Research on mechanical fault diagnoses methodology of a circuit breaker based on the voltage and current during its operation
The performance of a circuit breaker during its operation has great impact to the power system security and is of great concern to the operation and management department of power grid. This paper presents a new method to acquire the performance information of the circuit breaker during its connecting/disconnecting operation through the voltage and current waveforms‥ Due to capacitance effects between dynamic and static contact, the voltage and current parameters in the process of connecting/disconnecting can be decomposed into two parts by orthogonal transformation method. The two parts are active and reactive power. The reactive component is generated by the capacitance effects. When the circuit breaker mechanical failure, particularly in velocity of contact anomalies, the capacitance effects will naturally be affected, that is, the reactive component will contain abnormal part inevitably. This method can effectively suppress interference, highlight the major characteristic quantities of the circuit breaker, and evaluate its mechanical performance.
Analysis of asset health : an approach to monitoring and diagnostics for medium voltage circuit breakers
The Medium Voltage Electric Industry is a very conservative and risk adverse sector that has undergone very little change in the past 30 years when compared to other technologically dependent activities; this reality is rapidly shifting. The advent of cost-effective and reliable telecommunications, coupled with the drastic price decrease of wireless communication and sensing technologies, are steering the industry towards an information based era that is generically known as smart-grid. With an emphasis on medium voltage circuit breakers, the purpose of this thesis was to identify sensor technology and analytics that will allow electric utilities in North America-primarily the United States-to assess the health of their equipment and utilize this information for maintenance operational decisions. The main areas of research included in this work were the market context for medium voltage circuit breaker Monitoring & Diagnostics solutions, the financial justification for such applications, and the technical merit of multiple sensor technologies and associated analytics. The findings of this research helped support the development of an advanced Monitoring and Diagnostics kit currently deployed at a customer site as part of a pilot demonstration program. The prototype system provides real-time monitoring and trending information for six reactorswitching 15 kV circuit breakers. The completion of this thesis, and successful development of the advanced Monitoring and Diagnostics kit, was the result of the collaborative effort of a small interdisciplinary team assembled to identify smart-grid opportunities in the medium voltage space. This work took place at ABB's Medium Voltage Headquarters in the United States. Thesis Supervisor: Roy Welsch Title: Professor of Statistics & Management Science, MIT Sloan School of Management Thesis Supervisor: John G. Kassakian Title: Professor of Electrical Engineering, MIT School of Engineering
Fully Integrated Bidirectional CMOS-MEMS Flow Sensor With Low Power Pulse Operation
Leveraging More-than-Moore technology, we demonstrate an integrated CMOS MEMS flow sensor via a very compact system on chip (SoC) that can sense the bidirectional N2 gas flow. Our SoC features a very low-noise instrumentation amplifier that is implemented on a CMOS wafer and serves as a readout integrated circuit for a thermoresistive micro-calorimetric flow sensor which is fabricated on a MEMS wafer. A compact heterogeneous integration is achieved by combining the two wafers via the proprietary InvenSense AlN process. The measured sensitivity of our CMOS MEMS flow sensor is 98 mV/sccm which is three times better than the state-of-the-art counterpart. The flow range measured by our SoC is from −26 to 26 m/s (from −50 to 50 sccm). Moreover, the pulsed heater operation makes this proposed SoC flow sensor a very low power (<9 mW) and, thus, a promising candidate for the Internet-of-Things applications in smart home/green buildings.