Saturation factors and T'do in WECC/NERC generator model validation

This chapter presents the calculation results of model (type XT) parameters of a synchronous generator (PN = 44 kW) operating in the laboratory obtained with the use of the measured waveforms after introducing a PRBS disturbance in the generator voltage regulation channel. Determination of model parameters of synchronous generators operating in power plants is also presented. Sample calculations of mathematical model parameters of synchronous generators were made on the basis of dynamic waveforms recorded at the Pątnow Power Plant (PN = 230 MW—GENROU model) and Halemba Combined Heat and Power Plant (PN = 50 MW—RL models, GENROU model). Determination of parameters of the excitation system models is described in the further part of this chapter. Sample calculations of mathematical model parameters of the excitation systems operating in the Polish PS were carried out based on the dynamic waveforms recorded in the Pątnow Power Plant (electromachine excitation system model) and Skawina Power Plant (static excitation system model). Conclusions drawn from the calculations of the synchronous generator and excitation circuit model parameters as well as some comments on the errors of parameter estimation of the generating unit element models are given at the end of the chapter.

Summary This paper presents the implementation of the International Electrotechnical Commission (IEC) generic Type 1A wind turbine generator (WTG) model in Power Factory (PF) and the validation of the implemented model against field measurements. The IEC generic Type 1A WTG model structure is briefly described. The details are explained regarding how the two mass mechanical model is implemented when the generator mass is included in the PF built-in generator model. In order to verify the IEC generic Type 1A WTG model, the model to field measurement validation method was employed. The model to field measurement validation of the implemented model was carried out by using the “play-back” approach and the measurement data from Siemens Wind Power. The results of the model to field measurement validation show that there is a good match between the simulation results and the measurements. The errors between the simulation results and measurements were calculated according to the voltage dip windows and the index definition specified in the IEC 61400-27-1 committee draft. Copyright © 2014 John Wiley & Sons, Ltd.

New requirements for the validation of simulation models based on measurements in many grid codes show that existing generic approaches for generator and converter models of doubly fed generator systems (DFG) may not be accurate enough. The authors show that by applying a detailed analysis of the generator equations and the converter control design, a reduction of the model complexity is possible while maintaining a high level of accuracy. The generator model presented in this paper allows an improved representation of the stationary and dynamic response of wind turbines equipped with DFG systems especially during grid faults and during voltage recovery. The model is designed to represent modern DFG systems independently of vendor specific hardware and software. The results of simulations are compared to measurements of a voltage dip involving wind turbines. The generator model has been proposed as extension to the WECC/IEEE generator models and has been accepted as reference for IEC TC88 working group 27 (standard IEC 61400-27-1) on modeling and model validation of wind turbines.

Load-side Voltage Compensation of Small Hydropower Grid-connected System Using DVR based on PV Source

The paper presents the two-dimensional, field-circuit model of a high power synchronous generator verified by measurements. The model enables determining the waveforms of electromagnetic quantities in steady and transient states. Verification of the model was based on comparison of the measured and calculated waveforms after a disturbance in the voltage regulation system of a TWW-200-2 generator operating in Połaniec Power Plant. There are also presented the field methods for determining electromagnetic parameters (synchronous reactances and time constants) when using the distributions of static and quasi-static, magnetic and electromagnetic fields calculated by the finite element method (FEM). The set of these parameters was used as the starting parameters of the optimization algorithm for estimation of electromagnetic parameters of the synchronous generator circuit model. The dynamic waveforms under the generator load conditions calculated by the finite element method are the basis of parameter estimation. The parameter estimation of the generator model was performed with the use of the least squares method.

Phasor measurement units (PMUs) performance changes among instrument models and the data delivered to the applications may vary widely in quality. To date, there is not a clear understanding of how problems that develop in the data process path may affect the performance of synchrophasor applications. To assess the severity of these problems, we need a simulation platform capable of modeling the entire data process. The basic idea is to model and to simulate PMU measurements in presence of dynamic events in the electrical network, for then to study application's performance when different kinds of impairments are applied to the input signal. These impairments could include uncompensated effects from transformers, A/D converters, errors in the PMU estimation algorithms, problems with the communication channels, etc. The construction of such an experimental platform is under way at the National Institute of Standards and Technology (NIST). In particular, in this work, we have designed and used this open source simulator to evaluate applications to perform modal analysis, state estimation, and generator model validation. For each application, different estimation techniques were tested: Prony's method, least squares and the extended Kalman filter, respectively. Finally, we analyze these results and we elaborate on the appropriateness of the requirements imposed by the present PMU standards.

Parameter estimation of a synchronous generator model under unbalanced operating conditions

In this paper a real-time short-circuit calculation method for large-scale distribution systems with a high penetration of distributed generators is proposed. Recent years have witnessed increasing penetration of distributed generators. Thus, distribution systems have become active, where the fault current flow is no more straightforward. Additionally, modern distributed generator's models differ from the classical synchronous generator's models. Hence, traditional short-circuit calculation methods are not applicable in today's systems. The proposed method is based on the superposition theorem. An improved back/forward sweep in the sequence domain is used for calculation of the faulted system state. Results show that the proposed method is highly accurate and particularly suitable for real-time applications in large-scale systems, where the calculation time is of critical interest.

