DC Intermediate Bus Energy Router for Urban Railway
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Solution Overview
Problem
The existing energy feedback systems in urban railway trains face inefficiencies in regenerative braking energy distribution and integration of photovoltaic energy due to high conversion losses and lack of controllable energy flows, leading to reduced energy conservation and inefficient energy utilization.
Innovation Solution
An optimized energy interconnection system featuring a DC intermediate bus and multi-port flow controllable energy routers, which actively direct regenerative braking energy and integrate photovoltaic energy, reducing transmission losses and enhancing energy utilization by connecting with distributed power generation and storage systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If regenerative braking energy is fed back to AC power grid through existing energy feedback device, then energy feedback function is achieved, but energy conservation evaluation is difficult and extra electric energy consumption occurs
Solution Approach 1:
The patent introduces a DC intermediate bus as an intermediary component between the DC traction power grid and AC power grid. This DC intermediate bus serves as a mediator that receives regenerative braking energy from the DC traction power grid and distributes it to trains that need power, avoiding direct conversion to AC and subsequent conversion back to DC, thereby reducing energy loss and enabling controllable energy circulation.
Solution Approach 2:
The DC intermediate bus performs multiple functions: it serves as an energy storage buffer, a distribution hub for regenerative braking energy, and a connection interface between DC and AC power systems. This multi-functionality eliminates the need for separate energy feedback devices and simplifies the overall system while improving energy conservation.
2Loss of energy
If photovoltaic electric energy is integrated into traction power grid through DC-DC conversion and DC-AC conversion with power transformer, then integration is achieved, but conversion efficiency is greatly reduced due to multiple conversion stages
Solution Approach 1:
The patent extracts the DC-AC conversion stage from the photovoltaic energy integration path by directly connecting the photovoltaic array to the DC intermediate bus through DC-DC conversion only. This eliminates the unnecessary AC conversion and power transformation stages, significantly reducing conversion losses while simplifying the system architecture.
3Device complexity
If photovoltaic electric energy is integrated into traction power grid through DC-DC boost conversion only, then conversion stages are reduced, but transmission loss is larger
Solution Approach 1:
The DC intermediate bus acts as an intermediary that enables efficient energy distribution. By connecting photovoltaic arrays to the DC intermediate bus and using the bus's capacitance and active power filter for energy buffering and regulation, the system achieves low transmission loss without requiring excessive conversion stages, as the DC intermediate bus naturally manages energy flow and reduces transmission inefficiencies.
4Loss of energy
If power transformer is used to connect energy systems to AC power grid, then connection is achieved, but no-load loss occurs and volume is large
Solution Approach 1:
The patent removes the power transformer from the system architecture by establishing a direct DC connection between the DC intermediate bus and the DC traction power grid. This extraction eliminates the transformer's no-load losses and reduces system volume, as the DC intermediate bus and its associated components (capacitors, active power filters) occupy less space and consume no idle power.
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 system accurately controls regenerative braking energy distribution, increases energy utilization, and reduces transmission losses by directing energy among all trains in a route, improving the overall efficiency of energy use and eliminating the need for intermediate conversion stages.
Implementation Method 1
The multi-port flow controllable energy routers are connected to the DC intermediate bus and the DC traction bus respectively, for directionally transferring regenerative braking energy from the DC traction bus
Implementation Method 2
a DC intermediate bus and multi-port flow controllable energy routers. The multi-port flow controllable energy routers are connected to the DC intermediate bus and the DC traction bus respectively
Implementation Method 3
a photovoltaic array undergoes a DC-DC boost conversion, and is integrated into a 1500V DC traction power grid
Data Source
AI summary
Disclosed is an optimized energy interconnection system for an urban railway train in the technical field of urban railway transportation power supply, for addressing the technical problem that distribution of regenerative braking energy flows cannot be accurately determined. The system includes a DC intermediate bus and a multi-port flow controllable energy router. The multi-port flow controllable energy router can comprehensively control a source and a load connected in parallel on the DC intermediate bus and thus can accurately determine the distribution of regenerative braking energy flows, thereby forming a well-developed system for evaluating usage of the braking energy.