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Frequency control is one of the most important tasks in electric power systems. At the same time, in modern power systems with inertia-free converter-interfaced generation, this task has become more complex. Such an issue is especially relevant for microgrids, which are characterized by a significant increase in the rate of change of frequency and its nadir or zenith. An effective way is through the use of energy storage systems (ESSs) with a grid-forming control in microgrids. For this purpose, this paper proposes a novel structure of the control algorithm based on a current-control virtual synchronous generator (CC-VSG), in which the damping is performed using a feedforward controller. In addition, a simple proportional–integral controller is added to the CC-VSG structure to control the state of charge of the ESS. The performed frequency analysis proves the independence of the different control loop operations within the developed CC-VSG. At the same time, a methodology based on the bandwidth separation of different control loops is proposed for the CC-VSG tuning, which allows for the achievement of the desired quality of frequency regulation in the microgrid, taking into account both the energy recovery and the permissible frequency variation. Finally, the time-domain simulation using PSCAD/EMTDC is performed to confirm the obtained results. [ABSTRACT FROM AUTHOR]

Gasoline engines are characterized by high power density and low fuel efficiency. Diesels, on the contrary, have high fuel efficiency, but low specific power. A promising (unified) workflow should combine the best qualities of gasoline engines and diesel engines and work on the entire existing range of fuels produced for them. This will make it possible to switch to a single unified fuel, including fractions of modern commercial fuels, which will significantly reduce the energy intensity and cost of their production.

In modern converter-dominated power systems, total inertia is very variable and depends on the share of power generated by renewable-based converter-interfaced generation (CIG) at each specific moment. As a result, the limits required by the grid codes on the rate of change of frequency and its nadir or zenith during disturbances become challenging to achieve with conventional control approaches. Therefore, the transition to a novel control strategy of CIG with a grid-forming power converter is relevant. For this purpose, a control algorithm based on a virtual synchronous generator (VSG) is used, which simulates the properties and capabilities of a conventional synchronous generation. However, due to continuously changing operating conditions in converter-dominated power systems, the virtual inertia formed by VSG must be adaptive. At the same time, the efficiency of adaptive algorithms strongly depends on the used VSG structure. In this connection, this paper proposes an enhanced VSG structure for which the transfer function of the active power control loop was formed. With the help of it, the advantages over the conventional VSG structure were proven, which are necessary for the effective adaptive control of the VSG parameters. Then, the analysis of the impact of the VSG parameters on the dynamic response using the transient characteristics in the time domain was performed. Based on the results obtained, adaptive algorithms for independent control of the virtual inertia and the parameters of the VSG damper winding were developed. The performed mathematical modeling confirmed the reliable and effective operation of the developed adaptive control algorithms and the enhanced VSG structure. The theoretical and experimental results obtained in this paper indicate the need for simultaneous development and improvement of both adaptive control algorithms and VSG structures used for this purpose. [ABSTRACT FROM AUTHOR]

This paper presents the analysis of application Hybrid Real-Time Power System Simulator (HRTSim), developed at National Research Tomsk Polytechnic University, as a device for setting and certification of automatic voltage regulators (AVR) for synchronous generators. The simulation results demonstrate that the proposed hardware-software complex (HSC) can be used for presented aim.

The dominant trend of the modern energy is the use of generating plants based on renewable energy sources, among which the most common is a wind power plant based on doubly fed induction generator (Type 3 WT). The large-scale introduction of Type 3 WT into the modern power systems significantly changes their dynamic properties. There are problems with ensuring the basic condition of the reliability and the survivability of power systems – the stability. The study and solution of the indicated problems is possible only with the help of the mathematical modeling of a large-scale power systems which is currently being carried out with the help of widespread purely numerical software tools of calculations of modes and processes, which are characterized by various simplifications and limitations. For the properties and capabilities of software tools for studying stability issues, mathematical models of Type 3 WT, the so-called generic models, which also have simplifications and limitations, are adapted. In this article, the reliability of stability calculations of a real power system with Type 3 WT using software tools was evaluated, which allows to identify the influence of the applied simplifications and restrictions with a purely numerical approach on the quality of solving problems of assessing the stability of power systems with Type 3 WT. Also, the studies made it possible to identify the areas of the application of generic models of Type 3 WT as a part of the model of the real dimension power system, at which the greatest and least errors arise, as well as their causes. Such a comprehensive assessment becomes feasible due to the alternative approach proposed in the article, based on the use of a detail benchmark tool model instead of the full-scale data to compare the results of modeling. [ABSTRACT FROM AUTHOR]

In article the analysis of substation electric part for the enterprises an oil and gas complex power supply is carried out: structure and switchgear schemes, uninterrupted reserve sources structure. Recommendations for power supply reliability are made.

