Load frequency control of power systems with large scale of wind power integrated based on particle swarm algorithm
Abstract: An interconnected power system with large scale of wind power integration is taken as our research object. In order to keep the stability of frequency, a PSO based load frequency controller is proposed. According to the amount of area control error (ACE), traditional load frequency controller is to adjust the output of units in order to make ACE approach to zero. Then output from all generators is matched to the demand from load. Output from wind units is taken as a negative load and an equivalent load is formed. Intelligent PSO is introduced into traditional load frequency controller and is expected to improve the control performance. The simulation based on the model, which is constructed on Matlab/Simulink platform demonstrates that, for the new design controller, its performance index whether frequency error of interconnected network or exchange flow for the interconnected line is better than that of traditional load frequency controller.
0 Introduction
With the depletion of the worlds fossil energy and environmental degradation, countries are taking measures to speed up the use of renewable energy and development. As a kind of inexhaustible clean energy, wind energy has been paid more and more attention. At present, wind power generation has become the fastest and most mature renewable energy generation technology. Due to the fluctuation of wind farms output power, its large-scale grid-connection will bring a series of problems to the power grid, such as power quality, system stability, scheduling and Operation Economy of the grid, etc. . And with the increase of the proportion of wind power capacity in the system, the above effects become more and more significant. Among them, the impact on the system frequency can not be ignored, it is directly related to the security and stability of power system operation. In this case, how to suppress the system frequency fluctuation caused by wind power access to ensure the frequency security and stability has become one of the important issues in wind power research.
At present, the main methods to overcome the frequency control problem after the wind power is connected to the system are as follows: improve the precision of the wind power forecast, do well the dispatching plan, which is helpful to reduce the system operation cost and spare capacity; By introducing a frequency response link into the wind turbine to improve its own active power regulation, the wind farm can participate in the system frequency regulation to a certain extent, balance The power fluctuation caused by wind power on the spot; utilize the frequency regulation ability of conventional units, i. e. existing speed governor and automatic generating device.
In order to maintain the balance of active power and ensure the maximum output of wind farm, the most practical means of frequency control is to fully exploit the frequency modulation ability of existing power system to meet the needs of larger wind capacity access. The most direct way to improve the frequency modulation ability of the existing system is the design of load frequency controller, which has the advantages of less investment and good effect.
In the previous research, this paper introduces the way of dealing with wind power output, that is, taking the fluctuation of wind power output as a negative load fluctuation, and illustrates the feasibility of frequency control of AGC in wind power access, but lacks the concrete control strategy design and the implementation. The intelligent controller has the advantages of good self-adaptability and dealing with non-linear system, and it can adapt to the control problem under the changing condition better than the traditional proportional integral controller, in this paper, the load frequency control system model of two-area interconnected system with wind power is established, and the load frequency control system model of two-area interconnected system with wind power is established, then the particle swarm control with fast convergence is applied to the interconnected power system with wind power access, and the improvement degree of the frequency performance index is analyzed, which is verified by an example on Matlab / Simulink.
1 Load Frequency Control Model of two-area interconnected system with wind power
Load Frequency Control LFC is based on Area Control Error, ACE to achieve the Control of the unit adjustment. It changes the total power level of the system by adjusting the output of the unit, and makes the regional control deviation ACE zero under the continuous regulation of the active power of the unit, so as to ensure the matching of the output and the load power of the whole system. 1.1 load frequency control system model for two-area interconnected systems the load frequency control system model for two-area interconnected systems is shown in figure 1, it consists of governor module, Prime Mover Module, generator-load module, tie-line module, LFC controller and so on.
