Variable over voltage, excessive tap counts and
voltage regulator (VR) runaway condition are major operational
challenges in distribution network while accommodating generation
from Photovoltaics (PVs). The conventional approach to
achieve voltage control based on off-line simulation for voltage set
point calculation does not consider forecast errors. In this work,
a stochastic optimal voltage control strategy is proposed while
considering load and irradiance forecast errors. Stochastic operational
risks such as overvoltage and VR runaway are defined
through a chance constrained optimization (CCO) problem. This
classical formulation to mitigate runaway is further improved
by introducing a stochastic index called the Tap Tail Expectation.
Operational objectives such as power losses and excessive tap
count minimization are considered in the formulation. A sampling
approach is proposed to solve the CCO. Along with other voltage
control devices, the PV inverter voltage support features are
coordinated. The simulation study is performed using a realistic
distribution system model and practically measured irradiance
to demonstrate the effectiveness of the proposed technique.
The proposed approach is a useful operational procedure for
distribution system operators. The approach can minimize feeder
power losses, avoid voltage violations and alleviate VR runaway.