The Modelling and Control of Multi-Terminal VSC-HVDC networks for Windfarm Integration

  • Imhotep Baptiste

Student thesis: Phd

Abstract

Name of University: The University of Manchester Candidate’s name: Imhotep Baptiste Degree Title: Doctor of Philosophy Thesis Title: The Modelling and Control of Multi-Terminal VSC-HVDC networks for Windfarm Integration Date: May 2018 Voltage source converter (VSC) technology has gained popularity in the recent years because it is a better and cheaper option than its line commutated converter (LCC) counterpart for connection to offshore windfarms. The existing literature provides complex models of the VSC and its controls but there is a lack of simplified converter models that can provide enough information for the design of multi-terminal control systems. The key contribution of this thesis is the development of an improved simplified state-space converter model that can be used as a tool for designing controllers for Multi-Terminal VSC-HVDC networks. AC power, DC voltage, and AC voltage controllers were developed to accurately control the converter. These controllers were verified using a detailed equivalent model (DEM) which was implemented in the electromagnetic transient (EMT) software PSCAD. Using the simplified state-space model and its associated controllers, a five-terminal MTDC case study that integrated windfarm generation, an offshore passive load, and onshore grid connected converters was developed. The local controllers and droop controllers were extensively tested using the case study, and windfarm curtailment was shown to be a suitable solution for some severe cases of operation. The behaviour of the standard power flow solver (PFS) was also investigated. A novel partial PFS was designed which proved to be robust, had an accuracy of within 10% of the power setpoint, and required fewer measurements from the MTDC network than the standard PFS. An upgraded PFS was also proposed which reduced the transient overshoot of the partial PFS and improved its accuracy.
Date of Award31 Dec 2018
Original languageEnglish
Awarding Institution
  • The University of Manchester
SupervisorMike Barnes (Supervisor) & Ognjen Marjanovic (Supervisor)

Keywords

  • HVDC Controls
  • Partial PFS
  • Power Flow Solver
  • MTDC
  • HVDC
  • State Space

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