Justification of the double fed induction generator model for estimation of the influence of wind power installations on the operation mode of power systems

Mathematical modeling of wind power plants is an urgent task, since the degree of their introduction into traditional energy systems is growing every year. At the same time, it is not always possible to obtain information about the processes in the power system. In such cases, it is possible to use the model of the power system. However, since the power systems are enormous, their model is also great, and therefore, with its detailed reproduction, many problems arise. One solution to such problem is to use simplified wind turbine models. The article substantiates the need to use detailed models of wind turbines to analyze their impact on the functioning of the power system

Analysis of the Influence of Wind Turbines on the Power Line Protection Operation

In the article an experimental power system consisting of Russian equipment, as well as 220 kV power line distance protection, are simulated in the RTDS Simulator. The settings were calculated and the polygonal characteristics of distance protection were constructed. A sequential installation of wind turbines into various nodes of the power system was carried out and the correct operation of the protection was verified. As a result of the study, the influence of wind turbines on the distance protection when they are connected between the protection installation site and the point of the short circuit is revealed. The analysis of this influence is made. Possible ways to solve the identified problems are proposed, such as the use of adaptive distance protection, as well as numerous studies of the behavior of wind turbines in various operating modes for further analysis and possible adjustment of guidelines for relay protection using new algorithms for calculating and configuring of distance protection. The results of this work can be used to improve and clarify the recommendations for tuning, produced by manufacturers of relay protection devices, which currently do not take into account the influence of wind turbines

Analysis of the Influence of Wind Turbines on the Power Line Protection Operation

In the article an experimental power system consisting of Russian equipment, as well as 220 kV power line distance protection, are simulated in the RTDS Simulator. The settings were calculated and the polygonal characteristics of distance protection were constructed. A sequential installation of wind turbines into various nodes of the power system was carried out and the correct operation of the protection was verified. As a result of the study, the influence of wind turbines on the distance protection when they are connected between the protection installation site and the point of the short circuit is revealed. The analysis of this influence is made. Possible ways to solve the identified problems are proposed, such as the use of adaptive distance protection, as well as numerous studies of the behavior of wind turbines in various operating modes for further analysis and possible adjustment of guidelines for relay protection using new algorithms for calculating and configuring of distance protection. The results of this work can be used to improve and clarify the recommendations for tuning, produced by manufacturers of relay protection devices, which currently do not take into account the influence of wind turbines

Validation of positive-sequence modeling of large-disturbance stability in a distribution network with distributed generation using the hybrid comprehensive simulator

One of the general trends in power industry is the penetration of distributed generation (DG) units. The ongoing transformation of electric power systems (EPS) due to this penetration leads to a significant change in the properties of power systems. The problem arises in the ensuring stability of distribution system with DG units and EPS as a whole, especially in the case of large disturbances. The main way of solving this problem is positive-sequence phasor time-domain simulation. However, the known simplifications and limitations are inevitably applied at such simulation. In this regard, the obtained simulation results need to be validated. This paper proposes an alternative approach for validation of processes calculations, based on the use of a benchmark tool instead of field data. The hybrid simulator is proposed to use as a benchmark tool, because such simulator allow to obtain comprehensive information about a single spectrum of wave, electromagnetic, electromechanical processes in power system in cases of different large disturbances. That makes possible to identify the impact of the applied simplifications and limitations in the positive-sequence simulation on the reliability of power system stability assessment in the case of large disturbances. The studies presented in this paper were carried out using the scheme of distribution system with DG units, which is part of a real EPS. The obtained results demonstrate the arising errors in stability calculations, the nature of their changing and causes of occurrence, as well as factors affecting them

Assessment of wind power generation impact on the distance protection operation

In the article an experimental power system consisting of Russian equipment, as well as 220 kV power line distance protection, are simulated in the RTDS Simulator. The settings were calculated and the polygonal characteristics of distance protection were constructed. A sequential installation of wind turbines into various nodes of the power system was carried out and the correct operation of the protection was verified. As a result of the study, the impact of wind turbines on the distance protection when they are connected between the protection installation site and the point of the short circuit is revealed. The analysis of this impact is made. Possible ways to solve the identified problems are proposed, such as the use of adaptive distance protection, as well as numerous studies of the behaviour of wind turbines in various operating modes for further analysis and possible adjustment of guidelines for relay protection using new algorithms for calculating and configuring of distance protection. The results of this work can be used to improve and clarify the recommendations for tuning, produced by manufacturers of relay protection devices, which currently do not take into account the impact of wind power generation

