HVDC Converter Control for Grid-Independent Renewable Power Supply
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Solution Overview
Problem
Existing methods fail to address the challenges of directly connecting renewable energy equipment to large-scale electrical loads without a utility power grid, leading to grid-related disruptions, inefficiencies, and the need for extensive grid expansion, while also failing to manage intermittent electricity production.
Innovation Solution
A method using an HVDC system with an AC/DC converter and VSC sub-system to provide direct electrical connection from renewable energy equipment to electrical loads, controlling voltage and phase angle to maintain steady-state power balance, enabling grid-independent operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If renewable energy equipment is directly connected to large-scale electrical loads without utility power grid, then grid independence and system efficiency are improved, but system stability and reliability deteriorate due to intermittent electricity production
Solution Approach 1:
The patent introduces a HVDC transmission system as an intermediary between renewable energy equipment and electrical loads. The HVDC system includes converter stations that convert AC to DC and back to AC, enabling stable power transmission despite the intermittent nature of renewable sources. This intermediary infrastructure provides grid-independent operation while maintaining system stability through controlled power conversion and transmission.
2Ease of operation
If existing grid-following power electronics interface is used, then connection to utility power grid is enabled, but direct connection between renewable energy equipment and electrical loads is prevented
Solution Approach 1:
The patent inverts the conventional grid-following approach by implementing a grid-forming HVDC interface. Instead of following the utility grid's voltage and frequency, the system establishes its own DC voltage reference and controls power flow directly to loads. This inversion enables direct connection between renewable energy equipment and electrical loads without requiring utility grid infrastructure.
3Loss of energy
If multiple AC-DC conversions are performed through utility power grid, then power distribution is achieved, but energy efficiency deteriorates due to conversion losses
Solution Approach 1:
The patent extracts the power conversion function from the utility grid infrastructure and implements it directly at the renewable energy site through HVDC converter stations. By taking out the AC-DC-AC conversion chain from the grid dependency and performing it locally, the system eliminates multiple conversion stages and associated losses, achieving direct power transmission from renewable sources to electrical loads with improved efficiency.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables efficient, grid-independent power supply to large-scale consumers, reducing disruptions and infrastructure needs, allowing co-location of generators and consumers, and improving system efficiency and reducing costs.
Implementation Method 1
providing an HVDC system comprising an AC/DC converter sub-system and a VSC sub-system, where the AC/DC converter sub-system comprises at least one AC/DC converter unit
Implementation Method 2
where the VSC sub-system comprises at least one VSC, an input electrically connected with the AC/DC converter sub-system, and an output electrically connected with at least one electrical load
Data Source
AI summary
An HVDC system comprising an AC/DC converter sub-system electrically connected to a renewable energy equipment and a VSC sub-system is provided. A method comprises operating the renewable energy equipment to function as a voltage source to energize an HVDC link between the AC/DC converter sub-system and the VSC sub-system; operating the VSC sub-system as a voltage source to energize an electrical load electrically connected thereto; if it is determined the power production rate of the renewable energy equipment is not within a designated parameter, operating the equipment to follow the VSC sub-system such that controlling the AC electric power output influences the power production rate. If it is within the designated parameter, operating the VSC sub-system to follow the renewable energy equipment such that the VSC sub-system adjusts the properties of its AC electric output to match the properties of the electric power generated by the renewable energy equipment.