing the inefficient use of water. Simulation results were obtained in Matlab®/Simulink® using models obtained from previous research and proven by means of experimental studies. The simulation of the proposed scheme shows that the frequency control in this plant is done in correspondence with the Cuban NC62-04 norm of power energy quality. In addition, it is possible to increase energy efficiency by reducing the value of the resistive dump load by up to 7.5% in a case study. The validation result shows a 60% reduction of overshoot and settling time of frequency temporal behavior of the autonomous micro-hydro.

Research on Multi-Stage Composite Loading Process Control Method for Roller Staking of Self-Lubricating Spherical Plain Bearings

The staking quality of Self-lubricating Spherical Plain Bearings (SSPBs) directly affects the safety of aircraft and the service life of bearings. Reliable loading process control methods and precise process parameter indexes will come into the creation of efficacious staking quality. Therefore, this paper aims to analyze the mechanical state of the roller staking process and give a load control method and corresponding parameter indexes for the high-quality roller staking process. First, based on the analysis of quality inspection requirements, five states of the deformation degree of the flanging lip of the V groove during the roller staking process were proposed, and their relationship with the requirements was studied. Then, the mechanical states corresponding to the five deformation states of the flanging lip deformation were obtained by numerical simulation, and the feeding displacement was determined. Meanwhile, a Multi-Stage Composite Loading (MSCL) process control method was first proposed to control the material damage of the flanging lip, i.e., the rotate speed of the roller tool was constant during the roller staking process, and the displacement–time control was adopted first; when the staking load reaches a staking value, the force–time control was used to make the staking quality meet the requirements. Finally, the staking quality of the MSCL method was verified though the test. The research shows that the feeding displacement needs to be added to the requirements, and the recommended value is 0.5–0.6 times of the V groove depth. A good surface quality and non-material-damage of the flanging lip is more likely to be obtained by the MSCL process control method. The research reveals the formation mechanism of process deformation, and gives more precise process control indexes. At the same time, it provides a theoretical reference for more reliable technical standards.

Overview of the Load-source Duality Modeling for Demand Side

With the increase of load and clean-green energy connect to the power system, big challenges are brought to the traditional control method of generation-follows-load (GFL). Therefore, it is important to study the load-follows-generation (LFG) models which can achieve active demand response by changing the load temporarily to reduce the difference between maximum and minimum load. This paper introduces the concept of LFG and GFL models, summarizes the difference between them and puts forward the concept of load-source duality at first. Then, introduces load response modeling, optimization objectives, constraints, scheduling methods and control methods of six LFG models based on the recent research results in this area. Each model can alleviate the pressure in maintaining stability on the generation side, improving the safety and reliability of the power system. Finally, this paper puts forward the future development trend of LFG models based on the overviews.

POST-PEAK RESPONSE AUTOMATIC SOLUTIONS IN STRUCTURAL ENGINEERING PROBLEMS – A REVIEW

The ill-condition of stiffness matrix at the unstable region for example at the strain-softening region, the load control method will not be valid to give the solution therefore the displacement control method is essential to use. The stiffness matrix is changed at different steps by used load control and solution is found using any nonlinear solution method of Newton’s family. Therefore, Newton’s method will not give a solution to the unstable region. The iteration method and solution process may also stop when the diagonal element of the stiffness matrix becomes negative or zero if Newton's method is adopted. These difficulties need to be overcome and a non-positive definite stiffness matrix is retained and used for iteration in the arc-length method. A scientific review of literature has been made to pinpoint the difficulties faced in the prediction of complete load-displacement response of structures and techniques available to overcome the same. Displacement control methods have been reviewed with emphases on the arc length methods which can be integrated with the traditional finite element method.

Privacy Preserving Load Control of Residential Microgrid via Deep Reinforcement Learning

Demand side management has been proved to be effective in improving the operating efficiency of microgrids, while posing a severe threat to user privacy. This paper proposes a novel privacy preserving load control scheme for the residential microgrid, in which the microgrid operator manages a multitude of home appliances including electric vehicles (EVs) and air conditioners (ACs). This problem is formulated as a partially observable Markov decision process, since users' privacy information including indoor temperatures associated with ACs and arrival/departure times of EVs cannot be observed by microgrid operator. To address the formulated problem with high-dimensional continuous action space caused by massive controllable appliances, we develop a novel deep reinforcement learning algorithm by introducing credit assignment mechanism. Moreover, we integrate recurrent neural network to accommodate the partial observability of state due to privacy issues. Simulation results demonstrate the superiority and flexibility of the developed algorithm and verify the advantages of the proposed scheme compared with prior privacy preserving load control method.

