Phase-Shifting Transformer With Shared Tapped Coils and Fewer OLTCs
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Solution Overview
Problem
Current phase shifting transformers (PSTs) require multiple tap-changers and large magnetic circuits to manage both voltage regulation and phase shift control, leading to high costs and sometimes inapplicability due to excessive line currents, especially in medium voltage networks.
Innovation Solution
A phase shifting transformer design that combines voltage regulation and phase shift control using two on-load tap-changer sets connected to the same tapped coil of an exciting transformer, reducing the number of required tap-changers and magnetic circuit size by utilizing 3 double-tapped coils for both phase shift and voltage regulation, allowing currents to flow in quadrature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional symmetrical PST solutions with one magnetic circuit are used, then high power transfers controlled over limited and larger phase-shift angles are achieved, but six single phase OLTCs for phase-shift control and three additional OLTCs for voltage regulation are required, making the solution expensive and sometimes not applicable when line current is too large
Solution Approach 1:
The patent combines two separate OLTC functions (voltage regulation and phase-shift control) into a single shared OLTC unit. The same OLTC taps the exciting transformer coil to provide both the voltage regulation winding and the phase-shift control winding, thereby reducing the total number of OLTCs from nine (six for phase-shift plus three for voltage regulation) to a single shared unit per phase, significantly simplifying the device complexity while maintaining high power transfer capability
Solution Approach 2:
The OLTC is designed with multi-functionality to serve dual purposes: it simultaneously provides voltage regulation through one winding and phase-shift control through another winding. This universal design allows a single OLTC to replace multiple specialized OLTCs, reducing device complexity and cost while preserving the full power transfer and control capabilities
2Power
If PSTs with two magnetic circuits are used to handle high line currents, then the current capacity is sufficient, but the cost becomes very high and the device complexity increases
Solution Approach 1:
The patent merges two separate magnetic circuits into a single shared magnetic circuit. The exciting transformer with its single tapped coil serves both the voltage regulation function and the phase-shift control function simultaneously. This consolidation reduces the magnetic circuit complexity from two separate circuits to one unified circuit, while the single OLTC design ensures adequate current handling capacity without requiring parallel magnetic paths
3Adaptability or versatility
If nine single-phase tap-changers are used (six for phase-shift and three for voltage regulation), then both voltage regulation and phase-shift control are achieved, but the cost becomes very high and applicability is limited
Solution Approach 1:
The patent merges the functions of nine separate tap-changers into a single shared OLTC unit. The OLTC taps the exciting transformer coil to provide both voltage regulation and phase-shift control through different windings, thereby reducing the component count from nine discrete tap-changers to one integrated unit, significantly lowering cost and improving adaptability
Solution Approach 2:
The single OLTC is designed with universal functionality to perform both voltage regulation and phase-shift control tasks. By tapping the same exciting transformer coil to feed both the voltage regulation winding and the phase-shift control winding, the OLTC becomes a multi-functional device that replaces nine specialized components, enhancing versatility while reducing complexity
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 design reduces the size and power requirements of the magnetic circuit, enabling efficient high-power transfers with reduced costs and maintaining effective phase shift and voltage regulation capabilities, even under high line currents.
Implementation Method 1
two on-load tap-changer sets connected to the same taped coil of the excitation (or exciting) transformer to form two windings
Data Source
AI summary
The present disclosure relates to a phase shifting transformer. The phase shifting transformer includes two exciting windings sharing the same three double taped coils,a first excited winding having three connected coils, for a phase shift regulation,a second excited winding comprising three connected coils, for a voltage regulation,each of the two exciting windings regulating the voltage of one coil of the second excited winding, and regulating the voltage level of one coil of the first excited winding.