Taiwan Power (Taiwan)

Although design of induction motor drives employing field-oriented control has reached a relatively mature state, relatively little effort has been expended on improving the reliability of these drives. A new, improved induction motor drive topology and control strategy are proposed that allow for continuous, disturbance-free operation of the drive even with complete loss of one leg of the inverter or motor phase. A complete analysis and computer simulation of the control and circuit concepts is included.>

Although design of induction motor drives employing field oriented control has reached a relatively mature state, relatively little effort has been directed toward improving the reliability of these drives. In this paper, a new, improved induction motor control strategy is proposed incorporating a multiphase machine that allows for continuous, disturbance-free operation of the drive even with complete loss of one (or more) legs of the inverter or motor phase. A complete analysis of both an even phase and an odd phase machine utilizing this new control and circuit concept is included.>

The consecutive and parallel reaction pathways show preferences for small Ni clusters and large Ni particles, respectively.

An improved induction motor control strategy is proposed incorporating a multiphase machine which allows for continuous, disturbance free operation of the drive even with complete loss of one (or more) legs of the inverter or motor phase. A complete analysis of both even phase and odd phase machines utilizing this control and circuit concept is presented. By using a five-phase or a seven-phase machine, it is possible to take advantage of the additional degrees of freedom as a result of more phases. It is shown that when one phase is open circuited, with appropriate control, the zero sequence current is no longer a necessary component as in a three-phase machine. That is, one can eliminate the need for a neutral line and the machine can still be controlled so as to produce a smooth nonpulsating torque. It has also been determined that the ratings of motor and inverter will both benefit by the use of extra phases.>

Wireless sensor networks (WSNs) and power line communications (PLCs) are used in this work to implement a smart home control network. The goals are to reduce the impact of wireless interference on a smart home control network and unnecessary energy consumption of a smart home. An isolated WSN with one coordinator, which is integrated into the PLC transceiver, is established in each room. The coordinator is responsible for transferring environmental parameters obtained by WSNs to the management station via PLCs. The control messages for home appliances are directly transferred using PLCs rather than WSNs. According to the experimental results, the impact of wireless interference on the proposed smart home control network is substantially mitigated. Additionally, a smart control algorithm for lighting systems and an analysis of the illumination of a fluorescent lamp were presented. The energy saving of lighting systems relative to those without smart control was evaluated. Numerical results indicate that the electricity consumption on a sunny or cloudy day can be reduced by at least 40% under the smart control. Moreover, a prototype for the proposed smart home control network with the smart control algorithm was implemented. Experimental tests demonstrate that the proposed system for smart home control networks is practically feasible and performs well.

With the advancements in wind turbine technologies, the cost of wind energy has become competitive with other fuel-based generation resources. Due to the price hike of fossil fuel and the concern of global warming, the development of wind power has rapidly progressed over the last decade. The annual growth rate has exceeded 26% since the 1990s. Many countries have set a goal for high penetration levels of wind generation. Recently, several large-scale wind generation projects have been implemented all over the world. It is economically beneficial to integrate very large amounts of wind capacity in power systems. Unlike other traditional generation facilities, using wind turbines presents technical challenges in producing continuous and controllable electric power. A distinct feature of wind energy is its nature of being ldquointermittent.rdquo Since it is difficult to predict and control the output of wind generation, its potential impacts on the electric grid are different from the traditional energy sources. At a high penetration level, an extrafast response reserve capacity is needed to cover the shortfall of generation when a sudden deficit of wind takes place. To enable a proper management of the uncertainty, this paper presents an approach to make wind power become a more reliable source on both energy and capacity by using energy storage devices. Combining the wind power generation system with energy storage will reduce fluctuation of wind power. Since it requires capital investment for the storage system, it is important to estimate the reasonable storage capacities for the desired applications. In addition, an energy storage application for reducing the output variation during the gust wind is also studied.

