Control Signal Transmission Research Articles

Implementation and research of a substation command interaction method using third party validation

This paper describes a method to improve the security of control signal transmission in substation by introducing third party authentication and applying encryption technology. We can use asymmetric encryption technology to ensure the safety of data transmission process. A third party authentication device is introduced to verify the rights and identities of both sides of the command and prevent the interception and tampering of command information. Use dynamic key and authorization expiration system to further protect control security. Finally, the character code is checked by the command and the error data is filtered effectively. This method can effectively prevent signals from being truncated or tampered and ensure the security of data. Restricting the operation crowd, isolating illegal users, protecting information security, greatly improve the information security of substation control process.

Resilient perimeter control of macroscopic fundamental diagram networks under cyberattacks

The perimeter control concept based on macroscopic fundamental diagram (MFD) modeling is now well-established in various literature. Recent research efforts are devoted to develop perimeter control schemes, which can be eventually applied to urban traffic control systems. Modern urban traffic control systems increasingly rely on information technology infrastructure, combining various network and physical facilities and use of communication technologies, which increases the vulnerability for cyberattacks. As witnessed in recent real-life events, modern urban traffic control systems are vulnerable and not protected from internal and external, malicious and accidental threats. Hence, applicable perimeter control algorithms should be robust not only against dynamic uncertainties, but in addition, it should be resilient against cyberattack issues for real future implementations.In this paper, a resilient perimeter control scheme is developed for a modified multi-region MFD system model. The developed perimeter control is a fully decentralized scheme, which operates based on online local regional information only. It achieves an a priori desired tracking performance with simultaneous compensation of (i) cyberattacks in the channels of control signals transmission, (ii) model parameter uncertainties, (iii) unknown but bounded disturbances, and (iv) control input constraints. A framework of adaptive control techniques is utilized to design the perimeter control. The proposed fault-tolerant perimeter control does not require on-line fault detection, as the fault effects caused by cyberattacks are continuously and adaptively compensated by the developed algorithm. Stability proof of the closed-loop system in terms of the tracking and parameter errors are introduced, and simulation results for three aggregate urban traffic regions are presented.

Strong γc-γcl H∞ stabilization for networked control systems under denial of service attacks

This paper is concerned with the strong γc-γcl H∞ stabilization problem for networked control systems (NCSs) subject to denial of service (DoS) attacks, which are common attack behaviors that affect the packet transmission of measurement or control signals. The purpose of the problem under consideration is to design a stable dynamic output feedback (DOF) controller (strong stabilizing controller) with the prescribed H∞ performance norm bound γc to tolerate multiple packet dropouts caused by DoS attacks, such that, the closed-loop system is mean-square stable and captures the H∞ disturbance attenuation norm bound γcl. Based on the Lyapunov functional and the stochastic control approach, some sufficient conditions with the form of matrix inequalities for the existence of the desired stable DOF controller are established. Then, by an orthogonal complement space technique, the controller gain is parameterized. Next, an iterative linear matrix inequality (LMI) algorithm is developed to obtain the controller gain. Finally, the usefulness of the proposed method is indicated by a numerical simulation example.

Structure Constrained Controller Design for Power Plants and EV Aggregator in Frequency Regulation Considering Time Delays

Frequency control is the major concern for the integration of renewable energy into power systems. Electric vehicles (EV) are suggested to mitigate the system frequency deviation due to its vehicle-to-grid (V2G) capability and quick response characteristic. In this paper, the EVs are modeled by an EV aggregator and responded to the measureable states, such as system frequency, outputs of power plants and EV aggregator. Thus, a structure constrained feedback controller for the power plants and the EV aggregator is designed. However, the time delays during the transmission of control signal and state variable are inevitable. To deal with the time delays in the input and state variables, the Pade approximation is applied to construct the state space equations for the time delays. An equivalent augmented system without time delay is derived, in which the linear quadratic regulator (LQR) method is applied to derive the structure constrained feedback controller. Effectiveness and correctness of the proposed method are validated by a simple Great Britain power system in 2020.

