Simulation Modeling for Electrical Switching System of Hydropower Station

Development and application of electric generation combined system simulation model with the equipment condition assessment system are described in the article. Simulation model was realized in Matlab Simulink environment. Current and voltage oscillograms of the model's operation under nominal and twofold electric load power have been obtained. The developed model can be used when designing renewable energy objects and developing and testing control and monitoring systems algorithms. The equipment condition assessment system together with fuzzy logic apparatus can be used to support the electric power system's operator in making a decision of replacing or repairing the equipment as necessary.

The RELAP5 code, designed to predict the behavior of reactor systems during accident conditions, is used widespread over the world. This work aims to show and describe the RELAP-MV graphical software developed using computer language (XML) and Visualized Modularization software technology to recognized best estimated transient simulation program of Light water reactor, in combination with new options for improved modeling methods, advanced programming, computational simulation techniques and integrated graphics displays. RELAP5 code is complex and inconvenient for utilizing method of data cards and close logic relationship of data in input file. The main purpose of developing RELAP5-MV is to simplify progress and increase simulation efficiency. Traditional modeling method and modular modeling method are supported with RELAP5-MV to achieve aims of device and system simulation. For traditional modeling method, all kinds of components are developed such as single volume, single junction, pipe, branch, time dependent volume, etc. For modular modeling method, the module library is established in the software. The library packages include the main system equipments of primary and secondary loops such as reactor core, U tube steam generator, once through steam generator, pump, pressurizer, steam turbine, condenser, heat exchanger, deaerator, etc. in a pressurized water reactor, which can be analyzed and modeled in details. From the library the capabilities are easy to select icons interface from the library packages. The analysis results show that the software can effectively simulate nuclear power system by RELAP5. Plot and data binding function is supported for post-processing of calculation result. Personal computer interface of RELAP5-MV makes it more convenient, fast and visualized in simulation system establishing process. Performance Relap5 related analysis activities, such as creating and modifying input file, viewing component division figures and generating output files can be realized by RELAP5-MV. The interactive simulation interface feature allows the users to simulate specific reactor transients and accidents — such as LOCA, LOFA, scram, etc. Accuracy and reliability of RELAP5-MV have already been confirmed by simulating main coolant system of Pressurize Water Reactor (PWR) and modeling efficiency increases significantly by using RELAP5-MV. Visualization modeling, analysis and computational simulation for thermal hydraulic analysis of nuclear reactor can not only lower the RELAP5 threshold but also improve the efficiency of nuclear science research greatly, and also promoting the development of related research in RELAP5 safety analysis. RELAP5-MV can give an approach to build, verify and assess simulation design of reactor power system.

The main function of ship fuel supply system is to provide fuel oil of suitable pressure and viscosity for the main engine, auxiliary engine and auxiliary boiler of the ship. Practice has shown that in ship accidents, it is not uncommon to see downtime or even engine damage caused by crew's mismanagement of fuel supply system. Therefore, it has become one of the important contents of the training of the engine simulator to strengthen the training of the crew in the fuel supply system. Due to the complexity of the fuel supply system structure, the simulation model of the fuel supply system in the existing engine simulators has been simplified to different degrees, which can no longer meet the training requirements of maintenance, troubleshooting and emergency handling. In this paper, to address the problems of simplified model and insufficient training functions in the existing fuel supply system simulation model, a mathematical model of the ship's fuel supply system is established by using the modular modeling method, which includes: fuel pipe network and valve parts, fuel tank , pump and safety valve, regulator, quick-closing valve, self-cleaning filter, fuel heater, viscometer, viscosity controller, pressure controller, etc. the calculation program of the above model is written by using VC++. The simulation experiments show that the calculation results basically match the data of the navigation test, and the simulation error is less than 5%, and the simulation accuracy and real-time performance of the model can meet the requirements of the marine engine simulator training. The simulation experiments show that the Human Machine Interface (HMI) is similar to the physical interface of the actual equipment, and can realize the operations of maintenance, troubleshooting and emergency handling. The simulation model and HMI are integrated into the existing turbine simulator, replacing the original system model and HMI, and meeting the training requirements of the engine simulator.

