Kenichiro Yamane

Control method for voltage regulator based on estimated amount of photovoltaic generation power

In this paper, we propose a control method for a voltage regulator to reduce voltage violation of a distribution line under the constraint of the upper limit of tap changes. The proposed method determines the current tap position by considering potential voltage fluctuation caused by changes of the photovoltaic (PV) output power. The estimation value of the current output power of PV is used to forecast voltage changes caused by the maximum change of PV output power. In this paper, we describe an algorithm to control the tap changer of a voltage regulator and present simulation results of applying the method to voltage regulators with a sample distribution network model.

Constrained state estimation with partial measurements in unobservable distribution network

We developed a constrained state estimation method that clarifies the range of the feeder voltage in an unobservable distribution network in which the number of telemetric sensors is smaller than the number of state variables to be estimated. Instead of using pseudo-measurements, whose reliability is affected by unexpected power flow conditions, the method uses constant nominal boundaries as inequality constraints in the least squares problem. The ranged estimation is the maximum likelihood solution that satisfies the least squares criterion against the sensor measurements and satisfies the given inequality constraints at the same time. We evaluated the method in a case study simulation on a 30-node benchmark network with partial measurements. The evaluation result showed that the method clarified the feeder voltage ranges including or close to unmeasured exact values and that the size of the estimation range and error were sufficiently smaller compared with the allowable voltage fluctuation.