This study aims to propose an alternative hybrid approach to model renewable energy sources (RESs), which provide the most reliable results in comparison with the existing simulating tools. Within the framework of this approach, a specialized hybrid processor for modeling converter-interfaced generation (CIG) is developed. This study describes its structure and validation in the test system by comparing the results with commercial modeling tools, and also presents experimental studies of its operation as parts of the practical power system. The results obtained confirm the adequacy of the developed tools. [ABSTRACT FROM AUTHOR]

The transience and unpredictability of processes in electric power systems (EPS) determine complexity of its control. This problem is especially relevant for EPS with renewable energy sources and flexible alternating current transmission systems technologies. Automatic control systems simplify the solution of this problem. Despite this, many issues related to EPS state control are solved by power system operators. Decision support systems (DSS) are applying to increase efficiency of operators work. However, existing algorithms in practice are inoperable in some cases: unrealizable decisions are formed, or decision cannot be found at all, etc. Another important problem is impossibility to preliminarily verify the proposed solution. In this regard, operators can additionally use EPS simulators, which are usually limited either by the size of simulated scheme or by the details of equipment mathematical models. The limitations are a consequence of numerical methods using, which are badly applicable for large-scale power systems simulation. In this article, a novel DSS has been developed based on a hybrid approach to EPS modeling combining properties and capabilities of several simulation techniques: analog, physical and digital. The implicit integration of differential equations in analog way makes possible modeling faster than real time. Such opportunity allows operator to verify more decisions and select the most effective ones. The algorithm for DSS application has been developed and described in the article. The properties and capabilities of the developed DSS are confirmed by experimental studies and tests in a real EPS. [ABSTRACT FROM AUTHOR]

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

One of the problems associated with the integration of renewable energy sources is reducing the total inertia of the electric power system. By substituting the traditional synchronous generators to wind turbines connected to a network via power electronics devices the system the inertia constant is sharply reduced. In addition, the inertia of the system changes over time due to the wind turbine power change. Systems with lower inertia in the serious faults incident loses its stability easier. The question of the reduction of energy system inertia influence on the out-of-step mode parameters is not answered yet. Authors created a grid test model using software-hardware hybrid simulation tool HRTSim. The several experiments to determine the influence of type 4 wind turbine on the parameters of the out-of-step mode is realized. The oscillograms confirming the influence of the wind turbine on the parameters of the out-of-step mode are obtained. Problems of the influence of changes in the inertia of the power system during the integration of type 4 wind turbines on the parameters of the out-of-step mode are considered. The international experience in this field is analysed. The results of the analysis confirmed the insufficient study of this field and the almost complete lack of information about this in the grid codes of foreign countries. The experiments confirmed the theoretical expectation: the higher inertia induction stroke starts later, and the frequency slip is decreased. [ABSTRACT FROM AUTHOR]

Due to increasing complexity of power systems the task of ensuring adequate operation of relay protection becomes more urgent. Detailed mathematical models of relay protection together with modern power system simulators are proposed to be used as a solution of this problem. At the same time, the adequate simulation of instrumental transformers, in particular the magnetization process of the core, is very important because the waveform of signals controlled by relay protection largely determined by transducers' errors. The developed mathematical model of current transformer reproducing the magnetic hysteresis in accordance with the Preisach theory is presented in the paper. Unlike other similar models, the Preisach' particle distribution function in the developed model is based not on the reference typical magnetizing curves, but on the volt–ampere characteristic of current transformer. This approach is better applicable in practice, since typical magnetization curves are not always available and become less relevant during transformer operation. There are presented the results of impact assessment of different types and values of burden on current transformer operation and comparison of the implemented model with existing methods of magnetization and hysteresis modeling. The adequate behavior of the developed model has been confirmed by the research. [ABSTRACT FROM AUTHOR]

