Influence of saturation on estimated synchronous machine parametersin standstill frequency response tests

In this paper the measurement results of a series of standstill frequency response tests, performed at different magnetization levels, are discussed. For each data set an individual model is estimated, which allows the variation of the different parameters to be seen as a function of the saturation. Further, an estimator is presented which uses the different data sets to estimate one global model, including the field to armature turns ratio. Finally the expected error level of a more traditional saturated synchronous machine model is studied     

On-line evaluation of a round rotor synchronous machine parameterset estimated from standstill time-domain data

This paper presents a method for identifying the best linear circuit model parameters of a three-phase, round rotor synchronous machine. Standstill time-domain test data and the maximum likelihood estimator are used to identify the values for the equivalent circuit models. The estimated models are validated against standstill data and an online test. A steady-state error adjustment procedure is introduced and the results are analyzed. The final dand q-axis model selections are based on the minimization of the cost function, the concept of parsimony and how well the models predict the online dynamics of the machine. Issues related to the necessity of the L_fld differential leakage inductance and the necessity of the Z_fe eddy current branch are also discussed     

Maximum likelihood estimation of generator stability constantsusing SSER test data

The performance of the maximum likelihood (ML) method when used to determine simulation data for generators from standstill frequency response (SSFR) tests is evaluated. The robustness of the ML method is demonstrated by analyses made with SSFR data from tests on the Rockport 722 MVA generator. It is shown that a unique set of parameters can be obtained, and the noise effects can be dealt with effectively when the ML technique is used to estimate machine parameters     

Time-domain identification of synchronous machine parameters fromsimple standstill tests

A set of standstill measurements that allow time-domain identification of linear model parameters for direct and quadrature axes of a synchronous machine is proposed. The advantages of this method over conventional standstill frequency response testing include the simplicity of test equipment, the higher current levels achieved, the speed with which the measurements can be obtained, and the fact that the models are obtained directly in parametric form (in per-unit or measured units). The proposed method is illustrated by results measured on a 3 kVA, 220 V microalternator     

On-line synchronous machine parameter estimation from smalldisturbance operating data

This paper presents a step-by-step system identification approach to estimate the parameters of a three-phase salient-pole synchronous machine rated at 5 kVA from online small disturbance responses. The machine equivalent circuit model linear parameters and the nonlinear saturated parameters are estimated. The estimation is performed using the maximum likelihood algorithm. Simulation studies based on the online measured small and large dynamic disturbances are performed to validate the accuracy of the identified machine model including the saturation     

A standstill frequency response method for large salient pole synchronous machines

In this article, a Standstill Frequency Response Test (SSFR) is proposed, with the aim of determining the direct and quadrature axis operational impedances for salient pole synchronous machines. The method is applied with the rotor at standstill in a given arbitrary position, thus avoiding the difficulties in rotor mechanical alignment and rendering it suitable for large salient pole synchronous machines of hydroelectric power plants.     

Identification of synchronous machine parameters using loadrejection test data

This work shows a computational methodology for the determination of synchronous machines parameters using load rejection test data. By machine modeling one can obtain the quadrature parameters through a load rejection under an arbitrary reference, reducing the present difficulties. The proposed method is applied to a real machine     

Identification of synchronous machine linear parameters fromstandstill step voltage input data

This paper presents the results of a time-domain identification procedure to estimate the linear parameters of a 15 kVA salient-pole synchronous machine at standstill. A step voltage input test is performed, and the parameters of the time constant models and equivalent circuit models are estimated. The maximum likelihood algorithm is used for the estimation, and the best-fit model is selected from a set of increasing order models. The initialization values for the parameters to be estimated are determined from the operational inductances derived directly from the measured time domain data. The simulated equivalent circuit model response is validated against the measured standstill time domain and frequency domain data. In addition, simulation of the model response to an on-line small disturbance test is compared to the measured dynamic response     

基于线性相位的风机齿轮箱无键相同步平均分析

风电机组转速信号多由发电机编码器提供,由于SCADA与CMS存在时间差和采样率差异,难以实现高速轴键相信号与齿轮箱振动信号的同步采集。基于时域同步平均的阶次分析技术较难在风机齿轮箱故障诊断领域得到大范围应用,提出了以线性相位估计为基础的、可适应转速波动为10%的风机齿轮箱无键相同步平均分析方法。选择输出级啮合频带中信噪比最高频段,利用傅里叶FIR"理想"滤波技术,实现严格线性相位保持的窄带滤波;通过希尔伯特变换提取带通信号复相位,并进一步通过线性插值合成过零点序列;以此为基础,完成基于软件的等角度重采样,进而实现无键相的时域同步平均分析。在某型号机组连续10 s的现场实测数据中,有效地验证了所提方法正确性和工程实用性。     

A frequency-domain maximum likelihood estimation of synchronousmachine high-order models using SSFR test data