Function of essential chloride and arginine residue in nucleotide binding to vesicular nucleotide transporter

Vesicular nucleotide transporter (VNUT) plays a key role in purinergic signalling through its ability to transport nucleotides. VNUT belongs to the SLC17 family, which includes vesicular glutamate transporters (VGLUTs) and Type I Na+/phosphate cotransporters. All of these transporters exhibit membrane potential and Cl--dependent organic anion transport activity and have essential arginine in the transmembrane region. Previously, we reported that ketoacids inhibit these transporters through modulation of Cl- activation. Although this regulation is important to control signal transmission, the mechanisms underlying Cl--dependent regulation are unclear. Here, we examined the functional roles of Cl- and essential arginine residue on ATP binding to VNUT using the fluorescent ATP analogue trinitrophenyl-ATP (TNP-ATP). The fluorescence of TNP-ATP was enhanced by VNUT, whereas no enhancement was observed by VGLUT. Concentration-dependence curves showed that TNP-ATP was a high-affinity fluorescent probe for VNUT, with a Kd of 4.8 μM. TNP-ATP binding was competitive to ATP and showed similar specificity to transport activity. Addition of Cl- and ketoacids did not affect the apparent affinity for TNP-ATP. The Arg119 to Ala mutant retained TNP-ATP binding ability with slightly reduced affinity. Overall, these results indicated that Cl- and essential arginine were not important for ATP binding.

A Novel Submodule Voltage Balancing Scheme for Modular Multilevel Cascade Converter—Double-Star Chopper-Cells (MMCC-DSCC) Based STATCOM

A novel capacitor voltage balancing scheme for modular multilevel cascade converter-double-star chopper-cells (MMCC-DSCC)-based STATCOM is proposed in this paper. Compared with the conventional software voltage balancing methods, the proposed scheme has three main advantages. First, only six voltage sensors are needed, and other voltage sensors have been removed. Then, the control framework can be simple without sort and select process, or some balancing control loops. Additional delay process caused by the sampling and control signals transmission is also mitigated. Finally, the faster capacitor balancing speed can be obtained. In addition, compared with some other hardware voltage balancing schemes, there are superior characteristics in terms of the reduced number of switches and only the popular power modules in the additional units are applied. For these additional modules, the parameters design guide of the proposed scheme has been discussed. Verified results from the 13-level simulated system and 9-level experimental platform for the MMCC-DSCC based STATCOM show the effectiveness of the proposed scheme. By the proposed scheme, both DC capacitor voltage balancing control and reactive power compensation are simultaneously realized for the MMCC-DSCC-based STATCOM even in balanced and unbalanced load.

A Quasi-Average Estimation Aided Hierarchical Control Scheme for Power Electronics-Based Islanded Microgrids

Self-governed micro power networks are a promising solution for meeting the energy needs of isolated communities not having access to regular transmission networks. The control of such isolated networks requires regulation and “fair” sharing of several power generation and storage resources as well as efficient peer-to-peer coordination between power converters operating in the network. The regulation of key parameters as voltage, frequency and power sharing is to be ensured for the system to operate optimally. This paper proposes a new, de-centralized, and hierarchical control approach for power inverters in isolated micro networks with multi-layered controls, each addressing the regulation of key system parameters. The proposed scheme uses distributed quasi-averaging estimators at each participating node to achieve resilience towards disturbances caused by delayed transmission of measurement and control signals in the data acquisition and information exchange layer. Detailed system models are developed using MATLAB and Sim-power systems to test the effectiveness of the proposed scheme under varying control and network scenarios. The results of these studies are presented as pole zero evolutions, stability margins and case study wise simulations. The studies carried out verify the validity of the proposed control strategy for micro-distribution networks.

