Reactive power pricing: a conceptual framework for remuneration andcharging procedures

A new electrical sector regulation is being implemented in different countries all over the world. The new regulation stresses the role of competitive markets for the procurement and remuneration of ancillary services. Among these services stand the ones associated with reactive power supply and transmission network voltage control in order to maintain the required system security levels. The object of this paper is twofold. On one hand, reactive power supply and voltage control services, which today are bundled, are decomposed in two types: (i) voltage profile management and reactive dispatch, and (ii) voltage regulation. A theoretical approach based on marginal pricing is proposed in order to clarify the principles to remunerate the suppliers and to charge the consumers of these services. On the other hand, a practical organization of reactive supply and voltage service markets is presented to be implemented in a competitive environment     

Understanding transients: a conceptual interpretation

This paper provides a conceptual interpretation and a complementary understanding about power system transients through qualitative analysis. It introduces a few intuitive concepts by analyzing the transients of a two-winding transformer and a synchronous generator under a short circuit condition. A 90°-lagging rule of thumb is also introduced to describe the d- and q-axes voltage equations of a synchronous generator. Using the introduced concepts, the transient mechanism can be well understood with clear physical meanings of every term, including the various time constants, in the solution formulas     

Assured learning-enabled autonomy: A metacognitive reinforcement learning framework

Reinforcement learning (RL) agents with pre-specified reward functions cannot provide guaranteed safety across variety of circumstances that an uncertain system might encounter. To guarantee performance while assuring satisfaction of safety constraints across variety of circumstances, an assured autonomous control framework is presented in this article by empowering RL algorithms with metacognitive learning capabilities. More specifically, adapting the reward function parameters of the RL agent is performed in a metacognitive decision-making layer to assure the feasibility of RL agent. That is, to assure that the learned policy by the RL agent satisfies safety constraints specified by signal temporal logic while achieving as much performance as possible. The metacognitive layer monitors any possible future safety violation under the actions of the RL agent and employs a higher-layer Bayesian RL algorithm to proactively adapt the reward function for the lower-layer RL agent. To minimize the higher-layer Bayesian RL intervention, a fitness function is leveraged by the metacognitive layer as a metric to evaluate success of the lower-layer RL agent in satisfaction of safety and liveness specifications, and the higher-layer Bayesian RL intervenes only if there is a risk of lower-layer RL failure. Finally, a simulation example is provided to validate the effectiveness of the proposed approach.     

A reliability framework for traffic signal control

An important consideration for traffic signal control is that traffic arrivals are not deterministic. The effect of stochastic arrivals is mainly handled by introducing stochastic terms in delay formulas. Although convenient, this approach is somewhat indirect. Moreover, when the degree of saturation is high, the system becomes transient; it is questionable whether a static or time-invariant result in the form of a delay formula is applicable. In this paper, instead of relying on steady state or equilibrium probability measures, the transient effect is captured by analyzing the state of the system from cycle to cycle based on a probabilistic treatment of overflow in an event tree. This approach can be used to analyze an existing timing plan or to design a timing plan that satisfies a certain clearance reliability requirement. Some numerical results are included to demonstrate this approach.     

A multiple-constructs framework for teaching control concepts

The phenomenon of control is an essential component of the everyday natural, social, and artificial environment. Control-related concepts have become a central component of many core topics in modern technology education. Knowledge about students abilities to understand (analysis) and design (synthesis) controlled systems, however, is still poor. Evidence already collected shows that students have serious difficulties in transcending the phenomenal or behavioral understanding of a system's functioning toward more formal definitions of the control process. In this paper, a framework to start dealing with these and related issues is proposed. First, the nature of controlled systems is discussed. Then, a conceptual framework encompassing a variety of perspectives on and approaches to control is presented. The framework consists of two main components: the process component; and the representational component. The first relates to the stages in the process of defining and implementing control. The second is the repertoire of constructs used for defining and implementing control. Two main paradigms are suggested as the conveyors of very different cognitive approaches to control: programming; and design paradigms. Finally, the educational implications of the proposed framework at both the cognitive and the instructional levels are discussed     