For the spot electricity market, the quotation combining the hydropower stations is more resistant to uncertainties of runoff and spot price in market bidding. Therefore, it is of great significance to set up a spot quotation system for these hydropower stations. The paper first studied the fundamental characteristics of hydropower stations at different tiers, based on which the establishment of a quotation system of hydropower stations at different tiers and the bidding procedures were proposed. In addition, the paper investigated the joint bid model suitable for hydropower stations at different tiers based on cooperation between bidding stations. Finally, the paper established a coordinated management model and conflict-solving model for the quotation system of hydropower stations at different tiers, providing theoretical support for the system to take part in the spot electricity market and improve its marketing capabilities.

This paper analyzes and researches the intelligent information construction of the governor control system of hydropower station. Based on IEC-61850 communication protocol, this paper puts forward the composition framework and function strategy of the governor control system, which is suitable for digitalization, communication networking, integration standardization and decision-making intelligence of intelligent hydropower stations. It provides effective solutions for the safety and stability, intelligence, fault early warning diagnosis, and status trend analysis of the hydropower station's governor control system, which is beneficial to promote the construction of intelligent hydropower stations for reference.

Optimizing the sizes of wind and photovoltaic power plants integrated into a hydropower station based on power output complementarity

The results of the assessment and analysis of the operating modes of the power complex with the constructive and technological combination of hydraulic power plants (HPPs) with solar power plants (SFEU) in the presence of seasonal or daily regulation in the environmental hydro system are presented. The aspects of the operation of a hydroelectric power station with non-self-regulating derivation are considered in detail: when working in a load schedule with a maximum power equal to the installed one, and when the average daily power along the watercourse is approaching the provided one. It was found that in the first case, the influence of the SPEU regime on the joint work with the hydroelectric power station is to move a part of the load graph of the hydroelectric power plant with the maximum power to the base part of the schedule. In the second case, the influence of the SPEU mode consists in changing the variable part of the load graph, but the HPP, in contrast to the first case, retains its position in the load graph of the power system. The mode of operation of the hydroelectric power station becomes more uniform and at the same time, a smaller volume of the daily regulation basin (DRB) is required. For the example considered, the maximum power of the hydroelectric power station during the day increased from 50 MW to 54 MW. It has been revealed that even with the production of SPEU in 18% of the daily production of hydroelectric power plants, the volume of DRB is required approximately two times less. As a result, it is possible to increase the operating head at the hydroelectric power station and obtain the corresponding effect on power and electricity generation.

A comprehensive energy simulation model for energy-water-food nexus system analysis: A case study of the great Karun water resources system

The thermal issue causing by Integrated Power System (IPS) can't be neglected. This paper focuses on the electrical-thermal co-simulation of Integrated Engineering System (IES). IES has two high coupled subsystems, it is difficult to modeling such a complex system. Besides, the large difference between electrical and thermal dynamics results in number stiff which consume more time to run a simulation of IES. For this, this presents a modular modeling method of IES for the complexity problem and proposed a reduce-order model of IPS including power management for the stiff problem. A simulation case with several typical scenarios is posed using the proposed model of IES. The interaction of the electrical and thermal subsystems can be observed visually in the simulation results, and the validity of proposed model is proved theoretically.

This paper aims to develop the energy flow model of mechanical servo press, which serves as the quantitative analysis tool for servo press energy efficiency optimization. A modular modeling method is used to address the variety of component configuration and complexity in electromechanical coupling mechanisms of mechanical servo press. Based on the general function principles and structure model of the servo motor drive linkage press, the consisting modules of the energy analysis model are first identified and interactions between modules are established. Then, the module of the servo motor and linkage mechanism, which are the major configurable parts are presented with more details. A case study of six-bar servo press energy analysis using the proposed model is also presented. The proposed method can strengthen product model building and enhance the convenience of energy efficiency design of mechanical servo press.

