Transformer Primary Voltage Determination via Secondary Current
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for determining the primary voltage of transformers are imprecise and costly, particularly when using voltage measurement transformers, which are also intrusive as they require access to live parts of the primary circuit.
Innovation Solution
A method and system that measure primary and secondary currents and voltages using sensors, with an information processing unit calculating the primary voltage modulus and phase shift, allowing for precise determination without physical access to the primary side and using split core toroids for current sensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If voltage measurement transformers are used to measure primary voltage, then measurement capability is provided, but measurement precision is insufficient and cost increases
Solution Approach 1:
The patent uses current sensors (toroids) on the secondary side as an intermediary to indirectly determine primary voltage. Instead of directly measuring primary voltage with expensive transformers, the system measures secondary current and uses it to calculate primary voltage through the transformer relationship, achieving both precision and cost-effectiveness
Solution Approach 2:
The patent replaces the mechanical/electrical voltage measurement transformer with an electronic calculation system. By measuring secondary current with toroid sensors and computing primary voltage through mathematical relationships (considering transformer ratio and power factor), the system substitutes physical measurement hardware with electronic sensing and computation
2Measurement precision
If voltage measurement transformers are used to measure primary voltage, then measurement capability is provided, but device complexity and intrusiveness increase due to requiring access to live parts
Solution Approach 1:
The patent extracts the measurement function from the primary side (where it would be intrusive) and places it on the secondary side. By measuring only secondary current with non-intrusive toroid sensors and calculating primary voltage mathematically, the system removes the need for physical access to live primary parts while maintaining measurement capability
Solution Approach 2:
The patent introduces secondary current measurement as an intermediary approach. Instead of directly interacting with primary voltage (which requires intrusive hardware), the system uses secondary current as a mediator that can be measured non-intrusively and then used to derive primary voltage information through calculation
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
The system provides precise, cost-effective, and non-intrusive measurement of primary voltage, improving network voltage control and reducing operational costs by enabling remote monitoring and adjustment of transformer settings.
Implementation Method 1
measuring the secondary voltage using a voltage sensor
Implementation Method 2
measuring the primary current using a first current sensor
Data Source
Figure 1
Figure 2
Figure 3
AI summary
This method allows the determination of the primary voltage of an electrical transformer (18). The transformer has a no-load turns ratio and comprises a primary winding (52) designed to present the primary voltage between its ends and to carry a primary current (I1a, I1b, I1c), and a secondary winding (54) designed to present a secondary voltage between its ends and to carry a secondary current (12a, 12b, 12c). The determination method includes measuring the secondary voltage (U2a, U2b, U2c) using a voltage sensor (59A, 59B, 59C), and measuring the primary current (I1a, I1b, I1c) using a first current sensor (56A, 56B, 56C).The method further comprises the following steps: a) calculating a secondary voltage drop between the ends of the secondary winding (54), as a function of the transformer's own characteristics (18), the transformer's load factor (18), and the power factor of a load connected to the secondary winding (54) at the output of the transformer (18); b) calculating the magnitude of the primary voltage as a function of the measured secondary voltage, the voltage drop calculated in step a), and the no-load turns ratio; and c) calculating the phase shift of the primary voltage (U1j) with respect to the measured primary current (I1j) as a function of the phase shift of the measured secondary voltage (U2j) with respect to the measured primary current (I1j).