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Merge pull request #95 from NREL-Sienna/rb/add_yft
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add Yft, Ytf to power_network_matrix Ybus
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@jd-lara
jd-lara authored Feb 5, 2025
2 parents 7069dca + 0387d4b commit ec079ad
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175 changes: 140 additions & 35 deletions src/ybus_calculations.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -2,55 +2,85 @@
Nodal admittance matrix (Ybus) is an N x N matrix describing a power system with N buses. It represents the nodal admittance of the buses in a power system.
The Ybus Struct is indexed using the Bus Numbers, no need for them to be sequential
The fields yft and ytf are the branch admittance matrices for the from-to and to-from branch admittances respectively. The rows correspond to branches and the columns to buses.
The matrix columns are mapped to buses using fb, tb arrays of the matrix columns that correspond to the `from` and `to` buses.
Using yft, ytf, and the voltage vector, the branch currents and power flows can be calculated.
"""
struct Ybus{Ax, L <: NTuple{2, Dict}} <: PowerNetworkMatrix{ComplexF64}
data::SparseArrays.SparseMatrixCSC{ComplexF64, Int}
axes::Ax
lookup::L
yft::Union{SparseArrays.SparseMatrixCSC{ComplexF64, Int}, Nothing}
ytf::Union{SparseArrays.SparseMatrixCSC{ComplexF64, Int}, Nothing}
fb::Union{Vector{Int64}, Nothing}
tb::Union{Vector{Int64}, Nothing}
end

function _ybus!(
ybus::SparseArrays.SparseMatrixCSC{ComplexF64, Int},
y11::Vector{ComplexF64},
y12::Vector{ComplexF64},
y21::Vector{ComplexF64},
y22::Vector{ComplexF64},
br::PSY.ACBranch,
num_bus::Dict{Int, Int},
branch_ix::Int64,
fb::Vector{Int64},
tb::Vector{Int64},
)
arc = PSY.get_arc(br)
bus_from_no = num_bus[arc.from.number]
bus_to_no = num_bus[arc.to.number]
fb[branch_ix] = bus_from_no
tb[branch_ix] = bus_to_no
Y_l = (1 / (PSY.get_r(br) + PSY.get_x(br) * 1im))
Y11 = Y_l + (1im * PSY.get_b(br).from)
if !isfinite(Y11) || !isfinite(Y_l)
error(
"Data in $(PSY.get_name(br)) is incorrect. r = $(PSY.get_r(br)), x = $(PSY.get_x(br))",
)
end
ybus[bus_from_no, bus_from_no] += Y11
y11[branch_ix] = Y11
Y12 = -Y_l
ybus[bus_from_no, bus_to_no] += Y12
#Y21 = Y12
ybus[bus_to_no, bus_from_no] += Y12
y12[branch_ix] = Y12
Y21 = Y12
y21[branch_ix] = Y21
Y22 = Y_l + (1im * PSY.get_b(br).to)
ybus[bus_to_no, bus_to_no] += Y22
y22[branch_ix] = Y22
return
end

function _ybus!(
ybus::SparseArrays.SparseMatrixCSC{ComplexF64, Int},
y11::Vector{ComplexF64},
y12::Vector{ComplexF64},
y21::Vector{ComplexF64},
y22::Vector{ComplexF64},
br::PSY.DynamicBranch,
num_bus::Dict{Int, Int},
branch_ix::Int64,
fb::Vector{Int64},
tb::Vector{Int64},
)
_ybus!(ybus, br.branch, num_bus)
_ybus!(y11, y12, y21, y22, br.branch, num_bus, branch_ix, fb, tb)
return
end

function _ybus!(
ybus::SparseArrays.SparseMatrixCSC{ComplexF64, Int},
y11::Vector{ComplexF64},
y12::Vector{ComplexF64},
y21::Vector{ComplexF64},
y22::Vector{ComplexF64},
br::PSY.Transformer2W,
num_bus::Dict{Int, Int},
branch_ix::Int64,
fb::Vector{Int64},
tb::Vector{Int64},
)
arc = PSY.get_arc(br)
bus_from_no = num_bus[arc.from.number]
bus_to_no = num_bus[arc.to.number]
fb[branch_ix] = bus_from_no
tb[branch_ix] = bus_to_no
Y_t = 1 / (PSY.get_r(br) + PSY.get_x(br) * 1im)
Y11 = Y_t
b = PSY.get_primary_shunt(br)
Expand All @@ -60,50 +90,70 @@ function _ybus!(
)
end

