Investment Model for Power Generation and Transmission Network Expansion in Turkey

Provision of adequate electricity is one of the major factors for industrial and commercial development. However, decisions on the expansion of electricity are bogged down by high investment requirements and nonsynchronized expansion between electricity generation and transmission systems. As a rule, the investment requirements for these types of projects are immediate but their benefits can be obtained only in the long-term basis albeit electricity planners base their decisions on immediate requirements of shorter terms. As investment funds are very hard to come by, the funds, if available, should be utilized to maximum by minimizing the investment through a synchronized expansion planning of both electricity generation and transmission systems. This paper attempts to address this opportunity. We have proposed here a mixed integer model to develop concurrent transmission and generation investments plans. The model selects new generation plants or generation capacity expansions for existing plants that are located on the interconnected network by considering explicitly congestion in the transmission network. Hence the model contributes to this area by filling in the gap between models for developing long-term power generation policies and power flow models focusing on transmission network expansion. The application of the model in Turkey’s electricity network highlights the country’s congested areas in the transmission network, which might lead to loss of load and inefficient generation capacity expansion if not tackled properly. The analysis shows that a cost efficient generation expansion is possible to realize in congested regions if proper transmission expansion decisions are made concurrently with generation expansion decisions.     

近代电弧炉的容量和输入功率

70 t以上电弧炉已成为当代新建电弧炉厂的主导炉型。电弧炉的输入功率和冶炼周期应根据产品结构、生产炉型和市场需求来确定。     

Distribution Networks with Linear and Nonlinear Loads: Cost-Based Method for Planning Dispersed Generation and Capacitor Units under Uncertainty

This paper discusses the optimal allocation of capacitors and dispersed generation units in a medium-voltage distribution system with linear and nonlinear loads. An optimization problem is formulated and solved for optimal siting and sizing, with the objective of minimizing costs sustained by the distributor for reactive power service, even containing the impact of the waveform distortions. A three-step procedure, based on genetic algorithm and decision theory, is applied to obtain a solution for the optimization problem that takes into account the unavoidable uncertainties that the dispersed generation production and the loads introduce. The numeric applications performed on an 18-bus test distribution system demonstrate of the effectiveness of the proposed procedure.     

Reactive Power Adequacy in Distribution Networks with Embedded Distributed Energy Resources

This paper addresses reactive power adequacy problems in distribution networks that include a significant number of distributed energy resources. The voltage profile of the distribution network is analyzed under increasing amounts of generation provided by the distributed energy resources. Both static and dynamic voltage disruption phenomena resulting from increasing distributed generation are described and the need for remedial actions identified. Different reactive power control schemes are then proposed to keep both an appropriate voltage profile and an appropriate voltage stability margin. Finally, an economic appraisal of remedial actions is carried out and the responsible parties identified. Results from a realistic case study are presented and discussed. Conclusions are duly drawn.     

Economic Transmission Planning Model Suitable for a Regulated Network Service Provider

Conventional transmission planning models are subject to constant debate in the context of competitive markets, due to the functional unbundling of transmission sector from generation and distribution sectors and due to the new environment regulations. A value-based transmission planning model is proposed, suitable for an unbundled transmission network service provider having no assets in the generation sector. The model minimizes the long-term transmission investment costs and the expected social costs incurred to its clients, energy producers, and consumers, in the power auctions due to transmission bottlenecks. The uncertainties involved when incorporating short-term market models into long-term planning models are modeled with probabilistic representations for the bid prices, the component availabilities, and the hourly load variations. These features make this model suitable in the new environment paradigm. Generalized Benders decomposition technique with nonsequential Monte Carlo technique is employed to solve the final stochastic mixed-integer optimization model. Case studies are given to illustrate the performance of this model by implementing it in the modified Garver’s six-bus test system and the IEEE 24-bus reliability test system for a single planning year.     

Optimal Nonlocal and Asymmetric Structural Damping Using Regenerative Force Actuation Networks

A regenerative force actuation (RFA) network consists of multiple electromechanical forcing devices distributed throughout a structural system and actuated in such a way as to reduce the response of the structure when it is subjected to an excitation. The associated electronics of the devices are connected together such that they are capable of sharing electrical power with each other. This makes it possible for some devices to extract mechanical energy from the structure while others reinject a portion of that energy back into the structure at other locations. The forcing capability of an RFA network is constrained by the requirement that the total network must always dissipate energy. As such, it differs from fully active control devices in that its operation requires only a small amount of external power. Furthermore, its power-sharing capability gives it a forcing versatility beyond that attainable with semiactive and traditional passive damping systems. In this paper, RFA networks are analyzed in the context of their ability to apply supplemental linear structural damping, taking into account dissipation due to electrical resistances and viscous damping associated with the actuators. It is shown that these systems can be used to produce nonlocal damping (i.e., damping forces between distant degrees of freedom) and asymmetric damping matrices. By comparison, semiactive and passive devices can only impose local damping forces. The more generalized linear damping capabilities of RFA networks are shown to yield significant improvements in linear-quadratic optimal performance in stationary response. Examples are given in which a RFA network is used in various configurations to reduce the stationary response of the three-story shear structure to stochastic base excitation.     

