转运成本分摊方法的研究

提出命名为加权最小距离的多转运交易模式下转运成本分摊方案，该方法是在最优潮流基础上对转运成本在多个转运交易中进行公平合理地分摊。并用一算例进行了测试，结果显示本方法能提供一定的优化运行信号，还有助于消除转运定价的不连续性。     

转运服务中附加网损的分摊计算

转运服务在电力市场化进程中变得越来越普遍。由于电能在输电网传输过程中使输电网损耗增加,将由此产生的附加网损分摊到转运合同中已成为必然。分析了转运过程中附加网损的产生机理,提出基于边际潮流的附加网损计算方法,旨在解决附加网损费分摊计算问题。算例证明,该方法理论合理、简单可行。     

Benefits of economy transactions and wheeling in Canada

As part of a review of possible measures for increasing inter-utility cooperation and enhancing transmission access in Canada, the National Energy Board carried out a study to quantify some potential wheeling benefits. Computer simulations were performed, incorporating a planning time horizon and real system data, to determine potential benefits from bilateral exchanges of economy energy and the additional benefits which could result from various wheeling arrangements. From these simulations, the potential benefits for each system involved as well as the net potential benefits for the region were determined. The CPU time for the simulations ranged from 14 hours to 46 hours on a VAX 8200 mini computer. Sensitivity analyses were also performed to establish the dependency of the benefits obtained on some system parameters used in the studies     

Utility-cogenerator game for pricing power sales and wheeling fees

The authors have studied an extensive game model of an electricity market where a cogenerator sells excess electricity to an electric utility or to an end user. They found that a buy-back system (the utility purchases cogenerated power) is as efficient as a cogenerator-customer wheeling system and that these two systems are more desirable than a monopoly system for the regulator. The buy-back rate should be equal to (LP bargaining solution) or less than (Nash bargaining solution) the marginal cost of the electric utility. They also conducted an analysis of a two-period electricity market in which they found that the cogenerator that can supply excess power during peak period obtains the market advantage     

Monte Carlo simulation for evaluating retail wheeling effects

A Monte Carlo simulation method for evaluating retail-wheeling effects on power systems is formulated and solution methods are presented. The effects of wheeling on operating cost, transmission losses, and system security are considered. For a specific operating condition, the effects are quantified by the sensitivity of specific quantities of interest with respect to power wheeling level. Quantities of interest are total operating cost, transmission losses and security, which is quantified with several indices. This model is utilized within a Monte Carlo simulation to calculate probability distribution functions of the incremental effects of wheeling on operating cost, transmission losses, and system security. The model and solution methods are applied on an example power system and the results are presented.     

Long-run marginal cost based pricing of interconnected system wheeling

Each utility in an interconnected system has an obligation to guarantee sufficient transmission capability to maintain an efficient, economical, reliable and secure system during peak scenarios. Security is an important consideration underlying network investment. The standards of service have a direct impact on investment burdens and therefore definition and consensus among participants in respect of security standards are necessary. Charging for transmission services, ensuring the investment levels and recovery of sunk capital are new problems now receiving attention in the context of electricity supply industry unbundling. In this paper a method for long run marginal cost (LRMC) based pricing in multi-area interconnected system, based on the incremental use of each area's transmission network at times of peak flow, is proposed. The LRMC of transmission capacity is based on long term costs of transmission investment requirements. The marginal wheeling costs, with security taking into account, are computed using the sensitivities of the MW-mile of each area with respect to the bus power demand. These sensitivities are calculated using a linear expansion of the Kuhn–Tucker conditions of the investment cost optimization problem. Contingency ranking method is used to speed up the computation.     

Identification of wheeling paths by an extended sensitivity analysis

This paper proposes a practical method for identifying wheeling paths in deregulated electricity markets based on an extended sensitivity analysis. Using this method, it becomes possible to decide the proper and fair wheeling rate according to the degree of burden on transmission lines by each power flow transaction. Moreover, a wheeling rate based on the real power flow burden is also an important signal to new power suppliers in the markets. In order to show the validity of the proposed method, a series of simulations on the IEEE 30-bus test system were conducted.     

Game-theoretic analysis of a buy-back system and a cogenerator-customer wheeling system

Electricity markets are experiencing widespread changes that are significantly altering the industry. The purpose of this paper is to analyze the economic consequence of various rules of purchased power pricing and wheeling fees of an electric utility by game theory. A regulator, an electric utility, and a cogenerator are included in this model as players of the game. Consider an extensive game model of an electricity market where a cogenerator sells excess electricity to anelectric utility or an end user. The regulator behaves so as to maximize social welfare. The electric utility and the cogenerator intend to maximize their own profit. The wheeling fee between the electric utility and the cogenerator is adjusted to maximize the sum of incremental profits. We have found that a buy-back system (the utility purchases cogenerated power) and a cogenerator-customer wheeling system are equally efficient and are more desirable than a monopoly system. The buy-back rate should be equal to (in the LP bargaining solution) or less than (in the Nash bargaining solution) the marginal cost of the electric utility. We also conducted an analysis of two-period electricity market.     

