Masato Oshiro

Optimal Power Scheduling for Smart Grids Considering Controllable Loads and High Penetration of Photovoltaic Generation

The distributed generator (DG) has a huge economical and environmental potential, especially if it is based on renewable energy sources (RESs). It is very important for the future development of smart grids. However, high penetration of DGs into distribution systems can cause voltage deviations beyond the statutory range, and reverse power flow toward the substation transformer. Consequently, it can increase the distribution system losses if it is not well supervised. Thus, in order to meet smart grid objectives, DGs have to be controlled in coordination with other power resources existing in the distribution system. Controllable loads (CLs) can also help in promoting smart grids through demand response (DR) application. Therefore, this paper proposes a decision technique of an optimal reference schedule for DGs, battery energy storage system (BESS), CLs, and tap changing transformers. The main objective of the proposed optimization problem is to achieve loss reduction in the distribution system. However, other aims such as voltage control and power flow smoothing have been achieved. The optimization is performed based on predicted values of load demand and DG generation. Simulations are conducted for one operation day to illustrate the optimality of the proposed scheduling method and to assess the impact of CLs in smart grids.

Optimal Voltage Control Using Inverters Interfaced With PV Systems Considering Forecast Error in a Distribution System

In recent years, distributed generation (DG) and renewable energy sources (RESs) have been attracting special attention in distribution systems. RESs such as photovoltaic (PV) systems are used as a source of green energy. However, a large amount of DGs causes voltage deviations beyond the statutory range in the distribution systems. This paper proposes a methodology for voltage control using the PV interfaced inverters and tap changing transformers. The proposed method uses a one-day schedule of voltage references for the control devices, which is determined by an optimization technique based on the forecast values of load demand and PV power generation. However, since the forecast value includes a forecast error, there is a possibility that the voltage control performance is affected. Thus, this paper introduces a replanning of the control reference schedule in order to reduce the forecast error impact on the control performance and its objectives.

Optimal operation strategy by battery energy storage systems in distribution system

In recent years, distributed generation (DG) and renewable energies source (RES) are attracting special attention to distribution systems. Renewable energy such as photovoltaic system and wind turbine generator are used as the sources of green energy. However, the large amount of distributed generation causes voltage deviation beyond the statutory range in distribution systems. This paper proposes a decision technique of optimal reference scheduling of the battery energy storage system and the existing voltage control devices for optimal distribution system operation. In this proposed method, the formulated control objective is solved by optimization algorithm. The proposed method achieves the following be a tunes: The node voltage in maintained in the acceptable range, the fluctuation of active power flow in reduced at the interconnection point in the distribution system, and the total distribution loss are reduced. The effectiveness of the proposed method is verified by numerical simulations with using MATLAB®.

Optimal Operation Strategy with using BESS and DGs in Distribution System

This paper proposes a methodology for distribution system operation using battery energy storage system (BESS), interfaced inverter with DGs and existing voltage control devices. The proposed method decides the optimal operation schedule of each control device by optimal calculation. Optimal calculation uses a forecast information for a next day photovoltaic generator output and load demand. As a result, the proposed method achieves a voltage control for each of the node within the acceptable range, smoothing an interconnection point power flow and reducing of total distribution loss. The effectiveness of the proposed method is verified by using MATLAB.

Optimal operation for DC smart-houses considering forecasted error

From the perspective of global warming suppression and depletion of energy resources, renewable energy such as wind generation (WG) and photovoltaic generation (PV) are getting attention in distribution systems. Additionally, all electrification apartment house or residence such as DC smart-house have increase in recent years. However, due to fluctuating power from renewable energy sources and loads, supply-demand balancing fluctuation of power system become problematic. Therefore, smart-grid has become very popular in worldwide. This paper presents a methodology for optimal operation of a smart grid to minimize interconnection point power flow fluctuation. To achieve the proposed optimal operation, we use distributed controllable loads such as battery and heat pump. By minimizing the interconnection point power flow fluctuation, it is possible to reduce the maximum electric power consumption and the electric cost. This system consists of photovoltaics generator, heat pump, battery, solar corrector, and load. In order to verify the effectiveness of the proposed system, MATLAB® is used in simulations.

Optimal scheduling method in distribution system considering controllable loads

In recent years, distributed generation (DG) and renewable energies source (RES) are attracting special attention to distribution systems. Renewable energies, such as photovoltaic and wind turbine generator systems, are used as green energy. However, the large amount of distributed generation causes voltage deviation beyond the statutory range in distribution systems. Furthermore, power flow at interconnection point is fluctuated substantially. So distribution systems need a solution for voltage control and power flow control method. This paper proposes a decision technique of optimal reference scheduling of the battery energy storage system(BESS), controllable loads(CL), interfaced inverters with DG, and the existing voltage control devices for optimal distribution system operation. In this proposed method, the formulated control objective is solved by optimization algorithm. The proposed method achieves the following a tunes: The node voltage is maintained in the acceptable range, the fluctuations of active and reactive power flows are reduced at the interconnection point in the distribution system. The effectiveness of the proposed method is verified by numerical simulations using MATLAB®.

Cooperative control of interfaced inverter with PV system and existing voltage control devices considering forecasted error in distribution system

In recent years, distributed generation (DG) and renewable energy source (RES) are attracting special attention to distribution systems. RES such as photovoltaic (PV) system are used as a source of green energy. However, the large amount of distributed generation causes voltage deviation beyond a statutory range in distribution systems. This paper proposes a methodology for voltage control by using inverters interfaced with DG and tap changing transformers. The proposed method which uses a one-day schedule of voltage references for the control devices are determined by an optimization technique based on forecast values of load demand and PV power generation. However, if the forecast value includes a forecast error, there is possibility that voltage control performance is affected. To solve this problem, this paper introduces the re-planning of control reference schedule in order to reduce the forecast error.

A digital position controller of travelling wave ultrasonic motors

Ultrasonic motor offers great advantages for industrial applications due to its excellent intrinsic properties. However, when load torque is applied, a dead-zone occurs in the control input. Therefore, a digital controller is adopted for ultrasonic motor. The state quantities, such as acceleration, speed and position, are needed to apply the digital controller for position control. Yet, rotary encoder causes quantization errors in the speed information. To overcome these problems, this paper presents a digital position control method for ultrasonic motor. The state variables for digital controller are estimated by a Variable Structure System observer. Furthermore, a small, low cost and fast response digital controller is designed by using a micro computer that is essential in embedded system for the developments of industrial equipments. Effectiveness of the proposed method is experimentally verified.