Start-up Control Research Articles

The problem of block synthesis of missile preparation and start-up control system for missile complexes

According to the analysis of trends in the use and development of missile weapons, it is shown that in the coming decades such weapons (missile, anti-aircraft missile, anti-ship systems) will remain one of the main units of the armed forces of the advanced countries. At the same time, in the conditions of independent Ukraine there is a need to create its own production of appropriate samples in a “closed cycle”. The synthesis of such weapons includes conducting comprehensive research on the principles of construction and operation of their basic elements, namely: substantiation of algorithms for launch equipment, control systems and navigation of missiles. The article deals with an example of a general solution to the problem.

Optimal Adaptive Inertial Droop Control–Based Power System Frequency Regulation via Wind Farms

Wind farm–based frequency regulation of the power system has progressively attracted more attention owing to its higher power generation capacity. Among which the step start-up and adaptive inertial droop control of wind turbines with a maximum power point efficiently regulate the system frequency via fully utilizing the rotational kinetic energy. Besides, the coefficients of adaptive droop control and virtual inertial control will facilitate a significant influence on the frequency support performance and operation status of wind turbines for the power grid. To obtain optimal control parameters, a parameter optimization framework of a step start-up adaptive inertial and droop controller combined with the CGO algorithm is proposed, whose effectiveness is verified by a three-area four-terminal VSC-MT-HVDC–based WFs and AC system in MATLAB/Simulink. As a result, a set of parameters with a satisfactory and comprehensive dynamic control performance can be acquired by the proposed method under both 200 MW and 300 WM load increases compared with the trial-and-error approach.

PROGRAM AND METHODS OF EXPERIMENTAL RESEARCH OF BELT CONVEYOR START-UP

In the work, a program of experimental studies of a belt conveyor during its start-up is developed. The design of the laboratory model of the belt conveyor is presented. the most significant characteristics that need to be measured are selected. The selection of sensors (electric motor current, acceleration of conveyor metal structure, and velocity of belt linear movement) and appropriate equipment for recording and transmitting the received data are carried out. The places of installation of the necessary equipment on the laboratory model of the belt conveyor are shown. Experimental studies have been planned to determine the dynamic, kinematic, and energy parameters of the belt conveyor. The characteristics of the start (direct start, frequency-controlled with different dependences of the frequency increase (linearly ramped and S-curved), frequency-controlled according to the optimal law of the frequency increase), as well as the duration of the frequency increase, are chosen as independent factors. An additional independent factor is the type of conveyor start: with no load (without bulk material on the belt surface) and with a fully charged belt. A total number of experiments equals twenty. In order to implement a frequency-controlled start frequency inverter exploited, it is supplied with a power supply grid. Outputs of the frequency inverter are connected to the electric motor of the belt conveyor drive. For the recording of the data and converting it to a digital form device m-DAQ 14 is chosen. Corresponding software for its control is described. In addition to that, the software «OPTIMAL CONTROL OF BELT CONVEYOR» for optimal control of the belt conveyor start-up is developed. It realizes the control of frequency inverter via calculation of optimal start curve and sending control commands through the digital channel. In order to avoid noise in the recorded experimental data, the technique of its filtering and processing is presented. For this goal digital filters (moving median, moving average, and Savitzky-Golay) are chosen. For estimation of experimental and theoretical data deviations coefficient of variation is proposed to apply.

Turnkey generation of Kerr soliton microcombs on thin-film lithium niobate on insulator microresonators powered by the photorefractive effect

Generation of Kerr soliton microcombs on microresonators enables power-efficient, phase-coherent, and broadband frequency teeth generation, which has revolutionized a wide range of scientific areas such as astronomy, metrology, spectroscopy, communications, etc. However, compared with a conventional frequency scanning method that requires a complex start-up and feedback control, turnkey generation of soliton microcombs remains challenging and a more promising solution is desired. Here, we propose for the first time and numerically demonstrate that turnkey generation of soliton microcombs can be achieved on thin-film lithium niobate on insulator (LNOI) microresonators for polarization along the ordinary axis of lithium niobate (LN) for which the photorefractive (PR) effect dominates. The PR effect shows power-dependent refractive index change, which is strong and opposite to that of the Kerr effect and thermal effect, thus enables the self-routing and converge of the total pump-resonator detuning into the existence region of soliton. Our results show that initiated with a certain amount of initial pump-resonator detuning on either blue- or red-detuned side, generation of soliton microcombs can self-start, self-route, and finally get stable without any artificial frequency scanning. Moreover, we show that deterministic and turnkey generation of single soliton microcombs can be achieved by leveraging a phase-modulated pump laser. Thanks to the inherent electro-optic effect of LNOI, a lab-on-a-chip device with monolithically integrated high-speed phase modulators and high-Q microresonators is feasible.

