Digital Simulation System Research Articles

Improvement and Dynamic Simulation Test of the Power Electronic Device Applied to Phase Sequence Exchange Technology

Phase sequence exchange (PSE) is a recently developed emergency control technology. PSE uses power electronic devices to switch the three-phase sequence, which reduces the power angle of the generator by 120° and prevents the system from losing stability. In this work, the structure of the PSE device is improved. Based on the original nine solid-state circuit breakers (SSCBs), three mechanical circuit breakers (MCBs) are added. Normally, the current flows through the MCBs, which greatly reduces the conduction loss of the PSE device. Once the generator is identified as being out-of-step, the MCBs quickly open to transfer the current to the SSCBs. When the power angle threshold of the PSE is reached, the SSCBs are switched to complete PSE. In this article, the transient characteristics of the current transfer and PSE processes are analyzed. Based on the real time digital simulation system (RTDS) platform, dynamic simulation tests of the improved PSE prototype are carried out under different conditions. Experiments and calculations demonstrate that the improved PSE device can meet the technical requirements of PSE, and that the conduction power loss is reduced by 96% on average.

Modelling and Performance Analysis of Grid Connected PMSG Based Tidal Generation System

Globally, most national grid relies on fossil fuel with consequent economic burdens, environmental pollution and global warming. Hence, Tidal energy possesses the capacity to mitigate the emission of carbon dioxide because it is clean, abundant, less expensive and predictable. However, the power output from Tidal energy generation system (TEGS) fluctuates due to changes in tidal flow whereby causing power instability. This work is geared at fundamentally model, simulate and control TEGS since it encounters problems such as harmonics, frequency fluctuations and voltage sags. These problems are resolved using a nonlinear controller coupled with a high-speed simulation of circuit-oriented electrical and digital electronic systems. The generator power output is optimised by utilising various control methods as proposed to control the voltage and frequency which is a Voltage Oriented Control technique that relies on high level performance 𝑑𝑞‐coordinate controllers. The system simulation is implemented in the MATLAB/Simulink environment. The current controller and DC‐link voltage controller are designed using Internal Model Control method. The simulation results show the system performance in response to the load and dc‐bus voltage step changes while directly running a Simulink model as a controller. The performance and validity of the preferable control method is verified by the simulation results and corresponds to available literature. The simulated results show that the controller can stabilise the constant dc-link voltage under dynamic and steady-state performance of the system.

Design of Simulation for Time-Division Multiplexing Digital Optimal Frequency Band Transmission System

This paper designs a simulation experiment model of the overall structure of time-division multiplexing digital optimal frequency band transmission system based on MATLAB simulation platform. The parameters of each module in the simulation model are set. The working process and performance of the time-division multiplexing digital optimal band transmission system are simulated. The simulation results show that the digital optimal band transmission system achieves the best transmission receiving conditions and performance, and the designed time-division multiplexing optimal digital band transmission simulation system achieves its functions. The research in this paper will help to improve the level of digital communication technology and to understand the structure of time-division multiplexing digital optimal band transmission system.

Visual interfaces for the digital simulation system of the IPR-R1 Triga nuclear research reactor

Nuclear Technology Development Center (CDTN) offers the Training Course for Research Reactor Operator (Ctorp). This course is offered since 1974 and about 250 nuclear professionals were certificated by CDTN. Thus, a digital simulation system for the IPR-R1 Triga research reactor was developed to be a tool for teaching, training and recycling professionals. The simulator was developed using the LabVIEW® (Laboratory Virtual Instruments Engineering Workbench), with support calculation software, where mathematical models and graphical interface configurations form a friendly platform, which allows the trainee to be identified with the physical systems of the research reactor. A simplified modeling of the main physical phenomena related to the operation of the reactor and the reactivity control systems, reactor cooling and reactor protection was used. The digital simulator allows an HMI (Human-Machine Interaction) by manipulating system variables and monitoring trends in quantities during the operation of the reactor, showing an interactive tool for teaching, training and recycling for professionals in the IPR-R1 Triga nuclear research, allowing simulations of the start, power and stop operations. This paper presents the design and results of the user visual interfaces developed for the reactor operation simulator. This is the equivalent part of structured text programming and, therefore, the most significant part of the developed simulator.

