麝珠明目滴眼液质量操纵方法[精彩]

潮流分析--英文文献（原文 译文）中英对照 附录A 英文文献原文 Power Flow Analysis INTRODUCTION We consider next the important problem of power flow. In this analysis the transmission system is modeled by a set of buses or nodes interconnected by transmission links. Generators and loads, connected to various nodes of the system, inject and remove power from the transmission systemThe model is appropriate for solving for the steady-state powers and voltages of the transmission system. The calculation is analogous to the familiar problem of solving for the steady-state voltages and currents in a circuit and is just as fundamental. It is an integral part of most studies in system planning and operation and is, in fact, the most common of power system computer calculationsTo suggest the variety of possible studies, consider the system with the one-line diagram shown in Figure 10.1. The systems considered by power engineers would usually be larger, with as many as thousands of buses and thousands of transmission linksIn the figure, the are the injected complex generator powers and the are the complex load powers. The are the complex phasor bus voltages. Transformers are assumed to have been absorbed into the generator, load, or transmission-line models and are not shown explicitly. It should be understood that we are restricting our attention to the transmission system, which transmits ht bulk power from the generators to the bulk power substations. Thus the load powers shown in Figure 10.1 represent the bulk power loads supplied to large industrial consumers and/or to a “subtransmission” system for further dispersal to distribution substations and ultimately a network of distribution feeders. While we are considering only the top layer of a multilayer system the backbone of the overall system , it should be noted that the techniques developed in this chapter are applicable to the different layers of the system. A figure similar to Figure 10.1 might represent a subtransmission system with power injections from the transmission substations, and possibly some of the older lower-voltage generators as well. The reason we concentrate on the transmission system is its basic importance and the fact that there are some interesting and vital problems, such as stability, unique to it. The purpose of a power system is to deliver the power the customers require in real time, on demand, within acceptable voltage and frequency limits, and in a reliable and economic manner. We are concerned here only with the implications of this objective on the operation and design of the system at the transmission level. In the analysis we assume that the load powers are known constants. This assumption conforms to the driving nature of the customers’ demand, wherein we may make it to be the input, and to the usually slowly varying nature of it, wherein can be studied by considering a number of different cases; for each we assume steady-state conditions. Frequently, the cases treated are the ones for which some difficulties in meeting system requirements may be expected. What are some of these or one or more lines are thermally overloaded, System one-line diagram or that the stability margin for a transmission link is too small i. e, the power angle across a transmission link is too great, or that a particular generator is overloaded. Other studies relate to contingencies such as the emergency shutdown of a generator, or the loss of one or more transmission links due to equipment failure. With a given loading, the system may be functioning normally, but upon a single or multiple contingency outage the system in such a way that it is not overloaded in any way nor will it become so in the event of a likely emergency; in system planning there is a need to consider alternative plans to assure that these same objectives are met when the addition goes online. In system operation and planning it is also extremely important to consider the economy of operation. For example, we wish to consider among all the possible allocations of generation assignments what is optimal in the sense of minimum production costs i. e., the fuel cost per hour to generate all the power needed to supply the loads. We note in passing that the objectives i. e., economy of operation and secure operation frequently give conflicting operating requirements, and compromises are usually required. This list of problems, which is far from complete, gives an idea of the range of problems in which we are interested. In considering all these problems we need to know the relationships between the,, andThe relationships are given by equations called power flow equations. These are derived in the next section. POWER FLOW EQUATIONS We restrict attention to three-phrase balanced system operation, so that per phase analysis may be used. We have already considered a special case of the power flow