Multi-segment fuzzy control for start-up optimizing of LCC-based high-voltage power supply

Widely applied in medical, industrial, and military fields, the high-voltage power supply based on LCC resonant converter (LCC) is ought to establish tens kilovolts of output voltage within milliseconds according to many standards. And any overshoot during this start-up process is not allowed because of the issue or even deadly consequence it may lead. Traditional linear control schemes are powerless to fulfill these two conflicting requirements, especially for the LCC with nonlinear gain characteristics. In this paper, a multi-segment fuzzy control is proposed to tackle this problem. Firstly, the nonlinear gain curve of LCC is piecewise linearized based on its large-signal model, and the control requirements for different segments are determined. Then the control parameters for each part are selected by an off-line fuzzy algorithm. The allowed minimum frequency during the start-up is also piecewise linearized so that the gain ability of LCC is utilized. Finally, the proposed control scheme is verified with an 80kW/150kV X-ray power supply. A low-cost controller is used to implement the start-up control scheme since the control parameters can be pre-calculated and stored in the controller. Compared with the commonly used linear PI control, the non-overshoot start-up time with the proposed control scheme is reduced by more than 60%.

Cooperative Startup Control for Heterogeneous Vehicle Platoons: A Finite-Time Output Tracking-Based Approach

The connected vehicle (CV) technology has emerged in recent years. This article studies cooperative startup control of heterogeneous CVs in a platoon. First, from the perspective of cooperative tracking of heterogeneous multiagent systems, a hierarchical finite-time control framework is established, which consists of an upper-level interactive observer layer and a lower-level local controller layer. By separating neighboring information interaction from local dynamics control, the proposed framework allows to design upper-level observers and lower-level local controllers separately. Second, by introducing a potential function related to the consensus and observing errors, a distributed finite-time observer is designed for each CV to observe a startup reference trajectory available for only part of the CVs. Third, a distributed local finite-time controller is designed for each CV to track its observed startup reference trajectories. Within the proposed framework, finite-time observing and tracking of the startup reference trajectory are strictly proved to guarantee cooperative startup control. Numerical simulations are carried out to demonstrate the effectiveness of the proposed methods.

Non-Fourier Heat Conduction and Thermal-Stress Analysis of a Spherical Ice Particle Subjected to Thermal Shock in PEM Fuel Cell at Quick Cold Start-Up

Quick start at low temperature is one of the key bottleneck technologies that restrict the large-scale commercialization of proton exchange membrane (PEM) fuel cell vehicles. Ice and devices in battery systems based on thermal deicing are inevitably subjected to thermal shock. In order to study this problem, a non-Fourier heat conduction model is established to study the temperature response of a spherical ice particle subjected to thermal shock with different boundary conditions on the surface. Furthermore, distribution of thermal stress in the particle is obtained using the calculated temperature field, and the effect of thermal relaxation time and boundary conditions on the temperature response as well as the thermal stress field are also analyzed. The results, which are significantly different from that obtained using Fourier law of heat conduction, show that the mechanical stresses and the serious expansion of the ice particle may lead to the severe deformation of the devices connected to the ice during the cold start-up, imposing a great challenge in controlling structural reliability of PEM fuel cells. The numerical results are expected to provide a scientific theoretical basis for PEM fuel cell design and low-temperature start-up control.

Closed-Loop Black Start-Up of Dual-Active-Bridge Converter With Boosted Dynamics and Soft-Switching Operation

This letter proposes a closed-loop black start-up control for the dual-active-bridge (DAB) converter. With a simple combination of the extended phase-shift and triple phase-shift modulation schemes, the DAB converter can start up with the maximum allowable precharge current while realizing soft-switching operation in the trapezoidal current mode simultaneously. Compared to the conventional start-up procedure that usually requires multiple steps of operation and parameter fine-tuning, the proposed start-up method can be implemented simply into the existing closed-loop controller and can shorten the start-up transients of the DAB converter significantly. The presented methods are validated experimentally on a downscaled DAB converter prototype.

