Simulation Of Electric Power Systems Research Articles

Ambient Signals based Load Modeling with Two Three-phase Induction Motors

Abstract The traditional electric power system simulation and calculation are based on the simple load model including one motor and one static load. On the one hand, the power system load is getting more and more complex. On the other hand, it’s proved that two kinds of three-phase induction motors will show a little difference. As a result, in this paper, a new model load with two three-phase induction motors is proposed. Besides, the dynamic of the power system load is taken into account. The torque of those two three-phase motors will show different characteristics, that one is constant and the other is variable. Formerly, the dynamic of the load is regarded as the result of an induction motor. However, the single-phase motor and electronic load both lead to the complexity of the load. To get a more accurate calculation, we need a more proper load model. One of the ways to improve the load model is to pay more attention to the ingredients ignored. The single-phase motor and power electronic load make a great difference. Besides, it’s proved that the composited load model with two three-phase motors will be better in the calculation.

Modeling of electromagnetic influences of multi-wire traction networks for pipelines

In this work, digital models for determining the electromagnetic influences of multi-wire traction networks on pipelines are developed. When developing models, an approach based on multiphase behaviour simulation of electric power systems was used. This approach adequately addresses all the influencing factors, which include modules and phases of currents flowing through the overhead contact wire suspension, 6–10–25 kV power transmission lines laid on the supports of the overhead line, and lines of rails. In addition, it is possible to take into account similar parameters for stresses at the nodal points of a multi-wire system. Among the key factors are the railway clearance when laying pipes parallel to the railway track, railway clearance trajectory in the presence of non-parallel sections, and the electrical characteristics of the soil along the clearance route. The research results demonstrated that a 25 kV electromagnetically unbalanced traction network exerts significant influence on a pipeline running in parallel. It was shown that the maximum induced voltages at specific points along the pipe fall within the range of 300–700 V, which significantly exceeds the permissible level of 60 V. It was revealed that currents exceeding 20 A flowing through the pipe can have an adverse effect on anticorrosive protection devices. To mitigate electromagnetic impacts on the pipeline, the following measures are recommended: reducing the length of pipeline and railway clearance sections, increasing the gap between the traction network and the pipe, and installing an additional grounding source. The pipe can be connected to the supplementary grounding source through filters tuned to a frequency of 50 Hz, which involve capacitor units to prevent malfunctions during the operation of pipeline protection devices. Thus, the developed digital models allow the induced voltages generated by multi-wire traction networks and the currents flowing through the pipes to be adequately determined. These models offer an informed choice of measures that ensure the safety of pipeline maintenance.

Research on the judging method of the T-connected transmission line fault branch

When the T-connected transmission line fails, there is a certain relationship between the phases of the three-terminal power frequency fault current, which can be applied to protect the current differential of the T-connected line. In this paper, using the MATLAB/Simulink electric power system simulation software, when the T-connected transmission line is faulty, the power frequency fault current variation law monitored at the installation point is deeply studied, and the judgment method of the T-connected transmission line fault branch based on the power frequency current is proposed.

Artificial Neural Network PV Performance Prediction and Electric Power System Simulation of a Ship-tracking CubeSat

Artificial Neural Network PV Performance Prediction and Electric Power System Simulation of a Ship-tracking CubeSat

Simulation of an Autonomous DC Electric Power System with Solid-State Transformers

The trends and reasons that stimulate the transition of electric power systems to direct current are considered. The weight, size, energy, and other advantages associated with such transition are shown. A model of an autonomous DC power system constructed on the basis of a gas turbine, high-speed asynchronous generator, and solid-state power transformers is presented, which confirms the operability and feasibility of such system. The results of simulating the start-up of a gas turbine unit, self-excitation of a high-speed asynchronous generator, connection of cable power lines, rheostatic limitation of DC solid-state transformer starting currents, and load surge are presented. A system for automatically stabilizing the voltage at the power line beginning is considered, which is performed by adjusting the gas turbine rotational frequency under the influence of voltage and current feedbacks. A system for stabilizing the load voltage by using a PWM-controlled inverter, which is an integral part of a solid-state DC transformer, is presented.

