Systems and methods for islanding detection

摘要

A solar power inverter that detects islanding conditions includes a power generation component that generates alternating current (AC) from direct current produced by photovoltaic cells. The inverter generates AC for a load or an electrical power grid. The inverter also includes a component that generates synchrophasors from characteristics of electrically proximate AC. The inverter further includes a component that receives grid synchrophasors transmitted from a location on the electrical power grid (e.g., a transmission substation). The inverter further includes a controller that uses the inverter synchrophasors and the grid synchrophasors to calculate a degree of correlation between the electrical power grid AC frequency and the frequency of the electrically proximate AC. If the degree of correlation dips below a predefined value or exhibits certain patterns or behaviors that are indicative of a loss of mains (e.g., a loss of main power along the electrical power grid), the controller can cause the power generation component to stop generating AC or cause the inverter to intentionally island by electrically disconnecting from the electrical power grid.

主权项

1. A solar power inverter comprising:
a direct current (DC) input component configured to receive DC produced by one or more photovoltaic cells; a power generation component configured to generate alternating current (AC) from the DC produced by one or more photovoltaic cells; an AC output component configured to output generated AC, wherein the AC output component is electrically coupleable to an electrical power grid; a data input/output component configured to receive signals indicating electrical power grid synchrophasors, wherein the electrical power grid synchrophasors describe characteristics of AC transmitted by the electrical power grid; a phasor measurement unit configured to generate inverter synchrophasors, wherein the inverter synchrophasors describe characteristics of AC electrically proximate to the AC output component; and a controller coupled to the data input/output component and the phasor measurement unit, wherein the controller is programmed to-receive the electrical power grid synchrophasors from the data input/output component;
receive the inverter synchrophasors from the phasor measurement unit;based upon the electrical power grid synchrophasors, determine a first set of n frequency values for the AC transmitted by the electrical power grid;based upon the inverter synchrophasors, determine a second set of n frequency values for the generated AC; anddetermine a correlation coefficient representing a measure of a statistical correlation between the set of n frequency values for the AC transmitted by the electrical power grid and the set of n frequency values for the generated AC; wherein the correlation coefficient is determined byp^=n⁢⁢Σ⁢⁢xy-Σ⁢⁢x⁢⁢Σ⁢⁢y[n⁢⁢Σ⁢⁢x2-(Σ⁢⁢x)2]·[n⁢⁢Σ⁢⁢y2-(Σ⁢⁢y)2] where x is the electrical power grid frequency value measured at a particular time, v is the frequency of the generated AC measured at the same time, and n is the total number of samples in each set of the frequency measurements; anddetermining if the correlation coefficient falls below a threshold and if so, determining that an a islanding condition for the solar power inverter has occurred.