ybus[bus_from_no, bus_from_no] += Y11 - (1im * b)
ybus[bus_from_no, bus_to_no] += -Y_t
ybus[bus_to_no, bus_from_no] += -Y_t
ybus[bus_to_no, bus_to_no] += Y_t
y11[branch_ix] = Y11 - (1im * b)
Y12 = -Y_t
y12[branch_ix] = Y12
Y21 = Y12
y21[branch_ix] = Y21
Y22 = Y_t
y22[branch_ix] = Y22
return
end

function _ybus!(
ybus::SparseArrays.SparseMatrixCSC{ComplexF64, Int},
y11::Vector{ComplexF64},
y12::Vector{ComplexF64},
y21::Vector{ComplexF64},
y22::Vector{ComplexF64},
br::PSY.TapTransformer,
num_bus::Dict{Int, Int},
branch_ix::Int64,
fb::Vector{Int64},
tb::Vector{Int64},
)
arc = PSY.get_arc(br)
bus_from_no = num_bus[arc.from.number]
bus_to_no = num_bus[arc.to.number]
fb[branch_ix] = bus_from_no
tb[branch_ix] = bus_to_no

Y_t = 1 / (PSY.get_r(br) + PSY.get_x(br) * 1im)
c = 1 / PSY.get_tap(br)
b = PSY.get_primary_shunt(br)

Y11 = (Y_t * c^2)
ybus[bus_from_no, bus_from_no] += Y11 - (1im * b)
y11[branch_ix] = Y11
Y12 = (-Y_t * c)
if !isfinite(Y11) || !isfinite(Y12) || !isfinite(b)
error(
"Data in $(PSY.get_name(br)) is incorrect. r = $(PSY.get_r(br)), x = $(PSY.get_x(br))",
)
end
ybus[bus_from_no, bus_to_no] += Y12
#Y21 = Y12
ybus[bus_to_no, bus_from_no] += Y12

y12[branch_ix] = Y12
Y21 = Y12
y21[branch_ix] = Y21
Y22 = Y_t
ybus[bus_to_no, bus_to_no] += Y22
y22[branch_ix] = Y22
return
end

function _ybus!(
ybus::SparseArrays.SparseMatrixCSC{ComplexF64, Int},
y11::Vector{ComplexF64},
y12::Vector{ComplexF64},
y21::Vector{ComplexF64},
y22::Vector{ComplexF64},
br::PSY.PhaseShiftingTransformer,
num_bus::Dict{Int, Int},
branch_ix::Int64,
fb::Vector{Int64},
tb::Vector{Int64},
)
arc = PSY.get_arc(br)
bus_from_no = num_bus[arc.from.number]
bus_to_no = num_bus[arc.to.number]
fb[branch_ix] = bus_from_no
tb[branch_ix] = bus_to_no
Y_t = 1 / (PSY.get_r(br) + PSY.get_x(br) * 1im)
tap = (PSY.get_tap(br) * exp(PSY.get_α(br) * 1im))
c_tap = (PSY.get_tap(br) * exp(-1 * PSY.get_α(br) * 1im))
Expand All @@ -114,29 +164,33 @@ function _ybus!(
"Data in $(PSY.get_name(br)) is incorrect. r = $(PSY.get_r(br)), x = $(PSY.get_x(br))",
)
end
ybus[bus_from_no, bus_from_no] += Y11 - (1im * b)

y11[branch_ix] = Y11 - (1im * b)
Y12 = (-Y_t / c_tap)
ybus[bus_from_no, bus_to_no] += Y12
y12[branch_ix] = Y12
Y21 = (-Y_t / tap)
ybus[bus_to_no, bus_from_no] += Y21
y21[branch_ix] = Y21
Y22 = Y_t
ybus[bus_to_no, bus_to_no] += Y22
y22[branch_ix] = Y22
return
end

function _ybus!(
ybus::SparseArrays.SparseMatrixCSC{ComplexF64, Int},
ysh::Vector{ComplexF64},
fa::PSY.FixedAdmittance,
num_bus::Dict{Int, Int},
fa_ix::Int64,
sb::Vector{Int64},
)
bus = PSY.get_bus(fa)
bus_no = num_bus[PSY.get_number(bus)]
sb[fa_ix] = bus_no
if !isfinite(fa.Y)
error(
"Data in $(PSY.get_name(fa)) is incorrect. Y = $(fa.Y)",
)
end
ybus[bus_no, bus_no] += fa.Y
ysh[fa_ix] = fa.Y
return
end

