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SYSTEM AND METHOD FOR IMPLEMENTING A STARTUP ALGORITHM FOR SOLAR INVERTER

IP.com Disclosure Number: IPCOM000246315D
Publication Date: 2016-May-27
Document File: 4 page(s) / 47K

Publishing Venue

The IP.com Prior Art Database

Abstract

The invention proposes a system and method for implementing a startup algorithm for a solar power inverter. The system is configured to update the geographic data and determine sunrise and sunset time using a logic algorithm. The logic system is programmed to close the main DC switches with a set time period after sunrise. If the set time is not lapsed, the system will wait until it reaches that time. Then, DC voltage of the PV array is measured by the inverter to determine the next logical condition to proceed with the start-up sequence. If the desired voltage level is not generated, the system will wait until it reaches the voltage level, and start up the inverter thereafter. Advantages of the invention include consistent safe voltage levels from PV array to the inverter, preventing reverse current, increased power output due to precision in determining PV output and increased contactor lifetime.

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SYSTEM AND METHOD FOR IMPLEMENTING A STARTUP ALGORITHM FOR SOLAR INVERTER

BACKGROUND

The invention is in general related to solar power generation system and in particular to a system and method for implementing a startup algorithm for a solar inverter. A solar inverter is used for converting DC current from photovoltaic (PV) arrays into AC current for the electric grid. The inverters in PV arrays are connected to a main DC switch using feeders. Before starting the inverter or closing the main DC switches, a DC contactor is used to assess the voltage level of the PV arrays. The voltage level at the PV panel is reported to the controller, which determines if the voltage is high enough to close the main DC switches. The measurement is important because if the DC voltage of the PV array is too low, the current could flow backwards through the inverter into the PV arrays. For example, a DC contactor would measure the DC voltage of the PV arrays every 5 minutes during sunrise time, when the inverter is not yet running. This is inefficient because the contactor would primarily be used during the dark early hours of the morning when the inverter would never start up, but is necessary so as not to miss potential power production. As the sunrise and sunset varies from day to day, it is not possible to create a set point to turn on the inverter and use the daylight most efficiently.

Existing solar inverter do not have a localized measurement system to detect the presence of sunlight and the inverter must operate without communications to a control system. Thus, there is a need for a better means of determining sunrise and sunset, so that the inverter could be started optimally.

BRIEF DESCRIPTION OF DRAWINGS

The invention discloses a system and method for implementing a startup control algorithm for solar inverter, wherein:

FIG. 1 shows a method for implementing startup algorithm in solar inverter.

FIG. 2 shows startup algorithm for solar power inverter.

DETAILED DESCRIPTION

The invention proposes a system and method for implementing a startup algorithm for a solar power inverter. The system is configured to update the geographic data using a logic algorithm, as indicated in FIG. 1. The sunrise and sunset time is calculated and determined based on the geographic location. The logic system is programmed with a set time period after sunrise (for example 30 minutes) to close the main DC switches. If the set time is not lapsed, the system will wait until it reaches that time. Then, DC voltage of the PV array is measured by the inverter to determine the next logical condition to proceed with the start-up sequence. If the desired voltage level is not generated, the system will wait until it reaches the voltage level. Finally, after achieving the desired voltage level, s...