Fig. 1 Model of load frequency control for an
interconnected grid with two regions
For an interconnected power system, each control area controls only the load disturbances that occur in its own area under the premise of a given tie-line exchange power, the load frequency controller controls the system frequency and the tie line exchange power simultaneously. The tie-line frequency deviation control (TBCTBC) is often used in the load frequency controller, i. e. the two-zone frequency deviation is
1.2 wind speed model
The wind speed is the main parameter which affects the output of the generator. At present, the four-component model is widely used at home and abroad, that is, it is composed of basic wind, gust, gradual
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不同方法提高DGA解释准确率的研究进展
Shalaka Bhimrao Wanjare
Department of Electrical Engineering,
Government College of Engineering,
Aurangabad, Maharashtra, India
摘要— 溶解气体分析是估计变压器油中溶解气体含量的一种方法。变压器的健康状况主要取决于变压器油的状况。油中气体的百分比可能导致变压器的不同故障。分析变压器故障的方法有Rogers比值法（RRM）、Doernenburgs比值法（DRM）、Duval三角法（DTM）、Duval五边形法（DPM）和IEC比值法（IRM）。变压器中会产生各种气体。变压器油中释放的气体量会产生不同的故障。在变压器油中，通常会释放出氢气（H2）、甲烷（CH2）、乙烯（C2H4）、乙炔（C2H3）、一氧化碳（CO）、二氧化碳（CO2）、氮气（N2）和氧气（O2）。本文提出了用贝叶斯网络提高DGA解释精度的方法。
关键词-溶解气体分析，变压器故障预测
一、简介
电力系统的重要组成部分是电力变压器。电力变压器有多方面的问题需要考虑，以保持电力变压器的健康[1]。变压器发生各种故障的原因是多方面的。其主要原因之一是变压器油中气体的形成[3]。变压器油中气体击穿的原因是多方面的。对变压器油进行检查和监督，以检测和维护电力变压器的正常状态。电力变压器的制造成本非常高，因此不可能对其进行再投资，因此保持良好的健康或适当的状态非常重要。
Panchayya S.Swami
Department of Electrical Engineering, Government College of Engineering,
Aurangabad, Maharashtra, India
变压器发生故障的原因有外部故障和内部故障两种。
1.发生外部故障的原因如下：电力变压器外部短路、变压器内高压干扰、工频过电压。
2.电力变压器内部故障：绕组对地绝缘击穿、相间绝缘击穿、相邻匝间绝缘击穿、变压器铁心故障。
3.电力变压器内部接地故障如下。中性点阻抗接地星形绕组的内部接地故障
变压器油箱内气体的分解是造成变压器油箱故障的主要原因。石油中的气体是通过不同的方法去除的，比如：
- 部分脱气（单循环真空萃取）
- 合计脱气（多循环真空萃取）
- 用另一种气体冲洗油来剥离
- 通过顶空技术
溶解气体分析技术是一种用于变压器故障识别的技术。通常故障是由电晕或局部放电、热加热、电弧引起的。对于不同的温度水平产生不同的气体。
二、 监督机油状况
电力变压器充满了油。油的主要用途是保持温度尽可能低，另一个重要原因是给变压器绕组提供绝缘。变压器油箱中的油与变压器内部接触。在许多情况下，由于某些异常情况，变压器油箱内会产生各种气体。通过计算气体的量、性质，对变压器中的故障进行了分类。气体的产生和分解有许多原因。变压器油的监督是通过各种试验进行的。根据故障产生情况，每天、每周、每月进行测试或维护工作。DGA分四步进行：
- 从变压器油箱取样。
- 气体抽取。
- 用气相色谱仪、气相色谱仪分析提取的混合气体。
- 分析的解释。
通过以上步骤，可以监控变压器油箱中的油，并检测其中产生的气体量。变压器油中产生的气体清单-
- 氢气-H2
- 甲烷-CH4
- 乙烯-C2H6
- 乙烷-C2H6
- 乙炔-C2H2
- 丙烯-C3H6
- 丙烷-C3H8
- 一氧化碳-CO
- 二氧化碳-CO2
- 氧气-O2
- 氮气-N2
