Converter Station Voltage Control via Fundamental Amplitude
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Solution Overview
Problem
Existing methods for minimizing energy transmission losses via contact lines in electrical railway networks fail when the transmission of measured output voltages from substations to the converter station is disrupted, preventing optimal voltage synchronization and increased losses.
Innovation Solution
Determining a target fundamental oscillation amplitude and power factor allows for the calculation of active and reactive power setpoints, enabling the adjustment of the converter station's output voltage even in the absence of direct voltage measurements, using a network controller to manage power and voltage settings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the converter station adjusts its output voltage based on real-time measured output voltages from substations, then transmission losses via overhead lines are minimized, but the system becomes vulnerable to transmission failures that prevent voltage synchronization
Solution Approach 1:
The system performs preliminary determination of the fundamental amplitude of the measured voltage and calculates target fundamental amplitude and target power factor in advance. These preliminary calculations enable the converter station to determine active and reactive power setpoints that can be used even when real-time voltage transmission fails, thus maintaining energy efficiency while improving reliability
Solution Approach 2:
The invention introduces an intermediary calculation method that uses fundamental amplitude analysis and power factor determination as intermediate steps between raw voltage measurements and final voltage adjustment. This intermediary approach allows the system to derive meaningful control parameters (active and reactive power setpoints) even when direct voltage transmission is disrupted
2Reliability
If the system uses direct transmission of measured output voltages from substations to converter station, then voltage synchronization is achieved, but the system fails when transmission is disrupted
Solution Approach 1:
The system changes the parameters used for voltage synchronization from direct reliance on transmitted voltage measurements to using locally determined fundamental amplitude and power factor. By transforming the control parameters from transmitted voltage values to locally calculated power setpoints, the system maintains synchronization capability while adapting to transmission failures
3Reliability
If the converter station operates without real-time voltage transmission from substations, then system reliability under failure conditions improves, but transmission losses increase due to inability to optimize voltage
Solution Approach 1:
The converter station performs self-service by determining the fundamental amplitude and calculating power setpoints using locally available information and predetermined target values. This self-service capability allows the station to maintain optimized operation and minimize transmission losses even when external voltage transmission data is unavailable
Data Source
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Figure 3a~3b
AI summary
The method involves determining a fundamental oscillation amplitude of substations (11, 12) from measured voltage such that target fundamental oscillation amplitude i.e. voltage amplitude, and a target power factor i.e. average power factor, are predetermined. An active power reference value and a reactive power reference value are determined from the fundamental oscillation amplitude, the target fundamental oscillation amplitude and the power factor. Active power actual and reactive power actual values are determined from the fundamental oscillation amplitude, a phase and measured current. An independent claim is also included for a device for operating a converter unit of an electrical railway network, comprising a power supply regulator.