共查询到18条相似文献,搜索用时 187 毫秒
1.
2.
以两台变压器并列运行为例,分析了变压器自动投退的技术经济情况。结果表明,在变电站运行过程中自动投切变压器,改变其运行方式,可减少变压器运行损耗,提高经济效益,为优化电网运行提供有效途径。 相似文献
3.
4.
针对变电站电压无功控制中,存在的变压器分接头和电容器组投切频繁以及电容器投切对系统电压造成一定的冲击问题,将静止同步补偿器(STATCOM)用于变电站电压/无功调节控制中,提出了离散设备优先动作,连续设备精细调节的控制策略,协调有载调压变压器分接头、电容器组与STATCOM之间的运行,在电压发生波动时,投入STATCOM实现对电压快速和平滑的调节;在正常运行时,STATCOM有足够的裕量。在修正后的IEEE-9系统中对提出的的控制策略进行仿真分析,结果表明,提出的协调控制策略能够有效地减少变压器分接头和电容器的投切次数,减小电容器投切时对系统电压造成的冲击。 相似文献
5.
6.
7.
8.
针对采用临界值法投切变压器会造成变压器的频繁投切、影响电气开关寿命、降低电力系统可靠性的问题,基于短期预测到的未来1 d的负荷数据,将给定的时间段划分为多个时间区间,引入改进后的模糊决策法对时间区间影响进行数学优度值计算,进而选出最优对象,并通过算例进行了仿真。结果表明,改进后的模糊决策法简单,适用于解决配电变压器经济运行时投切时机的选取问题,且在降低变压器自身综合功率损耗的同时,减少了变压器相关电气元件的投切次数,延长了使用寿命,提高了电力系统的可靠性,减少了投资,满足经济运行和工程应用的要求。 相似文献
9.
[目的]现有换流站无功补偿方案下,调相机仅提供暂态无功支撑,交流滤波器承担稳态无功补偿与调整任务,两者间缺少协调方案,经济性不足。[方法]在保证调相机动态特性的基础上,基于直流送、受端系统运行特性,首先提出以调相机置换部分交流滤波器容量,两者共同参与稳态无功补偿的换流站无功优化方案。随后按照动作顺序先后提出换流站双层无功调整策略。第一层无功调整由调相机承担,通过在稳态运行范围内调节出力实现。第二层无功调节在第一层无功调整后启动,逐组投切交流滤波器进行无功调整,直至达到换流站无功调整要求。最后,在PSCAD中搭建LCC-HVDC(Line-Commutated Converter High Voltage Direct Current,LCC高压直流输电)系统仿真模型进行仿真验证。[结果]仿真结果表明文章提出的换流站无功补偿方案和双层无功调整策略能优化换流站交流滤波器配置组数,减少换流站交流滤波器投切频次。[结论]所提方案实现了对现有LCC-HVDC换流站无功补偿方案和无功调整策略的优化。 相似文献
10.
配电网无功优化就是在保证配电网安全可靠运行的前提下,根据不同负荷水平,调节配电网中已有的无功补偿设备来改变无功潮流在网络中的分布,从而达到降损节能的目的.在配电系统中,调节变压器变比对系统的无功影响很小,相对投切补偿电容器组对系统无功的影响可以忽略.
…… 相似文献
11.
[目的]在保证变电站平均负载率相对合理、提高变电站利用小时数的前提下,为了解决目前电网存在的高峰负荷过高造成的变电站主变压器短时间重载问题,延缓电网的建设投资,保证电网经济运行,文章提出了基于满足主变N-1供电要求的变电站储能定容方法。[方法]首先,建立储能定容数学模型实现对负荷运行曲线削峰填谷、降低变压器最高运行负载率;然后,构建锂离子电化学储能定容经济目标函数,并开展建设锂离子电化学储能和扩建主变的建设投资对比,分析储能定容经济性;最后,结合实际变电站,提出储能配建规模的建议及经济可行的储能建设成本。[结果]通过分析,随着未来锂离子电化学储能单位造价降低,储能功率可按照变电站容量15%、充放电时长2 h考虑,储能系统单位造价降低至1 200元/kWh左右时,建设储能的经济优势明显。[结论]所提出的储能定容方法可以有效解决变电站短时间重载问题,并具备较常规输变电工程更优的经济性。 相似文献
12.