Multisite calibration & validation of model reduces the uncertainty present in the model parameters and improve the SWAT model output. In the present study, an effort was made to set up SWAT model along with multisite calibration and validation for Kishna upper basin of India. A total of six gauging stations maintained by Central water commission across the area were selected for SWAT model calibration and validation. Sequential Uncertainty Fitting (SUFI-2) programme of SWAT-CUP (Calibration and Uncertainty Programme) was employed to calibrate the SWAT model. During sensitivity analysis of SWAT model, parameters which are highly sensitive that influences flow characteristics of different gauging station were identified. These parameters along with parameter range were used to calibration and validation of SWAT model each of the sub basins. Observed flow and predicted stream flows were compared with certain model performance indices. These indices indicated that for all six gauging stations, the SWAT model found to be very good. The performance indices like R2, NSE, RSR and PBIAS were ranged from 0.70 to 0.84, 0.67 to 0.76, 0.49 to 0.57 and -11.7 to 24.0% respectively during model calibration period and 0.70 to 0.93, 0.67 to 0.83, 0.41 to 0.58 and 8.5 to 22.9% respectively during model validation period. A good agreement between observed and simulated flows at all the gauging stations were observed. It can be concluded that SWAT model output was improved with multisite calibration and validation of the model.

Results of transient response tests on synchronous generators are presented along with derivations of generator model parameters from data.

The simulation model of synchronous generator has an important role in power system simulation. The correct values of parameters of the various generator models in different simulation tools are even more important. The methods of parameters transformation of synchronous generator model (with excitation system) in BPA and PSCAD are discussed in this paper. If the parameters of the same model are transferred correctly between different simulation software, the steady-state and dynamic characteristics should be consistent. Simulation results show the transformation presented in this paper is practical.

The paper presents a method for determining electromagnetic parameters of different synchronous generator models based on dynamic waveforms measured at power rejection. Such a test can be performed safely under normal operating conditions of a generator working in a power plant. A generator model was investigated, expressed by reactances and time constants of steady, transient, and subtransient state in the d and q axes, as well as the circuit models (type (3,3) and (2,2)) expressed by resistances and inductances of stator, excitation, and equivalent rotor damping circuits windings. All these models approximately take into account the influence of magnetic core saturation. The least squares method was used for parameter estimation. There was minimized the objective function defined as the mean square error between the measured waveforms and the waveforms calculated based on the mathematical models. A method of determining the initial values of those state variables which also depend on the searched parameters is presented. To minimize the objective function, a gradient optimization algorithm finding local minima for a selected starting point was used. To get closer to the global minimum, calculations were repeated many times, taking into account the inequality constraints for the searched parameters. The paper presents the parameter estimation results and a comparison of the waveforms measured and calculated based on the final parameters for 200 MW and 50 MW turbogenerators.

Because of the significant changes in environmental policies and electric power deregulation in the last decade, a lot of photovoltaic generations (PV) have been and will be installed into the power system in Japan and the ratio of PVs to other synchronous generators will be increased. As a countermeasure against the decrease in the rotational inertia in the whole power system, a virtual synchronous generator (VSG) model control of the PV has so far been proposed. However, the system stabilization effect of the VSG in large-scale power systems has been unclear. In this paper, a virtual step-out blocking method of VSG for improving the transient stability is proposed. In addition, the necessity of governor control of VSG in a large-scale power system is discussed. Finally, the rated kw and kwh capacities of the battery required for realizing the VSG-model control are evaluated.

This paper presents a new asymmetrical model of synchronous generators for power system transient stability simulations. The symmetrical component method has been used traditionally in the analysis of unbalanced faults in power systems. This is mainly because the synchronous generators, which play an important role in the power system, can be easily treated by the method. However, when analyzing a system that has elements with asymmetrical impedance, it may not be easy to use the symmetrical component method. In such cases, the simulations can be easily executed by using the phase coordinate method. However, there are few papers that derive a phase coordinate model of synchronous machines. This paper analyzes synchronous generators under asymmetrical conditions in detail by using the symmetrical component method, then derives a model of synchronous generators for the phase coordinate method. © 1997 Scripta Technica, Inc. Electr Eng Jpn 119(2): 46–59, 1997

This paper presents two pieces of method about how to improve performance of surfaced-inserted permanent magnet synchronous generator (PMSG). One way is increasing q-axle's synchronous inductance appropriately, this way can reduce voltage regulation rate which is an important point that let permanent magnet synchronous generator can be used widely. The other way is using skewed slot to reduce cogging torque, this can reduce axle's mechanical damage. This paper uses finite element method to build permanent magnet synchronous generator's model and result of calculation shows that the method above can improve permanent magnet synchronous generators' performance exactly.