Strathclyde Engagement with the National HVDC Centre: Phase I Converter and GB Network Modelling

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Strathclyde Engagement with the National HVDC Centre: Phase I Converter and GB Network Modelling

Project Background

The use of HVDC transmission systems facilitates UK’s increased exploitation of renewable energy resources, e.g. offshore wind power, provides efficient highways for transmitting large active power between generation and load centres, and supports the overreaching vision of European transnational power grids. As a result, GB electricity network is expected to undergo significant changes in the coming decades with rapid growth in the amount of power generated from power electronics interfaced renewable power plants and HVDC power transmission. The adoptions of HVDC systems to facilitate the development of offshore renewable energy and increased network connectivity, and to ensure efficient and safe operation of the GB power network, a number of control, operation and protection challenges need to be addressed at converter stations and AC and DC networks at large.

Detailed system modelling and simulation are usually required to assess system performance and identify potential issues for new HVDC connection during planning, design, commissioning and system operation. Real-time control hardware-in-the-loop simulation that uses converter control replicas interfaced with models running at real-time is the most effective way to reproduce near real system operation conditions for testing, performance evaluation and validation. Due to the complex structure of HVDC converters and existing control dynamics that spread over wide time-scale, the frequencies of interest for networks with significant converter penetration span a wide range, which demands much more detailed and accurate converter and system models when compared to those for traditional power system studies.

To study the performance and dynamic response of a real system, vendor-specific models from manufacturers are required. However, such models are usually provided as “black-box” models with predefined inputs and outputs, and with no access to the internal converter structure and system control by the users. The restricted access to key internal converter and control system variables that describe system dynamics may hinder understanding of potential issues that may arise at converter and system levels from continued evolution of the power network. Therefore, to aid future network development, and identify potential problems and solutions with large renewable generation and HVDC connection, it is essential that accurate and high fidelity converter models are available for system studies.

 

Recent modular and hybrid multilevel voltage source converters for HVDC applications have adopted the concept of modular power electronics building blocks that employ thousands of semiconductor switching devices and capacitors, with each building block or submodule contains few switching devices and capacitors. Such an approach has enabled scalability of a single converter to significantly higher voltages and rated powers such as 640kV and 1000 MW. However, the exponential increase in the numbers of submodule makes their modelling and understanding of their dynamics increasingly challenging.

The full Project Summary is below:

Details for each of the individual deliverables can be found on the following links:

Open Access Models

Project Report I : Development and Validation of Offline and Real-time User-defined Models of Alternative MMC Configurations

Project Report II : Validation of Real-time User-defined MMC Models

Project Report III : Offline DC grid model development

Project Report IV : Development and Validation of Offline and Real-time User-defined Models of Alternative MMC Configurations

Project Report V : DC Grid with User-defined Converter Models: Validation of Real-Time Model in RTDS against Offline Equivalents in PSCAD/EMTDC Environment

Publications and Presentation