Modelling and Simulation of All-Electric Machines and Renewable Electric Power Systems in Agricultural Operations

Modelling and Simulation of All-Electric Machines and Renewable Electric Power Systems in Agricultural Operations

Research on Energy Management Strategy of Vehicle Fuel Cell-Battery Hybrid Energy System Based on GT-SUIT/Simulink

Aiming at a fuel cell electric vehicle, this paper establishes a fuel cell electric vehicle power system simulation platform based on GT-SUIT and Simulink, and proposes a rule-based energy management control strategy. Under the selected European Driving Cycle (NEDC), the simulation results show that the control strategy can effectively distribute energy between the fuel cell and the battery, and meet the power demand of the vehicle. The SOC of the battery is always kept in a reasonable range.

Review and analysis of investment decision making algorithms in long-term agent-based electric power system simulation models

Long-term electric power system planning models are frequently used to provide policy support in the context of the ongoing transition towards a low-carbon electric power system. In a liberalized market, this transition relies on generation company investment decisions. These decisions are shaped by both economic and behavioral factors. Agent-based modeling allows the incorporation of both these factors in the description of the investment decision making process. Nevertheless, there are several challenges associated with the design of agent-based models such as the definition of the model structure and its lack of transparency. In this study, we aim to increase the transparency of investment decision making algorithms by shedding light on how implicit assumptions of the price projection methods used in these algorithms impact model results. To achieve this goal, we developed a core long-term agent-based model to assess different investment decision making algorithms from the literature and we introduced a novel price projection method based on optimization modeling. Our results show that investment decisions vary enormously depending on the assumptions and parameters used in investment decision making algorithms. We also found that our proposed price projection method is robust to parametric deviations. Thus, the proposed investment decision making algorithm enables agent-based modelers to mitigate the potential impacts of hidden implicit assumptions.

A Technique of Calculation of the Dynamic Mode in Computer Simulations of Electric Power Systems with an Arbitrary Configuration

The algorithmic implementation of calculations of the dynamic mode during computer simulation of electric power systems with arbitrary topology has been considered. This is more easily done when the electric circuit graph is used in full form (when just one circuit element can be placed at one branch) despite its redundancy. In this case, the graph branches can be connected with the elements of an electric circuit. Mathematical models of elements, which are based on the differential equations in the Park–Gorev axes rotating along with the rotor of a synchronous generator, allow one to eliminate variable coefficients in most differential equations of elements. In the computer simulations, the method of calculations based on the equations for nodal voltages is used. An algorithm to create conductivity and current matrices according to the technique of element-to-element contribution is given. The algorithm to determine an inverse matrix in the equation for nodal voltages is based on the Jordan–Gauss method. To calculate the dynamic mode, it is suggested to use the fourth-order Runge–Kutta method, which allows one to obtain a relatively accurate solution using information at just one previous point. In the view of the development of information technologies, the considered approach allows one both to automated separate stages of design, calculations, and analysis of operation of the electric power system and to take into account the correlation between all the stages of life cycle of the electrotechnical equipment starting with the design stage and ending with equipment decommissioning.

The novel approach for electric power system simulation tools validation

The reliability and efficiency of electric power system (EPS) operation depends on the adequacy of the information about processes in the EPS. The complexity of obtaining this information lies in the need to use large-scale EPS mathematical model for calculations. Within the framework of numerical integration, a satisfactory solution of such model is hardly to be ensured; consequently, the simplifications and limitations are applied. In this regard, every obtained solution should be validated. The most reliable way of validation is to compare simulation results with field data. However, it is not always possible to receive the necessary amount of field data. The paper proposes an alternative approach for validation: the adequate reference model (RM) usage instead of field data. The prototype of hybrid real-time power system simulator having the necessary properties and capabilities is used as the RM in this paper. The adequacy of proposed approach is illustrated by the fragments of the experimental studies.

A new real-time multi-agent system for under frequency load shedding in a smart grid context

Automatic under frequency load shedding schemes need to be carefully designed in order to reduce the risk of widespread system collapse. This paper proposes a centralized hierarchical multi-agent system that coordinates various stages of monitoring and decision making processes. The main contribution is to improve traditional contingency response algorithms such as load shedding schemes, taking advantage of the future smart grid infrastructure. The multi-agent system seeks for a minimum amount of load disconnection in a short period of time, causing the least possible disturbance in the system frequency. A hardware-in-the-loop simulation of a full electric power system using a real time digital simulator was utilized. The solution was embedded in a real time system, consisting of hardware and software, to test and validate the proposed methodology. In addition, the studied methodology was compared with two other load shedding philosophies through a load shedding metric score. Shedding was carried out in a single step and the amount of disconnected load was close to the dynamic power unbalance. The results show that it is possible to improve the traditional load shedding philosophy schemes and use advanced communication infrastructure, monitoring and embedded processing capabilities to provide better stability and reduce unnecessary load disconnections from the system.

