Star-Connected Power Conversion Control for Phase Balance
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Solution Overview
Problem
Power conversion devices face challenges in maintaining balance between phases of active power supplied to the load side, leading to imbalances that affect the power supply side AC systems.
Innovation Solution
A power conversion device comprising a first power converter and a second power converter, connected in a star configuration, which includes multiple arms and star connection lines to convert AC and DC power, with DCDC converter devices for bidirectional power transmission, and a control unit for stabilizing capacitor voltages and reducing low-frequency pulsations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a power conversion device uses indirect conversion methods with multilevel converters to handle large amounts of power, then the power conversion capability is improved, but the active power supplied to each phase becomes imbalanced due to load side events
Solution Approach 1:
A neutral point potential control mechanism is introduced as an intermediary between the multilevel converter and the load. This control system monitors and adjusts the neutral point potential to compensate for imbalances caused by load side events, thereby maintaining active power balance between phases while preserving the high power conversion capability of the multilevel converter configuration
2Adaptability or versatility
If the active power supplied to each phase becomes imbalanced, then the power conversion device can adapt to varying load conditions, but the power supply side AC systems are negatively influenced
Solution Approach 1:
A feedback control system is implemented that continuously monitors the active power distribution across phases and the neutral point potential. When load side events cause imbalances, the feedback mechanism triggers corrective actions through the neutral point potential control, reducing the harmful influence on the power supply side AC systems while maintaining adaptability to varying load conditions
Data Source
AI summary
A power conversion device in an embodiment includes a first power converter; a plurality of direct current-direct current (DCDC) converter devices; and a second power converter. The first power converter includes a plurality of first positive-side arms; a plurality of first negative-side arms; a first positive-side star connection line configured to connect the plurality of first positive-side arms in a star shape; a first negative-side star connection line configured to connect the plurality of first negative-side arms in a star shape; and a first terminal configured to connect the first positive-side star connection line and the first negative-side star connection line to each phase of a power supply side alternating current (AC) system and the plurality of first positive-side arms and the plurality of first negative-side arms mutually convert a first AC power and a first DC power of the power supply side AC system. A plurality of DCDC converter devices mutually convert the first DC power and the second DC power. The second power converter includes a plurality of second positive-side arms; a plurality of second negative-side arms; a second positive-side star connection line configured to connect the plurality of second positive-side arms in a star shape; a second negative-side star connection line configured to connect the plurality of second negative-side arms in a star shape; and a second terminal configured to connect the second positive-side star connection line and the second negative-side star connection line to each phase of a load-side AC system, and the plurality of second positive-side arms and the plurality of second negative-side arms mutually convert the second DC power and the second AC power.