Standardization of digital technologies of simulator systems as a method of ensuring reliability of conditions of service of power engineering facilities (part 3)

The article deals with the issues of creating standardized digital simulator systems, in order to ensure reliable service conditions of electric power facilities. The article presents the reasons which prevented all simulator designers in power engineering from ensuring efficient functional properties of simulation systems for operator training. The primary problem was the lack of methods and procedures for developing the simulator’s core subsystem – a mathematical model of a power facility, because the existing standards, norms and technical requirements were only concerned with the structure and functional properties of simulator subsystems. These reasons and circumstances determine the current state of the Russian simulator production; its negative trends are covered in depth in this article. There is also a critical assessment of simulators designed by some of the Russian engineers: these machines are not conducive to improving the quality of training and retraining of operating personnel of power companies. The article identifies the concept of a physical-statistical approach to developing a power facility simulation model: it includes preparing an analytical description of the physical processes at the simulation object, adapted to real processes, taking into account real-time sample observation, collecting and analyzing statistical procedure data, adjusting the model structure and assessing the parameters and states of the facility model. This approach concept defines the main aspect of modern methodology for setting and achieving all goals related to the energy facility modeling for simulator construction. Western sanctions and import substitution requirements dictate the necessity of developing home-grown technology, manufacturing and introducing new equipment in power engineering, including the sphere of simulator production. The designers of Russian simulators should understand that the principles and technical rules of power equipment imported from Western countries, including automatic control systems for such equipment, are different from the ones which the Unified Power System of Russia is based on. It is emphasized that, in real operating conditions of Russian power facilities, reliability of operation, maintenance and repair personnel is essential. It is noted that, in order to improve this reliability, it is necessary to develop a new regulatory document which would fully explore its topic: ensuring consistent and efficient methods for developing the structure and functions of digital technological systems for training power facility personnel.

Efficient container virtualization-based digital twin simulation of smart industrial systems

The great potential of digital twin (DT) in supporting smart industrial systems has brought huge requirements for on-demand DT-based simulation, a particularly useful and sustainable means, to assist various decision-making. However, there are major challenges to efficiently build and update the DT-based simulation system and provide simulation as a service (SimaaS): 1) virtualization machine based heavyweight methods to create simulation environments for DT models consume too much resource and time; 2) DT-based simulation systems in the cloud or developers’ desktops could not well support the real-time response and synchronize with the physical counterparts at the edge of the network. Therefore, a methodology of container virtualization based simulation as a service (CVSimaaS) is put forward to utilize lightweight containers to realize convenient DT system deployment and less resource consumption with high efficiency. Then a device-edge-cloud system architecture with a formal process are proposed to support the CVSimaaS paradigm. A matrix based management and scheduling model for computing infrastructure, container images and services is established to support the efficient CVSimaaS process. Finally, the methodology is applied to building a DT-based simulation system for intelligent manufacturing. The results show that the DT-based simulation system can be 1) easily deployed to heterogeneous infrastructure and terminals at the cloud, edge and device, and 2) parallelly scheduled and operated on high performance cloud/edge on demand for large-scale online analysis.

Iterative Methods for Solving Systems of Multi-Valued Logical Equations in the Simulation of Object Control Digital Systems

The article is devoted to the analysis of methods for solving systems of multivalued logical equations by iteration methods. Iterative methods for solving such systems of equations are a mathematical description of the main process of functional-logical simulation, which is used at the stage of designing digital systems for objects control to verify the correctness of the design. Consideration of multi-valued values of logical signals at the outputs of blocks and elements of digital systems is explained by the fact that in some cases, to analyze the correctness of time relationships when simulating the hardware of digital systems, a several valued representation of logical signals is used, as well as that recently, logical elements are being developed that implement four or more valued logic. Based on the analysis of the structure of the system of logical equations used in digital hardware simulation, using graph and logical models, an analysis is made of the existence of solutions and their number. Iterative methods of a simple and generalized iteration are analyzed, a relationship is shown between the number of solutions of the system of equations and its graph representation, which reflects a given circuit of connecting elements of the hardware of a digital control system. For the generalized iteration method, options with a different structure of the iteration trace are considered, in particular, it is shown that, with a certain structure of the iteration trace, the generalized iteration turns into a simple iteration or Seidel iteration. It is shown that the generalized iteration most adequately describes the process of simulating the switching of logical signals in a simulated circuit of digital control systems hardware. The correspondence between various options of functional-logical simulation of digital systems and the used methods of iterative solution of systems of logical equations is shown.

