ESS Charging Control for Train Catenary Voltage Stability
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Solution Overview
Problem
Existing energy storage systems (ESS) for trains lack efficient control methods for energy storage and usage, and require adaptable operation standards for various situations and locations, especially when integrating with renewable energy sources like wind and solar power.
Innovation Solution
An ESS charging and discharging operation method that checks the State of Charge (SOC) and performs catenary wire voltage control based on voltage and variation rate, allowing for charging or discharging and updating reference values to optimize energy efficiency and adaptability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If ESS control method is designed for specific installation location, then energy efficiency is optimized for that location, but adaptability to various situations and places deteriorates
Solution Approach 1:
The patent creates a universal ESS control method that can be applied to different installation locations (train-mounted or substation-mounted) and various operating situations. The control method uses standardized reference values and decision logic that adapt to different contexts without requiring location-specific customization, thus achieving both energy efficiency and broad adaptability.
Solution Approach 2:
The control method dynamically adjusts charging/discharging decisions based on real-time conditions such as catenary wire voltage, voltage variation rate, and ESS state of charge. This dynamic adaptation allows the system to optimize energy efficiency for each specific situation while maintaining a universal control framework that works across different installation locations and operating conditions.
2Stability of the object's composition
If ESS operation standards are fixed, then system stability is improved, but ease of updating and adaptation to new situations deteriorates
Solution Approach 1:
The control method segments the operation standards into distinct reference values (voltage reference, voltage variation rate reference, current reference, SOC reference) that can be independently adjusted. This segmentation allows the system to maintain overall stability through a structured framework while enabling easy updating of individual parameters without affecting the entire control system.
Solution Approach 2:
The patent enables easy updating of operation standards by allowing modification of key parameters such as voltage reference values, voltage variation rate references, and SOC thresholds. These parameter changes can be made to adapt to different installation locations and operating conditions while maintaining the stability provided by the overall control structure.
3Stability of the object's composition
If catenary wire voltage control is continuously performed, then voltage stability is improved, but energy consumption of ESS deteriorates
Solution Approach 1:
The control method implements periodic voltage control by checking catenary wire voltage and voltage variation rate at specific intervals and only performing charging/discharging operations when reference values are exceeded. This periodic action maintains voltage stability when needed while avoiding unnecessary ESS energy consumption during normal operating conditions.
Solution Approach 2:
The control method uses feedback from catenary wire voltage and voltage variation rate measurements to determine when ESS charging or discharging should occur. This feedback mechanism ensures voltage stability is maintained only when actually needed, preventing unnecessary energy consumption by the ESS during periods when voltage is already within acceptable ranges.
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 method enhances energy efficiency for regenerative braking in trains and railway substations, enables easy updating of operation standards, and maximizes energy utilization across different scenarios.
Implementation Method 1
A lithium-ion (Li) battery with a separator between anode and cathode and an electrolyte, as a representative secondary battery, stores and releases energy when lithium ions travel between anode and cathode electrodes through the electrolyte.
Implementation Method 2
the ESS for regenerative braking for trains draws the attention as a new application of the ESS and it has effects of increasing energy efficiency by storing energy generated and consumed when a train stops and starts
Data Source
AI summary
An ESS charging and discharging operation method may include the steps of: checking whether SOC of the ESS is within an operable range, and performing an SOC management operation if the SOC of the ESS is not within the operable range; performing, if the SOC of the ESS is within the operable range, a catenary wire voltage control operation based on range of catenary wire voltage and range of variation rate of the catenary wire voltage; performing the SOC management operation after the ESS is charged or discharged depending on the catenary wire voltage control operation over unit time, if output current of the ESS does not exceed current reference value; and stopping the catenary wire voltage control operation and switching the operation to a standby state.