The authors propose a numerical scheme for processing noisy signals originating from standstill frequency response (SSFR) tests on synchronous machines. Instead of using a univariate nonlinear least-squares procedure to fit only the weighted sum of magnitude responses, they minimize a multivariate prediction error criterion based on the determinant of the residuals covariance matrix. The algorithm pertains to a large class of prediction error methods and results in a multiresponse nonlinear regression procedure related to the maximum likelihood viewpoint when the residuals distribution is Gaussian. To demonstrate the efficiency of the proposed scheme, the implementation was tested using noisy simulated data, based on the Rockport model 3.3. It is shown, using actual data from the Nanticoke turbogenerator, dating back to the EPRI-project RP-9997-2 (1980), that the frequency-domain maximum likelihood approach can be effective for direct estimation of generalized circuits with up to five equivalent windings per axis, providing satisfactory predictions of both magnitude and phase as far as the 16th harmonic     

IPM synchronous machine drive response to symmetrical and asymmetrical short circuit faults

A closed-form solution is presented for the steady-state response of interior permanent magnet (IPM) synchronous machines to symmetrical short circuits including the effects of q-axis magnetic saturation. Machine response to single-phase asymmetrical short circuits is also investigated. Experimental data are presented to verify predicted behavior for both types of short circuits. It is shown that single-phase asymmetrical short circuit faults produce more severe fault responses with high pulsating torque and a significant threat of rotor demagnetization. A control strategy that purposely transitions such faults into symmetrical three-phase short circuits can minimize the fault severity and associated demagnetization risks. Implications for the design of IPM machines with improved fault tolerance are discussed.     

A `three transfer functions' approach for the standstill frequencyresponse test of synchronous machines

A three transfer functions approach for the standstill frequency response (SSFR) test of synchronous machines is proposed. Network theory is employed for the explanation of the three-function approach. The three-function and two-function approaches, as well as the one-function approach, are compared. The verification of the approach is obtained through simulations and an application to an SSFR test on a 3 kVA laboratory microalternator. The accuracy of the determined d-axis model parameters, particularly of the rotor circuits, is improved by the use of the suggested third transfer function (L _afo(s)) together with the two transfer functions ( L_d(s) and G(s)). This requires that the measurements of the three transfer functions be taken in the SSFR test and be involved in the d-axis model fitting instead of the common practice involving only L_d(s) and G(s)     

Test and simulation of network dynamic response using SSFR and RTDRderived synchronous machine models

The comparative testing of four 60 Hz two-pole generators indicates practical advantages for the SSFR (standstill frequency response) method over the RTDR (rotating time-domain response) method when synchronous machine models are to be synthesized from test data for network dynamic performance analysis. Manufacturer-provided data are compared to SSFR and RTDR derived parameters. All adequately duplicate synchronization, load rejection, and line switching tests. Deterministic sensitivity of CFCT (critical fault clearing time) to selected machine parameters is reported     

Rotor design optimization of synchronous reluctance machine

It is demonstrated that the rotor design of synchronous reluctance machines can be optimized in terms of a key geometric parameter, i.e., the ratio of the rotor insulation width to the rotor iron width so as to obtain maximum torque production. The equation which gives the maximum motor power factor in terms of the saliency ratio has been derived and it is shown that the power factor of 0.8 is a realizable value with the optimal rotor design. An experimental motor has been fabricated and the results of measurements of the motor parameters prove the validity of the rotor design optimization     

Determination of synchronous machine parameters using networksynthesis techniques

This paper deals with the problem of the determination of synchronous machine parameters starting from two-port information. Network synthesis techniques are used to show that no unique solution can be found for models containing more than one damper winding. Only a limited number of parameters can be determined in a unique way from two-port information     

Partitioning of synchronous machine windings for internal faultanalysis

This paper discusses a technique for partitioning the stator windings of large synchronous machines, for application to internal fault analysis, and determining corresponding winding inductances. The method employs a direct phase representation, which is shown to reduce to the classical phase representation when the partitioned windings are collapsed     

基于ANSYS的同步电机设计

分别采用磁路法和磁场法设计同步电机,探讨了同步电机的一般设计方法,并指出了设计要点。     

Unbalanced transients-based maximum likelihood identification of induction machine parameters

The paper describes an effective formulation of a maximum-likelihood identification algorithm for linear estimation of the equivalent-circuit parameters of cage-type (single cage and double cage) or deep-bar induction motors with measurement and process noises. A complete generalized model for symmetrical and asymmetrical test analysis of induction machines is developed for this purpose. The paper outlines the theory and reasoning behind the proposed statistical-based treatment of online data derived from generalized least-squares estimator and a Kalman filter. The method is successfully applied to online double-line independent finite-element (FE) short-circuit-simulated records of a deep-bar-type induction motor.     

A general model of synchronous machine for its steady-stateperformance analysis

A general model for analyzing a salient-pole machine as well as a nonsalient-pole machine under steady-state conditions is developed. The classical two-reaction theory method is replaced by the present method to analyze synchronous machines with salient-rotors. The method presented is applied to a 6.25 kVA test machine with a salient-rotor and is found to give accurate results