A general framework for brain-computer interface design

The Brain-Computer Interface (BCI) research community has acknowledged that researchers are experiencing difficulties when they try to compare the BCI techniques described in the literature. In response to this situation, the community has stressed the need for objective methods to compare BCI technologies. Suggested improvements have included the development and use of benchmark applications and standard data sets. However, as a young, multidisciplinary research field, the BCI community lacks a common vocabulary. As a result, this deficiency leads to poor intergroup communication, which hinders the development of the desired methods of comparison. One of the principle reasons for the lack of common vocabulary is the absence of a common functional model of a BCI System. This paper proposes a new functional model for BCI System design. The model supports many features that facilitate the comparison of BCI technologies with other BCI and non-BCI user interface technologies. From this model, taxonomy for BCI System design is developed. Together the model and taxonomy are considered a general framework for BCI System design. The representational power of the proposed framework was evaluated by applying it to a set of existing BCI technologies. The framework could effectively describe all of the BCI System designs tested.     

A framework for UMTS air interface analysis

An integrated approach is presented for uplink and downlink air interface capacity evaluation and traffic analysis for the multiservice Universal Mobile Telecommunications System (UMTS). Within this framework the effects of both soft handoff (SHO) and fast power control (FPC) are considered. The canonical capacity of any given service, defined as the maximum number of concurrent users of that service, is derived; and the network total load is described as a function of this parameter and the number of concurrent users. The concept of virtual slots is defined within this integrated framework to obtain an accurate estimate for the blocking probability of each service type. A number of case studies are also presented to compare the results of utilizing the proposed framework with the results of network simulation. This comparison demonstrates the accuracy and usefulness of the proposed approach for network design and dimensioning.     

A rolling-horizon unit commitment framework with flexible periodicity

In this work, we develop a mathematical model and framework to represent rolling-horizon unit commitment (UC) processes with multiple periodicities. In control center operations, UC is solved repeatedly to adjust device commands based on new information about load, generation availability, renewable energy production, and other aspects of system state as uncertain conditions are realized. We develop a three-level model including 24-h UC, rolling-horizon UC (RHUC), and economic dispatch (ED) and give formulations for the three problems including interdependencies. This framework allows for evaluation of, among other things, different periodicities of the rolling horizon problem and the benefits of more accurate forecasting information. Experimental results are shown for a 6-bus system and a 3012-bus system with wind generation in two wind scenarios. Although the generation costs are very similar, the deviation between RHUC schedules and actual deployment is noted to be superior for a 20-min periodicity compared to a 30-min periodicity. Additionally, less reserve is deployed in the 20-min RHUC case.     

A market-oriented hierarchical framework for residential demand response

The integration of a great deal of uncertain renewable sources in future grids will require more operational flexibility. Demand response (DR) can provide the load shaping potentials thereby assuaging the need for operational flexibility. To this end, this paper intends to develop a framework focusing on realization of domestic storage space heating DR capability in balancing market. The developed framework consists of two hierarchical stages named energy market stage and balancing power market stage. The first stage deals with customers’ day-ahead decisions in energy market. In this stage, the system operator releases day-ahead energy prices in response to which customers optimize their electricity usage to minimize their energy expenses. The second stage optimizes customers’ intra hour load scheduling decisions in balancing power market. In the second stage, up/down power regulation incentives are offered to customers who, in the hope of achieving monetary gains, modify their promised day-ahead decisions. Performance of the framework is verified through simulations on Finnish case studies. According to the obtained results, the framework allows the customers to make savings in energy expenses as well as the system operator to benefit from DR.     

A basic framework for sub-transmission system health analysis

The reliability of supply in sub-transmission systems is usually quantified in terms of two sets of indices, the individual supply/load point indices (average failure rate, average outage duration and average annual unavailability) and the system performance indices (SAIFI, SAIDI, CAIDI, ASUI, ASAI, etc.). These probabilistic indices are very useful not only for assessing the severity of system failures in future reliability predictions but also in assessing the system’s past performance. Many utilities, however, continue to use deterministic methods (rule-of-thumb methods) to assess the reliability of their systems. This paper presents a method designated as system well-being analysis, which in addition to the conventional probabilistic risk index of supply point unavailability, also incorporates the specified deterministic criteria in defining additional system healthy and marginal states. The proposed method is illustrated in this paper to calculate the well-being indices of electric sub-transmission systems. The proposed technique, which can be used to evaluate the adequacy of sub-transmission systems, is applied in this paper to a small but comprehensive test system to show the effects of some pertinent factors and deterministic criteria on the system well-being indices.     