A knowledge-based expert system was developed for the short-term load forecasting of the Taiwan power system. The developed expert system, which was implemented on a personal computer, was written in PROLOG using a 5-year database. To benefit from the expert knowledge and experience of the system operator, eleven different shapes, each with different means of load calculations, were established. With these load shapes at hand, some peculiar load characteristics pertaining to the Taiwan Power Company can be taken into account. The special load types considered by the expert system include the extremely low load levels during the week of the Chinese New Year, the special load characteristics of the days following a tropical storm or a typhoon, the partial shutdown of certain factories on Saturdays, the special event caused by a holiday on Friday or on Tuesday, etc. A characteristic feature of the knowledge-based expert system is that it is easy to add new information and new rules to the knowledge base. To illustrate the effectiveness of the system, short-term load forecasting is performed on the Taiwan power system by using both the developed algorithm and the conventional Box-Jenkins statistical method. It is found that a mean absolute error of 2.52% for one year is achieved by the expert system approach as compared to an error of 3.86% by the statistical method.>

The ${\overline{\ensuremath{\nu}}}_{\mathrm{e}}\ensuremath{-}{\mathrm{e}}^{\ensuremath{-}}$ elastic scattering cross section was measured with a CsI(Tl) scintillating crystal array having a total mass of 187 kg. The detector was exposed to an average reactor ${\overline{\ensuremath{\nu}}}_{\mathrm{e}}$ flux of $6.4\ifmmode\times\else\texttimes\fi{}{10}^{12}\text{ }\text{ }{\mathrm{cm}}^{\ensuremath{-}2}\text{ }{\mathrm{s}}^{\ensuremath{-}1}$ at the Kuo-Sheng Nuclear Power Station. The experimental design, conceptual merits, detector hardware, data analysis, and background understanding of the experiment are presented. Using $29882/7369\text{ }\text{ }\mathrm{kg}$-days of Reactor ON/OFF data, the standard model (SM) electroweak interaction was probed at the squared 4-momentum transfer range of ${Q}^{2}\ensuremath{\sim}3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}\text{ }\text{ }{\mathrm{GeV}}^{2}$. The ratio of experimental to SM cross sections of $\ensuremath{\xi}=[1.08\ifmmode\pm\else\textpm\fi{}0.21(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.16(\mathrm{sys})]$ was measured. Constraints on the electroweak parameters (${g}_{V},{g}_{A}$) were placed, corresponding to a weak mixing angle measurement of ${sin}^{2}{\ensuremath{\theta}}_{\mathrm{W}}=0.251\ifmmode\pm\else\textpm\fi{}0.031(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.024(\mathrm{sys})$. Destructive interference in the SM ${\overline{\ensuremath{\nu}}}_{\mathrm{e}}\ensuremath{-}\mathrm{e}$ process was verified. Bounds on anomalous neutrino electromagnetic properties were placed: neutrino magnetic moment at ${\ensuremath{\mu}}_{{\overline{\ensuremath{\nu}}}_{\mathrm{e}}}<2.2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10}\text{ }\text{ }{\ensuremath{\mu}}_{\mathrm{B}}$ and the neutrino charge radius at $\ensuremath{-}2.1\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}32}\text{ }\text{ }{\mathrm{cm}}^{2}<⟨{\mathrm{r}}_{{\overline{\ensuremath{\nu}}}_{\mathrm{e}}}^{2}⟩<3.3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}32}\text{ }\text{ }{\mathrm{cm}}^{2}$, both at 90% confidence level.

In this paper, a modular interleaved boost converter is first proposed by integrating a forward energy-delivering circuit with a voltage-doubler to achieve high step-up ratio and high efficiency for dc-microgrid applications. Then, steady-state analyses are made to show the merits of the proposed converter module. For closed-loop control design, the corresponding small-signal model is also derived. It is seen that, for higher power applications, more modules can be paralleled to increase the power rating and the dynamic performance. As an illustration, closed-loop control of a 450-W rating converter consisting of two paralleled modules with 24-V input and 200-V output is implemented for demonstration. Experimental results show that the modular high step-up boost converter can achieve an efficiency of 95.8% approximately.

