Type IV Wind Turbine System Impedance Modelling for Harmonic Analysis: On the Use of a Double Synchronous Reference Frame and Notch Filter

Several efforts are being done nowadays to improve the modelling of Wind Turbine Systems (WTSs) for harmonic analysis in Offshore Wind Power Plants (OWPPs). Due to the high influence of the different control structures in the Power Electronic Converters (PECs) on the dynamic response of a WTS, each structure needs to be modelled specifically....

Number of Levels, Arm Inductance and Modulation Trade-offs for High Power Medium Voltage Grid-Connected Modular Multilevel Converters

There is an increasing focus on integrating flexible dc links for bulk power routing in medium voltage distribution grids. In such applications, the ac-dc Modular Multilevel Converter (MMC) devised for medium voltage and high-power ratings can be an interesting choice. This paper highlights some less explored design trade-offs arising due to...

Output Impedance Modelling and Sensitivity Study of Grid-Feeding Inverters with Dual Current Control

In this paper, the output impedance of a three-phase inverter based on a dual current control (also called double synchronous reference frame current control) is modelled, which includes: the current loop gain, the control delay, and the Phase-<br/>Locked Loop (PLL). The impact of these parameters on the impedance is then analysed by a...

Impact of WTG converter impedance model on harmonic amplification factor of the Dutch 110kV transmission network using a 383MW wind farm case study

In this decade, a significant amount of additional wind and solar power will be integrated in the Dutch high voltage grid. The 383 MW nearshore Wind Park Fryslân is foressen to be connected to the Dutch 110kV grid in 2020 through two 55km cable circuits. To quantify the risks of exceeding emission levels for both the TSO and the wind farm...

On the Importance of Tracking the Negative-Sequence Phase-Angle in Three-Phase Inverters with Double Synchronous Reference Frame Current Control

A voltage imbalance at the AC terminals of a three-phase inverter creates a ripple in the power signal on the DC side. In order to minimize this ripple, several techniques can be applied, in which a double Synchronous Reference Frame (SRF) current control structure is very typical. In this approach, both the positive and negative sequence...

Impedance Modeling for Three-Phase Inverters with Double Synchronous Reference Frame Current Controller in the Presence of Imbalance

This article presents a small-signal model for power-electronics converters that use a typical control structure in wind energy applications: the double synchronous reference frame current control. The article considers the presence of unbalanced currents and voltages, and analyzes their impact on the frequency couplings of the converter. In...

Python Supervised Co-simulation for A Day-long Harmonic Evaluation of EV Charging

To accurately simulate electric vehicle DC fast chargers' (DCFCs') harmonic emission, a small time step, i.e., typically smaller than 10 μs, is required owing to switching dynamics. However, in practice, harmonics should be continuously assessed with a long duration, e.g., a day. A trade-off between accuracy and time efficiency thus exists. To...

Multi-timescale Modeling of Fast Charging Stations for Power Quality Analysis

To accurately simulate the harmonic emission of EV DC fast chargers (DCFCs) and the harmonic voltage of the power grid to which the chargers are connected, a small time-step, i.e., typically smaller than 10μs, is required. However, for harmonic assessment, a long timescale, typically a day, is required. A conflict between accuracy and time...

Guidelines for Stability Analysis of the DDSRF-PLL Using LTI and LTP Modelling in the Presence of Imbalance

In this article, the Linear Time Invariant (LTI) and Linear Time Periodic (LTP) models of two different implementations of the DDSRF-PLL in the presence of voltage imbalance are derived analytically. The accuracy of the models is investigated with time domain simulations, frequency scans, and stability analysis. On top of this, a guideline for...