Redundant Configuration Research Articles

Research on integrated measurement and control device and test technology in smart substation

According to the problems of low system integration, no redundant configuration and wide fault influence range of the measurement and control device, this paper research on the scheme of integrated measurement and control device in smart station, which can greatly reduce the number of measurement and control devices and effectively improve the reliability of integrated system. At the same time, the maintenance technology for integrated measurement and control device can improve the efficiency of maintenance for the whole station.

Navigation Grade MEMS IMU for A Satellite.

This paper presents a navigation grade micro-electromechanical system (MEMS) inertial measurement unit (IMU) that was successfully applied for the first time in the Lobster-Eye X-ray Satellite in July 2020. A six-axis MEMS gyroscope redundant configuration is adopted in the unit to improve the performance through mutual calibration of a set of two-axis gyroscopes in the same direction. In the paper, a satisfactory precision of the gyroscope is achieved by customized and self-calibration gyroscopes whose parameters are adjusted at the expense of bandwidth and dynamics. According to the in-orbit measured data, the MEMS IMU provides an outstanding precision of better than 0.02 °/h (1σ) with excellent bias instability of 0.006 °/h and angle random walk (ARW) of around 0.003 °/h1/2. It is the highest precision MEMS IMU for commercial aerospace use ever publicly reported in the world to date.

Design and Development of Fire Fighting System Using Hot Redundant PLC in COVID Situation

A firefighting system is the most foremost part of any industry and buildings as its aim to protect property, human and industrial equipment. In any pandemic situation like COVID19 it is utmost requirement to increase reliability of all important instruments which are directly involve to human life. In case of fire fighter fight against fire, this required time and skilled man power. Under these pandemic situation chances of infection spreading in firefighters and social distancing will not maintain during this situation. Only one way to resolve this problem is by implementation of fully automated reliable system. In this system we are trying to automate the total system by using hot redundant PLC which is fail safe. It consists of mainly three basic parts - fire storage tank, fire pumps and automated distribution system. Fire storage tank contains the water that used against fire. Fire pumps helps to fill the tank and automated distribution system will be activated during fire and instantly distribute water. There are three pumps one is main electrical pump, second one is diesel backup pump and last one is jockey pump.In redundant configuration there are two PLC acting simultaneously and the entire network component and power supply also has back up so that it will never fail. If one of the PLC fails during operation then second PLC automatically take care of the system within few millisecond. Similarly if power supply failure then UPS supply is also there for uninterrupted power supply.

A Dynamic Calibration and Compensation Method for the Asynchronous Time Between Two Inertial Navigation Systems

The carrier is usually equipped with two or more inertial navigation systems (INS) as redundant backup system configuration to improve reliability. In this case, information fusion from two or more INSs can achieve error detection and system state monitoring. However, due to the different information collection and process mechanism, the measurements from different INSs would not be synchronized, which would decrease the accuracy of the fusion algorithm and would cause wrong monitoring results. In this paper, a dynamic calibration and compensation method for the errors caused by time-gap between two asynchronous INSs is proposed. The causes of asynchronous time from different INSs are analyzed and the asynchronous time is modeled. Based on the model, an online estimation and compensation Kalman filter for asynchronous time is established. Using the difference of navigation information between two sets of INSs as measurements, the filter can estimate the asynchronous time between the two INSs. The simulation results show that the proposed method could achieve estimation accuracy of 0.027ms for the asynchronous time between different INSs, and the vehicle experimental results also demonstrate the effectiveness of the method.

High Quality NLM Method for Medium Voltage Hybrid Bridge MMC

Medium voltage hybrid bridge multilevel converter (MMC) usually has a lower number of links. Therefore, the traditional Nearest Level Modulation (NLM) method has the problems of low equivalent switching frequency and poor output quality. And the traditional Carrier Phase-shifted Pulse Width Modulation (CPS-PWM) modulation has problems such as difficulty in hybrid bridge control, difficulty in redundant configuration, and large amount of calculation. In response to the above problems, this paper proposes a new high-quality NLM method. Based on the traditional NLM modulation method, PWM modulation output and module voltage equalization are realized through the time difference between one module input and one module exit in each control cycle. It achieves the purpose of improving the equivalent switching frequency and output power quality, and at the same time has the advantages of the traditional NLM modulation method with small calculation amount, redundant configuration and hybrid bridge modulation. This article describes the three modulation methods and compares their effects. Finally, the theoretical analysis is verified by PSCAD simulation.

