Comprehensive Documentation for High-Voltage Direct Current (HVDC) Transmission System Using Voltage Source Converters (VSCs) for Efficient Long-Distance Power Transfer

System Overview

What is a VSC-HVDC System?

A Voltage Source Converter (VSC)-based HVDC system converts AC power to DC and vice versa using self-commutated power electronic switches (IGBTs, SiC MOSFETs). This enables bidirectional power flow, voltage control, and enhanced stability in modern power grids.

Purpose of the Simulation

The simulation aims to:

• Evaluate AC-DC-AC power conversion efficiency.
• Validate grid integration and dynamic response under disturbances.
• Optimize control strategies for voltage and frequency regulation.

Key Features

Independent Active and Reactive Power Control

VSC-HVDC enables decoupled control of active and reactive power, allowing improved voltage regulation and grid support. ➡️ HIL/PHIL Benefit: Real-time testing of control algorithms under various grid conditions enhances system reliability.

Black-Start Capability

Unlike conventional LCC-HVDC, VSC-based systems can restore grid operation without relying on external sources. ➡️ HIL/PHIL Benefit: Testing ensures proper startup sequences under various blackout scenarios.

Grid-Forming and Grid-Following Operation

VSC-HVDC systems can either follow an existing grid voltage or create a stable grid reference for weak networks. ➡️ HIL/PHIL Benefit: Simulation verifies seamless operation in both modes, improving grid resilience.

Connection to Weak Grids

VSC-HVDC can connect to weak or isolated grids without the need for additional infrastructure.

Compact and Modular Design

 VSC-HVDC stations are smaller and more modular than LCC-HVDC stations, reducing footprint and installation time.

Environmental Benefits

Reduces the need for overhead transmission lines, minimizing visual and environmental impact.

Simulation Objectives

This simulation helps evaluate:

• Power transfer efficiency over long distances.
• Response to grid faults such as voltage sags and frequency deviations.
• Performance under renewable energy integration. ➡️ HIL/PHIL Benefit: Enables real-time validation of operational scenarios before physical deployment.

Technical Description

System Configuration

• Input: AC grid (wind, solar, hydro, or conventional power plants).
• Power Conversion Stages: AC-DC conversion at sending end, DC transmission, and DC-AC conversion at receiving end.
• Output: Controlled AC voltage for grid or industrial loads.
• Control System: Vector control with phase-locked loops (PLLs) and predictive control algorithms.

Control Methodology

• Direct Torque Control (DTC) or Vector Control (VC): Ensures accurate power flow management.
• DC Voltage Regulation: Maintains stable DC link voltage under load variations.
• Fault Ride-Through (FRT) Capability: Enhances resilience during grid disturbances. ➡️ HIL/PHIL Benefit: Control algorithms can be fine-tuned in a real-time simulated environment, ensuring optimal grid interaction.

Advantages of VSC-HVDC Transmission

• Long-Distance Power Transfer: Enables efficient delivery of power with minimal losses.
• Asynchronous Grid Interconnection: Supports flexible grid interconnections without frequency synchronization issues.
• Lower Harmonic Distortion: Advanced switching techniques ensure high power quality. ➡️ HIL/PHIL Benefit: Full validation of these advantages across the entire development cycle ensures high system performance.

Applications

• Renewable Energy Integration

Offshore Wind Farms: VSC-HVDC is widely used to transmit power from offshore wind farms to onshore grids. It provides efficient power transfer over long distances and helps stabilize the grid by providing reactive power support.

Solar Power Plants: Large-scale solar farms in remote locations use VSC-HVDC to transmit power to urban centers with minimal losses.

• Interconnecting Power Grids

Cross-Border Power Exchange: VSC-HVDC systems are used to interconnect power grids between countries or regions, enabling efficient power sharing and enhancing grid stability.

Asynchronous Grid Interconnection: VSC-HVDC can connect grids operating at different frequencies (e.g., 50 Hz and 60 Hz) or with different voltage levels, facilitating power exchange without synchronization issues.

•  Urban Power Supply

Megacity Power Injection: VSC-HVDC is used to supply power to densely populated urban areas where space for overhead transmission lines is limited. Underground or submarine HVDC cables can deliver power efficiently.

Grid Congestion Relief: VSC-HVDC helps alleviate congestion in overloaded AC transmission lines by providing an alternative power transfer path.

HIL/PHIL Benefit: Accelerates the development of tailored solutions for each application scenario.

• Island and Remote Area Electrification

Power Supply to Islands: VSC-HVDC systems are used to supply power to islands that are far from the mainland grid, ensuring reliable and efficient power transfer.

Remote Mining Operations: Mining sites in remote locations use VSC-HVDC to receive power from distant generation sources, reducing reliance on diesel generators.

• Grid Stability and Power Quality Improvement

Reactive Power Support: VSC-HVDC systems can provide dynamic reactive power support to stabilize the grid during voltage fluctuations or faults.

Black Start Capability: VSC-HVDC can help restart power systems after a blackout by supplying power to critical loads and generators.

• Submarine Power Transmission

Undersea Cable Networks: VSC-HVDC is ideal for long-distance submarine power transmission due to its ability to handle capacitive loads and provide stable power transfer.

Cross-Sea Interconnections: Examples include the NordLink project between Norway and Germany and the BritNed project between the UK and the Netherlands.

Simulation Benefits

With this simulation, users can:

• Optimize HVDC transmission system design.
• Test grid interaction strategies for stability enhancement.
• Evaluate converter losses and efficiency. ➡️ HIL/PHIL Benefit: Simulation insights are directly applicable to hardware prototyping and validation.