WO2018188393A1 - 柔性直流电网潮流线性化确定方法及系统、计算机存储介质 - Google Patents
柔性直流电网潮流线性化确定方法及系统、计算机存储介质 Download PDFInfo
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- WO2018188393A1 WO2018188393A1 PCT/CN2018/071935 CN2018071935W WO2018188393A1 WO 2018188393 A1 WO2018188393 A1 WO 2018188393A1 CN 2018071935 W CN2018071935 W CN 2018071935W WO 2018188393 A1 WO2018188393 A1 WO 2018188393A1
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for AC mains or AC distribution networks
- H02J3/04—Arrangements for connecting networks of the same frequency but supplied from different sources
- H02J3/06—Controlling the transfer of power between connected networks; Controlling load sharing between connected networks
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J2103/00—Details of circuit arrangements for mains or AC distribution networks
- H02J2103/30—Simulating, planning, modelling, reliability check or computer assisted design [CAD] of electric power networks
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- the present invention relates to a power flow calculation method for a flexible DC power grid in the power industry, and particularly relates to a method and system for determining a linear current of a flexible DC power grid, and a computer storage medium.
- the processing method is based on the characteristics of high-voltage power flow calculation. Linearize the AC power flow calculations to construct a linear optimization model that considers power flow constraints.
- the power flow linearization method in the AC grid is not suitable for the flexible grid because the power flow calculation differs greatly from the AC grid.
- the embodiment of the present application provides a flexible DC power flow linearization determining method and system, and a computer storage medium.
- the technical solution of the embodiment of the present application is a flexible power grid linear power flow calculation method considering a flexible DC power grid control mode, based on injection power description and node voltage control.
- the power flow of the flexible DC grid is decomposed into: the power flow distribution of the constant voltage control node and the power flow distribution of the fixed power control node;
- the power flow distribution of the fixed voltage control node and the power flow distribution of the fixed power control node are calculated to calculate the final flexible DC power grid linearization power flow result.
- the method before decomposing the power flow of the flexible DC power grid in a controlled manner, the method further includes:
- the fixed power control node number is before the constant voltage control node number
- a branch data set is formed, which is expressed as [branch number, head end node, end node, branch resistance];
- a node admittance matrix is formed according to the node number and the branch data set.
- the calculating a power flow distribution of the constant voltage control node includes:
- the voltage of the constant voltage control node is set to a known control value, and the nonlinear equations are solved to obtain the power flow distribution P l,V of all the branch fixed voltage control nodes.
- the calculating a power flow distribution of the power control node includes:
- the flexible DC grid branch power is expressed as a linear combination of injection power based on sensitivity.
- the power flow sensitivity of all the fixed power control nodes to any one of the flexible DC power grids is calculated according to the following formula:
- the flexible DC grid branch power P l,P is expressed as a linear combination of injection power, calculated according to the following formula:
- P l,km is the injection power of the branch where the nodes k and m are located
- P i is the injection power of the node i
- ⁇ i,l is the sensitivity of the node i to the branch l
- i ⁇ A represents all the constant power control Node
- V i is the voltage of node i
- V k is the voltage of node k
- V m is the voltage of node m
- G ij is the conductance value between node i and node j, corresponding to the value of the admittance matrix of the node
- Negative, j ⁇ I denotes the node directly adjacent to node i
- G ii is the self-admittance of node i
- P l, P is the power flow distribution of the fixed power control node
- i, j, k, m are constant power Control node.
- the linearized power flow result of the flexible DC grid is calculated according to the following formula:
- P l, V represents the power flow distribution of the fixed voltage control node
- P l, P is the branch power of the flexible DC grid
- P l is the linearized power flow result of the flexible DC grid.
- the decomposition module is configured to decompose the power flow of the flexible DC grid into: a power flow distribution of the constant voltage control node and a power flow distribution of the constant power control node;
- a first calculation module configured to calculate a power flow distribution of the constant voltage control node
- a second calculation module configured to calculate a power flow distribution of the fixed power control node
- the third calculation module is configured to superimpose the power flow distribution of the constant voltage control node and the power flow distribution of the constant power control node to calculate the final flexible DC power grid linearization power flow result.
- the first computing module includes:
- the tidal current distribution calculation module of the branch is configured to set all the voltages of the constant voltage control nodes to known control values, solve the nonlinear equations, and calculate the tidal current distributions P l, V of all the branches.
- the system further includes: a flexible DC grid description module configured to node the number of the flexible DC grid before the power flow of the flexible DC grid is decomposed according to the control mode, and the fixed power control node number is at the constant voltage control node.