In this paper, the high-pressure common rail system of the marine diesel engine is taken as case study to establish a real-time simulation model of the high-pressure common rail system that can be used as the controlled object of the control system. On the premise of ensuring accuracy, the real-time simulation should also respond quickly to instructions issued by the control system. The development of the real-time simulation is based on the modular modeling method, and the high-pressure common rail system is divided into submodels, including the high-pressure oil pump, common rail tube, injector, and mass conversion. The submodels are built using the “surrogate model” method, which is mainly composed of MAP data and empirical formulas. The data used to establish the real-time simulation are not only from the empirical research into the high-pressure common rail system, but also from simulations of the high-pressure common rail system undertaken in AEMSim. The data obtained from this real-time simulation were compared with the experimental data to verify the model. The error in fuel injection quality is less than 5%, under different pressures and injection durations. In order to carry out dynamic verification, the PID control strategy, the model-based control strategy, and the established real-time simulation are all closed-loop tested. The results show that the developed real-time simulation can simulate the rail pressure wave caused by cyclic injection according to the control signal, and can feedback the control effect of different control strategies. Through verification, it is clear that the real-time simulation of the high-pressure common rail system can depict the rail pressure fluctuation caused by each cycle of fuel injection, while ensuring the accuracy and responsiveness of the simulation, which provides the ideal conditions for the study of a rail pressure control strategy.

Giant room-temperature electrical switching effects in water-in-oil emulsions

The construction method in electrical room with hydro power generation is well informed in drawings and according to this method, to master the actual working conditions. It's necessary to consult location of KEPCO liability threshold with the KEPCO side, therefore make a decision to install the underground cable in hydro power station in each state, including outdoor pipes and manholes. Undulating rigid polyethylene conduit (125C) and CNCV-W extra high cable are laid and installed, to make a closely analysis to the construction by reviewing its process. In this work, the key part of the KEPCO power system for House of Commons is actually based on liability threshold, even including outdoors pipeline construction, high voltage underground electrical wiring and switchgear installation. It directly reveals the contents of the proposed construction methods about Housing Corporation and the High Voltage Switchgear Installation Inlet.

Grounding faults are inevitable during the operation of cable systems. As the weak insulation component in the cable system, cable terminals are particularly susceptible to the effects of grounding faults, which may lead to subsequent breakdown incidents. Therefore, assessing the health status of cable terminals during grounding faults is essential for achieving life-cycle fault early warning. This study calculates the short-circuit current generated during a single-phase ground fault and employs an electromagnetic transient simulation model to analyze the induced sheath voltage and grounding current variations. These current and voltage parameters under fault conditions are then used as input conditions for a solid heat transfer simulation model and an electric field simulation model, respectively, to evaluate the thermal and electrical stresses within the tail pipe of the cable termination during a single-phase ground fault. The results indicate that under such fault conditions, overheating and partial discharge may occur within the insulation layer of the tail pipe, potentially initiating subsequent breakdown faults. This research contributes significantly to a deeper understanding of the fault initiation and development mechanisms in cable terminations.

The purpose of this research is to study how wheel radius affects the Electric Motorbike's performance. Based on mathematical models and the MATLAB SIMULINK software, an electric motorcycle simulation model, including a dynamic model and a battery model, was created to achieve this goal. The simulation model is used to determine the speed, thrust torque, and power consumption characteristics with changing wheel radius. The simulation results show that when changing the wheel radius from 0.1 m to 0.25 m, the maximum speed increases from 23 to 52 km/h, the travel distance increases from 400 to 850 m after 60 seconds of simulation time, and the battery voltage decreases from 59.9 to 57.7 V while the engine power consumption increases.