DOI: 10.17035/d.2016.0011647652
title: Fast Frequency Response from Offshore Multi-terminal VSC-HVDC Schemes

description: These data represent analyses of the frequency support characteristics of multi-terminal VSC-HVDC (MTDC) schemes using the energy transferred from wind turbine rotating mass and other AC systems. An alternative coordinated control (ACC) scheme, which gives priority to a frequency versus active power droop fitted to onshore VSCs has been proposed to: (i) transfer wind turbine recovery power to undisturbed AC grids and (ii) allow correct control operation of MTDC systems during multiple power imbalances on different AC grids. The fast frequency response capability of MTDC systems equipped with the proposed ACC scheme is compared against a coordinated control (CC) scheme, which uses a frequency versus DC voltage droop. The frequency control schemes were demonstrated on an experimental test rig which represents a 3-terminal HVDC system. Also, the MTDC frequency support capability when wind farms do not provide extra power was tested using a 4-terminal HVDC system. The data are provided in the folder (Metadata_PWRD) and described in a text file (Quantity_description.txt). The main folder consists of two sub folders namely ‘Results_SectionIV’ and ‘Results_SectionV’. A special software (MATLAB) is required to access the dataset stored in the two folders (‘Results_SectionIV’ and ‘Results_SectionV’). The .txt file describes the location of different quantities (Active Power, DC voltage, frequency and time).  The folder named ‘Results_SectionIV’ consists of two .mat files and three .m files. This folder contains PSCAD simulation results and experimental test rig results of a 3-Terminal VSC-HVDC system (shown in Figures 10 - 13, Section IV of the paper). The dataset underpinning the experimental results are stored in the file ‘experimental_results.mat’ with file size 3.4 MB and the dataset obtained from the PSCAD simulation results are stored in ‘simulation_results.mat’ with file size 34 MB. The three .m files houses a set instructions used to process and plot the dataset in the .mat files. Additional data on the experimental test rig parameters and the test system modelled in the PSCAD simulation tool have been included as Appendices A, B and C in the manuscript.  The folder named ‘Results_SectionV’ consists of five .mat files and two .m files. This folder contains results obtained from a SIMULINK tool system for a 4-terminal VSC-HVDC system for the case a single imbalance and multiple imbalance (shown in Section V of the paper). The dataset underpinning the results for the case of single power imbalance are stored in three mat files. These are: No_freq_support.mat (file size: 670 KB); CCS_freq_support_1imb.mat (file size: 1.51 MB); ACCS_freq_support_1imb.mat (file size: 1.5 MB). The data underlying results for the case of multiple imbalances are stored the following .mat files - No_freq_support.mat (file size: 670 KB); CCS_freq_support.mat (file size: 1.57 MB); ACCS_freq_support.mat (file size: 1.5 MB). The two .m files contains instructions written to process and plot the dataset in the format that displayed in SectionV of the paper.