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Fault Protection and Restoration Scheme for Integrated EV Charging Station with DC Collection Bus

IP.com Disclosure Number: IPCOM000248403D
Publication Date: 2016-Nov-25
Document File: 8 page(s) / 373K

Publishing Venue

The IP.com Prior Art Database

Related People

HaiLian Xie: AUTHOR [+4]

Abstract

The disclosure is composed of method and system for protecting integrated EV charging station which supply power for EV chargers by using utility converter or multi distributed generators (PV and Energy Storage) installed in DC bus and feeders. With the proposed protection scheme, fault detection, isolation and restoration functionality can be realized to ensure the secure and reliable operation of the system.

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Disclosure Title:

Fault protection and restoration scheme for integrated EV charging station with DC collection bus

Abstract:

The disclosure is composed of method and system for protecting integrated EV charging station which supply power for EV chargers by using utility converter or multi distributed generators (PV and Energy Storage) installed in DC bus and feeders. With the proposed protection scheme, fault detection, isolation and restoration functionality can be realized to ensure the secure and reliable operation of the system.

Statement of the Problem:

This disclosure aims to solve three problems to protect the DC integrated EV charging station which have potentially multiple sources for short current contribution, including utility converter, PV generator, Energy Storage (ES) converter, etc.:

1. How to design the protection architecture and principles to detect, locate and isolate the fault with high reliability and sensitivity, considering multiple sources of short-circuit current and bi- directional power flow;

2. How to coordinate the multiple protection relays and the control system of the DC integrated EV charging station to minimize the impact of fault on the continuous power supply, and to ensure the robust system restoration;

3. How to tune the parameters in a self-adaptive way for different protection relays in order to make sure that the proposed protection scheme can be used for both grid-connected mode and islanding mode, and under different system configuration and operation points which are determined by the controls for the DC integrated EV charging station.

Novel Feature

1. Three fault protections for integrated EV charging station with DC collection grid and multi DC generators will be focused, including over current fault, pole-to-pole short circuit fault and pole- to-ground short circuit fault. DC current differential protection method will be applied.

2. By comparing the measured current at each point with the set current threshold, the over current can be distinguished. By comparing the sum value of each branch current with the set current threshold, pole-to-pole short circuit and pole-to-ground short circuit can be distinguished. Different combinations will detect and locate different faults.

In summary, a new fault protection and restoration scheme design for integrated EV charging station with DC collection bus and feeders is developed in this disclosure in order to ensure its secure and reliable operation. It involves at least four aspects:

Protection architecture to minimize the fault impact on the continuous operation of the remaining system;

Protection principle design for integrated EV charging station with DC collection grid and multi DC generators to realize reliable and sensitive fault detection, accurate location and effective isolation considering multiple sources of short-circuit current and bi-directional power flow;


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Coordinated protection and control methods for integrated...