Currently, an issue of relay protection (RP) settings determination that ensures its correct operation in electric power systems (EPSs) has not been resolved completely. The main reason for this is the lack of methods and tools for adequate consideration of transients during a fault existence for RP settings calculation. In this study, a novel approach for RP settings determination is presented. Its main feature is the application of detailed mathematical models reproducing simultaneously processes in the entire set of elements in the RP scheme, including instrumental transformers, and in large-scale EPS mathematical model as a whole. This key feature can be achieved via the hybrid power system simulator -- hybrid real-time power system simulator -- implementing a methodically accurate analogue--digital solution of the EPS mathematical model. The numerical transformer differential protection (NTDP) based on this approach was set up via the standard dual-slope tripping characteristic. Also, a novel approach to the formation of the tripping characteristic is proposed. The key feature of this approach is applying a flexible curve that enveloping all fault characteristics Idiff = f(Irest) of those modes in which the NTDP should not trip. [ABSTRACT FROM AUTHOR]

Summary: Reliability and efficiency of electric power systems (EPS) operation depend on the adequacy of information about quasi‐state and transient processes in EPS used for their research, design, and operation. A value of short‐circuit currents (SCC), especially their maximum values, is one of the important information used for different tasks. The difficulty of obtaining this information is the need to use a large‐scale EPS mathematical model for SCC calculation. The total mathematical model of any large‐scale EPS is a stiff and nonlinear system of differential equations of high order. Such system cannot be solved analytically. Satisfactory solution is also impossible by using the numerical approach that leads to the need for applying simplifications and limitations reducing the adequacy of simulation results. Therefore, each solution should be validated. The comparison of simulation results with the field data is the most reliable way of validation. However, the acceptable amount of field data cannot be obtained in the foreseeable future in view of the obvious variety of EPS modes, especially emergency ones. An alternative way of validation is suggested in the paper: the using of an adequate reference model instead of field data. The experimental sample of hybrid real‐time power system simulator having the necessary properties and capabilities is used as the reference model. The indicated possibility of SCC calculation validation is proved by the experimental studies shown in the paper. [ABSTRACT FROM AUTHOR]

Currently, the world is widely introducing renewable energy sources including solar power plants (SPP). In order to predict their work, it is necessary to adequately simulate the processes occurring in solar panels, not only in standard conditions, but also in conditions of partial shading. At present, the effect of partial shadowing is considered from the point of view of changes in the luminous flux, however, for a more adequate and comprehensive simulation, it is also necessary to take into account the temperature change in the shaded areas of SPP, especially considering the area of powerful SPP, the temperature of individual sections of which can radically differ, which is undoubtedly will lead to a change in the output characteristics of the SPP. Failure to take this factor into account, when modeling high-power SPP leads to results that do not correspond to real data. [ABSTRACT FROM AUTHOR]

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Nowadays in the world a lot of attention is paid to the integration of renewable energy sources, especially wind power plants, into existing electric power systems. However, the modern simulation tools usage based on numerical integration for studying and assessment of renewables impact on transient processes in EPS is always associated with different simplifications and limitations. In this regard, the authors suggest the Hybrid Real-Time Power System Simulator (HRTSim) usage for comprehensive and accurate simulation of large-scale EPS with RES. The results of the synthesis of the wind turbine mathematical model as a part of the specialized module for the HRTSim are presented in the paper. The developed means are intended to solve the issue of this hardware-software simulator upgrade for comprehensive and adequate modelling of wind power generation facilities. [ABSTRACT FROM AUTHOR]

Currently, the number of distributed generation (DG) objects in the world is growing mainly due to renewable energy sources (RES). However, the integration of a large volume of DG based on RES into existing electric power systems (EPS) is associated with a number of significant problems. For a comprehensive study and solution of these problems, it is necessary to carry out detailed simulation of real EPS, which is not always feasible with the help of existing tools. Therefore, the article proposes the use of an alternative solution – the Hybrid Real-Time Power System Simulator (HRTSim). To confirm the properties and capabilities of the HRTSim, the simulation results of a test scheme obtained using the HRTSim and the widely used digital hardware-software complex RTDS were compared. The results of a comprehensive comparison in both complexes confirmed the adequacy of information about the processes in equipment and EPS as a whole, obtained by the HRTSim. Thus, it is proved that further use the HRTSim as a tool for detailed and adequate simulation of real EPS with DG will provide complete and reliable information about normal and abnormal quasi-steady-state and transient processes, which is necessary for reliable and efficient design, research and subsequent operation of EPS with DG. [ABSTRACT FROM AUTHOR]

