Monitoring and Evaluating Performance and Aging of Solar Photovoltaic Generation Systems and Power Inverters

Patent metadata

Field	Value
Publication number	US-2017366010-A1
Application number	US-201615188389-A
Country	US
Kind code	A1
Filing date	Jun 21, 2016
Priority date	Jun 21, 2016
Publication date	Dec 21, 2017
Grant date	—

Abstract

Techniques for detailed monitoring and evaluation of individual subsystems within solar photovoltaic power generation systems are provided. In one aspect, a method for monitoring a photovoltaic system having at least one array of photovoltaic panels and at least one inverter system configured to convert output from the panels from DC to AC includes the steps of: obtaining sensor data from the photovoltaic system; computing an efficiency of the panels and an efficiency of the inverter system using the sensor data; computing an aging parameter for the panels using the efficiency of the panels; computing an aging parameter for the inverter system using the efficiency of the inverter system; determining whether the aging parameter for the panels or for the inverter system exceeds a predetermined threshold level; and taking action if either the aging parameter for the array or for the inverter system exceeds the predetermined threshold level.

First claim

What is claimed is:

1 . A method for monitoring a photovoltaic system having at least one array of photovoltaic panels and at least one inverter system configured to convert output from the array of photovoltaic panels from direct current (DC) to alternating current (AC), the method comprising the steps of:
obtaining sensor data from the photovoltaic system, wherein the sensor data comprises i) ambient conditions at the array of photovoltaic panels, ii) photovoltaic panel current and voltage outputs, iii) current and voltage inputs to the inverter system, and iv) current and voltage outputs from the inverter system; computing an efficiency of the array of photovoltaic panels nPV using the sensor data; computing an efficiency of the inverter system nINV using the sensor data; computing an aging parameter for the array of photovoltaic panels using the efficiency of the array of photovoltaic panels nPV; computing an aging parameter for the inverter system using the efficiency of the inverter system nINV; determining whether the aging parameter for the array of photovoltaic panels or the aging parameter for the inverter system exceeds a predetermined threshold level; and taking action if either the aging parameter for the array of photovoltaic panels or the aging parameter for the inverter system exceeds the predetermined threshold level.

2 . The method of claim 1 , wherein the photovoltaic panel current and voltage outputs are obtained from individual photovoltaic panels in the array.

3 . The method of claim 1 , wherein the photovoltaic panel current and voltage outputs are obtained from the array of photovoltaic panels.

4 . The method of claim 1 , wherein the ambient conditions at the array of photovoltaic panels are selected from the group consisting of: irradiance, ambient temperature, surface temperature of the array of photovoltaic panels, and combinations thereof.

5 . The method of claim 1 , wherein the step of computing the efficiency of the array of photovoltaic panels nPV comprises the steps of:
computing an ideal output power Pvoltage for the array of photovoltaic panels using the ambient conditions, wherein the ideal output power for the array of photovoltaic panels is a maximum amount of power the array of photovoltaic panels can produce at a given output voltage; computing an actual output power Pdc for the array of photovoltaic panels using the current and voltage output from the array of photovoltaic panels; and computing the efficiency of the array of photovoltaic panels nPV based on the ideal output power Pvoltage and the actual output power Pdc as nPV =Pdc/ Pvoltage.

6 . The method of claim 1 , further comprising the step of:
normalizing the efficiency of the array of photovoltaic panels nPV using efficiency specifications provided by a manufacturer of the array of photovoltaic panels.

7 . The method of claim 1 , wherein the efficiency of the inverter system nINV is computed using the current and voltage input to the inverter system, and the current and voltage output from the inverter system.

8 . The method of claim 1 , further comprising the step of:
normalizing the efficiency of the inverter system nINV using efficiency specifications provided by a manufacturer of the inverter system.

9 . The method of claim 1 , wherein the aging parameter for the array of photovoltaic panels comprises a time derivative of the efficiency of the array of photovoltaic panels nPV.