The hybrid model of VSC HVDC

The trend in semiconductor developments has made the high-voltage direct current (HVDC) technologies based on voltage source converters feasible. This type of convertor has a number of potential advantages compared with “classic” HVDC, but deep analysis should be carried out before its integration in electric power system. In this paper, the results of realization of the VSC HVDC model based on a concept of hybrid simulation of electric power system are presented. Hybrid concept combines three approaches of simulation: analog, digital and physical, combination of which allows to achieve a maximum efficiency. The obtained simulation results have confirmed an adequacy of the model and possibility to integrate it to the hybrid real-time simulator for carrying out various researches and analyses of the operation of large electric power system, including HVDC technologies, in real time without any decompositions and limitations.

Simulation of Complex Electric Power Systems

Iron birds of power facilities allow solving various functional tasks. The interaction with the hardware of these simulation benches relies on the computer model of an electric power system (EPS). This article considers the main aspects of computer-aided simulation of complex electric power systems. The dynamic mode calculation is presented as a sequential calculation of static modes at each sampling interval. The developed mathematical model of the system consists of mathematical models of its elements and a model of their interaction. The models of the elements are differential equation systems in the (d, q) frame of reference. The algorithms for calculating dynamic and static modes actively use the T-list and allow performing these computations in an optimal manner. The developed software has an expandable and flexible graphical shell. Java programming allows doing without integrative modules for full-scale and half-sized models and ensures high performance and the fulfillment of the cross-platformity requirement. The module for mathematically simulating electric power systems can be used not only as part of subsystems for testing gas turbine power plants, but also for other functional tasks of half-sized sectional simulation of electric power systems.

Development Of Software–Hardware System for Real Time Simulation of Electric Power System with Smart Grids

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Behavioural modelling and power quality simulation of a HVDC electric power system for MEA

High-voltage direct current (HVDC) electric power system (EPS) is a promising architecture for more electric aircraft (MEA). With more electric power used, a higher voltage is necessary to make aircrafts more efficient and less weighted. However, there are no standards can be followed to evaluate the power quality of HVDC EPS, especially for 540 VDC system. In this study, a potential HVDC EPS is proposed and power quality is studied by simulation. Behavioural models of the system are established in detail from source to load. Three kinds of typical loads of MEA are defined and their impacts on power quality are analysed including resistances, power electronic converters, and motors. Some suggestions are provided for design and integration of the EPS for MEA.

Necessity and Targets of Future Electric Power System Simulation and Integration Studies for Realizing Higher Variable Renewable Energy Deployment and Lower CO2-Emission Society

Necessity and Targets of Future Electric Power System Simulation and Integration Studies for Realizing Higher Variable Renewable Energy Deployment and Lower CO2-Emission Society

On computation of the transformation coefficient in the computer simulation of electric-power systems of arbitrary configurations

We consider the possibility of computing the transient processes in an electric-power system of an arbitrary topology according to an algorithm taking into account the transformation coefficients of the transformers contained in the system under investigation. This problem arises when computing the dynamic modes since the structure of an electric-power system may be different at different time points. The key problem of calculating an electric-power system of an arbitrary configuration is the use in the system of elements such as transformers as the voltage levels in a part of the system are not known in advance. The problem can be solved by matching the transformer tree, which affects the voltage level of the branch for every branch of the scheme. This method is similar to the method of matching the trees of the key to every branch. When forming the matrices of the nodal conductances and driving currents, a topological list based on the principle of the element-by-element contribution is used. The main advantages of the method based on the topological list are that it does not require observation of the order of the line numeration and its high algorithmic level, which ensures minimization of the computational effort required for computerized derivation of the equations. To determine the transformation coefficient for a branch, it is necessary to pass into the depth on any of the arms of the transformer tree to the last leaf cell, subquentially multiplying the transformation coefficients of the enumerated transfomers. The complete transformer tree can be used to verify that the transformers are correctly connected to the circuit. From the point of view of trends in the development of information technologies, the approach in question allows not only automation of individual subject phases of the design, but also consideration of simulation of the interaction of electrical equipment in an electric-power system, generation of systems of scheduling, economic planning, determination of risks of equipment failure, etc.

