Optimum size of base load generators for growing demand

The price per unit generated electrical energy decreases with increasing size of the generator, which implies longer transmission line and hence larger transmission losses. Considering both these facts the optimum size of thermal power station for growing demand has been obtained by using life-cycle costing analysis. The demand may be met by (1) a combination of base load and peak load generators (Sodha and Chandra, 1992) and (2) by a combination of base load generators only. The second option has been analysed in this paper. The dependence of investment ratio (the ratio of present worth of net income to the capital investment) on relevant parameters has been studied. It is seen that there exists a particular pattern (optimum combination) of base load generators. The effect of electricity price, coal price and escalation rates on the optimum configuration has also been investigated. The cost data from recent study in India have been used.     

基于检修计划的水电站群联合调峰优化方案

基于检修计划的水电站群联合调峰优化问题,在优化调峰效益时充分考虑电网的实际水电负荷需求,以负荷爬坡阈值平抑锯齿,得到平稳的水电调峰系数曲线;同时,考虑机组额定容量、预想出力、可用台数等限制,构建了完整的水电站群中期联合优化调峰效益最大模型。该模型求解采用DDDP-DPSA混合算法,通过优化—检验—调整—再优化的循环模式对线路和机组的检修计划进行校验和调整,最终获得水电站群中期联合调峰优化方案。     

如何应对当前我国电力供应不足的问题

2003年我国经济增长速度将7.8～8.3%,全社会用电量需求增长也将达11～13%。本文分析了当前我国电力供需紧张的主要原因,电网负荷率降低使得可发电量有余、可供电力不足。为了解决当前电力供应不足的问题,本文提出采用需求侧管理的办法,通过拉大峰谷电价,推出尖峰电价及可中断负荷等措施,降低1000万kW的高峰负荷,缓解电力供应紧张的局面。     

青海电网抽水蓄能电站发展

根据典型日和典型周尖峰负荷需求与尖峰容量平衡分析了青海电网对抽水蓄能电站的需求,并详细分析了抽水蓄能电站在青海电网中的作用及经济性。结果表明,抽水蓄能电站在青海电网中的替代作用比较显著．在电力平衡中可充分发挥作用。因此,青海电网建设抽水蓄能电站是必要的。     

Off-grid solar powered charging station for electric and hydrogen vehicles including fuel cell and hydrogen storage

This paper designs an off-grid charging station for electric and hydrogen vehicles. Both the electric and hydrogen vehicles are charged at the same time. They appear as two electrical and hydrogen load demand on the charging station and the charging station is powered by solar panels. The output power of solar system is separated into two parts. On part of solar power is used to supply the electrical load demand (to charge the electric vehicles) and rest runs water electrolyzer and it will be converted to the hydrogen. The hydrogen is stored and it supplies the hydrogen load demand (to charge the hydrogen-burning vehicles). The uncertainty of parameters (solar energy, consumed power by electrical vehicles, and consumed power by hydrogen vehicles) is included and modeled. The fuel cell is added to the charging station to deal with such uncertainty. The fuel cell runs on hydrogen and produces electrical energy to supply electrical loading under uncertainties. The diesel generator is also added to the charging station as a supplementary generation. The problem is modeled as stochastic optimization programming and minimizes the investment and operational costs of solar and diesel systems. The introduced planning finds optimal rated powers of solar system and diesel generator, operation pattern for diesel generator and fuel cell, and the stored hydrogen. The results confirm that the cost of changing station is covered by investment cost of solar system (95%), operational cost of diesel generator (4.5%), and investment cost of diesel generator (0.5%). The fuel cell and diesel generator supply the load demand when the solar energy is zero. About 97% of solar energy will be converted to hydrogen and stored. The optimal operation of diesel generator reduces the cost approximately 15%.     

考虑分时电价的煤矿运输系统改造分析

介绍了生产流程中影响负荷转移的重要因素,分析了生产流程中的负荷构成,并考虑分时电价因素,建立了负荷转移模型。将该模型成功应用到煤矿传输系统中,借助分时电价,帮助煤矿企业合理转移负荷,避开峰时电价,达到节约用电成本的目的。     

Development of a three-part time-of-day electrical energy tariff

This paper presents an analytical technique for determining peak, offpeak and midpeak hours tariffs for various durations of these three periods. The technique considers the existing flat rate tariff, an hourly generation scenario of a utility on an average yearly demand day, the weighted average life time, annutised capital cost and fuel cost of base and peak load plants, and a break even point condition in the utility's revenue. The developed tariff has been applied to 30 representative industrial consumers served by the Bangladesh Power Development Board (BPDB) to estimate the minimum possible shift in consumption pattern and hence corresponding reduction in peak generation capacity requirement as well as peak time load shedding by BPDB. © 1998 John Wiley & Sons, Ltd.     