- the branch number of the flexible DC grid is formed into a branch data set, expressed as [tributary number, head end node, end node, branch resistance]; according to the node number and the branch data set, the node admittance is formed. matrix.
- the second computing module includes:
- the sensitivity calculation module is configured to calculate a sensitivity of the power of the fixed power control node to the power of any one of the flexible DC power grids;
- a linear combination calculation module configured to represent a flexible DC grid branch power as a linear combination of injection power based on sensitivity.
- the traditional power flow calculation based on injection power is a nonlinear model. When it is necessary to adjust the injection power to adjust the power flow of the soft grid branch, it cannot be linearly expressed, and the analysis is difficult.
- the method for calculating the linearization of the power flow of the flexible grid in the embodiment of the present application is one of the key technologies for constructing the safety constraint economic dispatch model of the flexible DC grid.
- the embodiment of the present application is a flexible power grid linear power flow calculation method based on injection power description and node voltage control, which is generally considered in the flexible DC power grid control mode.
- FIG. 1 is a flow chart of a method for determining a power flow linearization of a flexible DC power grid according to an embodiment of the present application
- FIG. 2 is a schematic diagram of a 5-node flexible grid in the embodiment of the present application.
- FIG. 3 is a structural block diagram of a power flow linearization determining system for a flexible DC power grid according to an embodiment of the present application.
- the embodiment of the present application provides a linear power flow calculation method for a flexible power grid based on injection power description and node voltage control considering a flexible DC power grid control mode.
- the flowchart is as shown in FIG. 1 and includes the following steps:
- the embodiment of the present application takes the 5-node flexible grid structure diagram shown in FIG. 2 as an example for subsequent description.
- the flexible grid of any number of nodes and any connection mode can be similarly obtained.
- the topology description of the flexible grid is no different from the conventional AC grid topology description. To ensure the integrity of the content description, it is still briefly described here.
- the node number is assigned to the flexible grid, and the fixed power control node number is ahead of the fixed voltage control node number.
- the nodes 1, 2, and 3 are fixed power control
- the nodes 4 and 5 are fixed voltage control. .
- branch data set which is expressed as [branch number, head end node, end node, branch resistance].
- branch number head end node, end node, branch resistance
- branch resistance For the branch 1 in Fig. 2, it is expressed as: [1, 1, 2, 2.35].
- the change of the injection power of the fixed power control node can represent the change of the power flow of the flexible grid branch. But the node with constant voltage control will not work.
- the embodiment of the present application proposes to divide the branch power flow into two components: the power flow distribution caused by the constant voltage control node and the power flow distribution caused by the fixed power control node.
- the power flow calculation of the flexible power grid needs to be related and deduced, and the derivation process is as follows.
- the power of the branch 1 between node i and node j in the flexible grid can be expressed as:
- P l, ij is the power flow of the branch l
- V i is the voltage of the node i
- G ij is the conductance value between the node i and the node j, which is the value corresponding to the negative in the node admittance array.
- the injected power of node i in a flexible grid can be expressed as the sum of the powers of all the branches connected to node i:
- G ii is the self-admittance of node i, which is the value corresponding to the node admittance array.
- the first term in the equation is only related to the voltage of node i itself, and the second term is related to the voltage of the adjacent node.
- Equation (6) describes the partial derivative of any branch power versus node voltage, ie the sensitivity of the node voltage to the branch current. If the value on the right side of equation (6) can be found, it means that the power change of the branch can be described by the voltage change of the node. Dividing equation (6) by equation (5) can obtain the partial derivative of any branch power to node i injection power, that is, the sensitivity of node injection power to branch power.
- equations (6) and (7) it is closely related to the control mode of the node.
- any node type (6) and formula (7) only need to solve one.
- the equation (6) is obtained; when the node is fixed power control, it is required to take the formula (7). ).
- equation (6) contains both the voltage itself and the derivative of the voltage, it can be seen that the sensitivity of the node voltage to the branch current can be linearly expressed only in a very small voltage variation interval. Therefore, we do not calculate the value of equation (6) here. We believe that the node voltages of all constant voltage control are known values, and the influence of the voltage variation of the constant voltage control node on the branch current is not analyzed.
- the equation (8) is solved.
- the partial derivatives of the nodes k, m and the nodes adjacent to i to V i are all variables to be determined.