Variational quantum simulation of ultrastrong light-matter coupling

We propose the simulation of quantum-optical systems in the ultrastrong-coupling regime using a variational quantum algorithm. More precisely, we introduce a short-depth variational form to prepare the groundstate of the multimode Dicke model on a quantum processor and present proof-of-principle results obtained via cloud access to an IBM device. We moreover provide an algorithm for characterizing the groundstate by Wigner state tomography. Our work is a first step towards digital quantum simulation of quantum-optical systems with potential applications to the spin-boson, Kondo and Jahn-Teller models.

Deep Belief Net-Based Fault Diagnosis of Flight Control System Sensors

The present study implements a model based on the deep belief net (DBN) into the sensor fault diagnosis of the flight control system. The principle of DBN system identification was adopted to simulate and establish a nonlinear observer of the unmanned aerial vehicle (UAV) for the online estimation of sensors’ output, which identified the fault type by analyzing the residuals of estimated data and the actual output. After the fault detection is completed, the measured value of the faulty sensor is isolated and replaced by the observer-generated value, in order to ensure the UAV normal flight. The proposed DBN model uses the data of normal flight control system sensors as training samples for offline training. A flight control digital simulation system was established to select the optimal DBN model via comparative test runs. Eventually, the common faults of sensors were analyzed and diagnosed online. The results obtained strongly indicate that the proposed method ensures a rapid and accurate diagnostics and isolation of faults, as well as provides a proper signal reconstruction.

Design and Analysis on an Optimized Interface Algorithm for Real-Time Integrated Simulation System of Renewable Energy and the Power Grid

The interface algorithm is critical for accuracy of the real-time integration simulation system of renewable energy and the power grid. To improve the overall performance of the existing interface algorithms, this paper proposes an optimized interface algorithm based on the auxiliary damping impedance method interface current feedback. We explain in detail the implementation principle of the new interface algorithm and the calculation method of impedance matching and also provide a parallel timing control logic. Using the new interface algorithm, we derive equations for voltage and current of the digital simulation system side and the device under test side and also compare it with the naturally coupled system without interface delay. Finally, we verify the accuracy of the new interface algorithm via establishing a complete model of the real-time integration simulation system with a wind turbine and the power grid. The results show that the accuracy can be improved 95% in the digital simulation system side and 17% in the device under test side by using the proposed interface algorithm in this paper.

Hierarchy of Linear Light Cones with Long-Range Interactions

In quantum many-body systems with local interactions, quantum information and entanglement cannot spread outside of a linear light cone, which expands at an emergent velocity analogous to the speed of light. Local operations at sufficiently separated spacetime points approximately commute -- given a many-body state, $\mathcal{O}_x(t) \mathcal{O}_y |\psi\rangle \approx \mathcal{O}_y\mathcal{O}_x(t) |\psi\rangle$ with arbitrarily small errors -- so long as $|x-y|\gtrsim vt$, where $v$ is finite. Yet most non-relativistic physical systems realized in nature have long-range interactions: two degrees of freedom separated by a distance $r$ interact with potential energy $V(r) \propto 1/r^{\alpha}$. In systems with long-range interactions, we rigorously establish a hierarchy of linear light cones: at the same $\alpha$, some quantum information processing tasks are constrained by a linear light cone while others are not. In one spatial dimension, this linear light cone exists for every many-body state when $\alpha>3$ (Lieb-Robinson light cone); for a typical state chosen uniformly at random from the Hilbert space when $\alpha>\frac{5}{2}$ (Frobenius light cone); for every state of a non-interacting system when $\alpha>2$ (free light cone). These bounds apply to time-dependent systems and are optimal up to subalgebraic improvements. Our theorems regarding the Lieb-Robinson and free light cones -- and their tightness -- also generalize to arbitrary dimensions. We discuss the implications of our bounds on the growth of connected correlators and of topological order, the clustering of correlations in gapped systems, and the digital simulation of systems with long-range interactions. In addition, we show that universal quantum state transfer, as well as many-body quantum chaos, are bounded by the Frobenius light cone, and therefore are poorly constrained by all Lieb-Robinson bounds.