Comparison of secondary equipment redundancy configuration of smart substations in China and overseas

This paper introduces the overseas smart substation technology scheme, describes the communication network architecture and equipment redundancy configuration in the typical overseas test smart substation scheme, and compares the similarities and differences between China’s smart substation redundancy configuration technology and the overseas smart substation configuration technology. The distribution of measurement and control functions of overseas smart substations that are different from China’s designs are explained in detail. The different architectures of overseas smart substations and China’s smart substations are illustrated. Finally, the suggestions of overseas Smart Substation and China’s smart substation are summarized.

Improving the Reliability of Solid Rocket Motor Demoulding Monitoring System through Software Configuration

Solid rocket motor demoulding is to take out the core mold solidified in the grain by pulling or pushing. At present, the manual demoulding mode with Jack or crown block auxiliary operation is often used in China, which can not effectively control the demoulding force and speed, and the change of friction sensitivity caused by the impact vibration and speed mutation is the main source of the accident. Therefore, this paper developed a remote real-time control system for the demoulding operation of small solid rocket. The operator can realize the remote real-time monitoring of the whole demoulding process in the isolated control room. Accordingly, the remote monitoring system has higher and higher requirements for equipment reliability. In view of this situation, this paper introduces several commonly used redundancy technologies and configuration environment century star, discusses the method of using soft redundancy technology to improve system reliability, and develops a set of specific implementation scheme. The practical application shows that the stability and reliability of the system have been improved obviously, and the operation effect of the system is good. The system can be widely used in data acquisition, data exchange and other occasions requiring continuous operation of the computer.

Methodological Approach to the Integrated Optimization of the Heat-Source Structure in the Problems of Developing Heat-Supply Systems

The question on the optimal development of the heat sources in the developing heat-supply systems (HSSs) is considered. The current state of research in the field in question is analyzed. It is noted that this issue has aroused increased interest in recent years. The description and mathematical formulation of the problem of optimizing the structure of the heat sources in the developing HSSs are provided. The best distribution of the load between the former is determined and the choice of the optimal parameters of the heat-supply networks under permissible technical, economic, and ecological restrictions is made. For the first time, the problem has been formulated and implemented using the method of directed search for possible variants of the heat source’s power and equipment content in a preplanned redundant heat-source configuration that was previously used to search for the best configuration of the heat-supply network. To devise redundant configurations and subsequently calculate them, methodological approaches oriented towards the construction of P-graphs and energy hubs that have been developed in recent years can be successfully applied. Every heat-source structure variant outlined within the framework of the redundant configuration competes with other variants not only in terms of the minimum costs but also in terms of the minimum impact on the environment. The proposed methodology was implemented in the form of a software package that enables the user to interactively communicate with the digital model of the system to obtain a solution for the development and reconstruction of the HSS under investigation. The practical application of the methodological and computational tools to solve the problem of the development of heat-supply systems is exemplified by the configuration of the heat-supply system of the settlement of Magistralnyi, Irkutsk region.

Application, Selection, and Design of Three-Winding Transformers in LNG and Petrochemical Facilities

Transformers are used in power systems to transform (step-down) voltages while maintaining the same frequency. Electrical engineers designing the power systems for a liquefied natural gas (LNG) or petrochemical facilities typically use two-winding transformers to feed multiple process units in redundant distribution schemes throughout the facility. This method is repeated further to derive different voltage levels to feed process loads. As the industry moves toward larger production facilities, which increase the power demand, multiple large two-winding transformers are utilized. This approach leads to an increase in substation footprint, switchgear equipment, power feeders, site works, etc. This article focuses on an alternative design using three-winding transformers for LNG and petrochemical facilities. The input and output of a three-winding transformer generally consist of one primary ( H ) input winding and two output windings defined as secondary ( X ) and tertiary ( Y ). The three-winding transformers are connected in a redundant configuration to feed multiple process units. In this article, different types of three-winding configurations and construction (radial or axial) methods are reviewed. In addition, this article addresses the application of tap changers, overall system performance, defining impedance parameters, and specification requirements.