- equation (9) can be reduced to:
- Equation (10) is actually a system of equations, except for node i itself and other nodes. Are unknown. For an n-node system, there are n-1 unknowns. There are a node (without i-node) for false power control, and (n-1-a) for fixed voltage control. According to equation (10), a equation can be obtained, and since the remaining (n-1-a) nodes are controlled by constant voltage, the voltage is not affected by other nodes, and is directly available. According to the comprehensive analysis, n-1 unknowns correspond to n-1 equations, and all can be obtained. Value.
- step S3 first, all injection powers of the fixed power control node are set to 0;
- the voltage of the constant voltage control node is set to a known control value, and the nonlinear equations are solved by the traditional numerical solution method to obtain the tidal current of all branches.
- This branch flow is expressed as P l,V , which represents the distribution of the current flow caused by the constant voltage control node.
- P i is the injection power of node i
- ⁇ i,l is the sensitivity of node i to branch l.
- i ⁇ A represents all fixed power control nodes. This means that if a P i is given arbitrarily, the corresponding branch power flow P l can be directly obtained linearly.
- step S3 Combining step S3 and step S4, the linear expression of the branch current at this time can be obtained as follows:
- nodes 1, 2, and 3 are fixed power control nodes
- nodes 4 and 5 are fixed voltage control nodes
- node 4 has a control voltage of 319.5 kV
- node 5 has a control voltage of 320 kV.
- equations of nodes 1, 2, and 3 are as follows:
- the sensitivity of the constant power node injection power to all branch powers can be obtained by taking the obtained partial derivative into equation (8). Similarly, the sensitivity of other nodes to all branches can be obtained. The results are shown in Table 1.
- step S4 and step S5 the branch power flow distribution after the constant power control arbitrary injection power is obtained can be calculated.
- node 1 injects power by 260 MW
- node 2 injects power by 340 MW
- node 3 injects power of -450.
- the flows of the branches calculated according to the embodiment of the present application are shown in the following table.
- Table 3 The voltage distribution of the branch after constant voltage control node and constant power control arbitrary injection power
- Branch road 1 Branch road 2
- Branch 3 Branch 4
- Branch road 5 Branch road 6
- This application -39.55 188.398 261.561 38.775 111.088 -74.301 Iterative method -39.3475 189.134 262.605 38.0196 110.215 -74.3012 deviation 0.0051201 -0.003907 -0.003991 0.0194816 0.0078586 -2.69E-06
- the embodiment of the present application further provides a flexible DC power flow linearization calculation system considering a DC control mode, and a structural block diagram thereof is shown in FIG. 3, including:
- the decomposition module 301 is configured to decompose the power flow of the flexible DC grid into a power flow distribution of the constant voltage control node and a power flow distribution of the constant power control node according to the control manner;
- the first calculating module 302 is configured to calculate a power flow distribution of the constant voltage control node
- the second calculating module 303 is configured to calculate a power flow distribution of the fixed power control node
- the third calculating module 304 is configured to calculate the final flexible DC grid linearized power flow result by superimposing the power flow distribution of the constant voltage control node and the power flow distribution of the constant power control node.
- the system further includes: a flexible DC grid description module configured to parameterize the node number of the flexible DC grid before the power flow of the flexible DC grid is decomposed according to the control mode, and the constant power control node number is before the constant voltage control node number;
- the branch number of the network forms a branch data set, which is expressed as [branch number, head end node, end node, branch resistance]; and a node admittance matrix is formed according to the node number and the branch data set.
- the first computing module includes:
- the tidal current distribution calculation module of the branch is configured to set all the voltages of the constant voltage control node to known control values, solve the nonlinear equations, and calculate the tidal current distribution of all the branches.
- the second calculation module includes:
- the sensitivity calculation module is configured to calculate a sensitivity of the power of the fixed power control node to the power of any one of the flexible DC power grids;
- a linear combination calculation module configured to represent a flexible DC grid branch power as a linear combination of injection power based on sensitivity.
- each module in the flexible DC power flow linearization computing system can be implemented by a central processing unit (CPU) located in a flexible DC power flow linearization computing system.
- CPU central processing unit
- a processor MPU, Micro Processor Unit
- DSP digital signal processor
- FPGA Field Programmable Gate Array
- the technical solution of the embodiment of the present application solves the traditional power flow calculation of the flexible power grid based on the injection power is a nonlinear model.
- the power of the soft power grid branch needs to be adjusted by adjusting the injection power, it cannot be linearly expressed. Analysis is difficult. Scheduling plan for the flexible grid
- the linearization of the straight flow is not realized, and the problem of optimal scheduling can not be achieved by the existing linear modeling method.
