About Evaluation of Complex Dynamical Systems

Telerobot system plays an important role in executing task under hazard environment. As the computer networks such as the Internet are being used as the communication channel of telerobot systems, varying time delay causes the overall system unstable and reduces the performance of transparency. In this paper, we propose twelve operation modes with different control schemes for telerobot on the Internet with time delay. And an optimal operation mode with control scheme is specified for telerobot with time delay, based on the tradeoff between passivity and transparency properties. We experimentally confirm the validity of the proposed optimal mode and control scheme by using a simple one DOF master-slave manipulator system.

Modern power systems are developing rapidly, with distributed energy, energy storage devices, adjustable loads, and other flexible resources consolidated through microgrids, virtual power plants, and integrated source–network–load–storage systems. This consolidation under various balancing zone models facilitates synergistic operations and has become critical to enhancing distributed power consumption and ensuring the reliability of electricity supply. Therefore, in light of the challenges of inadequate economic efficiency, reduced accommodation of renewable energy, and poorer operational reliability in distribution networks, this study proposes a category selection and flexibility resource scheduling method that considers the differences in multiple balancing zone models and modes. Firstly, the approach establishes a multi-dimensional characteristic evaluation index and multiple balancing zone operation models. The characteristic evaluation indicators are then utilized to assess the unique properties of the balancing zone system and eliminate unreasonable operating modes. Finally, through analyzing the effectiveness and differences of various balancing zone operation modes, an optimal operation mode is selected, and a scheduling plan is formulated. We conclude that the scheduling plan optimization method considering the operation mode can realize a reasonable choice of operation modes and achieve benefit optimization.

Optimization of Power Management Strategy for Parallel Air-Fuel Hybrid System

In this paper, numerical simulation methods are used to study issues related to the optimal operating modes of hyperspeed (rotor velocity 1000 m/s and above) model gas centrifuges (GCs) of various lengths and velocities of rotation. The possibility of gas extraction under optimal conditions is studied using three-dimensional modeling. It is shown that for hyperspeed GCs with the Pitot tube as gas extractor, simultaneous attainment of the optimal values for both friction power and waste flux, which are necessary for achieving the optimal operating mode, is unattainable, unlike GC models with a rotor velocity of 600 m/s. It is also shown that the working gas within the shockwave generated by the gas extractor can attain temperatures exceeding 1300 K, which raises the question of a possible accelerated decomposition of uranium hexafluoride.

The article compiled and solved a system of differential equations of motion of a material point along a porous (air-permeable) surface, which is inclined at an angle to the horizon. Based on the analysis of solutions to this system of differential equations, it is proposed to change the speed of grain movement by the frequency of oscillations of the support surface, the angle of inclination of the support surface to the horizon and the coefficient of friction. Also, the graphical dependences of the speed of grain movement on the angle of inclination of the support surface to the horizon, the coefficient of friction and the frequency of oscillations were obtained. The possibility of decelerating the vibration movement of grain by an air flow, which is fed from the bottom of the porous support surface against (at an angle) the direction of grain movement, as well as using an asymmetrically corrugated support surface with vertical perforations, is theoretically substantiated. A linear regression dependence of the change in the vibration displacement speed has been experimentally determined, which makes it possible to form the required speed mode of vibration displacement of grain by changing the parameters: the inclination of the vibrating plane is 50 ÷ 90, the vibration frequency is 45 ÷ 55 s-1, the air flow speed is 0.1 ÷ 2 m/s in optimal operating modes. installations for high-intensity heat treatment of grain with a vibratory conveyor.

This article presents the results of the design of acoustic–magnetic device thermal protection technology based on simulation. The acoustic–magnetic device (AMD) was installed in the heat supply system of a greenhouse complex with a geothermal heat source, developed and patented by the authors of this paper. Simulation was performed to investigate the possibility of maintaining the acoustic transmitter temperature of the acoustic–magnetic device in its operating range. The QuickField Student Edition v 6.4 simulation environment was used for this purpose. Based on the results of the simulation, the optimum thermal mode of the acoustic–magnetic device was developed and implemented. The optimum temporal operating mode of the acoustic–magnetic device is necessary for the optimization of the non-reagent treatment of geothermal water in a heat supply system of a greenhouse complex. It allows for a considerable reduction in the intensity of scale formation in the heat exchanger and equipment of a geothermal heating system. As demonstrated by the simulation thermal modes, the acoustic–magnetic device provides conditions for the work maintenance of the AMD acoustic transmitter at the resonance frequency, reduces the power expenses, and increases the efficiency of the acoustic influence on the scale formed in the heat supply system of a greenhouse complex. The results of the simulation were implemented in the greenhouse complex of JSC “Raduga”. The thermal protection technology was realized by installing two acoustic–magnetic devices and automation systems in the geothermal heating system a greenhouse complex.

The integration of battery energy storage systems (BESS) with renewable energy is a potential solution to address the disadvantages of renewable energy systems, which is irregular and intermittent power. In particular, residential BESS is advancing in numerous countries. The residential BESS connected to the photovoltaic system (PV) can store the PV power in the battery through charging, and supply the PV power, which was stored in the battery, to the load through discharging when there is no PV power. Therefore, the utilization of residential BESS with PV reduces the daily electric power consumption and the electricity bills that households have to charge. However, it is understood that there is no case of installing and using residential BESS in Korea yet. Most residential houses in Korea are apartment houses, and thus residential BESS can be used with balcony PV. This paper presents operation modes of residential BESS with balcony PV for apartment houses. The BESS capacity was estimated by considering the balcony PV capacity, which can be installed in households, and power consumption. The applicability of the residential BESS was analyzed through performance and economics evaluation under current and various conditions. The operation modes of BESS were divided into four types according to PV power supply priority and battery charging source, and a test took place in a demonstration house. The risk of fully discharging the battery has been discovered when PV power is first charged to the battery or when only PV power is charged with the battery. As a result, preferential charging of the battery with PV power and then with PV and grid power was found to be the most optimal operation mode. In addition, additional functions were proposed for residential BESS in apartment households. The results will contribute to effective application of residential BESS with balcony PV in the near future.

