Shinsuke Tsujita

A study on the number of principal components and sensitivity of fault detection using PCA

Selection of the number of principal components (PC) in the fault detection method using principal component analysis (PCA) is considered. In this paper, we focus on the relationship between the sensitivity of fault detection and the number of PCs to retain. Consideration of the signal-to-noise ratio of fault detection (Fault SNR) is proposed. The Fault SNR shows different dependency on the number of PCs for different kinds of faults. The number of PCs that gives the maximum sensitivity is easily determined for sensor faults by examining the Fault SNR. If a priori data is available, that is, operation data measured during faulty conditions, optimization of the number of PCs for the process fault is also possible. In a case where a priori information of the fault is not available, monitoring multiple models with various numbers of PCs in parallel is considered the next best strategy.

A study on autonomous decentralized voltage controller in distribution network considering control priority

It is of prime importance to introduce a large amount of distributed generators in order to solve the energy and environmental issue. In distribution network with a large amount of distributed generators, it becomes difficult to maintain the system voltage within an allowable range. Thus, we have developed a new voltage control method using reactive power control of system connection inverter. Especially, the method is based on the autonomous decentralized approach because it will be difficult to treat a large number of distributed generators by a centralized manner. And the method is composed by three control modes and they are switched by voltage change. However, such a switching control method often becomes unstable especially in the case the dead time is included in the control block. Hence, in this paper, we have developed a new method which is based on not the switching control but the continuous control. The autonomous decentralized controller for voltage profile maintenance is proposed and its dynamics are discussed in this paper.

Autonomous Decentralized Voltage Profile Control Method in Future Distribution Network using Distributed Generators

Takao Tsuji1, Tsutomu Oyama1, Takuhei Hashiguchi2, Tadahiro Goda2, Kenji Horiuchi3, Seiji Tange3, Takao Shinji4 and Shinsuke Tsujita4 1Faculty of Engineering, Yokohama National University 2Graduate School of Information Science and Electrical Engineering, Kyushu University 3Transmission & Distribution Systems Center, Mitsubishi Electric Corp. 4Smart Energy Technology Center, Tokyo Gas Co.,Ltd. Japan

A Study on Estimation Method of Reactive Power Control of DGs in Distribution Systems with a large amount of PVs

Abstract To solve the energy and environmental issues, it is expected that a large amount of Distributed Generators (DGs) such as renewable energy are introduced to power systems. In distribution systems with many DGs, the voltage maintenance becomes an important issue due to the reverse power flow. Although reactive power control of DG is effective for the voltage maintenance, the increase of distribution power loss may be caused by such a reactive power control. Additionally, the decrease of active power output of DG may be also required for the reactive power control when its reserve capacity is not sufficient. Thus, it is desired to reduce the amount of reactive power controlled by DGs. On the other hand, in general, distribution systems consist of High Voltage Systems (HVSs) and Low Voltage Systems (LVSs). Most voltage control equipments such as Load Ratio control Transformer (LRT) and Step Voltage Regulator (SVR) are included in HVSs, and DGs are introduced mainly in LVSs. To reduce the reactive power of DGs, the utilization of equipments in HVS is important. However, it is required for system operators to estimate the occurrence of reactive power control of DGs properly. Hence, we developed a new state estimation method of DGs by using sensor information supposing that existing section switchgears will be replaced with new ones that can measure voltage and current using their attached sensors.

A Study on the Selection of Model Dimensions and Sensitivity of PCA-Based Fault Detection

Abstract A method of determining model dimensions (number of principal components) which maximize the sensitivity of fault detection was studied. In this paper it is shown that the sensitivity of PCA-based fault detection generally depends on the number of principal components. Most of the existing methods give only one value as a recommended number of components, and so sometimes the sensitivity is poor for certain kinds of faults. Among existing methods, although the Variance of Reconstruction Error (VRE) criterion gives a recommended model dimension which depends on the kind of fault, it is not intended to maximize sensitivity. This paper presents a new method of determining the model dimension which maximizes the sensitivity of PCA-based fault detection

An Evaluation of Operating Reserve using Distributed Generators as an Alternative for Thermal Power Plants

AbstractElectric power systems, which include many renewable energy resources for worldwide low-carbon path, have a lot of problems and many studies are made for its solutions. Co-generation systems which consist of gas engine etc. have also been expected to make low-carbon path come true. One of difference between gas engines and renewable energy resources is their controllability. In this study, the operating reserve is considered as the ancillary service from distributed generator side. We have considered whether distributed generators are able to alternative thermal power plant when the peak demands. As the result, we have realized the generating cost of distributed generator possible to able to reduce against existing thermal power plant.