This paper presents a new Hopfield model based approach for the economic dispatch problem of power systems. To solve the economic dispatch problem using the Hopfield model, an energy function composing power mismatch, total fuel cost and the transmission line losses is defined. The weighting factors associated with the terms of the energy function can be either appropriately selected or directly estimated in the proposed model. Which, however, are determined by trial and error in the conventional Hopfield method. To minimize the value of the energy function, the computational procedures including a series of adjusting the weighting factor associated with the transmission line losses and updating the unit generations and power losses are carried out. Because the weighting factors are governed by some relationships developed, adjustment of the weighting factor is much simpler and more effective in steadily achieving solutions than adjustment of the /spl lambda/-multiplier in the lambda-iteration method for economic dispatch problems. Computational results reveal that this approach can find accurate solutions more simply and fast compared with the conventional lambda-iteration method.

A search of neutrino magnetic moments was carried out at the Kuo-Sheng nuclear power station at a distance of 28 m from the 2.9 GW reactor core. With a high purity germanium detector of mass 1.06 kg surrounded by scintillating NaI(Tl) and CsI(Tl) crystals as anti-Compton detectors, a detection threshold of 5 keV and a background level of $1\text{ }\text{ }{\mathrm{kg}}^{\ensuremath{-}1}\text{ }{\mathrm{keV}}^{\ensuremath{-}1}\text{ }{\mathrm{day}}^{\ensuremath{-}1}$ near threshold were achieved. Details of the reactor neutrino source, experimental hardware, background understanding, and analysis methods are presented. Based on 570.7 and 127.8 days of Reactor ON and OFF data, respectively, at an average Reactor ON electron antineutrino flux of $6.4\ifmmode\times\else\texttimes\fi{}{10}^{12}\text{ }\text{ }{\mathrm{cm}}^{\ensuremath{-}2}\text{ }{\mathrm{s}}^{\ensuremath{-}1}$, the limit on the neutrino magnetic moments of ${\ensuremath{\mu}}_{{\overline{\ensuremath{\nu}}}_{\mathrm{e}}}<7.4\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}11}{\ensuremath{\mu}}_{\mathrm{B}}$ at 90% confidence level was derived. Indirect bounds on the ${\overline{\ensuremath{\nu}}}_{\mathrm{e}}$ radiative decay lifetimes were inferred.

To enhance the cost effectiveness of the distribution automation system (DAS), this paper proposes the immune algorithm (IA) to derive the optimal placement of switching devices by minimizing the total cost of customer service outage and investment cost of line switches. The reliability index of each service zone defined by the boundary switches is derived to solve the expected energy not served due to fault contingency, and the customer interruption cost is then determined according to the customer type and power consumption within the service zone. To demonstrate the effectiveness of proposed IA methodology to solve the optimal placement of line switches, a practical distribution system of Taiwan Power Company (Taipower) is selected for computer simulation to explore the cost benefit of line switch placement for DAS

Several relationship marketing theories have suggested that businesses could build long-term customer relationships. The purpose of this study is to develop relational bonding strategies for a financial service business and examine the relationship between the various relational bonds and customer trust and commitment under the moderating effects of corporate website usage. The findings of this study are threefold. First, the relational bonds that foster customer trust and commitment can be categorised empirically into three types: economic, social and structural bonds. Second, all of these bonds are significantly positively correlated with the customers' trust and commitment. Finally, customer use of a corporate website significantly moderates the relationship between the relational bonds and customer relational performance.

Accurate load modeling is essential for power system dynamic simulation. In this paper, four dynamic load models are identified based on multiple online measurement data from the Taiwan Power System. The performances in modeling real and reactive power behaviors by dynamic and selected static load models are evaluated. Parameter variation with respect to different loading conditions is analyzed. A simple and efficient method is presented to estimate a representative parameter set for different loading conditions. The cross-validation technique is applied to validate the four dynamic load models in order to obtain a better estimate of their performance. Numerical studies indicate that linear dynamic load models studied in this paper give better results than two nonlinear dynamic load models in modeling reactive power behaviors during disturbance while they are comparable in modeling real power behaviors