MICROPROCESSOR CONTROL OF TWO MASS ELECTROMECHANICAL SYSTEM

All lifting mechanisms operate in a cyclic mode. It is important that these mechanisms operate in a constant mode. The time of their transients is relatively short, due to the fact that the moment of inertia of all working elements with the load reduced to the motor shaft is 8-12% of the moment of inertia of the motor rotor together with the clutch and brake pulley. Dynamic moments in transients are transmitted through kinetic links, significantly loading them. The elements of the transmission device from the engine to the working body and the metal structure are characterized by elasticity and the available backlash in the gears. Control and disturbances in such electromechanical systems cause transients associated with the exchange of energy between its links, create vibrations, reduce the accuracy of installation and quality of operations and cause additional loads in the links of the kinematic circuit. The possibility of microprocessor control of start-up of electromechanical system with backlash with simultaneous restriction at the arising at the same time dynamic loadings in kinematic links is considered. An algorithm and a program for controlling an industrial controller are proposed. The simulation results are given. The purpose of the work is to demonstrate the possibility of microprocessor control of the start of the electromechanical system with backlash, which provides the minimum time of transients and damping of oscillations of the suspended load with simultaneous restriction at the resulting dynamic loads in the kinematic links. The task of this work is to develop a program for an industrial controller in accordance with the control algorithm

Обеспечение испытаний бортовых блоков управления стартерами-генераторами

There are described the results of the creation by the developer of the on-board equipment – JSC "Element" – improved specialized test equipment for checking the parameters of the on-board control units of DC starter-generators – a stand-simulator of the starter-generator. The previously developed version improvement was carried out to increase the tests automatization because of preparation for control units' serial production stage. In addition, during the improvement process, the list of simulated starter-generators has been expanded, namely, to the starter-generators produced in France (THALES), Russia (STG9M-1, STG-3), and Ukraine (8260-12UD, 8260-9UD, STG-150UD) for the AI-450M engine and its modifications (with which the BZG-450 unit worked, providing control of start-up and generation) the STG-12TMO-1000 starter-generator was added. This STG-12TMO-1000 works with the AI-25TLT engine, for which Element JSC is currently developing an SGU-25 unit for control of start-up and generation. Stand-simulator improvement was based on an additional experimental study of the interaction between mentioned control units and real objects. The interaction was studied during the test process on the engine stand and aircraft of the State Enterprise "Ivchenko-Progress" and JSC "Motor Sich". The results achieved are shown. There are shown the structural diagram of improved stand-simulator and working screen of specialized software installed on a personal computer and providing the operator with the ability to control the test process. A list of simulated analog and frequency signals with ranges and errors indication is given. In addition to the stand-simulator description, attention is also paid to the quality checking method of the installation of printed circuit boards of control units by thermography means under electrical load and comparison with a specially prepared reference picture of temperature distribution. The need for such especially careful control during acceptance tests is due to the level of flowing currents – up to 20 A.

Control Method of Redundant Winding BLDC for Deep Lunar Soil Drilling

The deep lunar soil loading process is complicated and volatile; it is difficult to achieve stable and reliable drilling sampling. In order to realize the rotary drive control of low-speed high torque start-up and high-speed cutting dumping of the spiral drilling tool, the redundant double backup winding BLDC motor is used as the driving source of the spiral drilling tool, the mathematical model of torque and speed of the double winding BLDC motor is established, and a dual winding BLDC motor is designed. The drive circuit topology scheme of synchronous operation of winding is simulated and analyzed, and the control performance experiment is carried out combined with the prototype. The test results show that the topological structure of the driving circuit can meet the driving control requirements of lunar soil and lunar rock drilling sampling process, and improve the safety and reliability of the drilling sampling process.

Maximum lifetime convergecast tree in wireless sensor networks

We study the problem of building a maximum lifetime data collection tree for periodic convergecast applications in wireless sensor networks. We experimentally observe that if two nodes transmit the same number of data packets, the amount of energy consumption of the nodes is approximately the same even if the payload lengths of the transmitted packets are different. This is because the major energy consumption during a packet transmission arises from radio start-up and medium access control overhead. Our formulated lifetime maximization problem captures the energy expenditure due to message transmissions/ receptions in terms of the number of data packets transmitted/ received, in contrast to prior works, which consider the number of data units (amount of sensor data generated by a node) transmitted/ received. Variable transmission power levels of the radio and accounting for the sensor energy consumption are other factors that make our problem formulation different from those in prior work. We prove that this problem is NP-complete by reducing the set cover problem to it and propose an algorithm to solve it. The performance of the proposed algorithm is experimentally evaluated using Jain’s fairness index as a metric by implementing it on an actual testbed consisting of 20 sensor nodes and compared with those of the widely used shortest path tree and random data collection tree algorithms. The energy consumption of different nodes under the proposed algorithm are shown to be more balanced than under the shortest path tree and random data collection tree algorithms. Also, the performance of the proposed algorithm in large networks is studied through simulations and is compared with those of the state-of-the-art RaSMaLai algorithm, directed acyclic graph algorithm and clustering based OPTIC algorithm, and the shortest path tree, minimum spanning tree, and random tree based data collection schemes. Our simulations show that the proposed algorithm provides a significantly higher network lifetime compared to all the other considered data collection approaches.

