Default dae.t to -1 for power flow. TDS initialization will set `…

…dae.t` to 0.
CURENT · Sep 19, 2023 · ebbf5cf · ebbf5cf
1 parent 8f0d18c
commit ebbf5cf
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Showing 5 changed files with 22 additions and 8 deletions.
diff --git a/andes/core/discrete.py b/andes/core/discrete.py
@@ -1633,8 +1633,13 @@ def check_var(self, dae_t, *args, niter=None, err=None, **kwargs):
             return
 
         # allow unlimited switching in power flow
-        if dae_t == 0.0:
+        if dae_t < 0.0:
             self.t_enable[:] = 1.0
+
+        # reset `t_last` upon TDS initialization
+        elif dae_t == 0.0:
+            self.t_last = np.zeros_like(self.v.v)
+
         # consider delay for time-domain simulation
         else:
             self.t_enable[:] = (dae_t - self.t_last - self.dt.v) >= 0

diff --git a/andes/models/static/pq.py b/andes/models/static/pq.py
@@ -211,12 +211,12 @@ def __init__(self, system=None, config=None):
         # To modify P and Q during TDS, use `alter` to set values to `Ppf` and `Qpf`
         # after, before simulation, setting `config.p2p=1` and `config.q2q=1`.
 
-        self.a.e_str = "u * Indicator(dae_t <= 0) * " \
+        self.a.e_str = "u * Indicator(dae_t < 0) * " \
                        "(p0 * vcmp_zi + Rlb * vcmp_zl * v**2 + Rub * vcmp_zu * v**2) + " \
-                       "u * Indicator(dae_t > 0) * " \
+                       "u * Indicator(dae_t >= 0) * " \
                        "(p2p * Ppf + p2i * Ipeq * v + p2z * Req * v**2)"
 
-        self.v.e_str = "u * Indicator(dae_t <= 0) * " \
+        self.v.e_str = "u * Indicator(dae_t < 0) * " \
                        "(q0 * vcmp_zi + Xlb * vcmp_zl * v**2 + Xub * vcmp_zu * v**2) + " \
-                       "u * Indicator(dae_t > 0) * " \
+                       "u * Indicator(dae_t >= 0) * " \
                        "(q2q * Qpf + q2i * Iqeq * v + q2z * Xeq * v**2)"
diff --git a/andes/routines/tds.py b/andes/routines/tds.py
@@ -197,6 +197,7 @@ def init(self):
         # restore power flow solutions
         system.dae.x[:len(system.PFlow.x_sol)] = system.PFlow.x_sol
         system.dae.y[:len(system.PFlow.y_sol)] = system.PFlow.y_sol
+        system.dae.t -= system.dae.t   # set `dae.t` to zero
 
         # Note:
         #   calling `set_address` on `system.exist.pflow_tds` will point all variables
@@ -347,8 +348,8 @@ def run(self, no_summary=False, **kwargs):
         if no_summary is False and (system.dae.t == 0):
             self.summary()
 
-        # only initializing at t=0 allows to continue when `run` is called again.
-        if system.dae.t == 0:
+        # only initializing at t<0 allows to continue when `run` is called again.
+        if system.dae.t < 0:
             self.init()
         else:  # resume simulation
             self.init_resume()

diff --git a/andes/variables/dae.py b/andes/variables/dae.py
@@ -306,7 +306,7 @@ class DAE:
 
     def __init__(self, system):
         self.system = system
-        self.t = np.array(0.0, dtype=float)
+        self.t = np.array(-1.0, dtype=float)
         self.ts = DAETimeSeries(self)
         self.kcount = 0  # time step count
 

diff --git a/docs/source/release-notes.rst b/docs/source/release-notes.rst
@@ -6,6 +6,14 @@ Release notes
 
 The APIs before v3.0.0 are in beta and may change without prior notice.
 
+v1.9 Notes
+==========
+
+v1.9.0 (2023-09-XX)
+-------------------
+- Initially, ``dae.t`` is set to ``-1.0`` during power flow calculation. TDS
+  initialization will set ``dae.t = 0.0``.
+
 v1.8 Notes
 ==========