Voltage-Coordinated Control for AC/DC Distribution Systems
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Solution Overview
Problem
Traditional AC distribution systems face challenges in integrating distributed energy sources, managing power imbalances, and maintaining stability due to fluctuations in power output from sources like photovoltaic and wind power, as well as random charging demands from electric vehicles, leading to frequent power imbalances and instability in both AC and DC distribution systems.
Innovation Solution
A voltage-coordinated control method for AC/DC distribution systems with energy storage, utilizing voltage-current droop control for converters and voltage-power droop control for energy storage adapters, which generates reference signals to regulate output states and stabilize DC voltage, incorporating hierarchical control strategies to manage primary and secondary voltage regulations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If distributed power sources (photovoltaic, wind power) are integrated into the AC distribution system, then power supply diversity and environmental friendliness are improved, but power output fluctuations cause frequent power imbalances and system instability
Solution Approach 1:
The patent introduces a DC distribution system as an intermediary layer between distributed power sources and AC loads. DC-AC converters and AC-DC converters serve as mediator devices that enable smooth integration of DC-based distributed power sources (photovoltaic, wind power, energy storage) into the AC distribution system, isolating their fluctuations from the AC system while maintaining stability.
Solution Approach 2:
The patent changes the voltage parameter by introducing a DC voltage level (first voltage level) distinct from the AC voltage level. This parameter change allows distributed power sources to operate at their optimal DC voltage while the AC system maintains its AC voltage characteristics, resolving the conflict between integration and stability through voltage-level separation and conversion.
2Productivity
If DC-based distribution system is adopted to improve transmission capacity and controllability, then power quality and energy efficiency are improved, but random fluctuations in distributed power sources cause frequent power imbalances
Solution Approach 1:
The patent segments the distribution system into distinct functional zones: a DC distribution zone for high-capacity power transmission from distributed sources, and an AC distribution zone for end-user delivery. This segmentation allows the DC system to maximize transmission capacity while the AC system handles the variability of distributed power sources, maintaining overall power balance stability.
Solution Approach 2:
The patent employs DC-AC converters as intermediary devices that buffer the DC distribution system from AC load variations. These converters act as mediators that decouple the high-capacity DC transmission from the variable AC consumption, allowing the DC system to maintain full transmission capacity while preventing power imbalances from propagating.
3Device complexity
If traditional AC distribution system structure is maintained, then system simplicity is preserved, but it becomes incompatible with load development requirements and unable to meet modern power supply quality demands
Solution Approach 1:
The patent creates a dynamic hybrid AC-DC distribution system where the configuration can adapt to different load requirements. The system dynamically switches between AC and DC distribution modes based on load characteristics, enabling compatibility with diverse modern loads (data centers, electric vehicles, renewable sources) while maintaining operational simplicity through standardized converter interfaces.
Data Source
AI summary
Disclosed herewith is a voltage coordinated control method for an AC/DC distribution system, including steps of: acquiring an actual voltage and an actual current at a DC-side of a converter of the system to obtain a first DC voltage and a first DC current; generating a present reference current signal for the converter according to a voltage-current droop control model, and generating a first control signal to control an output state of the converter; and acquiring an actual voltage at a DC-side of an energy storage adapter in the system to obtain a second DC voltage, generating a present reference power signal for the adapter according to a voltage-power droop control model, and generating a second control signal to control an output state of the adapter.