- embodiments of the present application can be provided as a method, system, or computer program product.
- the application can take the form of an entirely hardware embodiment, an entirely software embodiment, or a combination of software and hardware.
- the application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) including computer usable program code.
- the computer program instructions can also be stored in a computer readable memory that can direct a computer or other programmable data processing device to operate in a particular manner, such that the instructions stored in the computer readable memory produce an article of manufacture comprising the instruction device.
- the apparatus implements the functions specified in one or more blocks of a flow or a flow and/or block diagram of the flowchart.
- These computer program instructions can also be loaded onto a computer or other programmable data processing device such that a series of operational steps are performed on a computer or other programmable device to produce computer-implemented processing for execution on a computer or other programmable device.
- the instructions provide steps for implementing the functions specified in one or more of the flow or in a block or blocks of a flow diagram.
- an embodiment of the present invention further provides a computer storage medium, wherein a computer program configured to perform a flexible DC power flow linearization calculation method according to an embodiment of the present invention is stored.
- the technical solution of the embodiment of the present application solves the traditional power flow calculation of the flexible power grid based on the injection power is a nonlinear model.
- the power of the soft power grid branch needs to be adjusted by adjusting the injection power, it cannot be linearly expressed. Analysis is difficult. Scheduling plan for the flexible grid
- the linearization of the straight flow is not realized, and the problem of optimal scheduling can not be achieved by the existing linear modeling method.
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Abstract
一种柔性直流电网潮流线性化确定方法及系统、计算机存储介质,包括:依据控制方式将柔性直流电网潮流分解为:定电压控制节点潮流分布和定功率控制节点潮流分布;计算定电压控制节点的潮流分布;计算定功率控制节点的潮流分布;叠加定电压控制节点的潮流分布和定功率控制节点的潮流分布计算最终的柔性直流电网线性化潮流结果。
Description
相关申请的交叉引用
本申请基于申请号为201710239444.4、申请日为2017年04月13日的中国专利申请提出,并要求该中国专利申请的优先权,该中国专利申请的全部内容在此引入本申请作为参考。
本申请涉及电力工业领域的柔性直流电网潮流计算方法,具体涉及一种柔性直流电网潮流线性化确定方法及系统、计算机存储介质。
