[en] This paper discusses methods of frequency-domain characterization of pulsed power sensors using vector network analyzer and spectrum analyzer techniques that offer significant simplification over time-domain methods, while mitigating or minimizing the effect of the difficulties present in time domain characterization. These methods are applicable to characterization of a wide variety of sensors

[en] Today's increasingly interacting national critical infrastructures (NCIs) can tolerate most stochastic local disturbances. However, they are extremely fragile under global disturbances, as the latter may either push the whole system into a critical state or reveal many unexpected hidden interdependencies, inducing or triggering cascading failures among all possible layers. This robust yet fragile duality is an inherent vulnerability of modern infrastructures. It is therefore expected that weather-related disasters will be more frequent under a changing climate. This paper proposed an interdependency control strategy (ICS) that would maintain the survival of the most critical services, and compensate for this inherent vulnerability during emergency states. The paper also proposed a generalized adjacency matrix (GAM) to represent the physical interdependencies intra/inter of various infrastructure networks. The vulnerable section in the network can be identified, based on computed results of GAM, number of islands in the network, and influence domain(s) of each component. These features render ICS more effective and convincing. Last, the paper proposed a survivability index for isolated sub-networks and described relevant measures for improving this index during the four phases of emergency management. It was concluded that the proposed strategy is an effective means to reduce the inherent vulnerability and increase the resiliency of these critical infrastructures networks. 20 refs., 5 figs

[en] The paper presents several opinions concerning general as well as specific aspects related to the risk management and the use of this concept in the field of power generation. Assessment possibilities of disturbing phenomena are analyzed including severe events leading to failures in power installations. Circumstances of occurring of such events are considered. This paper contains 4 sections. In the introduction the definition of the concept of risk is given. Risk is thus related to both events of a distinct nature with potentially dangerous consequences and events occurring in current operation of installations of different types. The risk notion is as important as other probabilistic indicators characterizing the power installation operation, i.e. availability, reliability, maintenance, etc. The section 2 approaches the concept of risk and argues for the necessity of quantifying it. Two probabilistic indicators are introduced, namely, the occurring probability of a disturbing event and the occurring frequency. To establish an algorithm of risk evaluation the risk notion should be dissociated into two components, the 'intrinsic' or 'initial' risk and the 'associated' risk. In turn, the latter could be divided into two types of risks, namely, the risk of an extant sustaining factor and the risk characterizing the exposure to the effects of the considered events. Applications of these notions for the cases of nuclear accidents, urban electricity or heating breakdown, energy supply breakdown in chemical facilities and others are given. The third section deals with risk management in power sector. Three objectives are here taken into account, i.e., ensuring the safety in operation of adopted systems, ensuring the safety of these systems from the consumers' standpoints and ensuring the environment protection. Examples for using the concepts introduced in case of electrical power stations or energy supply systems are given

[en] In this paper the controlled power source converter is computationally analyzed to represent the fusion reactor global decay heat characteristics. The converter is designed to be a miniature of the decay heat source for experimental purposes. This decay heat source exchanger of the cooling system of the fusion reactor under the decay heat power. A standard commercial simulator is used to analyze performance of the controlled power source converter

[en] This paper focuses on the long-term monitoring of thermal comfort and discomfort parameters in five small test buildings equipped with different heating and cooling systems. Calculations of predicted percentage of dissatisfied people (PPD) index and discomfort factors are provided for the room in winter season running three different heating systems – electric heater, air-air heat pump and air-water heat pump, as well as for the summer cooling with split type air conditioning systems. It is shown that the type of heating/cooling system and its working regime has an important impact on thermal comfort conditions in observed room. Recommendations for the optimal operating regimes and choice of the heating system from the thermal comfort point of view are summarized. (paper)

[en] Highlights: • An extreme learning machine is developed to describe the battery degradation mechanism. • The metabolic mechanism is introduced to update the input of the degradation state model. • The grey model is adopted to extrapolate error accumulation and correct the SOH. • The proposed SOH estimation framework is synthetically verified from different perspectives. Accurate estimation of battery state-of-health (SOH) is of great importance for ensuring the safety and reliability of battery energy storage system. Due to the complicated degradation mechanism of batteries, the transfer application of SOH estimation for different types of the batteries with unknown usage levels is challenging. To solve this issue, a novel metabolic extreme learning machine (MELM) framework for SOH estimation is proposed in this study. A degradation state model based on the extreme learning machine (ELM) is developed to describe the complex battery degradation mechanism, and the established model can map the relationship between the degradation features and the degradation dynamics for different batteries. To realize SOH estimation at different usage levels with a few data, the metabolic mechanism is introduced to update the input of the degradation state model and reflect the latest trend of degradation. To reduce the errors caused by the metabolism, the grey model is adopted to extrapolate the trend of error accumulation and correct the estimation results. The prominent performances of the MELM framework are synthetically verified from different aspects, the results indicate the MELM framework can effectively realize the SOH estimation for different types of batteries with unknown usage levels.

[en] Power system security is a new concern in the competitive power market operation, because the integration of the system controller and the generation owner has been broken. This paper presents an approach for dynamic security constrained optimal dispatch in restructured power market environment. The transient energy margin using transient energy function (TEF) approach has been used to calculate the stability margin of the system and a hybrid method is applied to calculate the approximate unstable equilibrium point (UEP) that is used to calculate the exact UEP and thus, the energy margin using TEF. The case study results illustrated on two systems shows that the operating mechanisms are compatible with the new business environment. (author)

[en] Month-hour equal mean zenith luminance contours are obtained from one year of data of zenith luminance measurements for cloudless, overcast and partly cloudy skies and also when the combined data for all sky types are considered. For many hours in different months, the overcast sky luminance values are roughly about three times the cloudless sky luminance values and one and a half times the partly cloudy sky values. The dependence of month-hour equal mean zenith luminance contours on the ratio of global to extraterrestrial illuminance on a horizontal surface is also given. From equal mean zenith luminance contours, the approximate values of the mean zenith luminance for different sky conditions and different hours and months of the year can be easily obtained. Month-hour equal mean diffuse illuminance contours are obtained from diffuse illuminance measurements performed during the period 1992-1998. The dependence on solar altitude of the monthly average hourly values of diffuse illuminance is given and compared to the corresponding one obtained from data for Bet Dagan (Israel)

[en] The artificial neural network (ANN) approach is a generic technique for mapping non-linear relationships between inputs and outputs without knowing the details of these relationships. This paper presents an application of the ANN in a building control system. The objective of this study is to develop an optimized ANN model to determine the optimal start time for a heating system in a building. For this, programs for predicting the room air temperature and the learning of the ANN model based on back propagation learning were developed, and learning data for various building conditions were collected through program simulation for predicting the room air temperature using systems of experimental design. Then, the optimized ANN model was presented through learning of the ANN, and its performance to determine the optimal start time was evaluated

[en] This paper presents a technique for the development of adequacy equivalents for composite generation and transmission systems using a d.c. load flow approach. Adequacy equivalent concepts can be very useful in large composite power system adequacy evaluation where extremely long computation times are usually required. The computation time burden can be effectively alleviated by using a reduced equivalent model to represent the unchanging portion of a composite system. These reduced models, designated as reliability or adequacy equivalents, retain the essential elements in their desired form but eliminate much of the system detail. Network flow methods are usually used to develop adequacy equivalents for composite systems. The d.c. load flow technique, however, is a more widely accepted procedure for composite system analyses as it can provide more accurate solutions than a network flow method. The concepts associated with developing adequacy equivalents using a d.c. load flow method are illustrated using simple power networks. Results and analyses of system studies based on two test systems are presented in the paper