Main Control Station Research Articles

Research on Distributed Autonomous Timekeeping Algorithm for Low-Earth-Orbit Constellation

The time of a satellite navigation system is primarily generated by the main control station of the ground system. Consequently, when ground stations fail, there is a risk to the continuous provision of time services to the equipment and users. Furthermore, the anticipated launch of additional satellites will further strain the satellite–ground link. Next-generation satellite navigation systems will rely on time deviation measurements from inter-satellite links to independently establish and maintain a space-based time reference, enhancing the system’s reliability and robustness. The increasing number of low-Earth-orbit satellite navigation constellations provides ample resources for establishing a space-based time reference. However, this also introduces challenges, including extensive time scale computations, increased link noise, and low clock resource utilization. To address these issues, this paper proposes a Distributed Kalman Plus Weight (D-KPW) algorithm, which combines the benefits of Kalman filtering and the weighted average algorithm, balancing the performance with computational resources. Furthermore, an adaptive clock control algorithm, D-KPW (Control), is developed to account for both the short-term and long-term frequency stability of the time reference. The experimental results demonstrate that the frequency stability of the time reference established by the D-KPW (Control) algorithm reaches 7.40×10−15 and 2.30×10−15 for sampling intervals of 1000 s and 1,000,000 s, respectively, outperforming traditional algorithms such as ALGOS. The 20-day prediction error of the time reference is 1.55 ns. Compared to traditional algorithms such as AT1, ALGOS, Kalman, and D-KPW, the accuracy improves by 65%, 65%, 66%, and 67%, respectively.

Design and application of sewage treatment technology in fieldbus control system

At present, most sewage treatment plants in China generally have low sewage treatment automation and low operating efficiency. In order to solve this problem, this article takes a sewage treatment plant in Hangzhou as an example to analyze the functions and control requirements of each process in detail. Adopting three-level sewage treatment process and multiple disinfection technology at the same time, a set of sewage treatment field bus automatic monitoring system for SBR comprehensive process is designed, and the overall structure of the control system, control system hardware, control program and host computer monitoring system are given. The system adopts siemens S7-300 as the main control station, and uses industrial ethernet to complete the data exchange between the bus control and the control station on the network configuration. With various testing equipment, the inverter and MCC serve as the slave stations form a profibus control network, and complete functions such as automatic control of sewage treatment equipment and dynamic process monitoring through Wincc7.4 and Step7 V5.5. At the same time, automatic online monitoring and sampling are adopted, and video monitoring replaces manual inspection. Practice shows that the system The operation is in good condition, the effluent indicators, reliability, safety, etc. have reached the design requirements, and good economic and social benefits have been achieved. It is an integrated control system with strong practicability and high degree of automation, which is useful for further improving the automation of sewage treatment. The degree has important reference value. At the same time, the technical achievements of automatic sewage control and comprehensive treatment can fully support the sewage treatment needs during the new coronavirus epidemic, and have a wide range of application prospects.

A Wide Area Service Oriented Architecture Design for Plug and Play of Power Grid Equipment

In this paper, we propose a wide-area service-oriented architecture design for plug and play power grid equipment, which adopts the service proxy mechanism to manage and control the service domain accessed to the wide area network through the domain management center. Accordingly, the service management center controls the service registration, the targeting (discovery) and the service information in the service domain. It also provides the functions of maintenance-free access and communication, service object management, service subscription and distribution between service providers and service consumers in wide-area interactions. Subsequently, our proposed architecture is able to achieve the servitization interaction of power grid applications, and enhance the level of information sharing and the capacity of business collaboration between the main station of dispatch and control and intelligent electric substation. It also can provide the practical guidance for automatic access of substation equipment, the function improvement of the main control station and the service transformation of its applications.

Wireless Sensor Network for Radiation Detection

In this paper a wireless sensor network (WSN) is designed from a group of radiation detector stations with different types of sensors. These stations are located in different areas and each sensor transmits its data through GSM network to the main monitoring and control station. The design includes GPS module to determine the location of mobile and fixed station. The data is transmitted with GSM/GPRS modem. Instead of using traditional SMS data string or word messages a digital data frame is constructed and transmitted as SMS data. In the main monitoring station graphical user interface (GUI) software is designed to shows information and statues of the all stations in the network. It reports any radiation leaks, in addition to the data; the GUI contains a geographical map to display the location of the leakage station and can control the stations power consumption by sending a special command to it.

Wireless Sensor Network for Radiation Detection

In this paper a wireless sensor network (WSN) is designed from a group of radiation detector stations with different types of sensors. These stations are located in different areas and each sensor transmits its data through GSM network to the main monitoring and control station. The design includes GPS module to determine the location of mobile and fixed station. The data is transmitted with GSM/GPRS modem. Instead of using traditional SMS data string or word messages a digital data frame is constructed and transmitted as SMS data. In the main monitoring station graphical user interface (GUI) software is designed to shows information and statues of the all stations in the network. It reports any radiation leaks, in addition to the data; the GUI contains a geographical map to display the location of the leakage station and can control the stations power consumption by sending a special command to it.

