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An auxiliary system for starting a PV inverter connected to a cold grid

IP.com Disclosure Number: IPCOM000240545D
Publication Date: 2015-Feb-09
Document File: 2 page(s) / 33K

Publishing Venue

The IP.com Prior Art Database

Abstract

This document describes a system where external auxiliary power supply is used for starting a PV inverter connected to a cold grid.

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1.Abstract

This document describes a system where external auxiliary power supply is used for starting a PV inverter connected to a cold grid.


2.Background

Some time ago the grid connected PV inverters were only able to start if there was voltage present at the grid. Some PV inverters are not directly connected to the PV generator and they need pre-charging of the DC-link from the grid prior the start-up. In the PV industry there has emerged a need for starting grid connected PV inverters in a black start situation. In order to support the grid and for commissioning purposes, PV inverters have been developed for also connecting to a cold grid. Various ways of supplying a temporary grid have been introduced, such as using a generator to mimic the grid with nominal electrical values for the inverter startup and when the first inverter is feeding to the grid, the generator can be stopped.


3.New solution

In central inverter commissioning or a cold start situation, a grid connection is not available. In this new solution, an external auxiliary power supply is used for pre-charging the power modules' DC link. DC link charging can be done by feeding the power either to the AC side or directly to the DC side as shown in the fig 1. The external power supply can be eg a generator or an energy storage connected inverter. With an external power supply the inverter's first wake-up can be done with or without PV power. The external power supply can also be used for supplying the inverter the auxiliary power it needs for controlling the inverter in the case that the power for the auxiliary sys...