panpower does not include load at slack bus in the external grid loading

[senzhanopt]

`import pandapower as pp

net = pp.create_empty_network()
b1 = pp.create_bus(net, 0.4)
b2 = pp.create_bus(net, 0.4)
b3 = pp.create_bus(net, 0.4)

pp.create_ext_grid(net, b1, s_sc_max_mva=1000, rx_max=0.1, x0x_max=1.0,
r0x0_max=0.1)

pp.create_line_from_parameters(net, b1, b2, length_km=0.1, r0_ohm_per_km=0.0848,
x0_ohm_per_km=0.4649556, c0_nf_per_km=230.6,
max_i_ka=0.963, r_ohm_per_km=0.0212,
x_ohm_per_km=0.1162389, c_nf_per_km= 230)

pp.create_line_from_parameters(net, b2, b3, length_km=0.1, r0_ohm_per_km=0.0848,
x0_ohm_per_km=0.4649556, c0_nf_per_km=230.6,
max_i_ka=0.963, r_ohm_per_km=0.0212,
x_ohm_per_km=0.1162389, c_nf_per_km= 230)

pp.create_asymmetric_load(net, b3, p_a_mw=0.25, p_b_mw=0.18, p_c_mw=0.20, type="wye")
pp.create_asymmetric_load(net, b2, p_a_mw=0.25, p_b_mw=0.18, p_c_mw=0.20, type="wye")
pp.create_asymmetric_load(net, b1, p_a_mw=0.25, p_b_mw=0.18, p_c_mw=0.20, type="wye")

pp.runpp_3ph(net)

print(net.res_ext_grid_3ph)`

[senzhanopt]

for the unbalanced case, the external grid loading will not include load as the slack bus. See this example.

[senzhanopt]

at the slack bus