CONTROL OF LOAD OF THE COMMUNICATION NETWORK WITH VIRTUAL FRAGMENTATION AND TAKING INTO ACCOUNT THE CURRENT «COMPOSITION» OF OVERLOADED FRAGMENTS

The problems of network load management for a generalized version of a large packet switching network are investigated. The network is divided into elementary fragments according to the selected rule. Data routing is "flat" (not hierarchical). Abstraction is used - a set of network fragments can be represented as a set of networked elements. For each fragment, a significant indicator of its load (for example, the average load of its nodes or another) is defined. The limit of this indicator is set, which provides the definition of an elementary fragment as a fragment with an increased load. In the entered imaginary "network of fragments" there are connected groups of fragments with the increased loading. For groups of elementary fragments with high load, modifications of the load control method are used due to the choice of the lowest cost paths, in which the routing takes into account the node's belonging to the fragments with high load.

Research on Test and Evaluation Technology of Hybrid Power Unit

With the adjustment of the strategic planning of China's automobile industry, the national policy strongly supports the development and large-scale application of hybrid power technology, but there is no guidance document on the testing and evaluation standards of hybrid power units. In this paper, the current situation of testing and evaluation technology of hybrid power units at home and abroad is analyzed in detail, and combined with the working characteristics of hybrid power units, the testing and evaluation methods that are more in line with the working characteristics of hybrid power units are put forward. They are the individual test of hybrid power unit parts, the test method of independent control of engine load and motor load, and the test method of total load control of hybrid power unit.

Real-Time Demand Response Strategy of Temperature-Controlled Load for High Elastic Distribution Network

With the development of distribution network, high elastic distribution system with multiple integration needs more response resources from the user-side to participate in the more flexible distribution network interaction. In the face of emergency or accident, the traditional power grid operating control system often takes part in the response in the form of cutting off the whole line load, which will greatly affect the power consumption of users. In this context, this paper proposes a temperature-controlled load shedding method for high elastic distribution network with real-time response. Taking the temperature-controlled load aggregate as the response resource, the temperature-controlled load control method suitable for system frequency and voltage recovery is analyzed, and the temperature-controlled load dispatching strategy participating in the emergency control of high elastic distribution network is formed. Specifically, according to the energy storage characteristics and service time flexibility of temperature-controlled load, the aggregate response model of temperature-controlled load is established to determine the control mode of temperature-controlled load. Then, a temperature-controlled load disaster reduction method based on the real-time response of high elastic load is proposed to realize the participation of temperature-controlled load in system disaster reduction. Finally, the voltage and frequency recovery characteristics of the system are analyzed in a 10 machine 39 bus system.

A Task-Driven Applicable Theory of Autonomous Load Control

Following manual manipulation to manual remote control, special vehicles are now developing towards task-oriented autonomous load control. Based on the original remote load control system, an autonomous control system architecture composed of “decision-making layer-planning layer-control layer-executive layer” was proposed in this paper, and the “task chain-action chain-instruction chain” autonomous task load control method was devised. This theory transforms the remote fire control system that receives operating instruction and controls units, into a task-driven load system that receives tasks to realize automatic/autonomous control. This provides theoretical support for the autonomous combat of unmanned equipment in the future.

Application of the DIC Technique to Remote Control of the Hydraulic Load System

Displacements or deformations of materials or structures are measured with linear variable differential transducers (LVDT), fibre optic sensors, laser sensors, and confocal sensor systems, while strains are measured with electro-resistant tensometers or wire strain gauges. Measurements significantly limited to a point or a small area are the obvious disadvantage of these measurements. Such disadvantages are eliminated by performing measurements with optical techniques, such as digital image correlation (DIC) or electronic speckle pattern interferometry (ESPI). Many devices applied to optical measurements only record test results and do not cooperate with the system that exerts and controls load. This paper describes the procedure for preparing a test stand involving the Digital Image Correlation system ARAMIS 6M for remote-controlled loading. The existing hydraulic power pack (ZWICK-ROELL) was adapted by installing the modern NI cRIO-9022 controller operating under its own software developed within the LABVIEW system. The application of the DIC techniques to directly control load on the real structure is the unquestionable innovation of the described solution. This led to the elimination of errors caused by the test stand susceptibility and more precise relations between load and displacements/strains which have not been possible using the previous solutions. This project is a synergistic and successful combination of civil engineering, computer science, automatic control engineering and electrical engineering that provides a new solution class. The prepared stand was tested using two two-span, statically non-determinable reinforced concrete beams loaded under different conditions (force or displacement). The method of load application was demonstrated to affect the redistribution of bending moments. The conducted tests confirmed the suitability of the applied technique for the remote controlling and recording of test results. Regardless of the load control method (with force or displacement), convergent results were obtained for the redistribution of bending moments. Force-controlled rotation of the beam section over the support was over 50% greater than rotation of the second beam controlled with an increase in the displacement.

