Accurate aggregated modelling of wind farm systems in modified sequence domain for stability analysis

Abstract

With the wind power penetration rate continuously rising, a suitable wind farm model considering both accuracy and simplicity is required for power system stability analysis. To accomplish this goal, an accurate aggregated modified sequence impedance model of the wind farm is established in this paper. The modified sequence impedance model of wind turbine generator is established, which considers the coupling between the positive-and negative-sequence impedances. The modified sequence impedances of the ac collection system, transformers, and ac grid are also derived. In this way, the impedance network of the entire wind farm system can be formed and simplified to acquire the accurate aggregated modified sequence impedance. Furthermore, the proposed model is compared with the traditional single-machine aggregated model which shows the necessity of establishing the accurate aggregated model. It is worth noting that the differences among each wind turbine generator's operation points can be included in the proposed model. Compared with the results of impedance measurements of a target wind farm, the accuracy of the proposed aggregated sequence impedance model of the wind farm is verified in frequency domain. The application of the proposed model in the stability analysis of a grid-connected wind farm is also presented with consideration of the ac grid strength. What is more, the effect of the inertial controller on the wind farm system stability is also analyzed to make the impact of this study much more appealing and up to date.

Generalized MIMO Sequence Impedance Modeling and Stability Analysis of MMC-HVDC With Wind Farm Considering Frequency Couplings

“…Firstly, the detailed impedance model [16] of the DFIG-based wind turbine is adopted, which considers the dynamics of the induction generator, rotor-side converter (RSC), grid-side converter (GSC) and dc-link. The whole impedance of the DFIG-based wind turbine contains three parts, i.e., GSC, RSC and equivalent dc-side, which is expressed as…”

“…The next step is to establish the impedance network of the wind farm, which shows higher accuracy in stability analysis [16]. The basic idea is to integrate the impedances of the wind turbines, transformers and cables into a circuit network as shown in Figure 18.…”

“…Nevertheless, careful attention should be paid to the reference frame transformation of individual impedances when formulating the final wind farm impedance. This issue has been well-discussed in [16]- [18] to acquire an accurate impedance aggregation model.…”

Analysis of Power Electronics-Dominated Hybrid AC/DC Grid for Data-Driven Oscillation Diagnosis

“…By rotating the converter's impedance model evaluated in respective dq-local reference frame to the same dqglobal reference frame [15], the system network matrix can be constructed in a systematic building-block manner. According to (5), ( 7) and ( 8), the node-branch incidence matrix A for the hybrid AC/DC grid is defined in (9).…”

A Design of the Real-Time Simulation for Wind Turbine Modeling with Machine Learning

“…In order to compensate for these problems, some studies have been carried out through a wind farm's dynamic equivalent model (DEM). An equivalent aggregate modeling method based on the equivalent admittance of wind farms is proposed in [14,15]. A modeling method based on state-space equations for large-scale wind farm complexes is proposed in [16][17][18].…”