Resource-efficient digital quantum simulation of d-level systems for photonic, vibrational, and spin-s Hamiltonians

Simulation of quantum systems is expected to be one of the most important applications of quantum computing, with much of the theoretical work so far having focused on fermionic and spin-frac{1}{2} systems. Here, we instead consider encodings of d-level (i.e., qudit) quantum operators into multi-qubit operators, studying resource requirements for approximating operator exponentials by Trotterization. We primarily focus on spin-s and truncated bosonic operators in second quantization, observing desirable properties for approaches based on the Gray code, which to our knowledge has not been used in this context previously. After outlining a methodology for implementing an arbitrary encoding, we investigate the interplay between Hamming distances, sparsity patterns, bosonic truncation, and other properties of local operators. Finally, we obtain resource counts for five common Hamiltonian classes used in physics and chemistry, while modeling the possibility of converting between encodings within a Trotter step. The most efficient encoding choice is heavily dependent on the application and highly sensitive to d, although clear trends are present. These operation count reductions are relevant for running algorithms on near-term quantum hardware because the savings effectively decrease the required circuit depth. Results and procedures outlined in this work may be useful for simulating a broad class of Hamiltonians on qubit-based digital quantum computers.

Generic characterization of electrical test benches for AC- and HVDC-connected wind power plants

Abstract. The electrical test and assessment of wind turbines go hand in hand with standards and network connection requirements. In this paper, the generic structure of advanced electrical test benches, including grid emulator or controllable grid interface, wind torque emulator, and device under test, is proposed to harmonize state-of-the-art test sites. On the other hand, modern wind turbines are under development towards new features, concerning grid-forming, black-start, and frequency support capabilities as well as harmonic stability and control interaction considerations, to secure the robustness and stability of renewable-energy-based power systems. Therefore, it is necessary to develop new and revised test standards and methodologies to address the new features of wind turbines. This paper proposes a generic test structure within two main groups, including open-loop and closed-loop tests. The open-loop tests include the IEC 61400-21-1 standard tests as well as the additional proposed test options for the new capabilities of wind turbines, which replicate grid connection compliance tests using open-loop references for the grid emulator. In addition, the closed-loop tests evaluate the device under test as part of a virtual wind power plant and perform real-time simulations considering the grid dynamics. The closed-loop tests concern grid connection topologies consisting of AC and HVDC, as well as different electrical characteristics, including impedance, short-circuit ratio, inertia, and background harmonics. The proposed tests can be implemented using available advanced test benches by adjusting their control systems. The characteristics of a real power system can be emulated by a grid emulator coupled with real-time digital simulator systems through a high-bandwidth power-hardware-in-the-loop interface.

Standardization of digital technologies of simulator systems as a method of ensuring reliability of conditions of service of power engineering facilities (part 2)

Issues are considered of normalization of digital training simulator systems to ensure the reliability of conditions for maintenance of electric power industry facilities. The reasons are identified of impossibility of achievement of the basic purpose of the first and subsequent standard documents, namely the unity of the structure and functions of engineering systems and means for training of personnel of power enterprises, power systems and associations. It is shown that the question - problem - hypothesis - analytical model - imitation model gnoseological chain defines both the structure and the essence of modern methodology of systemic imitation simulation of power facilities. At the same time, the most important modern methodological prerequisites for modeling are the probabilistic- statistical approach and multi-criteria optimization. Issues of analytical simulation, systemic concept, simulation in destabilization conditions, as well as systemic paradoxes of facility simulation are described in sufficient detail. The basic principles of systemic approach to construction of an all-mode real-time model, levels of its detailing and models of objects of control applied in practice are stated. At the same time, a great attention is paid to the physical-statistical approach to identification of simulation models, their verification and validation. A modern scientific classification of models, principles of their simplification is stated. On the basis of the stipulated positions it is stated that the approach to construction of an all-mode real-time model consists in separation of static and dynamic simulation functions with directional asymmetry of accuracy of separated functions. To generalize the aforesaid, an obvious conclusion is drawn that the previously adopted standards only defined requirements to a finished product and its subsystems, whereas the questions of methodology of working out a model and its digital (program) implementation were not considered at all. It therefore appears necessary to develop a new normative methodological document, in which the possibility of disclosing the purpose of its development should be provided, namely: assuring the unity of the methodology of development of the structure and functions of digital technological systems for training the personnel of power industry enterprises.

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.