Stochastic Modeling of a DFIG Wind Turbine in Matpower

One of the main trends in the electric power industry is the use of green energy – renewable energy sources (RES), especially wind power generation. The penetration of large wind turbine (WT) power capacity leads to changes in the topology and characteristics of electric power systems (EPS), which can cause an increase the likelihood of emergency processes and a decrease in the steady-state and transient EPS stability. The issue arises in ensuring the EPS stability with RES units, especially in the case of large disturbances. The main way to solve this issue is mathematical modeling. However, almost all the main currently used software programs are based on deterministic methods for calculating EPS processes, which are not able to consider all possible state uncertainties. To reliably determine all possible states of the system in which it can be, it is necessary to determine in a non-deterministic form how the values in the nodes and branches will be distributed. The peculiarity of this paper is associated with the use of a set of approaches to increase the accuracy of the results obtained: the approximation method in combination with two goodness-of-fit criteria for wind; the SIBD method, which generates the required probability density without loss of density values; and the controlled discretization of input variables. This paper assumes the formation of a WT stochastic model to study the impact of RES on stability in a non-deterministic form using the example of IEEE standard bus systems in the Matpower program

Comprehensive validation of transient stability calculations in electric power systems and hardware-software tool for its implementation

Reliability and survivability of electric power systems (EPS) depend on transient stability assessment (TSA). One of the most effective way to TSA is time-domain simulation. However, large-scale EPS mathematical model contains a stiff nonlinear system of high-order differential equations. Such system cannot be solved analytically. At the same time, numerical methods are imperfectly applied for such system due to limitation conditions. To make it appropriate, the EPS mathematical model is simplified and additional limitations are used. These simplifications and limitations reduce reliability of simulation results. Consequently, their validation is needed. The most reliable approach to provide it is to compare the simulation results with the field data. However, in practice, there are not enough data for such validation. This paper proposes an alternative approach for validation - the application of a reference model instead of field data. A hardware-software system HRTSim was used as a reference model. This power system simulator has all the necessary properties and capabilities to obtain reliable information required for comprehensive validation of transient stability calculations in EPSs. Main disturbances leading to instability in EPSs are investigated to conduct the validation (processes in cases of faults, single-phase auto-reclosing operation and power system interconnection). Fragments of corresponding experimental studies illustrate the efficiency of the proposed approach. Obtained results confirmed the possibility of the developed approach to identify the causes of numerical calculation errors and to determine disturbances calculated with the significant error. In addition, experimental studies have revealed that numerical calculations error depends on disturbances intensity

Research, Development and Application of Hybrid Model of Back-to-Back HVDC Link

Recent hybrid simulators (or co-simulators) of the electric power system are focused on scientific and research features to propose and develop novel and more accurate simulators. The present paper demonstrates one more hybrid modelling approach based on application and combination of three modeling approaches all together: physical, analog and digital. The primary focus of the proposed approach is to develop the simulation tool ensuring such vital characteristics as three-phase simulation and modeling of a single spectrum of processes in electric power system, without separation of the electromagnetic and electromechanical transient stages. Moreover, unlimited scalability of the electric power system model and real-time simulation to ensure the opportunity of data exchange with external devices have been considered. The description of the development of the hybrid model of back-to-back HVDC link based on the proposed approach is discussed and analyzed. To confirm properties of the mentioned hybrid simulation approach and hybrid model of back-to-back HVDC link, the simulation results of the interconnection of non-synchronously operating parts of the electric power system; power flow regulation; dynamic response to external fault and damping of power oscillation in electric power system are presented and examined. Moreover, to confirm the adequacy of the obtained results, the comparison with a detailed voltage source converter HVDC model (Simulink Matlab) and Eurostag software are introduced

Application of hybrid hardware-software simulator for automatic voltage regulators setting

Today mathematical simulation is practically sole method, with no alternative, for obtaining comprehensive and reliable information about regimes and processes in electrical power systems. This is due to the impossibility of making field tests in real EPS, and significant limits of physical models. Therefore, according to official standards and regulatory documents of JSC “SO UPS”, the development of the hardware-software simulators for real-time power system simulation with the purpose of automatic voltage regulators setting and certification is the most urgent issue. This paper proposes the Hybrid Real-Time Power System Simulator usage as the solution. The performed studies and tests (partially demonstrated in the article) show the possibility of such simulator usage for the stated aims

Wind Power Plants Influence on Out-Of-Step Operation Mode Parameters of the Power System

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