equations in section 4.6. Just as in the two-bus case, it is convenient to work with the power at each bus injected into the transmission system. Thus, we define the complex per phase bus power, , as follows: ? is what is left of after stripping away the local loadWe can visualize by splitting a bus. For example, in Figure 10.1 we may split bus 3 as shown in Figure 10.2is the net bus power injected into bus 3. Using conservation of complex power, we also have for the ith bus, = i1, 2,… ,n Where we sum over all the transmission links connected to the ith bus. We also define the bus current : = - = i 1, 2, … , nis the total phase a current entering the transmission system. For bus 3 in Figure 10.1 we may visualize as shown in Figure 10.3, where all the currents shown are phase a currents. In Section 9.1 we developed the relationship between the injected node currents and the node voltages given by9.1. Using I V, we get for the ith component, = i 1, 2, … , n physical significance of physical significance of We next calculate the ith bus power. Using 10.2 gives us = = = i1, 2, … , n Suppose we let ?? = ?? - + j Note that we use a polar representation for complex voltage but a rectangular representation for complex admittance. The are called conductances, and the are called susceptances. Then becomes = = i1, 2, … ,n Equations 10.3 and 10.4 are two equivalent forms of the (complex) power flow equations. Resolving 10.4 into real and imaginary parts, we obtain = = SUMMARY The power flow equations give the relationships between bus powers and bus voltages in terms of the admittance parameters of the transmission system. Operational and mathematical considerations lead us to define the following types of buses. There load P, Q buses, generator P, buses, and a slack or swing busA bus with reactive power injections from a capacitor bank is a P, Q bus if the Q injection is fixed but is a P, bus if the Q injection is varied to keep fixed. Comparing the computational burden of the two methods, it is found that each Newton-Raphson iteration takes longer than the corresponding Gauss or Gauss-seidel iteration, but convergence is obtained with fewer iterations so, overall, there is usually a saving in computation. For computations involving power systems under the usual operating conditions, some simplifications of the Newton-Raphson scheme are usually possible. One of these modifications is called decoupled power flow. It still requires the updating of Jacobian matrices for each iteration, but the dimensionality of the computation is reduced. Another modification is called fast-decoupled power flow. In this case, the updating of matrices is no longer required and the computational burden is greatly reduced. 附录B 英文文献翻译 潮流分析 我们考虑未来的潮流计算的重要问题。在这种分析中的传输系统是模拟 了一个由巴士传输链路或节点互连设置。发电机和负荷,连接到系统的各个节点, 并从注入传输系统的电源。 该模型是为稳定国家权力和传输系统电压适当解决。计算类似于为稳态 电压和电流的电路解决熟悉的问题,是同样重要。它是在系统规划和运作的组成 部分,大多数的研究,实际上,最常见的电力系统计算机计算。 建议可能的各种研究,考虑与图10.1所示的线图系统。电力工程师认为 该系统通常会较大,如巴士和传输链路成千上万很多。 在图中,被注入到发电机电能中并且为负载电能。为复杂的(功角)总线电压。假设变压器已投入发电机,负荷,或传输线模型吸收,没有显示明确。应该理解为,我们该限制对传输系统的注意,传输大容量的发电机功率羟色胺的大型电源变电站。因此,负载图10.1所示的权力代大电力供应大型工业用户负载和/或一个“分传输“进一步扩散,并最终以配电变电站的配电馈线网络系统。虽然我们只考虑一个多层系统(整个系统的骨干)顶层,应该指出,在这一章开发的技术适用于该系统的不同层。该图类似于图10.1可以代表一个由输电站注入功率分传输系统,并且一些旧的(低电压)发电机可能效果也很好。我们之所以对传输系统的集中是其基本的重要性,事实上,有一些令人感兴趣的重要问题,如稳定性,它独有的。 系统单线图 一个电力系统的目的是为客户提供电源的实时要求,要求在可接受的电压和频率的限制,并在一个可靠和经济的方式。我们这里只关心与操作和在传输系统设计的水平这一目标的影响。 在分析中,我们假设负载电能是已知的常数。对于这我们每个假设稳态条件,这种假设顺应了客户的需求推动的性质,其中,我们可以使之成为输入,并(通常)慢慢变它的性质,其中可以通过考虑不同个案研究。通常情况下,实例的处理是在满足系统要求的一些困难,可以预期的。这些行为有些是(热)超载,或为一个传输链路稳定裕度太小(一E的功角跨越输电线路太大),或者是一个特定的发电机超载。其他的研究涉及到突发事件,如发电机紧急关闭,或一个或多个传输链路 由于设备故障的损失。与给定负荷,系统可能正常运作,而是建立在单一的(或多个)的应急中断在这样的,这是不以任何方式重载,也不会成为了一个可能的紧急事件,这样的方法体系,在系统规划是有需要考虑替代,以确保这些相同的目标的实现时,除了联网。 在系统运行和规划也是非常重要的考虑运作的经济。例如,我们希望在所有可能的发电任务分配考虑什么是最低的生产成本意识(即每小时的燃料成本来产生所需的所有负荷的电力供应)我们注意到,在过去的目标(即,操作和安全运行的经济性)经常给冲突的操作要求,通常需要妥协。 这个问题的清单,这还远远没有完成,给出了一系列问题,使我们感兴趣的想法。在考虑所有这些问题,我们需要了解,和之间的关系,它们的关系都是通过所谓的潮流方程。这些的根据将在下一节显明。 潮流方程 我们限制注意三相平衡系统的运作,使每相分析可能被使用。我们已经考虑了在第4.6节潮流方程的特殊情况。正如在两总线的情况下,可以很方便地与电力工作注入到每个总线传输系统。因此,我们定义了每相总线供电,具体如下: 在洗去本地负载之后即是遗留下的。我们可以通过分割总线去设想。例如,在图10.1,我们可以分割总线3,如图10.2所示。是净总线电源注入到总线3。利用复杂的电源保护,我们还为第i个总线有: i1, 2,… ,n 我们了所有的传输链接的第i总线连接。 我们还定义了总线电流: i 1, 2, … , n 是当前阶段的总进入传输系统。对于总线3图10.1,我们可以想像为图10.3所示,所有的电流显示的是A相电流。 在9.1节我们制定了节点之间的注入电流和节点由(9.1)电压的关系。使用I V,我们得到的第i个组成, = i 1, 2, … , n 的物理意义 的物理意义 接下来我们计算第i总线电源。利用式(10.2)给我们 = = = i1, 2, … , n 假设我们让 ?? = ?? - + j 请注意,我们使用一个(复杂)电压极坐标表示,但对于(复)准入矩形表示。被称为电导,而被称为电纳。就变成 = = i1, 2, … ,n 方程(10.3)和(10.4),有两项(复)潮流方程的等价形式。为解决和实虚部(10.4),我们得到 = = 概要 给予的潮流方程中的参数传输系统的准入条件总线之间的电能和总线电压的关系。操作和数学考虑导致我们定义以下类型的总线。有负荷(P,Q)的总线,发电机P, 总线,和一个松弛摇摆总线。一个带有从电容器组注入无功功率的总线是P,Q总线,如果Q节点是固定的而不是一个P, 总线如果Q节点是变化的并保持固定。 比较两种方法计算的负担,可以发现,牛拉法迭代的时间超过了相应的高斯(或Gauss - Seidel迭代)循环,但却减少了迭代收敛这样得到的,总体而言,通常有一个计算量节省。 对于涉及一般工作条件下电力系统的计算,对牛顿迭代计划中的一些简化通常是可能的。这些修改的一个被称为解耦潮流。它仍然需要为每个迭代更新雅可比矩阵,但计算维度降低。另一个修改是要求快速解耦潮流。在这种情况下,矩阵的更新是必需的,不再计算负担大大降低。