An improved start-up control method for hybrid cascaded multi-terminal HVDC transmission system

Hybrid cascaded multi-terminal HVDC transmission system can not only naturally isolate the influence of DC line fault on voltage source converter (VSC) by line commutated converter (LCC), but also form multiple power receiving points by using multiple VSCs with flexible control and no commutation failure characteristics, which provides a more economical and flexible transmission approach for HVDC. Due to the simultaneous presence of two completely different types of converters, LCC and VSC, and the special topology that LCC and multiple parallel VSCs are directly connected in series in the inverter station, the start-up process presents unique features different from previous HVDC systems. In this paper, the problems of reverse transmission and imbalanced distribution of VSC power during the start-up progress of hybrid cascaded multi-terminal HVDC transmission system are firstly analysed, on the basis of a corresponding HVDC project being planned in China. Then, an improved coordinated start-up control method combining strict start-up sequence control of each converter and VSC active power control instruction switching is proposed to obtain a smooth and ideal start-up performance. A simulation model of ± 800kV/8000MW bipolar hybrid cascaded multiterminal HVDC transmission system with three VSCs based on the actual planning project is established in PSCAD/EMTDC. The comparative simulation results verify the effectiveness of the proposed start-up procedures.

PV String-Level Isolated DC–DC Power Optimizer with Wide Voltage Range

This paper proposes a photovoltaic (PV) string-level isolated DC–DC power optimizer with wide voltage range. A hybrid control scheme in which pulse frequency modulation (PFM) control and pulse width modulation (PWM) control are combined with a variable switching frequency is employed to regulate the wide PV voltage range. By adjusting the switching frequency in the above region during the PWM control process, the circulating current period can be eliminated and the turn-on period of the bidirectional switch of the dual-bridge LLC (DBLLC) resonant converter is reduced compared to that with a conventional PWM control scheme with a fixed switching frequency, resulting in better switching and conduction loss. Soft start-up control under a no-load condition is proposed to charge the DC-link electrolytic capacitor from 0 V. A laboratory prototype of a 6.25 kW DBLLC resonant converter with a transformer, including integrated resonant inductance, is built and tested in order to verify the performance and theoretical claims.

Self-Sustainable Long-Range Backscattering Communication Using RF Energy Harvesting

Radio-frequency (RF)-powered backscattering communication (BC) has many advantages, such as low-power consumption, battery-free, small size, low cost, full sealing, manual maintenance-free, and easy mass deployment. However, the weak RF energy harvested and the short BC distance have become the two critical obstacles in the real-world implementation of this potential technology. In this article, we propose a high-sensitivity RF energy harvesting (RFEH) and long-distance BC method, and for the first time, we demonstrate the RF-powered self-sustainable long-distance BC device named RFEH LoRa. In order to improve RFEH sensitivity, an ultralow-power (ULP) consumption voltage monitoring and startup control circuit topology is designed to reduce the power consumption to 245 nanowatt (nW) during the accumulation of RF energy. While in order to increase the BC distance, a direct digital frequency synthesis technology is used to generate a linear frequency modulation square wave sequence conforming to the LoRa specifications based on the ULP microcontroller unit, and the square wave is used to drive an RF switch to achieve long-distance BC of hundreds of meters. Test results show that the instantaneous BC current is as low as 130 microampere ( μA), and the standby current is only 52 nanoampere (nA). RFEH LoRa is implemented with commercial off-the-shelf components. It can self-startup by harvesting RF energy as low as -22.5 dBm, and send its sensing data to the receiver of 381-m away.

КОМПЬЮТЕРНОЕ МОДЕЛИРОВАНИЕ ОПТИМАЛЬНОГО ОПЕРАТИВНОГО УПРАВЛЕНИЯ ПУСКОМ И РАБОТОЙ КАСКАДА РЕАКТОРОВ

In the article on the example of isomerization in the cascade of reactors with countercurrent cooling the computer modeling of optimal operational control of start-up and operation of the cascade of reactors is considered. The decision of optimization tasks was performed within Mathcad using the developed original optimization procedure using Mminimize and procedures Rkadapt to solve the system of differential equations and Matlab using the fmincon optimization procedures, genetic algorithm and procedure ode15s to solve the system of differential equations. Fragments of programs and results of the solution using Mathcad, Matlab are given