Flexible demand response programs modeling in competitive electricity markets

In recent years, extensive researches have been conducted on implementation of demand response programs (DRPs), aimed to electricity price reduction, transmission lines congestion resolving, security enhancement and improvement of market liquidity. Basically, DRPs are divided into two main categories namely, incentive-based programs (IBPs) and time-based rate programs (TBRPs). Mathematical modeling of these programs helps regulators and market policy makers to evaluate the impact of price responsive loads on the market and system operational conditions. In this paper, an economic model of price/incentive responsive loads is derived based on the concept of flexible price elasticity of demand and customer benefit function. The mathematical model for flexible price elasticity of demand is presented to calculate each of the demand response (DR) program’s elasticity based on the electricity price before and after implementing DRPs. In the proposed model, a demand ratio parameter has been introduced to determine the appropriate values of incentive and penalty in IBPs according to the level of demand. Furthermore, the importance of determining optimum participation level of customers in different DRPs has been investigated. The proposed model together with the strategy success index (SSI) has been applied to provide an opportunity for major players of the market, i.e. independent system operator (ISO), utilities and customers to select their favorite programs that satisfy their desires. In order to evaluate the performance of the proposed model, numerical studies are conducted on the Iranian interconnected network load profile on the annual peak day of the year 2007.     

Demand response modeling considering Interruptible/Curtailable loads and capacity market programs

Recently, a massive focus has been made on demand response (DR) programs, aimed to electricity price reduction, transmission lines congestion resolving, security enhancement and improvement of market liquidity. Basically, demand response programs are divided into two main categories namely, incentive-based programs and time-based programs. The focus of this paper is on Interruptible/Curtailable service (I/C) and capacity market programs (CAP), which are incentive-based demand response programs including penalties for customers in case of no responding to load reduction. First, by using the concept of price elasticity of demand and customer benefit function, economic model of above mentioned programs is developed. The proposed model helps the independent system operator (ISO) to identify and employ relevant DR program which both improves the characteristics of the load curve and also be welcome by customers. To evaluate the performance of the model, simulation study has been conducted using the load curve of the peak day of the Iranian power system grid in 2007. In the numerical study section, the impact of these programs on load shape and load level, and benefit of customers as well as reduction of energy consumption are shown. In addition, by using strategy success indices the results of simulation studies for different scenarios are analyzed and investigated for determination of the scenarios priority.     

变风载下风力发电机齿轮传动系统动力学特性研究

根据风力发电机齿轮传动系统所处的由随机风速引起的复杂变工况环境,用自回归AR风速模型模拟实际风场的风速,获得了由随机风速引起的时变风载荷;采用集中质量参数法建立了传动系统的纯扭转动力学模型,求得了系统的固有频率和阵型;研究了传动系统在时变风载下的动态特性,求得了各齿轮的振动位移和各齿轮副的动态啮合力,为风力发电机传动系统的动态性能优化和可靠性设计奠定了基础。     

Techno‐economic optimization of hybrid power system using genetic algorithm

This paper presents an optimum sizing methodology to optimize the hybrid energy system (HES) configuration based on genetic algorithm. The proposed optimization model has been applied to evaluate the techno‐economic prospective of the HES to meet the load demand of a remote village in the northern part of Saudi Arabia. The optimum configuration is not achieved only by selecting the combination with the lowest cost but also by finding a suitable renewable energy fraction that satisfies load demand requirements with zero rejected loads. Moreover, the economic, technical and environmental characteristics of nine different HES configurations were investigated and weighed against their performance. The simulation results indicated that the optimum wind turbine (WT) selection is not affected only by the WT speed parameters or by the WT rated power but also by the desired renewable energy fraction. It was found that the rated speed of the WT has a significant effect on optimum WT selection, whereas the WT rated power has no consistent effect on optimal WT selection. Moreover, the results clearly indicated that the HES consisting of photovoltaics (PV), WT, battery bank (Batt) and diesel generator (DG) has superiority over all the nine systems studied here in terms of economical and environmental performance. The PV/Batt/DG hybrid system is only feasible when wind resource is very limited and solar energy density is high. On the other hand, the WT/Batt/DG hybrid system is only feasible at high wind speed and low solar energy density. It was also found that the inclusion of batteries reduced the required DG and hence reduced fuel consumption and operating and maintenance cost. Copyright © 2014 John Wiley & Sons, Ltd.     

Technology parameter for thermal power stations

The technology parameter which represents the ratio of fractional change of an investment to fractional change in cost of electrical energy has been computed for thermal power stations. The value lies below ten which signifies that the is good scope for additional investment (bigger power stations).     