Resilient Perimeter Control of Macroscopic Fundamental Diagram Networks under Cyberattacks

The perimeter control concept based on macroscopic fundamental diagram (MFD) modeling is now well-established in various literature. Recent research efforts are devoted to develop perimeter control schemes, which can be eventually applied to urban traffic control systems. Modern urban traffic control systems increasingly rely on information technology infrastructure, combining various network and physical facilities and use of communication technologies, which increases the vulnerability for cyberattacks. As witnessed in recent real-life events, modern urban traffic control systems are vulnerable and not protected from internal and external, malicious and accidental threats. Hence, applicable perimeter control algorithms should be robust not only against dynamic uncertainties, but in addition, it should be resilient against cyberattack issues for real future implementations. In this paper, a resilient perimeter control scheme is developed for a modified multi-region MFD system model. The developed perimeter control is a fully decentralized scheme, which operates based on online local regional information only. It achieves an a priori desired tracking performance with simultaneous compensation of (i) cyberattacks in the channels of control signals transmission, (ii) model parameter uncertainties, (iii) unknown but bounded disturbances, and (iv) control input constraints. A framework of adaptive control techniques is utilized to design the perimeter control. The proposed fault-tolerant perimeter control does not require on-line fault detection, as the fault effects caused by cyberattacks are continuously and adaptively compensated by the developed algorithm. Stability proof of the closed-loop system in terms of the tracking and parameter errors are introduced, and simulation results for three aggregate urban traffic regions are presented.

Optimal H 2 output-feedback control of sampled-data systems

ABSTRACT This paper addresses the output feedback control design problem with limited data-rate constraints. These communication constraints may affect the transmission of control signals or measurements, giving rise to different models, depending on the interconnection architecture. The closed-loop system composed by plant and controller can be modelled as a Hybrid System whose stability and performance can be determined in terms of necessary and sufficient Linear Matrix Inequalities. However, for the design of the appropriate feedback gains, those conditions become non-convex and we propose an approach to obtain satisfactory solutions. Numerical examples are included.

Performance Improvement of NCSs Under Complex Network via Concurrent Paths

Different from the single paths between controllers and plants of networked control systems (NCSs), the complex network provides widespread links and brings plenty of paths from the controller side to the plant side. Benefit from this advantage, a novel data transmission dispatching strategy is proposed. When the direct path can not satisfy the condition of system demand, neither stability nor performance, some specified paths compose a concurrent-path to transmit the control signal concurrently. Firstly, the networked control systems (NCSs) are expressed by the switched systems model with the constant network-induced delay, and the network communication is described as a packet-loss process. Secondly, taking system’s exponential decay rate as its performance indicator, the relationship between control signal transmission paths and system performance is quantitatively given by considering packet losses as the compound poisson process and the alternating renewal process. Then, due to that different combination of paths induces the different statistical properties of packet losses, the approach to find an appropriate concurrent-path is proposed concerning two mutually constrained factors, the system performance demand and the utilization of network resources. After the theoretical analysis, a distributed communication platform based on peer-to-peer (P2P) network technology is designed and implemented to realize the concurrent-path transmission on internet. Finally, the practical experiment on the platform demonstrates the validity and effectiveness of proposed approach.

Mechatronic treadmill for gait reeducation with control algorithm of treadmill speed adaptation

Different types of devices, from the simplest (medical walkers) to the most technologically advanced ones (mechatronic devices), are widely used to support the rehabilitation process for people who suffered strokes or have other disabilities—especially to enhance their mobility. This article presents a new mechatronic system for gait reeducation, which consists of two main components: training treadmill and body weight support system. The device is also equipped with sensors for measuring the rope inclination angle, rope tension and foot pressure on the ground. The transmission of measurement and control signals between the computer with control system and the electromechanical part of the device is realized by means of three real-time boards. This publication covers certain issues related to the device design process, integration of the main components, as well as the description of the developed treadmill speed adaptation algorithm and experimental verification of such control system. The speed of treadmill belt is adjusted by a feedback loop with a rope inclination angle measurement. Because of the kind of the connection of the treadmill (the control signals are sent to the buttons in the treadmill control panel) and related limitations, a proper conversion of the control signal was required, from a continuous one to a digital square wave signal with variable period. Developing an optimal treadmill speed control algorithm in this case was an interesting engineering challenge.