The various operation modes of substation automatic source switching over are introduced. Their reliability and loss caused are analyzed. An optimal operation mode which has good reliability and less power loss is proposed. An example is given to show the proposed operation arrangement is effective. (5 pages)

Problems of completing of machine-tractor unit are considered. Its optimal operation mode in specific working conditions is determined with the use of a portable measurement system.

The aim of the work is to develop a universal technique that will make it possible to determine -- both quickly and with high accuracy -- the optimal composition, parameters and operation modes of hybrid energy complexes containing power plants that use renewable energy sources and energy storage systems from the viewpoint of ensuring safe operation and guaranteed electricity and heat supply to isolated consumers and hard-to-reach areas. The article shows the effectiveness of research and development of recommendations on the choice of parameters and operation modes of hybrid energy complexes with a heterogeneous composition of generating plants and a high dependence on natural uncertain factors at all stages of the life cycle using the developed universal digital twin, which was verified on the example of real energy complexes with miscellaneous composition of equipment.

Dynamic Performance of Indoor Environment and Energy Consumption of Air Conditioning System under Intermittent Mode

The choice of a rational electrical mode of existing or newly commissioned electric arc furnaces (EAFs) is a very difficult task for process engineers in view of the influence of external disturbing factors. Based on an electric arc heat-transfer model (EAHTM), a method is proposed, using which the problem of determining the optimal electrical operation mode can be solved with the minimal number of simplifications and assumptions, and with taking into account the specific features of a particular EAF. In solving the problem, the following factors are taken into account: the arc heat transfer conditions in the melting space; the influence of the thermal operation conditions of the electrodes and the arc length on the structure of heat fluxes during the heating by arcs, and the effect the chemical composition of the working medium has on the thermophysical properties of the arc column plasma. The radiation from EAF arcs with taking into account the column temperature profile is calculated using the method of universal arc characteristics based on the solution of a system of nonlinear algebraic equations of the EAHTM column cylindrical model. The arc length calculation is based on the EAHTM structural characteristics method and consists of comparing the arc voltage value calculated using the furnace equivalent circuit equation and the arc voltage calculated using the EAHTM. Knowing the arc length, it is possible to calculate the arc radiation power in the EAF melting space. The choice of an electrical operation mode implies specifying an electrical parameter to be maintained by the controller for a certain period of melting. The value of this parameter (arc current or the EAF phase loop impedance) governs the other electrical parameters of the electric furnace installation, such as arc power, electrical losses, power factors, efficiency, etc. In addition, the correct choice of the electrical operation mode has an influence on other important operational characteristics, such as the specific consumption of electrodes, the duration of the interval between repairs, etc.

The energy storage system can effectively reduce the volatility caused by more and more renewable energy sources in the power grid, improve the utilization rate of renewable energy and the stability of system. In this paper, the optimized operation mode and capacity configuration method of pumped storage station in a renewable energy grid are studied by taking the practical energy storage facility as an example. The pumped storage station is operated under its capacity constraints, and it is divided into the energy storage condition and the power generation condition by positive or negative of the unbalanced power in the grid. On this basis, this paper puts forward the way of the pumped storage station participating in the power grid generation plan: Pumped storage station does not participate in the actual day-ahead power generation plan only plays a reserve role, in the real-time generation plan, the pumped storage station is preferentially called to equilibrium the deviation between day-ahead forecast value and real-time forecast value of equivalent load. The mathematical model of this method and the optimization method are also given. In addition, the capacity of pumped storage station is planned and designed by the method of probability statistics. Finally, through the analysis of the simple system with four elements and single busbar, the feasibility of the optimized operation mode is verified, and the sensitivity of the capacity of the pumped storage station is discussed qualitatively based on the operating cost of the conventional power grid.

We study a long‐term service agreement (LTSA) between an original equipment manufacturer (OEM) of a conventional power generator and a utility firm in the electricity supply chain. The OEM offers the LTSA to the utility firm, which specifies the service fee and the maintenance interval. The utility firm dynamically chooses among different resources (conventional, renewable, or emergency) to meet energy demand. An LTSA contracts on a generator's long‐term production schedule (i.e., the usage time and number of starts). We first characterize that the conventional generator's optimal operating mode (i.e., on or off) follows a two‐threshold policy, which shows a hysteresis phenomenon. Then, the optimal production from different resources can be obtained by minimizing the utility firm's cost of the current period. We prove that the OEM's optimal LTSA design on the maintenance interval and service fee can be solved sequentially, and capture the trade‐off between the service margin and the usage of conventional generator. Our numerical results show that the utility firm starts the conventional generator less often as the maintenance service fee of a start increases and the minimum conventional output decreases. The OEM has incentives to reduce the minimum output to make the conventional generator more flexible, but such improvement may not benefit the utility firm. Finally, increasing renewable penetration leads to more frequent cycling of the conventional generator and less conventional output. With more renewable generation and less conventional and emergency generation, higher renewable penetration reduces the utility firm's cost, the OEM's profit, and the total emission.

Multi-Thermal Recovery Layout for a Sustainable Power and Cooling Production by Biomass-based Multi-generation System: Techno-Economic-Environmental Analysis and ANN-GA Optimization