表1-DGA可检测的故障
|
序号 |
符号 |
错误 |
|
1 |
PD |
局部放电 |
|
2 |
D1 |
低能放电 |
|
3 |
D2 |
高能放电 |
|
4 |
T1 |
热故障，温度lt;3000C |
|
5 |
T2 |
热故障,300lt;温度lt;7000C |
|
6 |
T3 |
热故障，温度gt;7000C |
表2-DGA指南和标准[11]
|
标准 |
说明 |
|
IEEE标准C57.104.2008 |
变压器中气体分析的IEEE指南 |
|
IEEE标准C57.12.80-2002 |
配电变压器术语 |
|
IEEE 60599-2007-05 |
使用中的注入矿物油的电气设备 |
|
IEC 60599-2007-05 |
参考Duval三角形 |
三、油的性质
油被水和一些外来颗粒污染了。另一方面是油的持续老化。除了这些保护性能外，这些氧化产物还加速了纤维素绝缘层的丧失。测试次数如下所示，以检测油的性能。
1.电气性能
1.1击穿电压（IEC 60156）
油的抗电应力能力是非常必要的。低击穿电压是由于机油污染造成的。
1.2介质损耗因数（IEC 60247）
这个特性给出了油中介质损耗的概念。它给出了有关金属离子和酸的指示。
2.化学性质
2.1含水量（IEC 60814）
水分演化的原因是油的老化。变压器油箱也会漏水。由于高水分的存在，击穿电压较低。绝缘纸的老化速度是由于含水量高。
2.2酸性（IEC 62021）
酸是由于油中的氧化而形成的。氢氧化钾是用来中和酸的。
2.3抑制剂含量（IEC 60666）
为了减缓油的氧化，添加了抑制剂。它不允许在氧化过程中发生连锁反应。由于抑制剂的作用，油通常老化得很慢。由于缺乏抑制剂，氧化发生得很快。因此，对居住内容的监测非常重要。
3.物理特性
3.1颜色（ASTM D1500）
颜色不是那么重要的属性。但它给出了石油老化的概念。对于化学分析来说也是非常重要的。
3.2界面张力（IFT ASTM D 971-99）
极性污染物和破损产物的数量与油水界面张力有关。这是很重要的，以表明老化，它也是由非酸性氧化产物的倾向。
3.3腐蚀性硫（IEC 62535）
由于纤维素绝缘层中的硫化铜，设备出现了许多问题。由于石油中的腐蚀性硫成分，其他问题也随之而来。除了ASTM D1275或DIN 51353外，还开发了新的试验，这些试验对检测机械故障具有更高的灵敏度。
- DGA标准诊断方法
1.杜瓦尔三角法（DTM）
在duval三角1法中，故障诊断有两种方法，经典的方法是利用CH4、C2H4和C2H2三种气体的能量差来实现。Duval三角形4方法使用H2、CH4和C2H6气体诊断低能或低温故障。Duval triangle 4首先分类为Duval triangle 1断层，如PD、T1和T2。它从不检测像D1或D2这样的电气故障。Duval三角形4通常区分油的杂散气体、2500c以下的过热、3000C以上的纸张可能碳化、电晕局部放电。Duval triangle 5使用气体CH4、C2H4和C2H6进行高温故障检测。
2.杜瓦尔五边形法
在这种方法中，五种主要的烃类气体比率用于识别断层。烃类气体为H2、CH4、C2H6、C2H4和C2H2。在该方法中，用五边形的五个气体比率表示充油设备的故障。
3.国际电工委员会比率法（IRM）
IEC比值法采用先进的故障识别技术。故障分为7种类型：局部放电（PD）、低能放电（D1）、高能放电（D2）、热故障（T1）、热故障（T2）、热故障（T3）。在该方法中，状态评估使用了各种气体的限值，并评估了三种不同的气体比率。
表3-单个气体的IEC限值
|
气体 |
限制（外部OLTC） |
限制（内部OLTC） |
|
H2 |
60-150 |
75-150 |
|
CH4 |
40-110 |
35-130 |
|
C2H2 |
3-50 |
80-270 |
|
C2H4 |
60-280 |
110-250 |
|
C2H6 |
50-90 |
50-70 |
|
CO |
540-900 |
400-850 |
|
CO2 |
5100-13000 |
5300-12000 |
4.多尔内堡比率法（DRM）
在doernenburg比值法中，用四种不同的气体来评价三种不同的断层。该方法对每种气体都有限制，如下表所述。如果气体限值超过限值，则该比值会发生变化，在故障诊断时具有不同的值。
|
故障诊断 |
CH4/H2 |
C2H2/C2H4 |
C2H2/C H4 |
C2H6/C2H2 |
|
热分解 |
gt;1.0 |
lt;0.75 |
lt;0.3 |
gt;0.4 |
|
光晕 |
lt;0.1 |
- |
lt;0.3 |
gt;0.4 |
|
电弧 |
0.1-1.0 |
gt;0.75 |
gt;0.3 |
lt;0.4 |
5.关键气体法
在关键气体法中，对关键气体进行了识别。故障诊断是ieeec57.104[3]推荐的诊断方法。气量按可燃气体总量计算。这种方法的缺点是，在实际应用中，由于每一个早期断层都会产生大量的其它气体聚集到该断层的关键气体中，用确定的气体进行分析比较困难。
6.Rogers比率法（RRM）
罗
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