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State Estimation modifications for WLS #2414

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merged 31 commits into from
Dec 19, 2024
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@marcopau marcopau commented Oct 7, 2024

Fixed some bugs to state estimation code, like:

  • power injection results
  • shunts handling
  • current magnitude measurements handling

@vogt31337 vogt31337 marked this pull request as draft October 7, 2024 13:11
@Heiner92
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Great initiative! I hope these changes will improve the results I'm getting in distribution system state estimation where current measurements are usually only available as magnitudes.

root1 = ds_find(ar, bus1)
root2 = ds_find(ar, bus2)
if root1 == root2:
return
if bus_is_pv[root2]:
if bus_is_active[root2] and ~bus_is_pv[root1]: # if root2 is an active bus (load or gen) and root1 is not a PV bus, it will merge root1 into root2

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Here we should actually also make sure that root2 is not external grid or reference bus as well

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If root2 is an external grid it is still fine to merge root1 into root2. You want to keep the PV bus, and in this case root2 (which is the PV bus) would be kept.

if net._fused_bb_switches.any():
# Note: this might seem a little odd - first constructing a pp to ppc mapping without
# fused busses and then update the entries. The alternative (to construct the final
# mapping at once) would require to determine how to fuse busses and which busses
# are not part of any opened bus-bus switches first. It turns out, that the latter takes
# quite some time in the average usecase, where #busses >> #bus-bus switches.

# create mask arrays to distinguish different grid elements

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Redundant code

# one pv bus. Get bus from pv_buses_in_set
map_to = bus_lookup[pv_buses_in_set.pop()]
ref_bus = pv_buses_in_set.pop()

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not a very robust way since if pandapower decides to not have the first element as REF, this wont work and will be difficult to debug

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Explain what "if pandapower decides to not have the first element as REF" means. Feel free also to provide an example where this does not work, so I can look at it.

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if the pv_buses_in_set first element which you are popping is not REF bus because of breaking change from pandapower

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In pv_buses_in_set you have the list of pv buses for the considered set. What I am popping is a PV bus. That bus is then taken as bus to be kept later when doing the merging among multiple buses.

@@ -222,11 +220,12 @@ def _build_pp_gen(net, ppc, f, t):

# set bus values for generator buses
ppc["bus"][gen_buses[ppc["bus"][gen_buses, BUS_TYPE] != REF], BUS_TYPE] = PV

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why here all other buses are set to PV

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Here there is no change. Gen buses are always modelled as PV nodes in pandapower, sgens as PQ.

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yes i am aware of that, the question was why here are the PQ buses exclusively excluded

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This function only deals with gen_buses, and it assigns the label "PV" to them. Other buses are handled somewhere else.


vb = range(len(V))
diagV = sparse((V, (vb, vb)))
diagVnorm = sparse((V / abs(V), (vb, vb)))

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Here there should be try except block because division with zero can occur due to abs(V), it will help enormously if throughindices one could also find the pandapower element (in dataframe) which leads to this exception , for example NaNor zero g_us_per_km attribute for lines, etc

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A division by 0 when dividing by the voltage magnitude? The second part of the comment (looking at the pandapower elements that can bring a division by zero) is not something that has to be addressed in a function to calculate the Jacobian. There are other functions and routines in pandapower that do that.

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@AnkurArohi AnkurArohi Oct 14, 2024

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yes we have this many times for networks which have problems in attribute and is very central as then the algorithm does not work. I am unaware of other functions that does that

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I see, but then the problem in that case is with the network data and with its processing, not with this pull request or with this specific function, so I guess we should shift the discussion somewhere else.

ib = range(len(If))
idxf = abs(If) == 0
idxt = abs(It) == 0
diagIfnorm = sparse((conj(If) / abs(If), (ib, ib)))

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same here with the try and except block

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@marcopau marcopau Oct 14, 2024

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There is a routine in the WLS to avoid using the current magnitude measurements at the first iteration, when currents are initialized as zero. In the other iterations it is quite unlikely to have branch currents exactly equal to 0. If that case happens, I believe we should have some more elaborated routine to deal with it, not just a try and except. It is something that requires some thinking and that would come in one of the next round of updates. For the moment, the priority was to provide a Jacobian for current magnitude measurements that works, at least in most of the cases.

idxt = abs(It) == 0
diagIfnorm = sparse((conj(If) / abs(If), (ib, ib)))
diagItnorm = sparse((conj(It) / abs(It), (ib, ib)))
diagIfnorm[idxf,idxf] = 0

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why this is equated to zero?, please comment

dita_dv = (np.angle(1e-5 * dit_dv + It.reshape((-1, 1))) - np.angle(It.reshape((-1, 1))))/1e-5
difm_dth, difm_dv, ditm_dth, ditm_dv = dIbr_dV_new(self.eppci['branch'], self.Yf, self.Yt, V)
difm_dth, difm_dv, ditm_dth, ditm_dv = map(lambda m: m.toarray(), (difm_dth, difm_dv, ditm_dth, ditm_dv))
difa_dth, difa_dv, dita_dth, dita_dv = 0*difm_dth, 0*difm_dv, 0*ditm_dth, 0*ditm_dv

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why are all these values zero?

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At the moment, we are not yet supporting current phase angles for state estimation. I will add a line of comment there.

@@ -83,6 +86,7 @@ def estimate(self, eppci: ExtendedPPCI, **kwargs):

current_error, cur_it = 100., 0
# invert covariance matrix
eppci.r_cov[eppci.r_cov<(10**(-6))] = 10**(-6)

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This value of 10-6 should ideally be parameterizable

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It is an option I am considering, but I am not yet sure if to put it as an optional parameter for the user or not (I see some pros and cons). In any case, this will be definitely improved in the next round of updates, for the moment it was urgent to avoid having 0 or close to 0 values in the covariance matrix.

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This is central to the feasibility of the solution and to evaluate how good the estimate is and where are problems in the network, so one could change it and then simulate multiple usecases

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codecov bot commented Nov 22, 2024

Codecov Report

Attention: Patch coverage is 97.90210% with 3 lines in your changes missing coverage. Please review.

Project coverage is 76.19%. Comparing base (af65ef7) to head (71b7e3a).

Files with missing lines Patch % Lines
pandapower/pypower/dIbr_dV.py 92.30% 2 Missing ⚠️
pandapower/build_bus.py 98.33% 1 Missing ⚠️
Additional details and impacted files
@@             Coverage Diff             @@
##           develop    #2414      +/-   ##
===========================================
+ Coverage    76.12%   76.19%   +0.06%     
===========================================
  Files          284      284              
  Lines        33334    33437     +103     
===========================================
+ Hits         25375    25476     +101     
- Misses        7959     7961       +2     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

@marcopau marcopau self-assigned this Nov 27, 2024
@vogt31337 vogt31337 marked this pull request as ready for review December 19, 2024 14:30
@vogt31337 vogt31337 merged commit f6763c7 into e2nIEE:develop Dec 19, 2024
15 of 23 checks passed
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4 participants