A Heuristic Approach to Detect MPLS L3 VPN Misconfiguration in Multi-Homed Multi-VRF Site-Redundant CE Environments

MPLS L3 VPNs are often configured manually and are prone to errors. Misconfigured VPNs violate customer’s privacy and security. With the advent of the Multi-VRF (VRF-Lite) feature on the CE, it is now possible to support two or more routing domains on a single CE. Customers can also add more CE devices in redundant configurations having multi-homed connections to service providers’ PE routers for enhanced reliability and high availability of MPLS L3 VPNs. This scenario adds more complexity increasing the reasonable probability of misconfiguration. MINA algorithm can detect errors in the MPLS infrastructure without the cooperation of the service providers. However, the MINA algorithm works for single-homed CE configured for a single VRF per CE. In this paper, we extend the MINA algorithm using a heuristic-based approach to detect misconfiguration in the MPLS infrastructure connected to Multi-VRF, Multi-homed, site-redundant CE environments. We effectively utilize both control-plane and data-plane information to demonstrate the detection of one-way and discovery of two-way RT (Route Targets) misconfiguration. The heuristic method can further detect the probable location/site and pinpoint the shared CE-customer affected by this misconfiguration.

Research on multi-task command allocation method for flying wing aircraft

Flying wing aircraft adopts redundant multiple control surfaces configuration, especially the new type of drag based yaw control device is used in directional axis. Therefore, its command allocation problem has strong nonlinear and multi-axis coupling characteristics. According to the command allocation characteristics of flying wing aircraft, a multi-objective optimization based nonlinear programming method is used for command allocation, and the differences of the control surface command allocation results under different optimization targets is analyzed. The results are also carried out in the attitude tracking simulation based on flight control system designed with nonlinear dynamic inversion. It demonstrates that the different optimization targets have great and quite different impacts on flight states. It proves that the multi-objective optimization based control allocation method is a highly adaptable and flexible command allocation method for flying wing aircraft.

Configuration Optimization in Miniature Interferometric Fiber-Optic Gyroscopes for Space Application

With the development of small satellites, the space-borne interferometric fiber-optic gyroscopes (IFOGs) need to satisfy the requirements of high reliability, light weight and small size. Traditional multiple-axis redundant configurations are no longer applicable for miniature IFOGs. In this paper, a novel configuration reliability optimization method is presented for IFOGs, whereas limiting weight and volume. Firstly, a fault tree analysis for the space-borne single-axis IFOG is carried out and the effects of the space environment on IFOG components are discussed. Then, based on the failure features and performance degradation characteristics of the IFOG components, the reliability model is deduced. The configuration reliability optimization method is proposed for the first time to achieve high reliability of space-borne IFOGs, without increasing weight and volume. Traditional four single-axis IFOG configuration is employed to verify the effectiveness of the proposed method, the optimized results show that with our experimental IFOG parameters, the reliability is improved by 2.3%–3.1% in the first year, 21.4%–22.1% in the third year and 53.9%–55.0% in the fifth year, whereas the total weight dropped by 8.3% and the total volume is almost same. Therefore, the proposed method is efficient and easy to implement, which actually has been used in prototypes and products.

Reduction of time errors of the inertial measuring module by realization of its structural redundancy on the basis of three-axis micromechanical measuring instruments

Redundant inertial measurement units (IMU) are used in security-critical operations since the advent of inertial technology. This approach allows you to create fault-tolerant systems that can detect and isolate defective sensors. Besides, experimental results have shown that redundant IMU is also an effective way to improve the performance of navigation systems. The question is only in the dependence of the accuracy of the unit on the number of sensors used and their mutual orientation.
 This paper analyses the influence of spatial orientation on the accuracy of an IMU with a redundant configuration in the case of using triaxial orthogonal micromechanical measuring modules as atomic structural units.
 The first part of this article concentrates on the geometry of the redundant IMU. Analysis of its metrological model of a redundant showed that, when dealing with orthogonal IMU triads, its resulting accuracy is independent of the relative orientation between them. This fact presents important practical implications since it demonstrates that using complex large-scale installation structures can be avoided. As a result, it is enough to place instead of an array of units, for example, only on one printed circuit board with any orientation. Also, it was found the relationship between the number of sensors employed and the accuracy improvement that enables us to ascertain the exact number of sensors needed to design a navigation system with a certain precision.
 The second part of this article shows the experimental approval of theoretical conclusions during the testing of a prototype block based on three low-cost units (MPU6050) built according to a symmetric tetrahedron scheme.
 The accuracy of the redundant block was experimentally evaluated based on the value of the errors in determining the modulus of gravity acceleration and a given angular velocity of a test rotary platform in a series of positions. The performance of the tested inertial measuring block was better on average in comparison with anyone module from this block that proved the possibility of using these approaches for MEMS sensors in high-accuracy application areas.