Iterative Heuristic Response Surface Method for Transmission Expansion Planning

Transmission expansion planning has become a central challenge in the design of competitive electricity markets. The underlying optimization/decision problem exhibits a high level of complexity, being nonconvex, dynamic, and nonlinear, with multiple objective functions and a wide range of uncertainties. In this paper we propose a methodology for handling the expansion problem that involves a novel adaptation of an iterative optimization method based on response surface models already used successfully in the design and manufacture of integrated circuits. It is implemented in a distributed environment using Web services, and is validated and compared with a genetic algorithm based methodology. An application of the proposed methodology to the Chilean Central Interconnected System is then presented and analyzed. The results demonstrate its potential in the fields of risk analysis and decision support systems in power markets.     

真空感应炉熔炼过程供电制度的优化

通过对3～6t真空感应炉熔炼过程的能量需求与损失的系统分析与计算，利用热电平衡规律，推导得出真空感应熔炼过程能量平衡模型，并提出各熔炼阶段合理的电能供给制度。采用优化的供电制度在3～6t真空感应炉中通过所冶炼的38炉300M钢(％：0．4C，1．10Mn，1．64Si，0．29Co，1．85Ni，0．4Mo)的结果可得，冶炼电耗降低41 kWh／t，生产效率提高8．3％，Mn收得率提高1．6％，Cr收得率提高0．25％，并提高了坩埚使用寿命。     

超高功率电弧炉变压器容量及技术参数的确定

除电弧炉容量外 ,原料、辅助能源、冶炼品种、冶炼工艺和生产流程等生产状况均影响电弧炉变压器额定容量的确定。经分析得出以废钢为原料的超高功率电弧炉变压器额定容量P_n/kVA与吨钢电耗W、变压器功率利用率C₂ 、总通电时间t_on、出钢量G之间的关系式为 :P_n=(W·G·60 )/(t_on·cosφ·C₂ ) ,同时给出了二次电压的确定方法。结合高阻抗技术 ,给出超高功率高阻抗电弧炉电抗容量与变压器技术参数的确定方法以及确定石墨电极二次导体截面积的思路     

输电线路改造中的管理

随着企业生产规模的扩大和新建项目的增多,原有的供电模式会相应发生变化,输电线路的局部改造情况随之增多。该文结合莱钢输电线路改造中存在的一些实际问题,从改进设计、施工管理等方面入手,以达到最后输电线路安全运行的目的。     

Optimization of Investments in Natural Gas Distribution Networks

This paper presents an optimization model and solution procedure for planning investments in gas distribution networks for residential customers. The situation can be considered a capital budgeting problem under uncertainty. There is uncertainty about whether a potential customer will convert to gas service if a distribution main is built, the revenue generated if the household does convert, and the cost of constructing the main. A fixed annual budget is allocated to a set of discrete, competing projects over time. The allocation is done by maximizing the expected net present value (NPV) given the decision-maker’s risk preferences. The probability distribution of the NPV for each competing project is created from two statistical models. A binary probit model is used to estimate the probability of conversion for a potential customer. A random effects regression model is used to estimate the revenue generated should a particular potential customer switch to gas. A rollout value greedy heuristic was devised to solve the resulting optimization formulation. Two case studies based on data from a large gas company illustrate the analysis.     

Optimal Expansion Planning for the Deployment of Wind Energy

With the growing concern regarding climate change, the integration of renewable electric technologies into the grid has taken on increased importance over the past decade. In particular, the integration of wind energy is increasing the attention paid to power transmission investment planning, generation adequacy, and secure system operation. This attention calls for the development of new tools that can simultaneously address the economics, transmission, ancillary services, and reserve requirements associated with wind energy. This paper proposes a method for choosing the optimal plan for expanding transmission and generation considering optimal power flow, discrete plant sizes, and the resource variability of wind energy. The method minimizes total cost, i.e., the sum of the construction cost and the operation cost, to fulfill expected load. Due to the nature of transmission expansion planning and the economies of scale associated with conventional power plants, finding the expansion plan is an integer programming problem solved by a branch and bound method. The proposed method is tested by applying it to a nine-bus system.     

Stochastic Optimal CPS Relaxed Control Methodology for Interconnected Power Systems Using Q-Learning Method

This paper presents the application and design of a novel stochastic optimal control methodology based on the Q-learning method for solving the automatic generation control (AGC) under the new control performance standards (CPS) for the North American Electric Reliability Council (NERC). The aims of CPS are to relax the control constraint requirements of AGC plant regulation and enhance the frequency dispatch support effect from interconnected control areas. The NERC’s CPS-based AGC problem is a dynamic stochastic decision problem that can be modeled as a reinforcement learning (RL) problem based on the Markov decision process theory. In this paper, the Q-learning method is adopted as the RL core algorithm with CPS values regarded as the rewards from the interconnected power systems; the CPS control and relaxed control objectives are formulated as immediate reward functions by means of a linear weighted aggregative approach. By regulating a closed-loop CPS control rule to maximize the long-term discounted reward in the procedure of online learning, the optimal CPS control strategy can be gradually obtained. This paper also introduces a practical semisupervisory group prelearning method to improve the stability and convergence ability of Q-learning controllers during the prelearning process. Tests on the China Southern Power Grid demonstrate that the proposed control strategy can effectively enhance the robustness and relaxation property of AGC systems while CPS compliances are ensured.     