The electric power system elements are designed to transmit electricity to consumers. To ensure the transmission, in the design and construction of the power system provide for increased cross-section of lines, throughputs of transformers, cost for other procedures. To find the magnitude of the increase, it is necessary to determine the maximum power flow through the element. This is important for the digital substation operation, where all actions are subordinated to the automation elements, and the ability to control power flows, through the electrical equipment management, has the primary task. This solution is not absolutely effective, since it's not known how much the measures are related to the accident probability. It's needed to know where the maximum power consumption can appear. Therefore, it is necessary to determine in a non-deterministic form how the available power plants power is distributed over the grid to ensure power supply. The main problem is that obtaining the probabilistic characteristics of the parameters by standard statistical methods has no practical solution. In this regard, the method of selection of interval boundaries of input and output data (SIBD) is proposed, and its application for obtaining probabilistic characteristics of electrical quantities and their imbalances. [ABSTRACT FROM AUTHOR]

Electric power systems are becoming more complex. This is due to the widespread use of renewable energy sources (RES) and FACTS devices. At the same time, protection devices for equipment and automation of power systems are becoming subject to influence from new devices. The article pays attention to the study of such influence from the side of RES and FACTS devices on the operation of one of the most important automation systems ensuring the stable operation of the power system - out-of-step protection (OSP). At the first stage of the project, the main reasons for the difficulty of setting up resistance control devices of OSP in networks with FACTS devices and RES were identified, which are related to the fact that the parameters of these devices vary depending on the operation mode, therefore, the zone of the OSP resistance relay should also be changed. Based on the analysis, a new approach to the study of the functioning of OSP in power systems with FACTS devices and RES has been developed. The performed experimental studies confirm the theoretical research. [ABSTRACT FROM AUTHOR]

This paper is devoted to the description of a new approach for large-scale electric power systems (EPS) simulation, so-called hybrid simulation approach. The design and research of EPS require solving a large number of non-trivial tasks. Due to the well-known EPS specificity, mathematical modeling is the only way to proceed. According to the hybrid approach, several simulation techniques (analogue, digital, and physical) are used to achieve the best results. An analogue part provides the elimination of methodological integration error, which appears in a case of numerical methods usage. A digital part allows the realization of control and parameter changing algorithms on software level. In a physical part, the connection and switching of modeled elements are provided in a way as in real EPS. In addition, the paper presents hardware features of the simulator—hybrid real-time power system simulator (HRTSim), which is an alternative to the digital simulators currently used. The important part of this paper is the result of comparative analysis of transient processes oscillograms obtained by HRTSim and real disturbance recorders in Tomsk region power system, as well as HRTSim and real-time digital simulator. [ABSTRACT FROM AUTHOR]

The article presents the Hybrid Real-Time Dispatcher Training Simulator (HRTDTS). The main advantages of this simulator are the adequate simulation of a single spectrum of processes in the object for training – any real electric power system (EPS), as well as the real-time control of the equipment circuit-mode states in modes of the EPS operation. This is achieved by the HRTDTS development within the concept of hybrid simulation, which allows to surpass the modern widely-used simulators based purely on numerical simulation, which do not comprehensively reproduce processes in the EPS and limit the training of certain dispatchers skills. The dispatcher simulator structure and the developed specialized HRTDTS software are demonstrated. The developed dynamic dashboards for monitoring and operating, implementing the circuit-mode states visualization of the equipment or the EPS districts that correspond to specific objects for training, are presented. The special panels that display extended information about the processes in the EPS are also shown in the article. The comparison of simulation results with the data, obtained via RTDS, for the HRTDTS validation was carried out. The practical emergency scenario for the training of dispatching personnel, including the assignment of an emergency situation and the actions of dispatchers to eliminate it, was created for testing and demonstration of the HRTDTS capabilities. [ABSTRACT FROM AUTHOR]

The introduction of modern technologies significantly changes the modes of operation of electric power systems (EPS) and has an unpredictable impact on the functioning of relay protection devices (RP), in particular distance protection (DP). It is impossible to adequately measured the impact without detailed modelling of both EPS and RP devices. The subject of this research is the development of a detailed mathematical model of digital distance protection (DDP). When designing such a model, both current and voltage measuring transducers, analogue digital relay protection devices, and digital signal processing were taken into account. In this paper, studies are aimed at assessing the correctness of the third stage of the DP using the detailed and simplified model of the DDP. The operation of the compared models is tested on a 39-bus New England system via MATLAB Simulink simulation data, and a comparative assessment is provided. Such detailed DDP mathematical model in combination with an adequate EPS simulator could be used further for solution of different tasks, such as development, design, analysis, testing and setting of RP algorithms. The article presents the results of preliminary studies of the mentioned problem. [ABSTRACT FROM AUTHOR]