Working Load Characteristics of the PDC-Cone Composite Bit under Impact and Scraping

The PDC-roller hybrid bit combines the cutting structure of a tricone bit with a PDC bit. It can achieve good results, breaking rock in directional drilling, drilling in inhomogeneous formations, and drilling in formations with high levels of hardness, and it can achieve the engineering goals of increasing speed and efficiency. First, we analyzed the rock-breaking mechanism of the composite bit and the principles of cushioning, torsion reduction, and prebreaking of the cone teeth during the breaking of rock. Second, cutting load models of the cone teeth and PDC teeth were established through unit experiments and through the calculation methods of the axial force, lateral force and torque, and lateral bending moment of the composite bit. Third, the digital simulation and analysis system was improved to include the function of calculating the working load of the composite bit. Taking an 8-1/2 inch, 2 + 4 type composite bit as an example, the working load characteristics of three cutting structures (cone, blade, and composite) were analyzed and compared. The analysis shows that the composite bit has high drilling efficiency, obvious deviation advantages, and good working stability under specific formation conditions. This paper provides technical support for the performance analysis, formation adaptability evaluation, and cutting structure design optimization of the PDC-cone bit.

A structurally integrated water environmental modeling system based on dual object structure.

The GIS-based water quantity and water quality model is widely used to provide decision-making supports for water resource and water quality management. However, the existing integration patterns of GIS and model system mainly depend on data communication between themselves which may lead to low operating efficiency and time-consuming model setup. In this paper, a generalized data structure (dual object structure (DOS)) which can store the data of GIS objects and model objects together is proposed and realized for the first time, avoiding frequent data communication during the period of numerical simulation and result expression, realizing the fusion of GIS objects and model objects at the data structure level, improving the operating efficiency of the system. Finally, the water quantity and water quality modeling software (digital basin simulation system (DBSS)) based on DOS was developed by using C++ language. The software has been applied successfully in large-scale river basins of China, and one of the cases was demonstrated to show the application process and the outstanding results.

Анализ итерационных методов решения систем логических уравнений и их использование при моделировании цифровых систем

Анализ итерационных методов решения систем логических уравнений и их использование при моделировании цифровых систем

An FRTDS Real-Time Simulation Optimized Task Scheduling Algorithm Based on Reinforcement Learning

This paper presents a deep reinforcement learning (DRL)-based task scheduling algorithm that is applied to an FPGA-based real-time digital simulation (FRTDS) system to generate arrangements to minimize the makespan of a task sequence with limited resources. The algorithm has two parts, which are synthetic cost construction and DRL processing to make arrangements. The synthetic cost represents the cost of different selections of arrangements in both resource usage and blockage arranging probability. This study uses the cost to measure the state-action value function to process the deep Q network (DQN) procedure to generate an optimized scheduling strategy. We establish the reinforcement learning strategy generation process by instantiating the computing components in the hardware as agents, and RAM resources and communication I/O ports as environment. A hardware-design-based decision rule is constructed to ensure that the computing variables are distributed as evenly as possible in storage, while making full use of the pipeline characteristics of FPGA. A compiler is written to generate an FRTDS binary stream to drive FRTDS. Accuracy and performance of the proposed method are verified and evaluated. We present simulation results of the modeling method, as well as from a classic method. Comparing these results, the makespan obtained by the proposed method is significantly shorter. It corresponds to the possibility of having higher computing power and dealing with larger-scale real-time simulation.

5G Communication Based Distributed Fault Recovery Scheme of Active Distribution Network

As more and more distributed power sources are connected to low and medium voltage distribution networks, the traditional single-ended passive distribution networks have evolved into multi- terminal, multi-source active distribution networks. When distributed generations with high permeability are connected to a distribution network, the structure and power flow of this network will change significantly, thus the original fault detection method and reclosing scheme may be challenged, which may cause incorrect action of protection or failure of reclosing. On basis of that, this paper proposes an active distribution network fault recovery scheme based on 5G wireless communication, in which the topology recognition technology and smart terminal units with peer-to-peer communication capability are applied. To prove the method’s feasibility, delay of 5G communication is analysed and tested online. In addition, a model of 10 kV active distribution network is built on Real Time Digital Simulation system. Principle investigation and simulation indicate that the proposed scheme can adapt to the change of network structure and implement the fault self-healing quickly.