《Power and Energy Magazine, IEEE》2005,3(4):12-15
Some ideas on an evolutionary approach to enhancing functional characteristics of transmission equipment, such as transformers, through the adoption of solid-state switching are explored in this article with the intent of stimulating discussions among specialists in solid-state technology and transformer design and experts in power system planning and operation. This article proposes the use of solid state switching to give transformers the additional capability of var control similar to that in static Var compensators. Incorporating this functionality into transformer-based systems has the potential of adding a very useful system-wide voltage control capability, at a relatively small cost considering mass production and modularity. 相似文献
13.
14.
鉴于仪器设备笨重、现场接线复杂是造成电力互感器现场检定工作强度大、效率不高的主要影响因素,基于比较法互感器检定接线原理,设计了一套智能型电力互感器移动计量检定系统,该系统采用移动式检定技术,搭载了电流互感器、电压互感器现场试验所需的仪器设备,设计出自动切换变比的试验接线回路及后台管理软件,实现了仪器设备不下车即可开展检定试验及检定回路上位机控制等功能,可满足220kV及以下电力互感器现场试验要求。实例应用结果表明,本文设计的计量检定系统简化了互感器计量检定工作现场操作流程,提高了现场工作效率。 相似文献
15.
A three-phase current-fed dc/dc converter with a three-leg high frequency transformer for fuel cells
In this paper, a three-phase current-fed dc/dc converter with an active clamp is introduced, and a new three-phase three-leg high frequency transformer is proposed for the converter. The three-phase dc/dc converter transfers power through transformer leakage inductances in the discontinuous current mode; a single common active clamp branch is employed for zero-voltage switching (ZVS) in all active switches. Further, the converter's three-phase power configuration increases power transfer, and it reduces the rms current per phase, thus reduces conduction losses. Moreover, a delta–delta connection on the three-phase transformer provides parallel current paths and reduces conduction losses in the transformer windings. A three-phase transformer can be constructed by connecting three discrete single-phase transformers, but this process results in a higher volume and higher material costs. Therefore, a new three-phase three-leg high frequency transformer is designed with three discrete cores integrated into a single transformer core. The proposed transformer is analyzed according to the several operating modes of the converter, and its design rules are determined. Experimental results are obtained on a 500-W prototype unit; the design is fully verified and analyzed. 相似文献
16.
17.
针对大型变压器突然退运造成的潮流转移问题,提出考虑大型变压器退运的电力系统连锁故障风险评估方法,即先利用变压器在线监测技术对变压器的老化失效和偶然停运进行分析,建立变压器失效模型;然后,从系统能量和结构角度对潮流转移支路状态进行评估,定义了能量转移因子和支路传输能力因子,并结合连通率和失负荷率指标,得到元件风险集;最后,根据连锁故障阶段模拟和自组织临界状态辨识方法,对连锁故障演化路径进行了全面预测。仿真结果验证了该方法的可靠性,可为能源互联网下的电网安全调度提供参考。 相似文献
18.
From the viewpoint of high quality output voltage generation in a residential photovoltaic system, a multilevel inverter employing cascaded transformers can become a good substitute for the conventional pulse width modulated inverters and other multilevel counterparts. However, to obtain more sinusoidal output voltage waves, it should increase the number of switching devices and transformers resulting in a cost increase. To alleviate this problem, an efficient switching pattern is proposed and applied to a multilevel inverter equipped with two cascaded transformers, which have a series-connected secondary. Operational principle and analysis are illustrated focusing on a change of the switching pattern. High-performance of the proposed multilevel scheme embedded in a photovoltaic power conditioning system is verified by computer-aided simulations and experimental results. 相似文献