Expand All @@ -145,23 +199,43 @@ function _buildybus(
buses::Vector{PSY.ACBus},
fixed_admittances::Vector{PSY.FixedAdmittance},
)
buscount = length(buses)
num_bus = Dict{Int, Int}()

branchcount = length(branches)
fa_count = length(fixed_admittances)
fb = zeros(Int64, branchcount)
tb = zeros(Int64, branchcount)
sb = zeros(Int64, fa_count)

for (ix, b) in enumerate(buses)
num_bus[PSY.get_number(b)] = ix
end
ybus = SparseArrays.spzeros(ComplexF64, buscount, buscount)
for b in branches

y11 = zeros(ComplexF64, branchcount)
y12 = zeros(ComplexF64, branchcount)
y21 = zeros(ComplexF64, branchcount)
y22 = zeros(ComplexF64, branchcount)
ysh = zeros(ComplexF64, fa_count)

for (ix, b) in enumerate(branches)
if PSY.get_name(b) == "init"
throw(DataFormatError("The data in Branch is invalid"))
end
PSY.get_available(b) && _ybus!(ybus, b, num_bus)
PSY.get_available(b) && _ybus!(y11, y12, y21, y22, b, num_bus, ix, fb, tb)
end
for fa in fixed_admittances
PSY.get_available(fa) && _ybus!(ybus, fa, num_bus)
for (ix, fa) in enumerate(fixed_admittances)
PSY.get_available(fa) && _ybus!(ysh, fa, num_bus, ix, sb)
end
return SparseArrays.dropzeros!(ybus)
return (
y11,
y12,
y21,
y22,
ysh,
fb,
tb,
sb,
)
end

"""
Expand All @@ -175,17 +249,48 @@ function Ybus(
buses::Vector{PSY.ACBus},
fixed_admittances::Vector{PSY.FixedAdmittance} = Vector{PSY.FixedAdmittance}();
check_connectivity::Bool = true,
make_branch_admittance_matrices::Bool = false,
)
bus_ax = PSY.get_number.(buses)
axes = (bus_ax, bus_ax)
bus_lookup = make_ax_ref(bus_ax)
busnumber = length(buses)
look_up = (bus_lookup, bus_lookup)
ybus = _buildybus(branches, buses, fixed_admittances)
y11, y12, y21, y22, ysh, fb, tb, sb = _buildybus(branches, buses, fixed_admittances)
ybus = SparseArrays.sparse(
[fb; fb; tb; tb; sb], # row indices
[fb; tb; fb; tb; sb], # column indices
[y11; y12; y21; y22; ysh], # values
busnumber, # size (rows) - setting this explicitly is necessary for the case there are no branches
busnumber, # size (columns) - setting this explicitly is necessary for the case there are no branches
)
SparseArrays.dropzeros!(ybus)
if check_connectivity && length(buses) > 1
islands = find_subnetworks(ybus, bus_ax)
length(islands) > 1 && throw(IS.DataFormatError("Network not connected"))
end
return Ybus(ybus, axes, look_up)
if make_branch_admittance_matrices
yft = SparseArrays.sparse(
[1:length(fb); 1:length(fb)],
[fb; tb],
[y11; y12],
length(fb),
length(buses),
)
ytf = SparseArrays.sparse(
[1:length(tb); 1:length(tb)],
[tb; fb],
[y22; y21],
length(tb),
length(buses),
)
else
yft = nothing
ytf = nothing
fb = nothing
tb = nothing
end
return Ybus(ybus, axes, look_up, yft, ytf, fb, tb)
end

"""
Expand Down
6 changes: 4 additions & 2 deletions test/test_ybus.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -28,8 +28,10 @@
@test isapprox(Y5NS[10, 4], -3.3336667 + 33.336667im, atol = 1e-4)

Y5NS = Ybus([branches_5[b] for b in Br5NS_ids], [buses_5[b] for b in Bu5NS_ids])
for buf in Bu5NS_ids, but in Bu5NS_ids
@test isapprox(Y5NS[buf, but], Ybus5_matpower[buf, but], atol = 1e-3)
for buf in Bu5NS_ids
for but in Bu5NS_ids
@test isapprox(Y5NS[buf, but], Ybus5_matpower[buf, but], atol = 1e-3)
end
end

@test Ybus5[buses_5[1], buses_5[2]] == (-3.5234840209999647 + 35.234840209999646im)
Expand Down

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