A combined framework for service identification and congestionmanagement

Service identification and congestion management are important functions of the ISO in maintaining system security and reliability. Most approaches in the literature solve the problem sequentially, which may lead to an under or over-estimation of the service requirement and transaction curtailment. A few of them do it iteratively which is quite time consuming. In this paper, a combined framework for service identification and congestion management is proposed. The ideal objective function is to maximize the overall profit of all market participants. Practically, an upper bound cost minimization is suggested and has been applied to identify two of the services, the reactive support and real power loss services, in case of congestion. The service costs plus the congestion cost are minimized. Results show that the proposed approach results in a smaller transaction curtailment. The curtailment also depends on the relative cost of congestion with respect to the cost of services     

一种新型油浸式变压器绝缘纸板含水量检测方法

变压器绝缘纸板绝缘材料中含有过高的水分,会加速变压器的老化,还会带来绝缘性能下降等危害,因此测试变压器绝缘纸的水含量十分必要.本文主要介绍一种综合采用极化—去极化电流和频域(变频)分析对变压器进行含量水量测试的方法,并列举现场应用实例,应用结果证明该方法的实用性.     

Diagnosis of moisture in oil/paper distribution cables - Part I: Estimation of moisture content using frequency-domain spectroscopy

Dielectric spectroscopy (dielectric response measurements) has been applied for nondestructive estimation of humidity in oil-paper cable insulation. The experiments have been based upon two field-aged cables, 20 and 50 years old. Paper samples from these cables have been characterized and subjected to environments with different relative humidity. Dielectric loss and capacitance have been measured in a frequency range 1 MHz to 1 kHz and related to the moisture content determined by Karl Fisher titration. A method has been verified where the moisture content is correlated to the minimum value of loss tangent (tan/spl delta/). A number of field measurements have been performed where the method has been applied to estimate the moisture content in the distribution cables.     

A basic framework for generating system operating health analysis

A probabilistic technique is presented in this paper to assess the operating reserve requirements in a system. In this approach, the generation system is classified into different system operating states. This technique combines deterministic with probabilistic indices to monitor the well-being. The system well-being as designated by deterministic criteria are identified as being healthy, marginal and at risk. A risk index designated as the generating system operating state risk (GSOSR) is defined in this paper as the probability of residing in an undesirable operating state. Technique together with the effect on the GSOSR and the system operating state probabilities of factors such as lead time, system peak load, load forecast uncertainty and generating unit derated states are illustrated by application to the IEEE-RTS (reliability test system)     

适应我国电力市场改革的一种模式

西方电力供应工业（ESI）的市场化重组使中国认识到电力行业迫切需要改革和竞争。然而，随着三峡等电站的逐步建立、直流输电技术的发展、电力体制改革的深入和全国电力资源的优化配置，形成且需要统一的国家输电网；同时美国加州电力灾难揭示了电力市场环境下可靠性仍处于很重要的位置，因此很有必要构建区域电力市场（RTO）基础之上的全国性电力市场。据此，针对中国特点，提出一种全国性电力市场模型，既不同于流行的趋势，又不同于其它地区的经验简单变化而来的模式，将有助于我国开发电力市场。     

A design attribute framework for course planning and learningassessment

A new method for course planning and learning assessment in engineering design courses is presented. The method is based upon components of design activity that are organized into a design attribute framework. The learning objectives of design courses can be expressed within this framework by selecting from among these components. The framework can also be used to guide the development of survey instruments for use in assessment. These two uses of the design attribute framework are illustrated in the context of a freshman engineering design course     

A framework for constructing databases for supervisory control systems

This paper presents a framework for constructing databases for supervisory control systems. The proposed framework utilizes a generation-based approach and object-oriented framework libraries. In this framework, a database is designed for the target system from a design template, and the software for the database system is generated from the database design. The generated database system includes a domain-specific object system and a diagram and plant data editor, which provides effective data input functions. © 1998 Scripta Technica, Electr Eng Jpn, 123(1): 32–42, 1998