Customer-Focused Assessment of Electric Power Microgrids

The cost-effectiveness of interconnected microgrid systems with combined heat and power is examined for 36 cases involving six microgrid applications in six different U.S. locations. In the baseline analysis, microgrids are found to be good investments in areas with relatively high “spark spreads” (electricity/natural gas price differentials). Customers with a higher value for electric reliability realize greater benefits. Results become more favorable over time if the rate of increase of electricity prices is at least 60% of the rate of increase of natural gas prices—a plausible scenario in states with substantial natural-gas fired capacity. Sensitivity analyses reveal that the choice of microgrid customer mix has a much greater impact on system economics than climate. Economies of scale are shown to be fairly modest for the systems considered here, but microgrids do show clear benefits over traditional single customer distributed generation. If performance goals of current U.S. Department of Energy research programs for IC engines and microturbines are met, rates of return for microgrid investments increase 10–20%.     

Optimal Retailer Load Estimates Using Stochastic Dynamic Programming

In this paper, we describe a stochastic dynamic programming methodology for determining optimal forward load estimates for electric power retailers to their suppliers. This work describes both a model as well as results based on real data for the Electric Reliability Council of Texas market and provides insights useful for planning purposes for electric power retailers in the face of uncertain market prices and end-user loads.     

Recursive Design of Pressurized Branched Irrigation Networks

This paper presents a new method to design pressurized branched irrigation networks. This method is called recursive design and is based on application of the problem-solving technique known as backtracking to the problem of the optimum design of pressurized branched irrigation networks with a known delivery piezometric head (pipe-sizing). Recursive design is a heuristic optimizer, like genetic algorithms, and has been implemented in a fast, versatile computer application. After presenting and precisely defining the design problem, the writers review the theoretical foundations of some of the main existing design methods: maximum velocity, recommended velocity, Mougnie velocity, constant hydraulic slope, Lagrange multipliers, linear programming, Labye’s method, and genetic algorithms. Next, the writers explain what recursive design consists of and apply its methodology in detail to a simple network. In the results section, the solutions obtained by recursive design are compared with those obtained by the other design methods, giving satisfactory results. For example, in an analyzed standard network, genetic algorithms take more than 20?minutes to offer a solution, whereas recursive design offers a cheaper solution with less than 3?seconds of computation time.     

大功率多雾化电弧喷枪的研制

设计二进四出多雾化电弧喷枪,改变雾化气流场和流速,使雾化气流场合理分布,提高了喷涂粒子的射流速度,改善了雾化效果,使雾化粒子更细小更均匀,降低了涂层孔隙率,获得更大喷涂幅宽。应用对比试验标明,其性能已达到甚至超过国际同类产品。     

超高功率电弧炉的无功动态补偿

抚顺钢厂拟建第二台５０ｔ（或６０ｔ）超高功率电孤炉，本文通过对四种方案的计算，得出结论：无论采用哪种方案，都必须新建无功动态补偿装置和滤波装置。     

Estimation of Electric Transformer Service Life from Oil Degradation Kinetics

Petroleum-based transformer oil performs the dual roles of insulator and electrolyte depending on charges in the oil. The availability of charges for conduction influences the level of voltage breakdown in the mineral oil and depends on the intensity of physicochemical processes such as redox action, hydrolysis, photodegradation, sludge/particle development, and gas formation arising from thermal, mechanical, chemical, and electrical stresses in the oil. Previous investigators have focused mostly on single oil aging indicators to build models for estimation of the aging rates of transformer oils, within a time frame that is too short relative to the operational service life of transformers. In this research, the interdependence of oil voltage breakdown and changes in oil physicochemical characteristics was investigated experimentally using T24 and T14 oils. Tests were performed with a DTS-100D oil tester for voltage breakdown and a HKV 4000 series high kinematic viscosity bath. The calculated activation energies are 26.2?KJm?3 for T24 and 25.4?KJm?3 for T24 transformer oils, respectively. Neglecting catastrophic failure from environmental hazards, the estimated service lives of T14 and T24 transformers that are herein analyzed are 40 and 43 years, respectively. Their degradation constants were experimentally determined to be 7.38×10?12 and 6.98×10?12?L?1?S?1, respectively.     

太钢电力调度自动化系统

介绍了太原钢铁公司电力调度自动化系统的配置、功能、特点，目前运行情况及 设想。