Nobumasa Matsui

A new approach of optimum energy scheduling of emergency generators using linear programing in a large hospital

The purpose of this paper is to present a new approach of optimum energy scheduling using linear programing for an emergency isolated power generator installed in a large hospital. In our previous work, we have developed a simulator to analyze the power grid conditions when a power failure occurred in medical facilities. Analyzing the power supply and demand balance in medical facilities with our developed simulator can estimate the suitable capacity of a power generator and a battery which are necessary in emergency. In addition to that, it is necessary for facilities to minimize a fuel consumption of the emergency power generator in disaster. In this work, we propose, therefore, analysis method of optimum energy scheduling of the emergency isolated power generator. For the sake of validation of our proposed approach, the optimum energy scheduling of power generators is estimated to balance the power supply and demand in the actual large hospital load. This paper presents optimum energy scheduling in the emergency isolated power generator due to minimization of fuel consumption. As a result, fuel consumption is improved 5% in summer, and winter is calculated 7%.

An Improved Model-Based Controller for Power Turbine Generators on Grid System of Shipboard

The purpose of this paper is to present an improved model based controller for a power turbine generators (PTG) on shipboard grid system that is employed by an identification method on the basis of an overall system model. The proposed controller is evaluated by comparing it with the conventional controller. Furthermore, the proposed controller is evaluated in a prototype. In the simulation result using the proposed controller, a limit speed overshooting as a transient response is improved by more than 25% In the prototype test, a limit frequency overshooting is 0.60% and a settling time is 3.8s. Hence, the proposed controller is confirmed to have excellent property.

A consideration of transient response for sensorless model control DC-DC converter

The purpose of this paper is to discuss a current prediction algorithm for sensorless model control dc-dc converter. In the proposed method, the sensing resistor for the current detection is eliminated by predicting the output current. The output current is predicted from the equation of the relationship between the output and input voltage in the static state using the duty ratio and the output voltage. The predicted output current is substituted the static model. Two different equations according to the operation mode of the dc-dc converter are used for the current presumption. They should be switched smooth and seamless for the output current prediction.

An FPGA Based Heterogeneous Redundant Control System Using Controller Virtualization

This paper describes heterogeneous redundancy of FPGA based control system using cloud. Since conventional cloud servers have problems in responsiveness, we propose the concept and architecture of controller virtualization using FPGAs. However, we should consider the negative effect on the controllability by the communication delay when control is performed using the cloud. We evaluated the stability of control using cloud by means of a simulation for a representative process control model.

Improvement of solar radiation model based on physical parametrization

In this paper, we describe a method of modeling the global solar irradiance on a clear sky. The proposed method is based on astrological phenomena, with which we can estimate the global solar irradiance of the few days, several months, and some years. To estimate the irradiance with high accuracy, it is necessary to calculate the solar radiation outside the Earths atmosphere taking into account the Earths revolution around the sun and rotation on its axis. Our proposed model is compared with data in the Chronological Science Tables as well as those measured on a horizontal surface. The simulation results using proposed model agree very well with the measured data.

Stable output current estimation for switching power converter

This study presents a sensorless static model based with output current estimation method for digital PWM control dc-dc converters. The static model is a feedforward type control method adopted in coordination with the standard PID control and it can improve characteristics of wide input and output range of dc-dc converter by using information of output current. The one of the drawbacks of the static model is that it requires an additional sensing circuitry of output current and it causes the power loss for sensing, increase of cost and computation burden. In the presented method, the output current required to adopt the static model is obtained from the estimation with the static equation of the on-time duration. Since the estimation uses the calculated on-time duration, the estimated results tend to oscillate and it also causes the oscillation of the output voltage. Therefore, a simple filter function is adopted to obtain smooth estimation results. By this filtering, such oscillation is avoided and the superior characteristics is maintained. In this article, the analytical results of stability are obtained to design the filter function when whole converter and controller are modelled with the continuous averaging method. The digital controller is implemented by using these analytical results. Evaluation results show that the effectiveness of the presented method both in transient and steady states when a buck-type dc-dc converter is used as a case study.

Wide input digital peak current mode DC-DC converter for DC power feeding system

The aim of this paper is to present a superior transient response of a digital peak current mode dc-dc converter in order to address input voltage fluctuation. In the dc power feeding system, a quick response is important for not only load fluctuation but also input voltage fluctuation. Since the proposed peak current mode control method can detect the peak current in real time, the transient response can improve compared with the conventional digital voltage mode PID control. As a result, the convergence time and undershoot of output voltage is suppressed by more than 50%.

Improvement for fast response of current sensorless model control dc-dc converter

The switching power supply is required the wide load range operation for the energy saving. In such a situation, the output voltage must be regulated. The model control is able to regulate the output voltage, because the bias value is varied depending on the static model equation. Thus, it is effective for switching power supply to implement the model control. The existing sensorless model cannot have a quick response. The purpose of this paper is to improve the transient response of the sensorless model control dc-dc converter by setting the parameter of the function that changes the operating point for a short time at the start of the transient state. It suppresses the undershoot of output voltage. The validity of the proposed method is confirmed by comparison with existing model control method and the proposed sensorless model method.

A development of evaluation and verification system of smart grid with modeling of green energy in university campus

This paper presents a developing of a high-speed simulator and a real time emulator for energy management system using a hybrid DC/AC system in smart grid. In order to improve the accuracy of solar power generation model in this system, a global solar irradiance model based on Bouguers equation is installed as a new boundary condition model. The system can be use to make estimations for prediction and verify a management strategies. The system consists of the DC bus line while load and utility-grid are connected to the AC bus line with a secondary battery connected to several renewable energy supply sources as simulation models. Additional power is supplied from the secondary battery and the utility-grid when the renewable energy power becomes lower than the demand. It is necessary to develop a simulator for operational analysis to optimally control the state of energy balance. Moreover, simulation and emulation using actual devices is essential verification. The high-speed simulator for realization of energy management is effective in predicting and analyzing because of using an energy usage patterns. In the simulation with the system, it evaluates a design as a capacity and combination of power system in a large hospital. As a result, the capacity of photovoltaic power should be installed more than 1000kW in the hospital.

Improvement of optimizing operation method for energy saving of large electric machine in combined heat and power plant

This paper presents an improvement in the optimization of operation method of large electric machine for energy conservation in combined heat and power plant (CHP). The third power plant of CHP (CHP3) is placed in Ulaanbaatar, Mongolia. CHP3 of a coal-firing plant is expected to make Ulaanbaatar a smart city because the utility grid cannot control its plant at present. Since CHP3 needs to realize energy making instead of a new plant, one of the utility control methods is to use a battery. Therefore, energy saving is the way to make more energy. When an inverter driven mode is used for a large electric machine of boiler feed water pump (BFP) to save energy from a conventional motor driven mode, the improvement in the optimization method reduces the throttle loss of the plant system. The amount of energy saving and control method are evaluated by a simulation using the inverter driven BFP. As a result, the energy saving can be expected as 24.9% at rated, 39.4% at 80% of boiler load, and 50.5% at 60% of boiler load for improvement using by optimization. This excellent result also reduces greenhouse gas emission in CHP3 using coal.