Lightweight optimal rotor design of a 10MW-scale wind turbine using passive load control methods

The present paper investigates the potential to reduce the mass of the blade of the 10MW DTU Reference Wind Turbine through build-in, material bend-twist coupling (BTC). It is materialized by introducing an offset angle on the plies of the uni-directional material over the spar caps of the blade. Optimum BTC designs are obtained on the basis of an integrated optimization framework combining an aeroelastic solver for the calculation of the structural loads of the blade and a cross-sectional tool that provides beam-like structural properties of the blade and stresses distributions. The derived designs are verified based on a subset of representative fatigue and ultimate design loads cases of IEC 61400-1. Reduction of the combined bending moment at the root of the blade by 5% and reduction of the blade mass by 10% is achieved with a hybrid model consisting of three span-wise segments having different constant ply offset angles.

Effect of loading frequency on corrosion fatigue crack growth rate of 7N01 aluminum alloy

The fatigue damage of engineering structures is mostly caused by cyclic stress and external environmental factors. Therefore, the study of corrosion fatigue crack propagation is of great significance to the safety and durability of structures. The effects of different loading frequencies (10Hz, 1Hz and 0.1Hz) on fatigue crack growth rate of 7N01 aluminum alloy in humid air were studied by using load control method. The results show that the corrosion fatigue crack growth rate is basically the same at 10Hz and 1Hz, When the loading frequency decreases to 0.1Hz, the corrosion fatigue crack growth rate is slightly higher than 10Hz and 1Hz.

Fracture toughness of amorphus SiC thin films using nanoindentation and simulation

Fracture toughness of SiC on Si thin films of thicknesses of 150, 750, and 1500 nm were measured using Agilent XP nanoindenter equipped with a Dynamic Control Module (DCM) in Load Control (LC) and Continuous Stiffness Method (CSM) protocols. The fracture toughness of the Si substrate is also measured. Nanovision images implied that indentations into the films and well deep into the Si caused cracks to initiate at the Si substrate and propagate upward to the films. The composite fracture toughness of the SiC/Si was measured and the fracture toughness of the SiC films was determined based on models that estimate film properties from substrate properties. The composite hardness and modulus of the SiC films were measured as well. For the DCM, the hardness decreases from an average of 35 GPa to an average of 13 GPa as the film thick increases from 150 nm to 1500 nm. The hardness and moduli of the films depict the hardness and modulus of Si at deep indents of 12 and 200 GPa respectively, which correlate well with literature hardness and modulus values of Si. The fracture toughness values of the films were reported as 3.2 MPa√m.

Design of direct load control device and its effect on load reduction

Demand for air conditioning is rising at an unprecedented level. Sudden increase in air conditioning usage has a potential of destabilizing the power grid and at extreme condition can cause power outages. Ability to control air conditioning is therefore a very significant subject for both the electric power utility and electric power consumer. In some developed countries, this is realized by a program called demand-side management. The progress of information technology and the increasing affordability of the cost of fabricating electronic devices have given rise to new concepts in the implementation of demand-side management programs, namely the direct load control method. Direct load control is a mechanism that allows demand-side management programs to run automatically without interference from consumers. This is done by directly controlling consumer electricity equipment through the internet or other wireless communication networks. This study analyzes a method to design a controlling device to be used in direct load control implementation. Load demand of the system is compared between before and after the installation of direct load control devices. Significant load reduction is noticed after the installation of direct load control devices.

A Load control method with reactive power control capability and enhanced flexibility based on smart load

To promote the real‐time supply–demand balance of power grids and to improve the economy and security of power systems, the load control technology of power systems is becoming increasingly important. Electric spring (ES), first proposed in 2012, is a power electronic device used in power systems to achieve power consumption that can vary with power generation. Based on a smart load (SL), which comprises an ES and a noncritical load (NCL), a new load control method is proposed here, aiming to solve the problems of weak flexibility and uncontrollable reactive power in the traditional method. First, the power control model of an SL is established taking into account its basic principles. Next, the control method of a single SL is proposed, and the control loops are designed. Subsequently, the cooperative control strategy of multiple SLs is proposed using the particle swarm optimization (PSO) algorithm. Finally, our simulation and experimental results prove that both the active power and reactive power of SL can be controlled flexibly and smoothly using the method proposed here. © 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.