Tsukasa Onishi

Security Constrained Integrated Unit Commitment Using Quadratic Programming

We have developed an innovative power generation scheduling method using quadratic programming (QP). The advantage of using our method is that it simultaneously solves unit commitment and economic load dispatch. We relax the binary variables of the unit state into continuous variables to apply QP to this problem. We also add the penalty term to converge the value of those variables to 0 or 1 to the objective function; the sum of fuel costs and start-up costs. This penalty term depends on per-unit fuel cost. The possibility of its variable converging to zero increases as the cost increases. This method was applied to a test system of daily generation scheduling that consisted of 29 thermal units, two pumped-storage units, four cascaded-hydro units, and one transmission. The schedule satisfied all constraints, i.e., load-power balance, operation reserve, power flow, minimum up/down-times, and fuel consumption. This result shows that the developed method is effective.

Proposal of environmental adaptation for the next-generation distribution SCADA system

We address the issue of design of a power distribution SCADA (Supervisory Control And Data Acquisition) system. Our work is motivated by the anticipation that large quantities of PV (photovoltaic) power generation will be connected to power grids in near future. To maintain proper voltage in the presence of large-scale connection of PV to the grid, new-generation distribution SCADA systems need to better observe and control power supply than do the existing SCADA systems. In this work we first clarify the communication speed required by the field network of a new-generation SCADA system. The results of our estimation show that the new field network requires much faster speed than the existing network. This suggests that it is likely that a new fast network will be installed in near future; however, the installation of a fast network will not happen instantly and thus we have to manage a network consisting of slow subnetworks and fast ones. To cope with this situation by adapting the gradual changes of the network environment, we propose the use of middleware as a building block of a SCADA system.

A monitoring point selection approach for power distribution systems

A power distribution system is a system of systems which integrates a power grid and a SCADA (Supervisory Control And Data Acquisition) system. In this paper we discuss SCADA systems that support a future power grid which accommodates large quantities of PV (photovoltaic) power generation. First we clarify the communication capability required for a SCADA system to fully monitor the future power grid. The result suggests that a considerable improvement needs to be made. However, as such improvement incurs huge cost and thus will not happen instantly, it is necessary to adapt to situations where communication speed is limited. To this end we propose a method that selects monitoring points within the limitations. This selection process aims to cover sensing points where abnormal voltage is most likely to occur. We evaluate the proposed method to show its usefulness by simulation.

Next generation SCADA system for distribution network with large amounts of renewable energy

Electric power supply qualities such as voltage quality and high efficiency use of equipment are essential in the future distribution network in which large amounts of renewable energy will be installed. To solve the power supply quality problems, we are now considering the development of built-in sensor in line switches, installing Advanced Metering Infrastructure (AMI) solution integrating system with information exchange technology, the development of new control devices and enhancement of functionality in SCADA (Supervisory Control And Data Acquisition) systems. Especially, in distribution network, development of SCADA/DMS (Distribution Management System) system and voltage control unit is important for maintenance of power quality, cost minimization for countermeasures and CO2 emission reduction. In this paper, we introduce next generation SCADA/DMS system technologies that help maintain power quality.