From 0d5c0872f62b3f6e2d1baac60ab5600826105306 Mon Sep 17 00:00:00 2001 From: Cliff Hansen Date: Wed, 17 Apr 2024 10:26:11 -0600 Subject: [PATCH] edit definitions of mode --- docs/examples/snow-detection/snow-mode.py | 38 +++++++++++++---------- pvanalytics/features/snow.py | 31 +++++++++--------- 2 files changed, 37 insertions(+), 32 deletions(-) diff --git a/docs/examples/snow-detection/snow-mode.py b/docs/examples/snow-detection/snow-mode.py index 154bb89b..159e0172 100644 --- a/docs/examples/snow-detection/snow-mode.py +++ b/docs/examples/snow-detection/snow-mode.py @@ -6,17 +6,22 @@ The effect of snow is classified into one of five categories: - Mode 0: The system is covered with enough opaque snow that the system is - offline due to voltage below the inverter's turn-on voltage. - Mode 1: The system is online and covered with non-uniform snow, such that - both operating voltage and current are reduced. - Mode 2: The system is online and covered with opaque snow, such that - operating voltage is reduced by the snow, but transmission - is consistent with snow-free conditions. # TODO seems contradictory - Mode 3: The system is online and covered with light-transmissive snow, - such that current is decreased but voltage is consistent with all - system substrings being online. - Mode 4: Current and voltage are consistent with snow-free conditions. + * Mode 0: Indicates periods with enough opaque snow that the system is not + producing power. Specifically, Mode 0 is when the measured voltage is + below the inverter's turn-on voltage but the voltage modeled using + measured irradiance is below the inverter's turn-on voltage. + * Mode 1: Indicates periods when the system has non-uniform snow and + both operating voltage and current are decreased. Operating voltage is + reduced when bypass diodes activate and current is decreased due to + decreased irradiance. + * Mode 2: Indicates periods when the operating voltage is reduced but + current is consistent with snow-free conditions. + * Mode 3: Indicates periods when the operating voltage is consistent with + snow-free conditionss but current is reduced. + * Mode 4: Voltage and current are consistent with snow-free conditions. + + Mode is None when both measured and voltage modeled from measured + irradiance are below the inverter turn-on voltage. The procedure involves four steps: 1. Using measured plane-of-array (POA) irradiance and temperature, model @@ -380,12 +385,11 @@ def wrapper(voltage, current, temp_cell, effective_irradiance, This function illustrates a workflow to get to snow mode: - 1. Model effective irradiance based on measured current using the SAPM - 2. Calculate transmission - 3. Uses transmission to model voltage with the SAPM. - # TODO How is this voltage different than measured (snow-affected voltage)? - # Answer: All cells are modeled to get the incoming irradiance - 4. Determine the snow mode for each point. + 1. Model effective irradiance based on measured current using the SAPM. + 2. Calculate transmission. + 3. Model voltage from measured irradiance reduced by transmission. Assume + that all strings are producing voltage. + 4. Determine the snow mode for each point in time. Parameters ---------- diff --git a/pvanalytics/features/snow.py b/pvanalytics/features/snow.py index ca7543bf..0922d7cd 100644 --- a/pvanalytics/features/snow.py +++ b/pvanalytics/features/snow.py @@ -155,20 +155,21 @@ def categorize(vmp_ratio, transmission, measured_voltage, modeled_voltage, Modes are defined in [1]_: - * Mode 0: system is covered with enough opaque snow that the system is - offline due to voltage below the inverter's turn-on voltage. Excludes - periods when voltage modeled using measured irradiance does not - exceed the inverter's turn-on voltage. - * Mode 1: system is online and covered with non-uniform snow, such that - both operating voltage and current are decreased by the presence of snow. - * Mode 2: system is online and covered with opaque snow, such that - operating voltage is decreased by the presence of snow, but transmission - is consistent with snow-free conditions. - * Mode 3: system is online and covered with light-transmissive snow, such - that transmission is decreased but voltage is consistent with all - system substrings being online. - * Mode 4: transmisison and voltage are consistent with snow-free - conditions. + * Mode 0: Indicates periods with enough opaque snow that the system is not + producing power. Specifically, Mode 0 is when the measured voltage is + below the inverter's turn-on voltage but the voltage modeled using + measured irradiance is below the inverter's turn-on voltage. + * Mode 1: Indicates periods when the system has non-uniform snow and + both operating voltage and current are decreased. Operating voltage is + reduced when bypass diodes activate and current is decreased due to + decreased irradiance. + * Mode 2: Indicates periods when the operating voltage is reduced but + current is consistent with snow-free conditions. + * Mode 3: Indicates periods when the operating voltage is consistent with + snow-free conditionss but current is reduced. + * Mode 4: Voltage and current are consistent with snow-free conditions. + * Mode is None when both measured and voltage modeled from measured + irradiance are below the inverter turn-on voltage. Parameters ---------- @@ -196,7 +197,7 @@ def categorize(vmp_ratio, transmission, measured_voltage, modeled_voltage, Returns ------- - mode : int + mode : int or None .. [1] E. C. Cooper, J. L. Braid and L. M. Burnham, "Identifying the Electrical Signature of Snow in Photovoltaic Inverter Data," 2023 IEEE