Voltage Source Converter Phase Current Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Voltage source converters in power transmission networks face challenges in efficiently managing active and reactive power transfer, especially in weak AC electrical networks with high impedance or low inertia, which affects energy transfer efficiency and stability during transient events.
Innovation Solution
A voltage source converter with a controller that determines independent active and reactive phase current reference values based on instantaneous voltage measurements, allowing for optimal energy transfer between AC and DC networks, minimizing current usage, and maintaining synchronization with the AC network, even under fault conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional voltage source converters are used in weak AC networks, then the converter can operate in high impedance or low inertia conditions, but the energy transfer efficiency deteriorates and stability is reduced during transient events
Solution Approach 1:
The converter is divided into independent single-phase limbs, each with its own controller that independently determines current reference values. This segmentation allows each phase to be optimized independently for energy efficiency while maintaining overall system stability during transient events in weak AC networks.
Solution Approach 2:
The controller dynamically determines current reference values based on instantaneous voltage measurements and power demands. The system adapts its operation in real-time to maintain optimal energy transfer efficiency while ensuring stability during transient events, transitioning between different operating conditions as network conditions change.
2Use of energy by moving object
If independent phase current reference values are determined for each single-phase limb, then the current requirements are minimized and energy transfer is optimized, but the control system complexity increases
Solution Approach 1:
The control system is segmented into independent controllers for each single-phase limb, where each controller independently determines current reference values based on instantaneous voltage measurements and power demands. This segmentation minimizes current requirements by optimizing each phase independently while keeping the control architecture modular and manageable.
Solution Approach 2:
Each single-phase limb's controller independently determines its own current reference values using instantaneous voltage measurements and power demand information. This self-service approach minimizes the need for complex inter-phase coordination while optimizing energy transfer, reducing overall control system complexity through decentralized decision-making.
3Adaptability or versatility
If the converter operates in weak AC networks with high impedance, then the converter can be deployed in island or wind farm applications, but the power transfer capability and stability are reduced
Solution Approach 1:
The controller dynamically adjusts current reference values based on instantaneous voltage measurements and power demands, enabling the converter to maintain optimal power transfer capability in weak AC networks. This dynamic adaptation allows deployment in island or wind farm applications while compensating for the high impedance characteristics of these networks.
Solution Approach 2:
The system changes operating parameters (current reference values) based on the specific conditions of weak AC networks. By adjusting these parameters in real-time according to instantaneous voltage measurements and power demands, the converter maintains effective power transfer capability despite the high impedance environment, enabling deployment in challenging applications like isolated islands or wind farms.
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
In the field of high voltage direct current (HVDC) power transmission networks, a voltage source converter (10) comprising a controller (36) configured to; receive an active power order comprising the desired amount of active power to be transferred by the convertor and receive an reactive power order comprising the desired amount of reactive power to be transferred by the convertor; receive a measurement of the instantaneous voltage of each phase of the multi- phase AC electrical network; determine an active and reactive phase current reference value for each single- phase limb which is independent of the or each other respective phase current reference and which defines the current each single-phase limb is required to draw from or pass to a corresponding phase of the AC electrical network to effect the active power and reactive power exchanges with the AC electrical network defined by the active and reactive power orders; the active phase current reference values determined based on the received active power order, the instantaneous voltage measurements and a determination of a resultant instantaneous reactive power using said active phase current reference values; and/or the reactive phase current reference values determined based on the received reactive power order, the instantaneous voltage measurements and a determination of a resultant instantaneous active power using said reactive phase current reference values.