A 100 kV, 20 A, 1 ms long pulse solid-state Marx modulator for klystron

Due to difficulties associated with the conventional gas tube based modulators, solid-state switch based klystron modulators are gaining popularity in the scientific community. Research, design, and development of high voltage solid-state modulators for electron and proton accelerators are in progress at Raja Ramanna Centre for Advanced Technology (RRCAT), Indore. A prototype of 100 kV, 20 A, 1 ms pulse duration Marx modulator has been designed and developed. The modulator has been constructed using 34 numbers of Insulated Gate Bipolar Transistors (IGBT), based 3 kV main modules for generation of a 100 kV base pulse. A droop correction scheme, consisting of 24 numbers of 1 kV corrector modules, has been adopted to compensate the droop in the output pulse. Before incorporating the droop compensation technique, the modulator had droop of 16% in the output voltage pulse. A microcontroller based control unit is used for the programmed staggered triggering of all the main modules and corrector modules. Fiber optic based control signal transmission was done to realize electrical isolation between high voltage circuits and control circuits. The modulator has been tested for 100 kV, 20 A, 1 ms pulse duration at 1 Hz, initially without droop compensation and later with the activation of the correction scheme for droop compensation. With the droop compensation scheme, less than 1% droop could be achieved in the output voltage pulse. Output voltage pulses of 1 ms pulse width, 1.4 μs rise time and 9.7 μs fall time at 100 kV have been achieved successfully. The present effort forms a strong basis for further development of this technology for higher average power as well as for replacing the earlier thyratron based modulators.

Prediction Based Hierarchical Compensation for Delays in Wide-Area Control Systems

The closed-loop delay is one of the most important factors affecting the control performance of a wide-area control system (WACS), due to the network transmission of feedback and control signals. A prediction based hierarchical delay compensation (PHDC) method is proposed in this letter at the data processing level to deal with delays. For the control strategy on the top-level, all feedback and control information are real-time and transparent without consideration of delay. The PHDC method compensates the random and distributed delay effectively and reduces the impact of delays on the control performance.

Sampled-data synchronization of chaotic Lur’e systems via an adaptive event-triggered approach

In this paper, based on nonuniform sampling, the master-slave synchronization in a class of Lur’e systems is studied via using the sampled outputs of error system. Different from existing results, the transmission of control signals is determined by a novel adaptive event-triggered scheme, where the triggering thresholds depend on the dynamic behaviors of controlled systems rather than the predetermined constants as some traditional ones. Through choosing two augmented Lyapunov–Krasovskii functionals (LKFs), some delay-dependent synchronization criteria are formulated and the conservatism can be effectively reduced owing to the utilization of Wirtinger-based inequalities and delay-product-type LKF terms. Especially, the existence of the controller can be easily checked since the derived conditions are presented via LMI forms. Finally, two numerical examples with comparisons and simulations are given to illustrate the proposed results.

Improved approaches on adaptive event-triggered output feedback control of networked control systems

This paper studies the static output-feedback control in a class of networked control systems. Different from the existing results, the transmission of control signals is based on a novel adaptive event-triggered scheme, where the adaptive thresholds depend on the dynamic error of the system rather than predetermined constants as the traditional ones. The amount of the releasing data is regulated by the adaptive thresholds that play an essential role in decision of whether releasing the sampled data or not. Through fully using the information on network-induced delay and introducing two adjusting parameters, an augmented Lyapunov–Krasovskii (L–K) functional is constructed. Especially, some novel Wirtinger-based integral inequalities are utilized to reconsider those previously ignored information, which can help reduce the conservatism. Furthermore, a novel constructive method is developed to obtain the controller gain by solving the achieved linear matrix inequalities (LMIs). Finally, three numerical examples are given to illustrate the efficiency of the presented results.

Development and experiment of the Internet-based telesurgery with MicroHand robot

Robot-assisted telesurgery can perform complex surgical manipulations from remote locations. Against the requirements of remote controlling for minimally invasive laparoscopic surgery robot, a prototype telesurgery system integrated on the existing “MicroHand S” robot was built. The prototype worked with the Internet, and a telesurgery communication protocol was set up based on Transmission Control Protocol/Internet Protocol. The stereo images of laparoscopy were transmitted by a hardware-based H.264 encoder/decoder. A demonstration environment of robot-assisted remote minimally invasive surgery between the medical robot laboratory of Tianjin University and the visual surgery laboratory of the PLA Rocket Force General Hospital, which is about 150 km away, was set up. Control signal and laparoscope image transmission test between these two places were conducted. After the pegboard task and knot-tying task of phantom training, the first remote gall bladder removal surgery on the sow of China was successfully performed, on the basis of remote surgery robot system integration. The experimental results show that the developed prototype telesurgery system has enough remote control performance and operability for telesurgery.

