Communication Network Channel Research Articles

Corrective Evaluation of Response Capabilities of Flexible Demand-Side Resources Considering Communication Delay in Smart Grids

With the gradual increase in the proportion of new energy sources in the power grid, there is an urgent need for more flexible resources to participate in short-term regulation. The impact of communication network channel quality will continue to magnify, and factors such as communication latency may directly affect the efficiency and effectiveness of resource regulation. In this context of a large number of flexible demand-side resources accessing the grid, this article proposes a bidirectional channel delay measurement method based on MQTT (Message Queuing Telemetry Transport). It can effectively evaluate the real-time performance of communication links, considering that resources mainly access the grid through the public network. Subsequently, focusing on two typical types of resources on the demand side, namely, split air conditioners and central air conditioners, this article proposes an assessment method for correcting the response capabilities of air conditioning resources considering communication latency. Experimental simulations are conducted, and the results demonstrate that under given communication conditions, this method can more accurately estimate the response capability of air conditioners. This provides a basis for formulating more reasonable scheduling strategies, avoiding excessive or insufficient resource regulation caused by communication issues, and aiding the power grid in achieving precise scheduling.

Robust adaptive regulation of magnetic levitation systems with input quantization and external disturbances

This paper investigates two intricate problems in magnetic levitation systems: the loss of the information during the transmission over a limited communication network channel and the chattering caused by external disturbances. By combining input quantization technique with two infinitesimal smooth functions, we successfully construct a continuous robust adaptive feedback controller which stabilizes the position of the levitated electromagnet at the equilibrium point. Compared with the existing methods, the proposed quantized control strategy not only guarantees the global stability with asymptotic state regulation of the system even if there are external disturbances, but also exhibits better performance than that of traditional PID control. The simulation validates the robustness and effectiveness of the proposed scheme.

Suppression Of Channel Interference In Optical Communication Networks Based On Blind Signal Separation

In order to overcome the problem of low accuracy and poor stability caused by the one-sided information blind separation analysis of the current communication channel interference suppression research methods, this paper proposes the optical communication network channel interference suppression method based on blind signal separation algorithm. The receiver unit, field programmable gate array (FPGA) unit, memory chip group and other modules are used to construct the channel signal acquisition system, and the collected signals are preprocessed by centralisation and whitening. Based on the signal preprocessing results, the blind separation of instantaneous linear mixed signals, blind separation of convolutional mixed signals and blind separation of sparse sources were comprehensively analysed to obtain the source signals and realise channel interference suppression of optical communication network. Experimental results show that this method has high interference precision, strong stability and good application prospect.

The Implementation of Covert Channel in IPV6 using Linux Kernel

Nowadays indirect communication is used as a mechanism to bypass the direct communication network channel. Such indirect communication channels prove as a threat to information-sensitive systems that don’t allow leakage of information like Military communication. Developing a covert channel in the network requires some carriers like TCP Headers or Protocols. The only challenge is that it possesses strict semantics. If it is manipulated by even a single bit, the entire semantics will change. The packet will be considered as a forged packet and will get rejected automatically by a firewall. To avoid this, we have proposed a unique way of covert commumcation - TCP and IPv6 Referencing Model. In our proposed referencing model, instead of embedding any bit and destroying the semantics of the header, we are going to use the referencing method to send the covert bit from sender to receiver end. Thus the packet will appear a part of normal distribution and gets transmitted securely within the channel. Here we are using the TCP Sequence Number (SQN) to make this possible.

Suppression of channel interference in optical communication networks based on blind signal separation

In order to overcome the problem of low accuracy and poor stability caused by the one-sided information blind separation analysis of the current communication channel interference suppression research methods, this paper proposes the optical communication network channel interference suppression method based on blind signal separation algorithm. The receiver unit, field programmable gate array (FPGA) unit, memory chip group and other modules are used to construct the channel signal acquisition system, and the collected signals are preprocessed by centralisation and whitening. Based on the signal preprocessing results, the blind separation of instantaneous linear mixed signals, blind separation of convolutional mixed signals and blind separation of sparse sources were comprehensively analysed to obtain the source signals and realise channel interference suppression of optical communication network. Experimental results show that this method has high interference precision, strong stability and good application prospect.

Distributed Resilient Adaptive Control of Islanded Microgrids Under Sensor/Actuator Faults

To compensate for the voltage and frequency deviations caused by the droop control in islanded microgrids (MGs), employing an additional control level, called the secondary control, is necessary. Therefore, distributed control methods based on the sparse communication network, are recently employed in secondary control of MGs, because they are more reliable and flexible. However, traditional methods use the centralized communication network, which is neither economical nor efficient due to its large communication burden. Distributed control methods solve many challenges in the secondary layer of MGs, such as disturbances, uncertainties, unmodelled dynamics, noises, delays, attacks, and actuator faults. This paper proposes the novel resilient adaptive consensus-based voltage and frequency control protocols to compensate for the adverse effects of both sensor and actuator faults in communication network channels of islanded MGs. To this end, local adaptive sensor and actuator compensators eliminate the adverse effects of failures on sensors and actuators. The robust stability analysis based on the Lyapunov analysis is given to validate the results. Finally, the understudy islanded MG system is built in MATLAB/SimPowerSystems to verify the theoretical results. It is shown that the proposed secondary control strategies based on the adaptive protocols can highly increase the reliability and resiliency of the MG system compared with the existing distributed resilient methods.