A computer emergency trainer for dispatchers of the united power system of Ukraine

The purpose of this work is forming structure of emergency trainer for dispatchers of the IPS of Ukraine. The research method is computer simulation of electric power systems. The trainer structure is developed using dynamics calculations after big disturbances using software AVR-74 and virtual structures to display post emergency EPS modes using full-scale mode simulator PORT. Operation of the developed trainer has been demonstrated for an example of dispatcher training on the theme «Balancing mode of the IPS of Ukraine after wearing-out of emergency automatics in case of line disconnecting in the IPS cross section West-Vinnitsa». As an information model, is used the test-based model of the West-Vinnitsa section (54 bases, 72 branches, 18 generators), in which the electric network of 750 kV and 330 kV of the South-Western EPS and its connections with adjacent regional power systems are presented. Electric mode of the IPS of Ukraine is isolated from the UPS of Russia. The calculations of the stability at the cross section of West-Vinnitsa for planning the regime of winter maximum load showed the need for automatic unloading of the Rivne nuclear power plant (RNPP), which, in the case of switching off power transmission line 330 kV Shepetovka-Zhytomyr, turns off the units 1,2 RNPP. The current frequency in the post emergency mode after wearing-out of emergency automatics is the 49.88 H. It requires action to restore the normal frequency level. Consistent steps to increase the frequency are: loading Dnipro-1 hydro power plant (HPP) up to a maximum capacity of 600 MW, loading Kremenchug HPP at 150 MW, loading two units of Trypilsky power plant up to 630 MW. As a result, the frequency is set to 49.92 Hz.Computer emergency trainer for dispatchers provides:formation of the calculation model of the UPS with the use of information about retrospective regimes from the archive of the software KOSMOS;calculations of normal, repair, weighted and self-aligned on frequency and voltage of post-emergency stationary electric modes of the IPS;verification of static and dynamic stability of the UPS taking into account the automatic regulators of excitation of synchronous generators, automatic regulators of turbine speed and hydro units of power stations, system anti-emergency automatics;calculations of long transient processes after a sudden disturbance of the balance of active power of the IPS, taking into account the effect of frequency unloading automation and automation of limiting the increase of the frequency of current;execution of calculations of cascading accidents in a given scenario;issuance of operative information about the mode of IPS to remote monitors of the simulator, which is carried out by means of a full-function mode simulator PORT.Ref. 3, fig. 7.

SAInt – A novel quasi-dynamic model for assessing security of supply in coupled gas and electricity transmission networks

The integration of renewable energy sources into existing electric power systems is connected with an increased interdependence between natural gas and electricity transmission networks. To analyse this interdependence and its impact on security of supply, we developed a novel quasi-dynamic simulation model and implemented it into the simulation tool SAInt (Scenario Analysis Interface for Energy Systems), the first published software application that allows the combined simulation of gas and electric power systems in a single time frame and simulation environment. The model is composed of a transient hydraulic simulation model for the gas system and an augmented AC-Optimal Power Flow model for the electric power system, which includes a model for dispatchable power system loads and considers time transitional constraints, such as the ramp rate and the start-up time of generation units. Both models take into account the control and constraints of the most relevant facilities present in both systems. The bidirectional interconnection between both systems is considered and established by coupling equations describing the fuel gas offtake for power generation in gas fired power plants, and the electric power supply to LNG terminals and electric driven compressors in gas compressor stations. The resulting system of equations for the combined model are solved in a single simulation time frame. In order to quantify the impact of different contingencies on the operation of the combined system, a number of security of supply parameters are proposed, which can be utilised to compare the impact of different contingencies on security of supply and the effectiveness of countermeasures to mitigate this impact. The capabilities of the combined model and the functionality of the simulation tool SAInt are demonstrated in a case study of a sample gas and power transmission system. Results indicate how the combined simulation of gas and electric power systems can give insight into important and critical information, such as the timing and propagation of contingencies cascading from one system to the other or the grace period to react to these contingencies. Such information can contribute to improving the coordination between gas and power transmission system operators in the event of a disruption, thus, increasing the resilience and the level of security of supply in the combined energy system. The information provided by the combined model cannot be obtained by the traditional co-simulation approach, where both systems are solved in different time frames. Furthermore, the studies stress the importance of using transient gas simulation models for security of supply analysis instead of steady state models, where the time evolution of gas pressure and linepack are not reflected appropriately.

Проблема верификации средств моделирования электроэнергетических систем и концепция ее решения

Проблема верификации средств моделирования электроэнергетических систем и концепция ее решения