Design and implementation of a triple-redundant dynamic positioning control system for deepwater drilling rigs

Triple-redundant control architecture of the main control station is proposed for dynamic positioning (DP) system from a practical point of view according to the International Maritime Organization's (IMO) DP Class 3 notation. To improve the single fault tolerance, both operator station systems and real-time control computer systems are designed with triple modular redundancy. Hierarchical software layers of the triple-redundant control architecture are implemented based on the different real-time response requirements of the layers. Input and output voting are incorporated to the positioning task to detect and isolate faults in the sensors and in the control system. Hard-in-the-loop (HIL) testing system together with model-scale tests are conducted to verify the proposed triple-redundant control architecture. The feasibility and fault-tolerant capability of the triple-redundant hardware and software architecture both in HIL and model tests are demonstrated.

LAROB: Laser-Guided Underwater Mobile Robot for Reactor Vessel Inspection

In a nuclear power plant, there are several cylindrical vessels such as a reactor vessel and pressurizer. The vessels are usually constructed by welding large rolled plates or nozzle pipes together. To ensure the integrity of the vessel, their welds should be periodically inspected using sensors such as ultrasonic transducers or visual cameras. To inspect these welds effectively, we developed an underwater mobile robot, which is guided by a laser pointer. The robotic system was devised to reduce the inspection time and schedule during mandatory code inspections compared to a conventional inspection machine with a large structure. The system mainly consists of an underwater mobile robot, a laser positioning unit, and a main control station. The underwater mobile robot is guided by a laser positioning unit with a precise resolution of 0.05°. The mobile robot moves on the reactor vessel wall with four magnetic wheels. This paper presents the design and implementation of the underwater mobile robot. The laser guidance control of the mobile robot is also described along with the experimental results. The system was integrated with the main control station, and tested in the reactor vessel of a Korean nuclear power plant. After many improvements in its design and engineering, the system is expected to dramatically reduce the critical path of the reactor vessel inspection, if the system is used practically.

Communication Feasibility Analysis for Smart Grid With Phasor Measurement Units

The conventional power system is going through a paradigm change towards smart grid. Phasor measurement units (PMUs) have emerged as the edifice for information technology related to wide-area monitoring systems (WAMSs) for power system monitoring, information communication, and control purposes. The PMUs require communication links for a complex interconnected power grid, and proper spatial coordination plays a vital role for wireless communication network. Geographical information system (GIS) provides a rich set of functions to analyze the power network incorporating geospatial features. This paper investigates the impact of topological attributes on commissioning of wireless communication network for PMUs incorporating GIS aided analysis and to optimize one of the PMU location as main control station. This will not only serve for monitoring automation purposes, but will also ensure control automation. Case studies related to the eastern grid of India corroborate the efficacy of GIS-aided wireless communication for linking PMUs.

Point Sources Pollution of Nutrient Situation and Prediction of Gan River Basin

Forecast about nutrient (mainly referring to nitrogen, N and phosphorus, P) emission from point sources of Gan River was made on the base of pollution state and spatial-temporal variety regularity from 1999 to 2009. During the research period, maximum of total nutrient emission was in Ganzhou (TN 1.64×104t, TP 0.21×104t), which is followed by Nanchang. Just in terms of 2009, total nutrient emissions from Ganzhou and Nanchang account for 60% and Nanchang, as a main control station, per capita nutrient emissions increased at the speed of 7.96% and 7.17% in 2008 and 2009, respectively. According to the prediction model, TN and TP emissions from Gan River basin will be 5.25×104t and 0.68×104t, respectively. Meanwhile, point sources still is the principal part of total nutrient emission from Gan River, which will have a negative impact on water quality of estuary and Poyang Lake. Therefore, the key to comprehensive management of water pollution is point sources.

Research on the time synchronization technology based on the GEO Positioning System

The method of common-view is characterized by higher precision, good convenience in use, and cheap instrument. A new time synchronous method for multiple users system by common-view technology is presented based on the GEO Positioning System (GEOPS). And the GEOPS common-view theory is studied for which is different from the other GNSS system. This paper introduces the working process and the time service pattern of the GEOPS. In the GEOPS, the pseudo- range found by the receiver through testing is actually the measurement of the whole link from the main control station and through the satellite to the receiver. Due to the different distances between the main control station and each satellite, this measurement has to be done using the upload delay correction by the main control station. The upload delay adopts a polynomial model and the polynomial parameters are demodulated from the navigation message to calculate the delay correction value during the adjustment. In accordance with these characteristics of GEOPS, we propose the GEOPS common-view theory. The format parameters of GEOPS common-view and data calculating method are presented. The time synchronization system, the error analysis and the applied plan of GEOPS common-view technology are introduced. Index Terms-GEOPS; multipel users system; time synchronization; common-view