DC Tap Electrical Assembly for HVDC Power Distribution
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Solution Overview
Problem
Existing power transmission networks face inefficiencies and high costs when transmitting low levels of power over long distances using high-voltage DC systems, as they require significant hardware modifications and installations of high-voltage step-down converters at remote locations to make the power suitable for end-users.
Innovation Solution
An electrical assembly comprising a voltage source converter, a DC tap with DC blocking capacitors, and a controller that generates non-fundamental frequency alternating currents to enable power transmission and distribution using existing high-voltage DC systems, allowing for simultaneous transmission of high and low power levels without the need for hardware modifications or additional step-down converters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high-voltage DC systems are used to transmit low levels of power over long distances, then power transmission capability is improved, but hardware complexity and cost increase due to requiring high-voltage step-down converters at remote locations
Solution Approach 1:
The patent segments the power transmission system into two functional paths: a high-voltage DC path for bulk power transmission and a low-voltage AC path for local distribution. The DC tap structure divides the transmission line into segments, allowing selective tapping of power at different voltage levels without requiring complete system redesign or additional high-voltage converters at remote locations.
Solution Approach 2:
The patent introduces a DC tap as an intermediary structure that mediates between the high-voltage DC transmission line and the low-voltage AC distribution network. This intermediary contains DC blocking capacitors that enable voltage transformation and power transfer without requiring direct high-voltage connection to the local network, thereby eliminating the need for high-voltage step-down converters at remote locations.
2Adaptability or versatility
If high-voltage step-down converters are installed at remote locations, then power distribution capability is improved, but device complexity and installation cost increase
Solution Approach 1:
The DC tap structure serves multiple functions simultaneously: it acts as a voltage transformer, a power divider, and an interface between DC and AC systems. By integrating these functions into a single structure with DC blocking capacitors, the patent eliminates the need for separate high-voltage step-down converters, reducing device complexity while maintaining versatile power distribution capability.
Solution Approach 2:
The DC blocking capacitors in the DC tap structure automatically perform voltage transformation and power transfer functions without requiring external control or additional active components. The capacitive reactance naturally blocks DC while allowing AC power transfer, providing self-regulating voltage adaptation that simplifies the overall system architecture.
3Productivity
If existing high-voltage DC systems are modified to transmit low power levels, then system utilization is improved, but manufacturing cost and hardware modifications increase
Solution Approach 1:
The patent enables dynamic power transmission capabilities by allowing the existing high-voltage DC system to simultaneously support both high-power bulk transmission and low-power local distribution through the DC tap structure. The system can dynamically adjust power distribution levels without physical modifications to the main transmission line, maximizing system utilization while avoiding manufacturing costs.
Solution Approach 2:
Instead of modifying the existing high-voltage DC system, the patent creates a parallel low-voltage AC distribution path through the DC tap structure. This copying approach allows the original system to remain unchanged while providing additional low-power distribution capability, thereby improving system utilization without incurring modification or manufacturing costs.
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
This configuration allows for economical, space-saving, and efficient transmission and distribution of low power levels using existing high-voltage DC systems, reducing hardware requirements and costs, while maintaining the voltage of DC blocking capacitors within the DC electrical network.
Implementation Method 1
each tap limb portion including a respective DC blocking capacitor
Data Source
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AI summary
An electrical assembly (20) comprises: a voltage source converter (22) including first and second DC terminals (26,28) and at least one AC terminal, the first and second DC terminals (26,28) being respectively connectable to first and second DC power transmission media (38,40) connected to a DC electrical network (41), the or each AC terminal being connectable to an AC electrical network (46); a DC tap (24) including first and second tap terminals (52,54), the first and second tap terminals (52,54) being respectively connectable to the first and second DC power transmission media (38,40), the DC tap (24) including a tap limb (48) extending between the first and second tap terminals (52,54), the tap limb (48) having first and second tap limb portions (48a,48b) separated by a third tap terminal (56), each tap limb portion (48a,48b) including a respective DC blocking capacitor, the third tap terminal (56) being connectable to an electrical load (64); a current return path (58) configured to electrically interconnect the or each AC terminal to the third tap terminal (56); a converter unit (22); and a controller (100) configured to selectively control the converter unit (22) to generate at least one first non-fundamental frequency alternating current component (70a,70b,70c) at the or each AC terminal to drive a non-fundamental frequency alternating current (72) to flow through the current return path (58) and in the third tap terminal (56), and to selectively control the voltage source converter (22) to modify the or each first non-fundamental frequency alternating current component (70a,70b,70c) at the or each AC terminal so as to form a first current (74a) flowing between the first DC terminal (26) and the first tap terminal (52) and to form a second current (74b) flowing between the second DC terminal (28) and the second tap terminal (54), each of the first and second currents (74a,74b) including a direct current component and at least one second non-fundamental frequency alternating current component, so as to enable the DC tap (24) to draw power from the DC electrical network (41) for supply to the electrical load (64).