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Resolve #140 snlinverter night tare power issue #141

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Merged
merged 5 commits into from
Apr 12, 2016
Merged

Resolve #140 snlinverter night tare power issue #141

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c90b7d0
Resolve #140 snlinverter night tare power issue
ejmiller2 Mar 23, 2016
e5d591d
Test for Pnt error with microinverter
ejmiller2 Mar 23, 2016
1371b4d
Update v0.3.1.txt
ejmiller2 Mar 23, 2016
edc4177
Update night tare issue description.
ejmiller2 Mar 24, 2016
2a9d4cc
Reformatted bug fix description.
ejmiller2 Mar 24, 2016
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7 changes: 7 additions & 0 deletions docs/sphinx/source/whatsnew/v0.3.1.txt
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Expand Up @@ -15,8 +15,15 @@ Enhancements
Bug fixes
~~~~~~~~~

* Fixes night tare issue in snlinverter. When the DC input power (p_dc)
to an inverter is below the inversion startup power (Ps0), the model
should set the AC output (ac_power) to the night tare value (Pnt).
The night tare power indicates the power consumed by the inverter to
sense PV array voltage. The model was erroneously comparing Ps0 with
the AC output power (ac_power), rather than the DC input power (p_dc).


Contributors
~~~~~~~~~~~~

* ejmiller2
2 changes: 1 addition & 1 deletion pvlib/pvsystem.py
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Expand Up @@ -1662,7 +1662,7 @@ def snlinverter(inverter, v_dc, p_dc):

ac_power = (Paco/(A-B) - C*(A-B)) * (p_dc-B) + C*((p_dc-B)**2)
ac_power[ac_power > Paco] = Paco
ac_power[ac_power < Pso] = - 1.0 * abs(Pnt)
ac_power[p_dc < Pso] = - 1.0 * abs(Pnt)

if len(ac_power) == 1:
ac_power = ac_power.ix[0]
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11 changes: 11 additions & 0 deletions pvlib/test/test_pvsystem.py
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Expand Up @@ -384,6 +384,17 @@ def test_snlinverter_float():
assert_almost_equals(pacs, 132.004278, 5)


def test_snlinverter_Pnt_micro():
inverters = sam_data['cecinverter']
testinv = 'Enphase_Energy__M250_60_2LL_S2x___ZC____NA__208V_208V__CEC_2013_'
vdcs = pd.Series(np.linspace(0,50,3))
idcs = pd.Series(np.linspace(0,11,3))
pdcs = idcs * vdcs

pacs = pvsystem.snlinverter(inverters[testinv], vdcs, pdcs)
assert_series_equal(pacs, pd.Series([-0.043000, 132.545914746, 240.000000]))


def test_PVSystem_creation():
pv_system = pvsystem.PVSystem(module='blah', inverter='blarg')

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