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Sezaki Laboratory (University of Tokyo, Japan)


The current research topics of our laboratory are as follow.

A Semi-Realtime Map-Matching Method for Mobile Application

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SoMoS: An Interactive Social Network Service-enabled Middleware for Wireless Sensor Network

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Estimating Outbreak of Influenza Like Diseases Using Social Media

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Vehicle-to-Grid Frequency Regulation with

So far, most of the researches have been focused on the economic feasibility of V2G. The only technical approach has been about the physical interfacing between the grid and vehicles. In particular, electric infrastructure regarding the backward electricity flow has been the main issue. Thus far, few studies have been done regarding the actual implementation of the V2G services. Typically, power capacity of the vehicle battery ranges around 1-20 kW which is just a small noise in a power grid. Contrarily, transactions are carried out in MW basis in most electricity markets, and thus an intermediate system, called an aggregator, is essential to aggregate the small-scale powers of individual vehicles for providing a V2G service on the appropriate scale. The V2G aggregator will choose the vehicles as well as the amount in which they must charge/discharge (each in KWs range) in response to a grid operator’s request to supply or absorb the power (in MWs range). Considering the conditions such as state-of-charge and/or the time to departure are different between the vehicles, the decision should be made to meet all the different constraints simultaneously while yielding a maximum throughput.
Designing the aggregator is one of our main research topics. We proposed a detailed framework for the aggregator regarding the frequency regulation service. A performance measure was built incorporating two typical price factors, regulation market clearing price (RMCP) and locational marginal price (LMP), each of which reflects the revenue paid to the vehicle owner for providing the power capacity and the expense paid by the vehicle owner for charging the battery from the grid, respectively. In addition, an energy constraint arising from the limit of energy capacity of the battery is devised and reflected to the RMCP. At this stage, the optimal schedule could be obtained using dynamic programming. Currently, we are elaborating the control strategy with a more sophisticated and practical model. This model considers the impact of not only the active charging control but also the passive energy deviation caused by the regulation signal. To incorporate the multiple constraints in real time, a hybrid approach combining the DP method with a mathematical optimization, the quadratic programming, is being devised.
Market participation of the V2G aggregator is also an important research interest. In order for a V2G aggregator to join the electricity market, precise estimation of the achievable power capacity (APC) is crucial. However, the plug-in behavior of each pertaining vehicle is purely random, hence disabling a deterministic estimation of the APC. Consequently, the APC should be illustrated in a stochastic manner, for which we suggested a novel method of estimating the probability distribution of the APC. In addition, with the estimated APC, optimal contract size was retrieved considering several penalty cases.
Meanwhile, the big portion of the frequency regulation has been performed by combined cycle generators for their load following ability. However, the ramp rate restricts the load following ability up to just a few percent of the rated power of the generators hence requiring excessive facility capacity for the frequency regulation. The amount of introducible wind power has been usually restricted by this factor. With V2G frequency regulation, however, the load following capacity can be procured through the battery power, and thus more renewable power can be employed without extra investment for the generators. Currently, we are assessing the introducible wind power in a stochastic manner considering the V2G frequency regulation. Some meaningful results were derived proving the effectiveness of the V2G frequency regulation in increasing the renewable power.

Mobile Ad hoc Network

Research of routing protocol of the ad hoc network and application for context aware service

Sensor Network

Developing the MAC protocol of the sensor network which is formed by the terminal loading the small-sized sensing device, Mica implementation,etc.

Haptic collaboration

Research of real-time collaboration of several users crossing the network using PHANTOM haptic devices

Location based service

Application for addressing and routing using location information, terminal location assumption, various services cooperating with Ad hoc network

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