RELIABILITY COMPARISON OF TWO UNIT REDUNDANCY SYSTEMS UNDER THE LOAD REQUIREMENT

AbstractThis paper compares the reliability functions of the cold standby, hot standby, and load-sharing redundancy configurations, each of which is composed of two identical components for meeting a given system requirement. Thus far, no research has been done into the conditions that make one configuration more reliable than another because their reliability functions have no closed forms even when the component follows a Weibull lifetime distribution. In this paper, two analytical results are obtained given that the reliability of each configuration is expressed in terms of the design and operational loads of the component. First, higher reliability can be achieved in a cold standby configuration than in a load-sharing configuration if the increase in the component reliability obtained from the reduction in the operational load is not significant. Second, a cold standby configuration exhibits better reliability and carries a higher load than a hot standby configuration if the design load can be increased with a less decrease in the component reliability.

Torque Vectoring Algorithm of Electronic-Four-Wheel Drive Vehicles for Enhancement of Cornering Performance

This paper introduces a new torque vectoring (TV) algorithm with regards to enhancing the cornering performance of the electronic-four-wheel drive (e-4WD) vehicles. The proposed TV algorithm aims to distribute the in-wheel motor (IWM) torques to the left and right wheels assisting the vehicle in following the driver's intended trajectories. The proposed TV algorithm first included a yaw rate controller reference for neutral-steering which leads to the improvement of vehicle cornering agility. Thereafter, in-vehicle sensors and a standalone global positioning system (GPS) combined with a smooth sliding mode controller (SMC) were used based on a vehicle bicycle model to generate desired yaw moment values to track the reference. Finally, a novel torque distribution algorithm using the Daisy-chaining allocation, which is suitable for redundant actuator configuration, was utilized. Noteworthy, the Daisy-chaining allocation algorithm takes into account a torque operation area with the characteristics of IWM. In this manner, based on the vehicle bicycle model and using the CARSIM interface, the simulations, evaluation and verifications of the proposed control technique were done. Thereafter, considering a real-car based experiments with various driving scenarios, the effectiveness of the proposed TV algorithm was evaluated. It was confirmed that some evaluation factors in terms of the cornering performance were improved. The following main contributions makes the proposed TV algorithm be a meaningful solution to enhance the cornering performance of e-4WD vehicles: 1) improvement of both smoothness and convergence rate of control action, 2) a practical and intuitive way to distribute IWM torques, and 3) high applicability to mass-produced vehicles.

Modeling and simulation of FPGA-based redundant digital systems

AbstractReliability is one of the most important criteria that characterize last generation digital systems. In a wide range of applications the required reliability level is achieved by using hardware redundant configurations. Perhaps their most common form is the triple modular redundancy (TMR) based on a majority voting structure. Researchers that use this strategy make a major assumption: in fault-free operation mode the outputs of these digital systems match in all. This paper proves that synchronization and matching in all the outputs of such systems is not such a trivial problem. In this endeavor FPGA-based (Field Programmable Gate Arrays) redundant topologies are considered for study and experiments. Upon these structures specially conceived redundant models have been developed and simulated. The results outline that synchronization of complex digital systems is a difficult engineering undertaking and any initial assumption should be managed with the adequate circumspection.

