Transformer Input Voltage Determination via Current Measurements
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Solution Overview
Problem
In power distribution networks, especially in transforming stations, determining the medium voltage on the input side is challenging due to the lack of instrumentation and compact design, making it difficult to monitor power flows and voltage profiles, and unpredictable power generation from decentralized sources can lead to excessive voltages damaging end-user appliances.
Innovation Solution
A method and device for determining the input voltage of a transformer in a transforming station by measuring input and output currents and voltages, and calculating the transformation ratio and complex admittances of parallel elements using a processor, allowing for the calculation of the input voltage without prior knowledge of transformation ratios or no-load currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If direct voltage measurement instrumentation is installed at transforming stations, then input voltage can be accurately measured, but device complexity and installation difficulty increase due to compact design
Solution Approach 1:
The patent uses current measurements and calculations as an intermediary method to indirectly determine input voltage, avoiding the need for direct voltage measurement instrumentation at the transforming station. By measuring currents at accessible points and using transformer characteristics to calculate the input voltage, the system achieves measurement accuracy without physical installation complexity
Solution Approach 2:
The patent replaces physical voltage measurement instrumentation with a computational approach. Instead of using hardware voltage sensors that would require installation in compact transforming stations, the system uses mathematical calculations based on current measurements and transformer parameters to determine input voltage
2Measurement precision
If transformation ratio and no-load current are known, then input voltage can be calculated from output measurements, but these parameters are unknown in existing installations
Solution Approach 1:
The patent performs preliminary measurements and calculations to determine the transformation ratio and no-load current characteristics of the transformer before using them for input voltage determination. By characterizing the transformer parameters in advance through measurable quantities, the system enables accurate ongoing calculations without requiring pre-existing knowledge of these parameters
Solution Approach 2:
The patent uses feedback from output current and voltage measurements, combined with input current measurements, to continuously refine and determine the transformation ratio and no-load current parameters. This feedback loop allows the system to learn transformer characteristics operationally and use them for accurate input voltage calculation
3Adaptability or versatility
If decentralized generating installations are connected to medium-voltage level, then renewable energy is utilized, but load peaks and excessive voltages occur damaging end-user appliances
Solution Approach 1:
The patent implements a monitoring system that continuously measures currents and calculates voltages to detect load peaks and excessive voltage conditions caused by decentralized generating installations. This real-time feedback enables early warning and protective actions before damage occurs to end-user appliances
Solution Approach 2:
The patent enables preliminary detection of potentially harmful voltage conditions through continuous monitoring and calculation. By identifying excessive voltages before they reach damaging levels, the system can trigger protective measures in advance, preventing harm to connected equipment
4Reliability
If monitoring instrumentation is installed at all transforming stations, then power flow and voltage profile are monitored, but cost and complexity increase significantly
Solution Approach 1:
The patent extracts the essential monitoring function from complex physical instrumentation and implements it through simplified current measurements and calculations. By taking out only the necessary measurement elements (current sensors) and using computational methods, the system achieves reliable power flow and voltage monitoring without the complexity of installing comprehensive instrumentation at every transforming station
Data Source
AI summary
A method and device are provided for determining an input voltage of a transformer of a local network station. The method includes measuring an input current of the transformer, an output current of the transformer, an output voltage of the transformer, and a phase angle between the output current and output voltage. The method also includes determining a translation ratio and an admittance of a cross-member of a p-equivalent circuit diagram of the transformer of the local network station using the measured input current, the measured output current, the measured output voltage and the phase angle between the output current and the output voltage. The method also includes determining the input voltage of the transformer of the local network station based on the determined translation ratio and the determined admittance of the cross-member of the p-equivalent circuit diagram.