基于跟踪潮流法的转运费用研究

为了提高跟踪潮流计算的精度与速度,在分析其原理与算法的基础上,提出了在两节点间增加辅助节点以改进网损分摊计算的方法,并将其运用于电力市场转运费用的计算中,文中推导出了其对应的计算公式。算例结果表明,该方法显著地改善了跟踪潮流与转运费用计算的精度,它简单快捷,切实可行。该方法可应用于网损与输电设备利用分额等输电网费用分配的问题中。     

考虑短期运行成本的输电网过网费定价策略

基于长期增量成本法提出一种新的计算输电网过网费的定价模型,考虑了电网的短期运行成本对定价决策的影响.新的定价模型主要反映输电网短期运行成本对输电网元件投资时间的影响以及输电网的短期运行成本对输电网过网费的影响.为便于分析,所考虑的短期运行成本主要为电网阻塞成本.所提新的长期增量成本定价模型分别采用2母线和IEEE 30母线测试系统为例,通过与传统定价模型对比验证了所提模型的有效性.     

Allocation of fixed transmission cost to wheeling transactions bycooperative game theory

This paper describes a methodology to allocate the cost of transmission network facilities to wheeling transactions in decentralized power systems. The authors propose that the responsibility placed on transmission facilities involved in each transaction be according to the transmission usage pattern. Their proposal incorporates the MW-mile method and considers economies of scale of transmission network facilities. They also incorporate a nucleolus scheme in the cooperative game theory to deal with matters of conflict. The applicability of their method is demonstrated in a numerical example     

LNA characterization methodologies

Joint characterization of low‐noise amplifiers regarding stochastic and deterministic parameters based on output power measurement for a set of known input termination impedances is considered. As an advantage of this method, both noise parameters and the input impedance can be obtained for narrow and broad band applications without special equipment. This method is mathematically developed and practically verified by simulations and measurements. With the knowledge of at least four real‐valued stochastic, and three real‐valued deterministic parameters, the amplifier is characterized, and the noise figure, gain, and input reflection can be calculated as function of the matching network. Two different ways of processing measured data will be shown. Advantages of the proposed method compared with established methods are as follows:

• No special equipment (e.g., network analyzer, calibrated noise source, noise figure meter, slide screw tuner,…) is needed, just a tunable power meter with known noise bandwidth.
• The four real‐valued noise parameters can be obtained with four terminating impedances only.
• With three additional terminating impedances, the input impedance of the low‐noise amplifiers can be obtained.
• With every additional terminating impedance, the accuracy of the measurement is improved.
• Outliers are detected and eliminated.

Copyright © 2016 John Wiley & Sons, Ltd.     

Genetic algorithms based economic dispatch for cogeneration unitsconsidering multiplant multibuyer wheeling

A new method based on genetic algorithms (GA) is proposed for optimal dispatch among multiplant (cogeneration systems) with multicogenerators, which transmit MW to designated buyers (load buses) via wheeling. The operation constraints in the cogeneration systems and security constraints in the third party (transmission system owner) were considered. Varying weighting coefficients for penalty functions and determination of gene variables for GA were discussed. The IEEE 30- and 118-bus systems were used as test systems to illustrate the applicability of the proposed method     

Power flow based monetary flow method for electricity transmission and wheeling pricing

This paper proposes a transmission and wheeling pricing method based on the monetary flow tracing along power flow paths: the monetary flow–monetary path method. Active and reactive power flows are converted into monetary flows by using nodal prices. The method introduces a uniform measurement for transmission service usages by active and reactive powers. Because monetary flows are related to the nodal prices, the impacts of generators and loads on operation constraints and the interactive impacts between active and reactive powers can be considered. Total transmission service cost is separated into more practical line-related costs and system-wide cost, and can be flexibly distributed between generators and loads. The method is able to reconcile transmission service cost fairly and to optimize transmission system operation and development. The case study on the IEEE 30 bus test system shows that the proposed pricing method is effective in creating economic signals towards the efficient use and operation of the transmission system.     