The optimal fuel mix and redistribution of social surplus in the Korean power market

This paper investigates the difference between the optimal fuel mix incorporating a pre-installed generation capacity constraint and the actual fuel mix in the Korean power market. Since the restructuring of the market, the fuel mix has been determined partly by investors and partly by the Basic Plan for Long-Term Electricity Supply and Demand (BPE). Both the system marginal price (SMP), and the capacity payment (CP), which has been based on the fixed cost of a specific gas turbine generator, were intended to provide an investment incentive in the market; however, they did not bring about an optimal fuel mix in Korea. Under the circumstances of a shortage of base load generators, these generators may garner excessive profits due to a high SMP level. However, the adjustment scheme of profit between KEPCO and Gencos left scant profit for generators. This paper suggests that a contract is needed to create the appropriate profit and tax levels for these base load generators. The redistribution of profit improves equality between consumers and generators, and the proper margin creates incentives for base load technology investment in Korea.     

兴建三峡抽水蓄能电站,提高三峡电能质量

三峡工程由于库容相对较小，水量调节程度低，所发电量大部分是基荷电量，以火电为主的华东电网接受大量三峡基荷电，更大大中调峰缺口，三峡坝址附近有条件优越的抽水蓄电站站址，兴建三峡抽水蓄能电站，提高三峡电能质量，作为减少华东电网调峰缺口的措施之一。     

Price,environment and security: Exploring multi-modal motivation in voluntary residential peak demand response

Peak demand on electricity grids is a growing problem that increases costs and risks to supply security. Residential sector loads often contribute significantly to seasonal and daily peak demand. Demand response projects aim to manage peak demand by applying price signals and automated load shedding technologies. This research investigates voluntary load shedding in response to information about the security of supply, the emission profile and the cost of meeting critical peak demand in the customers’ network. Customer willingness to change behaviour in response to this information was explored through mail-back survey. The diversified demand modelling method was used along with energy audit data to estimate the potential peak load reduction resulting from the voluntary demand response. A case study was conducted in a suburb of Christchurch, New Zealand, where electricity is the main source for water and space heating. On this network, all water heating cylinders have ripple-control technology and about 50% of the households subscribe to differential day/night pricing plan. The survey results show that the sensitivity to supply security is on par with price, with the emission sensitivity being slightly weaker. The modelling results show potential 10% reduction in critical peak load for aggregate voluntary demand response.     

Optimum operation strategy and economic analysis of a photovoltaic-diesel-battery-mains hybrid uninterruptible power supply

This paper presents the optimum operation strategy and economic analysis of a photovoltaic-diesel-battery-mains hybrid uninterruptible power supply (UPS). The system involves a photovoltaic, battery and bi-directional inverter that is connected in parallel to the grid. A diesel generator is required when the grid is not available for a longer time. The optimum operation strategy of the system is proposed for the diesel-connected mode (when the grid fails for several hours), while the economic analysis is evaluated for the grid-connected mode. The optimum strategy determines the ‘set point’ value for starting and stopping the diesel generator, resulting in a lower system operation cost within its lifetime. The optimum value is obtained by comparing the cost of the diesel fuel consumption and the battery wear. The economic analysis includes the system operation as UPS and demand side management. The system will reduce the power flow from the mains by increasing the power from the inverter to the load when the tariff is high. However, when the grid tariff is low, the power from the mains is used to charge the battery and to meet the load simultaneously.     

调峰电站及其蓄能技术

介绍了调峰电站在电力供应、电网调峰方面的作用和意义 ,概述了调峰电站的主要类型以及国内外的应用现状 ,指出寻找新的蓄能方法的重要性 ,并列举了目前几种主要的蓄能方法     

风光互补对电网输电服务价格的影响

风电和光电各自出力的不稳定性提高了输电服务成本,制约了它们的发展.利用风能和太阳能的互补性可提高发电的可靠性.研究了风光互补后对电网输电服务价格的影响,提出了考虑可再生能源并网的输电服务价格函数表达式,建立了以该函数值最小为目标,以系统发电不足概率(LOLP)和能量缺失率(LPSP)为约束条件的输电服务价格优化模型.采用粒子群算法对目标函数进行求解,对风光互补前后的输电服务价格进行对比,并求出使输电服务价格最低的风光容量配比.通过对实例系统进行计算,验证了该方法的有效性,指出风光互补能有效地降低输电服务价格.     

独立光伏发电系统在移动通信基站中的设计与应用

介绍了太阳能独立光伏发电在移动通信基站中的应用,重点介绍了太阳能独立光伏发电系统的组成、系统设计指导原则、移动通信基站的负载类型、太阳能阵列最佳倾角和蓄电池容量的计算步骤与方法等。