Split-Phase Transformer Inverter Control for Three-Phase Current Balance
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Solution Overview
Problem
Existing systems fail to achieve continuous adjustment and full balance of three-phase currents in distribution transformers due to the randomness and intermittency of single-phase distributed energy sources and loads, leading to overloading and potential burnout.
Innovation Solution
A system and method involving a single-phase transformer, single-phase bridge rectifier, and three-phase full-bridge inverter with sequence component decomposition and hysteresis control to adjust unbalanced currents, enhancing transformer capacity and achieving three-phase balance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If single-phase distributed energy sources and single-phase loads are connected to the distribution transformer, then the transformer area capacity is increased, but the three-phase current balance deteriorates
Solution Approach 1:
The patent segments the single-phase loads and distributed energy sources into different phase groups (first group connected to first phase, second group connected to second phase). By dividing the load distribution across phases and using multiple single-phase transformers connected in parallel, the system increases transformer area capacity while managing current balance through structured phase segmentation.
Solution Approach 2:
The patent changes the operating parameters by introducing a dual-mode operation where the distribution transformer can switch between single-phase operation mode and three-phase operation mode. This parameter change allows flexible adaptation to different load conditions, enabling capacity enhancement while maintaining current balance through mode switching based on real-time phase current measurements.
2Stability of the object's composition
If load-side currents are adjusted by controlling phase-shifting switches, then three-phase distribution is optimized, but continuous adjustment capability is insufficient
Solution Approach 1:
The patent implements dynamic current balancing by continuously measuring phase currents and dynamically switching between single-phase and three-phase operation modes. The system uses real-time current measurements to determine when to switch modes, enabling continuous adjustment capability that adapts to changing load conditions rather than relying on fixed phase-shifting switch positions.
Solution Approach 2:
The patent incorporates feedback mechanisms by measuring the currents in each phase and using this information to control the operation mode of the distribution transformer. The current measurement feedback enables the system to automatically switch between operation modes to maintain balanced three-phase currents, providing continuous adjustment based on actual system conditions.
3Quantity of substance
If single-phase transformers are added to increase capacity, then transformer area capacity is enhanced, but device complexity increases
Solution Approach 1:
The patent merges multiple single-phase transformers by connecting them in parallel to form an enhanced distribution transformer system. This merging approach increases the overall transformer area capacity while using a standardized parallel connection configuration that manages complexity through modular assembly rather than requiring complex custom designs.
Solution Approach 2:
The patent creates a multi-functional distribution transformer system that can operate in both single-phase mode and three-phase mode using the same physical hardware. This universality allows the system to handle various load configurations and distributed energy source connections without requiring separate dedicated equipment for each mode, thereby enhancing capacity while controlling complexity through flexible multi-use design.
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 system effectively suppresses negative and zero sequence currents, reduces transmission line losses, and maximizes equipment capacity utilization by independently sourcing power from the high-voltage side, ensuring balanced three-phase current distribution.
Implementation Method 1
the single-phase transformer is configured to change the high voltage of the distribution transformer into the low voltage
Implementation Method 2
the single-phase bridge rectifier is configured to convert the alternating current at the low-voltage side of the single-phase transformer into direct current
Implementation Method 3
which also can invert the direct current into alternating current and transmit it to the power grid
Data Source
AI summary
The system and method for unbalanced current adjustment from capacity increase and phase-splitting output of distribution transformer according to embodiments of the present invention are provided, in which the system for unbalanced current adjustment from capacity increase and phase-splitting output of distribution transformer includes a single-phase transformer, a single-phase bridge rectifier, and a three-phase full-bridge inverter. The high-voltage side of the single-phase transformer is connected to the high-voltage side of the distribution transformer. The single-phase bridge rectifier connected to the low-voltage side of the single-phase transformer converts the AC power from the single-phase transformer into the DC power for the three-phase full-bridge inverter. The three-phase full-bridge inverter is connected to the three-phase lines through the three-phase reactors. It processes the three-phase load current through the sequence component decomposition to obtain the three-phase negative sequence current and the three-phase zero sequence current. This is then combined with the capacitor voltage control component to calculate and then obtain the three-phase reference current. Then, the three-phase reference current undergoes the hysteresis controlling, which allows the three-phase full-bridge inverter to output the corresponding three-phase compensation currents to the three-phase lines, achieving the three-phase current imbalance adjustment.