Interchange costing and wheeling loss evaluation by means ofincrementals [electricity]

The authors consider the incremental pricing concepts and incremental loss concepts for use in real-time operations involving interchange evaluation and wheeling loss evaluation. They provide an overview of methods to evaluate the cost of electrical energy for purchases and sales using incrementals (i.e. derivatives of energy costs and energy losses). Since incrementals are directly available from economic dispatch, the methods are well suited for rapid on-line costing. The authors extend the incremental methods to calculate on-line losses associated with three-party or wheeling type transactions. The accuracy of the method of calculating wheeling losses is verified by a load flow comparison. The potential impacts to the production cost for such transactions are also evaluated using a large system model. Finally, it is pointed out that the overall production cost of the wheeling utility may increase or decrease, even though the wheeling losses are completely accounted for, due to the change in generation profile which results from adjustments in the economic dispatch     

区域电网过网损耗实用化分摊方法研究

针对当前区域电网内“谁用电谁承担网损”原则下的网损分摊问题，对国内外各种算法进行了研究比较，在平等对待区域电网用户的前提下提出了区域电网过网损耗实用化分摊算法，并进一步提出了网损基数认定和联络线的简化处理方法。针对目前研究集中于某一运行方式下网损分摊方法的现状，提出了一种根据负荷曲线合理制定典型运行方式并按照其计算结果对年网损电量进行结算分摊的方法，对电网公司在电力市场运营中分析和掌握自身输电成本的构成具有重要的指导意义。     

Evaluation of wheeling and nonutility generation (NUG) optionsusing optimal power flows

The application of optimal power flow for the evaluation of wheeling and nonutility generation (NUG) related options is presented. Both wheeling and NUG options affect vital attributes such as system security, voltage profile, losses, and VAr reserves. These options put a strain on the existing transmission system and may restrict economic utility dispatching. Optimal power flows may be used to determine the best control settings to accommodate wheeling or NUG options so as to maintain system security while minimizing losses or production cost. Short-term marginal wheeling costs may be derived using optimal power flows. Case studies involving the Northeast Utilities and IEEE test systems are presented. These cases show that optimal power flows can be used effectively to address a broad range of wheeling or NUG related planning issues     

Operation and economy of a refuse‐fired generating system with electricity wheeling service

Electric power markets have been partially liberalized and liberalization will be proceeding steadily. On the other hand, refuse‐fired generating systems (RGS) are constructed in many municipal corporations as on‐site power sources. This paper discusses the operation of an RGS which can transfer its excess energy to consumers through the electricity wheeling service of the electric utility. The RGS is operated by the dynamic programming method under the constraints of RGS operation and electricity wheeling service. In the DP method, the estimation function is the annual total electricity charge of both the RGS and the consumers, and the control variable is the residual amount in the refuse pit. A university, hospitals, welfare apartment houses, and their combinations are selected as consumers. The main results obtained are as follows: (1) electricity wheeling service is more economical than the absence of electricity wheeling service when the annual demand of the consumer is higher than 70% of the excess energy of RGS; (2) it is more economical as the load factor increases if the annual demand is the same; (3) the most economical consumer is the combination of four hospitals and five welfare apartment houses, for which the total electricity charge can be reduced to 84% of that in the absence of wheeling service. It is concluded that the total electricity charge of the RGS with electricity wheeling service could be decreased considerably by selecting the consumers appropriately. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 146(1): 59–69, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10211     

Dispatch methodologies for open access transmission systems

Managing dispatch in an open access environment is a new challenge facing independent transmission system operators who are mandated to provide a level playing field for all transmission users. Two issues are especially important viz; use-of-transmission-system charges and congestion management. This paper examines aspects of these issues with emphasis on the latter. Pool, bilateral and multilateral dispatch co-ordination are explored and mathematical models developed for each case. The practical case when all three modes coexist is discussed with respect to both forward and real time dispatch     

HVDC故障恢复特性的分析及改善措施

为了探究影响高压直流输电(HVDC)故障恢复特性的主要因素及改善其恢复特性的措施,文章分析了包括交流系统强度、直流输电极控制中相关参数的设置及故障恢复期间交流系统的无功补偿特性在内的各种因素在系统切除故障后对电压及功率恢复的影响,提出了包括AC-VDCOL与DC-VDCOL相结合的低压限流环节(VDCOL)并且在故障恢复期间改变VDCOL的特性曲线,增大系统故障期间熄弧角整定值的优化控制、采用SVC进行无功补偿等措施来改善HVDC故障恢复特性。利用PSCAD/EMTDC仿真软件在CIGRE直流输电标准测试系统中进行故障仿真。结果表明当系统发生故障时,交流系统强度越强越有利于系统故障后电压及功率的恢复,采用SVC无功补偿、优化的低压限流环节和熄弧角控制有利于改善故障的恢复特性。