Energy Planning for Autonomous Driving of an Over-Actuated Road Vehicle

In this work, an energy planning strategy is proposed for over-actuated unmanned road vehicles (URVs) having redundant steering configurations. In fact, indicators on the road geometry, the actuation redundancy, the optimal velocity profile, and the driving mode are evaluated for each segment of the URV's trajectory. To reach this objective, a power consumption estimation model is developed for the URV. Due to the presence of unknown dynamic parameters of the URV and uncertainties about its interaction with the environment, an artificial intelligence (AI) technique, based on data-learning qualitative method, is used for the power consumption estimation, namely Adaptive Neuro Fuzzy Inference System (ANFIS). The ANFIS model is obtained using trained data from a Real URV dynamics. Then, an energy digraph is built with all feasible configurations taking into account the kinematic and dynamic constraints based on a 3D grid map setup, according to velocity, arc-length, and driving mode. In this weighted directed graph, the edges describe the consumed energy by the URV along a segment of a trajectory. The vertices describe the start and end points of each segment. Subsequently, an optimization algorithm is applied on the digraph to get a global optimal solution combining driving mode, power consumption, and velocity profile of the URV. The obtained results are compared with the dynamic programming method for global offline optimization. Finally, the obtained simulation and experimental results, applied on RobuCar URV, highlight the effectiveness of the proposed energy planning.

Cost and reliability optimization of modular multilevel converter with hybrid submodule for offshore DC wind turbine

The hybrid modular multilevel converter (HMMC) consisting of half- and full-bridge submodules (SMs), with DC fault ride-through capability, have become a promising candidate for offshore wind energy conversion system, especially all-DC output wind turbines. The topology of HMMC needs to be optimized for lower cost and higher reliability with active redundancy. This paper presents an optimization method for HMMC topology with cost and reliability objectives. The reliability is defined to be not only reliable under normal operation, but also able to ride through DC fault even with faulted SMs, which is different from the former model. Firstly, reliability and cost models with power loss, considering active redundancy configuration, are derived. Then, cost and reliability, with different numbers of original and redundant SMs, are quantified by taking a case study of 10-MW and 10-kV HMMC for offshore DC wind turbines. Finally, a multi-objective optimization approach that regards maximum reliability and minimum cost is proposed, and the optimal solution from Pareto-optimal set is selected according to fuzzy membership function, which determines the optimal topology for HMMC. The results show that reliability can be improve with redundant full-bridge SMs (FBSMs) but weakened with excessive half-bridge SMs (HBSMs). Furthermore, the incremental cost with a redundant FBSM is approximately 3 times that of HBSM. The optimal topology, 10 original SMs per arm (5 HBSMs and 5 FBSMs) with 1 redundant HBSM and 4 FBSMs, is validated by comparing with the results of former reliability model and single-objective optimization.

A Two-Stage Stochastic Programming Model of Component Test Plan and Redundancy Allocation for System Reliability Optimization

This article presents a new two-stage stochastic model for the simultaneous optimization of component test plan and redundancy allocation. The optimal number of tests is determined for each component of the system in the first stage, and the system redundancy configuration is optimized in the second stage, after the realization of the system working condition. Scenario analysis is used for modeling variations in working conditions. A multiobjective reliability problem is formulated for series-parallel systems, and the allocation of redundancy is optimized by a genetic algorithm. The results of the feedback control system demonstrate the performance of the proposed model.

Architecture Design of Distributed Redundant Flight Control Computer Based on Time-triggered Buses for UAVs

With the rapid development of unmanned aerial vehicles (UAVs) performance and their increasingly complex tasks, the current centralized flight control computer (FCC) architecture based on the event-triggered mechanism cannot meet the requirements of openness, reliability, and real-time processing. In view of the development trends and technical requirements of future UAVs, a distributed redundant FCC architecture design method based on commercial off-the-shelf (COTS) technology and a set of dual-channel redundant time-triggered buses is proposed. With this architecture, new UAV flight control design methods are then proposed, such as distributed fault-tolerant management, Byzantine fault-tolerant design based on dual-core self-monitoring, and an open/integrated design method for airborne multi-sensor information processing and fusion. According to the characteristics of the redundant FCC based on the time-triggered buses, a distributed task scheduling and communication model is established, and an optimal static scheduling and real-time analysis algorithm of distributed tasks based on a search tree is proposed. Finally, the real-time performance and reliability of the FCC are analyzed and verified. The verification results show that, compared with the centralized FCC architecture based on the event-triggered mechanism, the proposed UAV FCC architecture has better task schedulability and system scalability. Moreover, it has a higher task reliability under the same redundancy configuration, which means that it can provide a distributed, synchronous fault-tolerant and redundant reconfigurable technology platform for future UAV FCCs.