Fault Diagnosis Observer and Fault-Tolerant Control Design for Unmanned Surface Vehicles in Network Environments

This study focuses on the network-based fault estimation and fault-tolerant controller designing for an unmanned surface vehicle submit to actuator faults, along with transmission delays, packet dropouts and packet disordering in the communication network channels between sampler and observer, and between controller and actuator. Compared with manned surface vehicles, unmanned surface vehicles in the network bring certain competitive superiorities as well as challenges. By using an intermediate variable, an observer is devised in network environments to estimate the states and actuator faults of the unmanned surface vehicle simultaneously. A sufficient condition is introduced and proved for the fault observer being uniformly ultimately bounded. Based on the fault observer, a fault-tolerant controller is proposed, which can ensure that the network-based closed-loop control system is uniformly ultimately bounded theoretically. Theoretical analysis and simulation results verify the performance of the fault observer and fault-tolerant control in network environments for an unmanned surface vehicle.

Network-Based Fault Detection Filter and Controller Coordinated Design for Unmanned Surface Vehicles in Network Environments

This paper is concerned with the network-based modeling, and observer-based fault detection filter (FDF) and controller coordinated design for an unmanned surface vehicle (USV) in network environments. Network-based models for the USV subject to actuator faults and wave-induced disturbances are established for the first time by introducing an observer-based FDF, and considering network-induced characteristics such as delays and packet dropouts in the sampler-to-control station communication network channel and the control station-to-actuator communication network channel. Based on these models, network-based FDF and controller coordinated design criteria are derived to asymptotically stabilize the residual system. The designed network-based FDF and controller can guarantee the sensitivity of the residual signal to faults and the robustness of the USV to external disturbances. Fault detection performance analysis verifies the effectiveness of the proposed network-based FDF and controller coordinated design scheme for the USV in network environments.

A convex optimization approach to signal reconstruction over switching networks

In this paper we consider signal reconstruction over communication network channels that can be modeled as input switching systems. Such systems can be associated with a variety of applications including control and estimation over networks. In particular, we formulate the signal reconstruction problem as a prototypical model matching problem where the various mappings involved belong to a class of input switching systems. The design interest is placed on minimizing the worst case or stochastic average performance of this model matching system over all possible switchings with an H 2 norm as the performance criterion. This minimization is performed over all stable receivers R in the class of input switching systems. For the particular setup at hand, and in the case of matched switching, two convergent sequences to the optimal solution from above and below respectively are formulated in terms of quadratic programs. An approximate solution with any a priori given precision is possible by finite truncation. Also, it is shown that in the cases of arbitrary, partially matched or unmatched switching, the optimal receiver R need not depend on the switching sequence and that it can be obtained as a linear time-invariant solution to an associated H 2 norm optimization.

Assessment of Switched Communication Network Availability for State Estimation of Distribution Networks With Generation

Active management of complex distribution networks with distributed generation requires state estimation. As complete supervisory control and data acquisition systems are seldom available on 11-kV or lower voltage distribution networks, real-time measurements at remote points on 11-kV distribution networks are expensive. Therefore, the economical selection of a communication system for active management of distribution networks with distributed generation becomes an important issue. This paper presents the investigations into a leased communication system made of public-switched communication network channels for a distribution network state estimation application. It analyzes the effects of a different number of primary channels for real-time measurements on the distribution network state estimation accuracy. The leased communication system availability performance has also been analyzed and used to identify a number of reserve channels required to improve the leased system availability. The overall cost for improving the leased communication system availability has been calculated and compared with both a fiber-optic communication system and a power-line carrier communication system. The results show that the leased communication system is able to provide the lowest overall cost performance for the distribution network state estimation application.

An efficient approximate technique for solving fluid models

Stochastic fluid-flow models have been widely used as an important tool for the analysis of a variety of computer and communication models. In particular, when the event rates of the system under investigation vary in orders of magnitude, the use of fluid models results in considerable computational savings when compared to traditional models where all events are explicitly represented. This is true for instance, in the so called <i>performability</i> models [10], where events that represent structural changes in the system (e.g., failure and repair events) occur at much lower rates than those associated with some performance measure, such as the arrival and service of jobs. As another example, consider a queueing model of a communication network channel. The intervals between events associated with packet arrival and departure from a buffer may be orders of magnitude smaller than the intervals that represent changes in the arrival rate.