Illegal use of electric energy is a widespread practice in many parts of the world. Smart metering enables the improvement of customer load model, theft and stressed asset detections. In this paper, a state estimation based approach for distribution transformer load estimation is exploited to detect meter malfunction/tampering and provide quantitative evidences of non-technical loss (NTL). A measure of overall fit of the estimated values to the pseudo feeder bus injection measurements based on customer metering data aggregated at the distribution transformers is used to localize the electricity usage irregularity. Following the state estimation results, an analysis of variance (ANOVA) is used to create a suspect list of customers with metering problems and estimate the actual usage. Typical Taiwan Power Company (TPC) distribution feeder data are used in the tests. Results of NTL detection under meter defect and energy theft scenarios are presented. Experiences indicate that the proposed scheme can give a good trace of the actual usage at feeder buses and supplement the current meter data validation estimation and editing (VEE) process to improve meter data quality.

A heuristic search approach for service restoration of a distribution system is presented. The purpose is to devise a proper restoration plan after the location of a fault has been identified and the faulted zone has been isolated. Since service restoration is an urgent matter in distribution system operation, the restoration plan must be reached in a very short time. In addition, the out-of-service area must be minimized to enhance system reliability. To reach a restoration plan which satisfies all practical requirements, a set of heuristic rules was compiled through interviews with experienced operators at Taiwan Power Company. A heuristic search algorithm was developed for service restoration following a fault on distribution feeders. The effectiveness of the proposed heuristic search approach is demonstrated by the restoration of the electricity service following a fault in an underground distribution system.>

Accurate dynamic load models allow more precise calculations of power system controls and stability limits, which are critical in the planning and operation of power systems. The development of dynamic load models using the measurement approach for the Taipower system are described. Two dynamic load model structures are developed. A procedure for applying a set of measured data from an online transient recording system to develop dynamic load models for the Taipower system is described. A technique based on the concept of confidence interval is used to validate the developed high-order load model structure. Case studies are also presented.>

This paper derives the mathematical models of doubly fed adjustable-speed pumped storage units (DFASPSUs) to be utilized in the power system analysis. It adopts the improved induction machine model with ac excitation on the wire-wound rotor as well as the field-oriented control theory for the study and analysis of DFASPSU models. First, the rotor excitation voltage is separated into two components, i.e., the q-axis voltage and the d-axis voltage, so as to control the output active and reactive powers, respectively. Next, a dynamic model of DFASPSU is derived using the swing equation of rotary electric machine and the equation of motion of rotor rotating mass. Finally, computer simulation is carried out to compare its results with practical examples in terms of dynamic characteristics for verifying the correctness of the proposed models.

This paper proposes a proper rate making strategy for a public owned utility by taking into account the customer load characteristics. The load survey system has been well designed by sampling theory to find the customers for power consumption information collection. By this manner, the typical load patterns derived can effectively represent the load behavior of each customer class. The load patterns of each test customer during different seasons are solved by statistical analysis according to the load information collected. The seasonal typical load pattern of each customer class is then determined by integrating the load patterns of the same type customers. The power consumption of the customer class is then estimated by the typical class load pattern and the energy consumption of all customers in the same class, which can be retrieved from the customer information database. The typical load pattern of whole power system is then determined by aggregating the power consumption of all customer classes. The estimated system load consumption is then compared to the actual system load profile, it is found that a rather accurate system load profile can be predicted by the load survey system.

This paper presents a 15kV silicon carbide (SiC) MOSFET gate drive, which features high common-mode (CM) noise immunity, small size, light weight, and robust yet flexible protection functions. To enhance the gate-drive power reliability, a power over fiberbased isolated power supply is designed to replace the traditional design based on isolation transformer. It delivers the gate-drive power by laser light via optical fiber over a long distance (>1 m), so a high isolation voltage (>20 kV) is achieved, and the circuit size and weight are reduced. More importantly, it eliminates the parasitic CM capacitance coupling the power stage and control stage, and thus eradicates the control signal distortion caused by high dv/dt in switching transients of the high-voltage SiC devices. In addition, the gate-drive circuit design integrates comprehensive protection functions, including the overcurrent protection, undervoltage/overvoltage lockout, active miller clamping, soft turn off, and fault report. The overcurrent protection responds within 400 ns. The experimental results from a 15kV double-pulse tester are presented to validate the design.