Real‐Time Video Latency Measurement between a Robot and Its Remote Control Station: Causes and Mitigation

This work presents a detailed study, characterization, and measurement of video latency in a real‐time video streaming application. The target application consists of an automatic control system in the form of a control station and the mini Remotely Operated Vehicle (ROV) equipped with a camera, which is controllable over local area network (LAN) and the Internet. Control signal transmission and feedback measurements to the operator usually impose real‐time constraints on the network channel. Similarly, the video stream, which is required for the normal system control and maneuvering, imposes further strict requirements on the network in terms of bandwidth and latency. Based on these requirements, controlling the system in real time through a standard Internet connection is a challenging task. The measurement of important network parameters like availability, bandwidth, and latency has become mandatory for remotely controlling the system in real time. It is necessary to establish a methodology for the measurement of video and network latency to improve the real‐time controllability and safety of the system as such measurement is not possible using existing solutions due to the following reasons: insufficient accuracy, relying on the Internet resources such as generic Network Time Protocol (NTP) servers, inability to obtain one‐way delay measurement, and many solutions only having support for web cameras. Here, an efficient, reliable, and cost‐effective methodology for the measurement of latency of a video stream over a LAN and the Internet is proposed. A dedicated stratum‐1 NTP server is used and the necessary software needed for acquiring and measuring the latency of a video stream from a generic IP camera as well as integration into the existing ROV control software was developed. Here, by using the software and dedicated clock synchronization equipment (NTP server), it was found that normal video latencies in a LAN were in the range of 488ms – 850ms, while latencies over the Internet were measured to be in the range of 558ms – 1211ms. It is important to note that the values were obtained by using a generic (off‐the‐shelf) IP camera and they represent the actual latencies which might be experienced during control over long range and across international territory borders.

Ventili kao upravljačke komponente hidrostatičkih sistema

Modern agricultural engineering involves the wide application of hydraulic and pneumatic systems for the transmission of power (energy) and control signals. This paper presents the most commonly used types of valves in hydraulic systems. In the literature, more classification of hydraulic valves is reported, according to their construction, purposes, etc., which, even within the same classification criteria, sometimes strongly differ one from the another. Therefore, this presentation is organized by principled valve assignment into four basic groups based on purpose, although there are other divisions according to the purpose of the valve. Other classifications, although present in the available literature, have not been commented in detail, due to space constraints. In this manuscript, the basic elements of the construction of the most important types of valves are described and analyzed, their most important characteristics are described, the base functional principles and technical limitations described, and the given guidelines and recommendations for their optimal application.

Development Trends of Mobile Communication Systems for Railways

With the widespread deployment of high-speed railways and the increasing speed of trains, timely and reliable wireless transmission of train control signals and passengers' mobile Internet access become critical. To meet these demands, mobile communication systems for railways is shifting from narrowband global system for mobile communications-railway (GSM-R) to broadband systems. In contrast to GSM-R, broadband LTE-R and 5G for railway system could provide more services such as real-time video surveillance, multimedia dispatching and railway Internet of Things. In this paper, we first briefly review the existing GSM-R system and discuss its limitations. Then, we discuss future development of user demands and various data services, which suggests the key performance indicators of the future mobile communication systems for railways. Afterwards, we survey the recent wireless technologies and network architectures that may be applied in mobile communication systems for railways in the near future. Finally, we summarize the technical challenges of future mobile communication systems for railways and conclude this paper.

Design of remote smart home control system based on the Internet of Things

With the continuous innovation of related technology and the rapid development of information industry, the Internet of things, as a new product of information technology, has been applied in many fields, especially in the field of residential home. It is of great significance to promote the quality of people's daily life. In view of this, this paper briefly analyzes the collection and transmission of indoor remote control signal. On the basis of this, the design of remote control software is analyzed and discussed. Finally, the practical application test shows that the remote smart home control system designed by this research can realize the effective transmission of the indoor electrical control of information. It can meet the needs of practical use both in controlling accuracy and the delay.