Chuzo Ninagawa

Fine-time-granularity fast demand control of building HVAC facilities for future smart grid

Real-time demand control is expected for the future smart grid with intensive renewable energy sources (RESs). The Variable Refrigerant Flow (VRF) building HVAC (Heating Ventilation and Air-Conditioning) facilities are popular in modern buildings in Japan, Europe, and other countries. The VRF HVAC type uses sophisticated refrigerant flow control devices. We propose a fine-time-granularity fast demand control scheme that replaces traditional coarse and slow demand controls, such as on/off adjustment of power consumption. However, the power consumption forecast of the VRFs devices for the entire building is extremely complicated. Therefore, we chose statistical forecast model approach. A 5-minute-interval Auto-Regressive (AR) model system identification was introduced. We conducted a trial simulation of fine-time-granularity fast demand control using our 5-minute-interval AR model as a preliminary evaluation for actual experiments.

Data transmission of IEEE1888 communication for wide-area real-time smart grid applications

The increasing demand for Renewable Energy Sources like solar and wind power opens up adoption of Web services communications for wide-area and real-time smart grid applications. Since the behavior of web services with TCP/IP is stochastic, detailed characteristics of data transmission delay should be investigated for time-constraint smart grid communications. In this paper, we have chosen a new Web services standard IEEE1888 as the protocol for soft-real-time applications such as Automated Demand Response (ADR) aggregation. The statistical distribution of data transmission delay was measured using our emulator experiments and NS2 network simulations. We found that the variation of delay sometimes reaches more than ten times of the average in the cases of heavy packet loss rate. Although the IEEE1888 is better than conventional protocols, attentions on time-out occurrence should be paid for the smart grid web services communications.

Communication performance simulation for object access of BACnet Web Service building facility monitoring systems

This paper proposes a network traffic simulation model for BACnet Web service (BACnet/WS) object access of building facility monitoring systems to evaluate the communication performance. The simulation model was verified by experiments using a network traffic emulator. In our simulation study, access times of BACnet/WS for 1000 objects are approximately 5 to 20 times longer than those of BACnet/IP. In addition, the study indicates that there exists an optimum number of objects, i.e. the length of each BACnet/WS message in the cases of heavy background traffic.

Smart grid ADR aggregation delay model on large-scale distributed building HVAC facilities

In the future, Automated Demand Response (ADR) Aggregators will be expected to gather power curtailments as quickly as possible. In this research, the total delay for the ADR aggregation of large-scale building HVAC facilities was evaluated by test-bench experiments. A power curtailment delay model of 100 buildings was constructed by using time-series data measured from actual office building HVAC facilities. Our test-bench experiments have shown that it took 5.8 minutes on the average to gather power curtailments of 5 MW from the delay model emulator of 100 buildings assuming conventional Watt-hour power metering and the Internet firewall policy. Approximately 70% of the delay has come from stochastic timing differences between the Aggregators command setting and all the curtailment result reports that had to be invoked periodically from each buildings BEMS gateway.

Mirror Reflectivity Dependence of Transverse-Modes in Semiconductor Lasers

A new device construction of GaAs semiconductor lasers for optical transverse-mode control is reported. An antireflective coating is deposited partially on the right and left outer regions of the front facet of a laser in order to confine laser oscillation to the central narrow portion of the active layer, and to obtain a single transverse-mode. The laser oscillation in the coated regions was suppressed at currents up to 1.09 times of the threshold in the case of a photoresist coating, and up to 1.20 times in the case of a ZnO coating. An optimum reflectivity distribution in the front facet for transverse-modes is discussed.

State variable integration in SOA Energy Management System for building air-conditioners

Advancement of Energy Management Systems (EMSs) for building facilities is becoming more important for sustainable development. The Service Oriented Architecture (SOA) will be a powerful approach for these systems. Distributed type building air-conditioners, which are dominant in Japan, have many distributed raw state variables required by an EMS. This makes it difficult to apply the SOA to those EMSs. We have introduced our concept of state variable integration that realizes loose-coupling and proper-granularity in Web services of an SOA-EMS. We have confirmed the effectiveness of our state variable integration in a field test with an office building. In this case, our integration services provide 4 integrated state variables from 172800 raw data for a day. Auto Regressive (AR) system identification with our integrated state variables has been carried out using a time series of the field test data for 60 days.

Transmission reserve table buffer for CSMA type control networks of embedded systems

This paper proposes a new transmission buffer framework for CSMA type control networks for resource-limited networked embedded systems. The unique points of our buffer are prioritized push-out and packet concatenation with limited resources. The effectiveness of our proposed buffer was validated in comparison with a conventional FIFO buffer using our network traffic simulator for CSMA type control networks.

Analysis of Collided Signal Waveform on the Long Transmission Line of UART-CSMA/CD Control Network

In this paper, waveforms of collided digital signal bits are analyzed by superposition of step responses of a distributed constant circuit for a transmission line. Our analysis indicates narrow voltage spike on the leading edge of bit pulses in collided waveforms. The width and peak of the spike calculated by our analysis were matched with those of experiments. Since the spike might cause signal collision detection failure and cause deterioration of communication performance, our analysis is effective to estimate the allowable maximum length and/or bit rate of a transmission line for control communication network.

Signal Waveform Distortion on Terminatorless Transmission Line of UART-CSMA/CD Control Network

Regarding a control network for a building air-conditioning system, signal wave- forms on the transmission lines without terminators were calculated and compared with experi- ments. The calculation predicated the severe distortion in the signal waveform due to line end re∞ections in the cases of improper line connections such as loops or long branches. 1. INTRODUCTION Cost is one of the most important factors in control networks for building facilities such as aircondi- tioning or lighting systems. As the total length of a control network is very long such as a thousand meters, reducing installation cost is strongly demanded. We have proposed a low-cost media access control method UART-CSMA/CD (Carrier Sense Multiple Access with Collision Detection using Universal Asynchronous Receiver Transmitter) which enables to omit terminators for impedance matching on the transmission line (1). However, the afiection of signal re∞ections has been studied only in the case of a point-to-point connection using a lossless transmission line model (2). In this research, we use our new model for waveform calculations assuming lossy transmission line and complex line connections. The calculation results have been verifled by comparing with the experimental results. Our new model predicts the level of the returning re∞ection signal for a variety of terminatorless line connections. In the case of an improper connection such as a loop connection, our calculation and experiment indicate a wide distortion region in the front part of one bit pulse resulting in wrong bit sampling. We conflrmed that our calculation is useful for prior evaluation of actual line connections in the building. 2. UART-CSMA/CD CONTROL NETWORK Figure 1 shows the concept of a control network for air-conditioning facility. In a typical building airconditioning system, there are hundreds of controllers distributed throughout the building. Fig. 2 shows the structure of an UART-CSMA/CD controller connected to the transmission line. The total line length often reaches as long as approximately 1000m. Therefore, not only the costs of each controller but also cost of network installation should be decreased.

Theoretical performance analysis on transmission reserve table buffer with triage ranking for resource‐limited control networks

Performance of the ‘transmission reserve table’ (TRT) buffer, which the authors recently proposed, is theoretically investigated. The buffers triage ranking queuing was designed for resource-limited control networks that are possibly exposed to a rush of control commands. Our previous study analyzed the performance of the TRT buffer by means of computer simulation. In this paper, we derive a stochastic analytical model for the TRT buffer and verify the model in comparison with computer simulations. Theoretical calculation demonstrates that the triage ranking of the TRT plays a crucial role in keeping the real-timeness of the control network even in a rush of commands by our triage ranking mechanism.