10 . The method of claim 1 , wherein the aging parameter for the array of photovoltaic panels comprises a time derivative of the efficiency of the inverter system nINV.

11 . The method of claim 1 , wherein the step of taking action comprises the step of:
modifying the photovoltaic system by bypassing or disconnecting the array of photovoltaic panels if the aging parameter for the array of photovoltaic panels exceeds the predetermined threshold level.

12 . The method of claim 1 , wherein the step of taking action comprises the step of:
scheduling service for the array of photovoltaic panels if the aging parameter for the array of photovoltaic panels exceeds the predetermined threshold level.

13 . The method of claim 1 , wherein the step of taking action comprises the step of:
modifying the photovoltaic system by bypassing or disconnecting the inverter system if the aging parameter for the inverter system exceeds the predetermined threshold level.

14 . The method of claim 1 , wherein the step of taking action comprises the step of:
scheduling service for the inverter system if the aging parameter for the inverter system exceeds the predetermined threshold level.

15 . A system for monitoring a photovoltaic system having at least one array of photovoltaic panels and at least one inverter system configured to convert output from the array of photovoltaic panels from DC to AC, the system comprising:
sensors configured to obtain data from the photovoltaic system, wherein the data obtained from the photovoltaic system comprises i) ambient conditions at the array of photovoltaic panels, ii) photovoltaic panel current and voltage outputs from the array of photovoltaic panels, iii) current and voltage inputs to the inverter system, and iv) current and voltage outputs from the inverter system; and a processor device coupled to a memory, wherein the processor device is operative to:
compute an efficiency of the array of photovoltaic panels nPV using the sensor data;
compute an efficiency of the inverter system nINV using the sensor data;
compute an aging parameter for the array of photovoltaic panels using the efficiency of the array of photovoltaic panels nPV;
compute an aging parameter for the inverter system using the efficiency of the inverter system nINV;
determine whether the aging parameter for the array of photovoltaic panels or the aging parameter for the inverter system exceeds a predetermined threshold level; and
take action if either the aging parameter for the array of photovoltaic panels or the aging parameter for the inverter system exceeds the predetermined threshold level.

16 . The system of claim 15 , wherein the ambient conditions at the array of photovoltaic panels are selected from the group consisting of: irradiance, ambient temperature, surface temperature of the array of photovoltaic panels, and combinations thereof

17 . The system of claim 15 , wherein the processor device when computing the efficiency of the array of photovoltaic panels nPV, is further operative to:
compute an ideal output power Pvoltage for the array of photovoltaic panels using the ambient conditions, wherein the ideal output power for the array of photovoltaic panels is a maximum amount of power the array of photovoltaic panels can produce at a given output voltage; compute an actual output power Pdc for the array of photovoltaic panels using the current and voltage output from the array of photovoltaic panels; and compute the efficiency of the array of photovoltaic panels nPV based on the ideal output power Pvoltage and the actual output power Pdc as nPV=Pdc/Pvoltage.

18 . The system of claim 15 , wherein the efficiency of the inverter system nINV is computed using the current and voltage input to the inverter system, and the current and voltage output from the inverter system.

19 . The system of claim 15 , wherein the aging parameter for the array of photovoltaic panels comprises a time derivative of the efficiency of the array of photovoltaic panels nPV.

20 . The system of claim 15

Assignees

• IBM

Inventors

• Chen Sue Ann
• De Hoog Julian
• Kalyanaraman Shivkumar
• Kolluri Ramachandra R
• Vishwanath Arun

Classifications

• H02J3/381

  Dispersed generators · CPC title

• H02J2101/25

  involving maximum power point tracking control for photovoltaic sources · CPC title

• H02S50/00

  Monitoring or testing of PV systems, e.g. load balancing or fault identification · CPC title

• H02J3/50

  Controlling the sharing of reactive power · CPC title

• H02S50/10

  Testing of PV devices, e.g. of PV modules or single PV cells (testing of semiconductor devices during manufacturing {H10P74/00}) · CPC title