Induction Motor Load Model Research Articles

Robust Time-Varying Parameter Identification for Composite Load Modeling

With the increasing integration of uncertain resources, e.g., renewables, electric vehicles, and demand responses, it is imperative to understand the characteristics of loads for power system analysis and control. Challenges of load modeling come from a variety of load components and time-varying compositions. In addition, the existence of outliers in measurements further complicates the problem. This paper proposes a robust time-varying parameter identification technique for composite ZIP and induction motor load models. A batch-model regression form, including time-varying parameters, is established based on state transition models and observation models with current observations and previous predictions to guarantee data redundancy. To deal with outliers, down-weighting coefficients of measurements are calculated with a projection statistics approach. Based on the batch-model regression and the down-weighting coefficients, parameter identification at each sample time is formulated as a weighted least squares optimization, which is solved by the Newton-Raphson approach with the previous estimated parameters as the initial iteration values. In addition, parameters’ sensitivities to different outliers in measurements are analyzed. Results on the IEEE 57-bus system and IEEE 118-bus system show that the proposed algorithm can robustly identify time-varying parameters for the composite load models.

Representative static load models for transient stability analysis: development and examination

Load representation has a significant impact on power system analysis and control results. Currently, static load models are still popular in power industry for transient stability analysis. Dynamic load models are recommended in both industry and academia for possible improvement in analysis accuracy. The accuracy of using static (nonlinear) load models with suitably identified parameters for transient stability analysis is examined. Numerical studies conducted using on-line measurement data indicate that static load models, as compared with induction motor load models, are acceptable for modelling real power behaviours during disturbances and hence are adequate for transient stability analysis. Using multiple sets of on-line measurements, representative model parameters of five static nonlinear load models are derived and their performance in modelling dynamic behaviours of both real and reactive powers is compared. A method is presented to determine a representative set of parameters of static (nonlinear) load models for each loading condition.

Modelling induction motor loads for voltage stability analysis

This paper deals with modelling induction motor loads for voltage stability analysis. A simple first order induction motor load model and a detailed third order induction motor load model suitable for this purpose are derived in terms of real power, reactive power and slip. It is shown analytically that the generic dynamic load models (GDLM) proposed in the literature, in their present form, are incapable of capturing induction motor characteristics. The generic dynamic load model is modified to capture the dynamics represented by the proposed induction motor load models. The appropriateness of the proposed dynamic load models in analysing the transient and steady state stabilities of induction motor loads are evaluated. It is shown that the first or third order induction motor models can be used for studying the power system voltage stability, with different degrees of accuracy.

Verification and expansion of a method of transient analysis of voltage collapse based on the induction motor load model

AbstractVoltage instability is now under intensive study in Japan, and some dynamic methods for analyzing voltage collapse have already been presented. However, the suitability of load models used in the methods and the generality of the results have not been verified.In this paper, useful voltage collapse data acquired in real power systems are presented. The measured data are compared with the result of dynamic digital simulation to verify the suitability of an induction motor load model.In the latter half of this paper, dynamic simulations of voltage collapse with consideration of generator dynamics are carried out. An interconnected power model system with 10 nodes is analyzed. The generality of basic characteristics concerning voltage collapse which have already been obtained without considering generator dynamics is verified by such simulations.

誘導機モデルを用いた電圧崩壊現象の過渡解析の検証と一般系統への拡張

誘導機モデルを用いた電圧崩壊現象の過渡解析の検証と一般系統への拡張