Synchronous Soft-Start Networking for EMU Auxiliary Converters
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing EMU systems face challenges in quickly completing parallel networking of auxiliary converters during both normal and emergency traction modes, leading to potential startup failures due to voltage and current imbalances, especially in emergency situations where network guidance is absent.
Innovation Solution
A synchronous soft-start networking control strategy is implemented, utilizing fast networking logic to determine the first auxiliary converter and bus fast-tracking strategies to quickly synchronize with bus voltage, combined with a PQ droop control strategy to enhance current sharing, ensuring reliable and timely networking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If multiple auxiliary converters are connected to the bus simultaneously as the first auxiliary converter to quickly complete networking, then the networking speed is improved, but voltage and current imbalances occur causing overvoltage or overcurrent
Solution Approach 1:
The patent applies preliminary action by implementing a pre-networking phase where auxiliary converters prepare and synchronize their output voltages before actually connecting to the bus. This includes voltage amplitude adjustment, phase synchronization, and frequency matching performed in advance, ensuring that when converters connect simultaneously, no voltage or current imbalances occur.
Solution Approach 2:
The patent applies dynamics by making the auxiliary converters dynamically adjustable during the networking process. The converters can dynamically change their output voltage parameters (amplitude, phase, frequency) to match the bus conditions, and the system transitions from a static connection state to a dynamic synchronization state, allowing adaptive response to different networking scenarios.
2Loss of time
If auxiliary converters complete networking within the prescribed time limit, then the EMU startup succeeds, but the networking process becomes complex requiring precise coordination
Solution Approach 1:
The patent applies self-service by enabling auxiliary converters to autonomously complete the networking process without external intervention. Each converter independently detects bus conditions, adjusts its parameters, and executes the connection sequence automatically. The system includes self-diagnosis and self-correction capabilities that monitor networking progress and adjust parameters in real-time, reducing the need for complex external control while meeting the 15-second requirement.
Solution Approach 2:
The patent applies segmentation by dividing the networking process into distinct sequential phases: voltage parameter preparation, phase synchronization, frequency matching, and final connection. Each phase has specific control objectives and can be independently optimized, breaking down the complex 15-second networking requirement into manageable segments that are easier to control and verify.
3Adaptability or versatility
If auxiliary converters operate in emergency traction mode without network guidance, then the EMU can still run to a nearby station, but the automatic networking process becomes unreliable
Solution Approach 1:
The patent applies beforehand cushioning by preparing backup networking capabilities and protective measures in advance for emergency situations. The system pre-configures alternative networking pathways and protective control parameters that activate automatically when network guidance is unavailable. This includes pre-established synchronization algorithms and voltage/current protection thresholds that cushion against the unreliability of unguided automatic networking.
4Productivity
If the output contactor is closed to establish bus three-phase power, then the networking is completed, but voltage imbalances cause rectified state and overvoltage of supporting capacitor
Solution Approach 1:
The patent applies feedback by implementing real-time monitoring of voltage and current parameters during the networking process and the subsequent operation after contactor closure. The system continuously detects voltage imbalances and provides feedback to the control system, which automatically adjusts converter parameters to eliminate imbalances and prevent overvoltage or overcurrent conditions, ensuring safe and efficient operation.
Data Source
AI summary
A synchronous soft-start networking control strategy for parallel auxiliary converters of EMU, that is, when a first auxiliary converter is connected to the bus, non-first auxiliary converters complete the networking during an amplitude soft-start process of the first auxiliary converter. Specific solution is: fast networking logic, bus fast-tracking logic and PQ droop networking control strategy. Wherein, the fast networking logic comprises recognizing the first auxiliary converter and the non-first auxiliary converter; the bus fast-tracking logic comprises tracking phase, frequency and amplitude; the PQ droop networking control strategy comprises introducing a correction coefficient K. The synchronous soft-start networking control strategy for the parallel auxiliary converters of EMU can realize quickly and reliably automatic networking in an emergency traction mode of EMU, and significantly shorten networking time in a network normal mode of EMU. Therefore, it can ensure that EMU can complete startup loading within a specified time under various working conditions, which provides strong guarantee for stable and reliable operation of EMU.