Experimental Testing on an Air-Cooled Condenser Motor, Gearbox and Fan

The majority of South Africa’s electricity is generated from coal-fired power stations. After expansion through the turbine stage the heated steam is condensed by air-cooled condensors (ACCs). In water scarce areas air-cooled condensers are used to reject heat by means of convection through an array of fans that force air over the heated steam tubes positioned in a A-frame structure above the fan. The ACC system consists of an induction motor, two-stage gear reducer and an axial fan. For this research, the rotational velocity of the gearbox’s output shaft is measured as well as the bending and torsional strain experienced during different stages of operation. A proximity sensor and various sets of strain gauges are used to record the measurements respectively. Testing was conducted at three different sites that utilize different control methods for the induction motors. The purpose of testing at different sites was to evaluate the effectiveness of each start-up control system and its application inside an ACC. The results obtained in each of the three cases are quite clear that any motor controller is beneficial to the overall system simply due to the reduced inrush current and torque peaks.

Treatment of real domestic sewage in a pilot-scale aerobic granular sludge reactor: Assessing start-up and operational control.

Aerobic granular sludge (AGS) has been considered a breakthrough in the wastewater treatment sector given its key characteristics, such as excellent settleability, simultaneous removal of organic and nutrient pollutants, and compactness. However, the formation of granules often delays the start-up of granular-based systems, especially in large-scale settings. This study addressed the start-up of a pilot-scale AGS sequencing batch reactor (SBR) treating domestic sewage, monitored for over 280days. The challenges faced during aerobic granulation using a mixture of activated sludge and anaerobic granular sludge as inoculum and the performance of the reactor on organic matter, nitrogen, and phosphorus removal were discussed. Results showed that robust and stable granules were formed after an initial period of around six months, with the settling time playing a key role on granules development. At least 80% of granules had a diameter greater than 0.2mm and 60% >1mm. In general, the reactor achieved high nitrogen removal efficiency, as well as satisfactory removal of soluble COD. However, total COD abatement was impaired by the various episodes of suspended solids loss with the effluent. Overall, this study demonstrated that the reactor was efficient in the treatment of domestic sewage, but its performance was adversely affected from sudden changes in the influent quality. PRACTITIONER POINTS: Aerobic granular sludge (AGS) applied to small-scale domestic sewage treatment. The control of sludge age in AGS can be a problem due to short sedimentation times. High DO to maintain aerobic granulation can economically make the process economically unfeasible in tropical countries. A sludge with excellent sedimentation properties was obtained. However, maintaining the granule over time is a challenge.

Modeless Start-Up Control for Operational Flexibility of Combined Cycle Power Plants

The flexible operations of gas turbine combined cycle power plants, especially with reduction of start-up time, are important. In this paper, the modeless start-up method without determination of the start-up curves corresponding to the start-up modes (e.g., hot start, warm start, and cold start) were developed. This method generates the start-up curves in which the start-up time is minimized against the initial steam turbine metal temperature by optimizing the start-up parameters. Based on the candidates of these start-up parameter values obtained during the optimization process, the look-up tables corresponding to the initial metal temperature for the parameters are estimated. The start-up time of the start-up curves generated by referring to the look-up tables continuously vary against the initial metal temperature without exceeding the thermal stress limit of the steam turbine rotor. The results obtained by the developed method show that modeless start-up curves for gas turbine combined cycle power plants can be generated. In addition, by visualizing the relationship of the start-up time and the initial metal temperature, the start-up curves can be interactively selected to facilitate planning of the plant start-up schedules.

Modular modeling and dynamic response analysis of a driveline system during start-up process

This study is aimed at exploring the effect of the structural parameters of a driveline system on its dynamic response, during the start-up process. For this purpose, a modular modeling method was proposed, based on the power flow and mechanical connections in the driveline. Moreover, a dynamic model of the driveline for vehicle start-up was established, taking into consideration the time-varying mesh stiffness, shaft stiffness, damping, and the variation of the wet clutch friction coefficient with the relative slipping speed. Modal analysis of the driveline system was performed, and the influence of time-varying mesh stiffness of the gear set on the natural frequency was analyzed. Furthermore, an engine constant start-up control strategy was adopted, and the start-up process of the vehicle was simulated. The simulation model was verified with the experiment data. A new evaluation indicator was proposed taking into consideration the phase difference and amplitude change, induced by the time-varying stiffness and the self-excited vibration in the system. Lastly, the influence of the structural parameters on the dynamic response of the driveline system, during start-up, was investigated.