随着风光等清洁能源将继续快速发展。各种大规模可再生能源接入电网,传统的电力设备、电网结构和运行技术等在接纳超大规模可再生能源方面越来越力不从心,有必要研发新技术、新装备和新电网结构来满足未来能源格局的深刻变化。而基于柔性直流的多端直流输电系统和直流电网技术是解决这一问题的有效技术手段之一。柔直电网调度计划作为柔直电网调度运行的重要组成部分,是保障柔直电网安全经济运行的重要环节。在常规交流电网的调度计划业务中,其依托的核心技术是安全约束机组组合和安全约束经济调度,技术的关键点之一就是“电网安全约束”,处理方式是根据高电压等级潮流计算的特点,将交流电网潮流计算线性化,从而构建考虑潮流约束的线性优化模型。在柔直电网中,由于潮流计算与交流电网相差迥异,因此交流电网中的潮流线性化方法已不适应柔直电网。
发明内容
为解决上述技术问题,本申请实施例提供了一种柔性直流电网潮流线性化确定方法及系统、计算机存储介质。
本申请实施例的技术方案是一种考虑柔性直流电网控制方式,基于注入功率描述和节点电压控制的柔直电网线性潮流计算方法。
本申请实施例提供的柔性直流电网潮流线性化计算方法,包括:
将柔性直流电网潮流分解为:定电压控制节点潮流分布和定功率控制节点潮流分布;
将定功率控制节点的注入功率置零,将定电压控制节点置为控制值,计算定电压控制节点的潮流分布;
基于注入功率对柔性直流电网支路功率的灵敏度,计算定功率控制节点的潮流分布;
叠加定电压控制节点的潮流分布和定功率控制节点的潮流分布计算最终的柔性直流电网线性化潮流结果。
在一实施方式中,在将柔性直流电网潮流按照控制方式分解之前,所述方法还包括:
对柔性直流电网的节点编号,定功率控制节点编号在定电压控制节点编号之前;
对柔性直流电网的支路编号,形成支路数据集,表示为[支路编号,首端节点,末端节点,支路电阻];
根据节点编号和支路数据集,形成节点导纳矩阵。
在一实施方式中,所述计算定电压控制节点的潮流分布,包括:
将定功率控制节点的所有注入功率设置为零;
将定电压控制节点的电压设置为已知的控制值,求解非线性方程组,得到所有支路定电压控制节点的潮流分布P
l,V。
在一实施方式中,所述计算定功率控制节点的潮流分布,包括:
计算定功率控制节点注入功率对柔性直流电网支路功率的灵敏度;
基于灵敏度将柔性直流电网支路功率表示为注入功率的线性组合。
在一实施方式中,所有定功率控制节点对柔性直流电网中任意一条支路的潮流灵敏度,根据下式计算得到:
将柔性直流电网支路功率P
l,P表示为注入功率的线性组合,根据下式计算得到:
式中:P
l,km为节点k、m所在支路的注入功率,P
i为节点i的注入功率,λ
i,l为节点i对支路l的灵敏度,i∈A表示所有定功率控制节点,V
i为节点i的电压,V
k为节点k的电压,V
m为节点m的电压,G
ij为节点i和节点j之间的电导值,对应所述节点导纳矩阵的值取负,j∈I,表示与节点i直接相邻的节点,G
ii为节点i的自导纳;P
l,P为定功率控制节点的潮流分布,i、j、k、m均为定功率控制节点。
在一实施方式中,当柔性直流电网各节点电压相等时,所述柔性直流电网线性化潮流结果,根据下式计算得到:
P
l=P
l,V+P
l,P
式中:P
l,V表示定电压控制节点的潮流分布,P
l,P为柔性直流电网支路功率,P
l为柔性直流电网线性化潮流结果。
本申请实施例提供的柔性直流电网潮流线性化计算系统,包括:
分解模块,配置为将柔性直流电网潮流分解为:定电压控制节点潮流分布和定功率控制节点潮流分布;
第一计算模块,配置为计算定电压控制节点的潮流分布;
第二计算模块,配置为计算定功率控制节点的潮流分布;
第三计算模块,配置为叠加定电压控制节点的潮流分布和定功率控制节点的潮流分布计算最终的柔性直流电网线性化潮流结果。
在一实施方式中,所述第一计算模块包括:
设置模块,配置为将定功率控制节点的所有注入功率设置为0;
支路的潮流分布计算模块,配置为将所有将定电压控制节点的电压设置为已知的控制值,求解非线性方程组,计算所有支路的潮流分布P
l,V。
在一实施方式中,所述系统还包括:柔性直流电网描述模块,配置为在将柔性直流电网潮流按照控制方式分解之前,对柔性直流电网的节点编号,定功率控制节点编号在定电压控制节点编号之前;对柔性直流电网的支路编号,形成支路数据集,表示为[支路编号,首端节点,末端节点,支路电阻];根据节点编号和支路数据集,形成节点导纳矩阵。
在一实施方式中,所述第二计算模块包括:
灵敏度计算模块,配置为计算定功率控制节点注入功率对柔性直流电网中任意一条支路功率的灵敏度;
线性组合计算模块,配置为基于灵敏度将柔性直流电网支路功率表示为注入功率的线性组合。
与最接近的现有技术相比,本申请实施例提供的技术方案具有的有益效果是:
1、传统的基于注入功率的柔直电网的潮流计算是一个非线性模型,当需要通过调整注入功率调节柔直电网支路潮流时,无法对其进行线性表达,分析存在困难。本申请实施例能对柔直电网潮流计算线性化的方法,是构建柔性直流电网安全约束经济调度模型的关键技术之一。
2、柔直电网的调度计划当考虑安全约束时,不实现柔直潮流的线性化 表达则无法通过现有的线性化建模方式实现优化调度。本申请实施例是以后总考虑柔性直流电网控制方式的,基于注入功率描述和节点电压控制的柔直电网线性潮流计算方法。
3、通过本申请实施例,可以将直流电网定功率控制节点对支路潮流的影响进行线性描述,为直流电网的快速潮流计算及潮流控制提供了可行的技术手段。
图1是本申请实施例的柔性直流电网潮流线性化确定方法的流程图;
图2是本申请实施例的5节点柔直电网示意图;
图3是本申请实施例的柔性直流电网潮流线性化确定系统的结构框图。
下面结合附图对本申请的具体实施方式作进一步的详细说明。
以下描述和附图充分地示出本申请的具体实施方案,以使本领域的技术人员能够实践它们。其他实施方案可以包括结构的、逻辑的、电气的、过程的以及其他的改变。实施例仅代表可能的变化。除非明确要求,否则单独的组件和功能是可选的,并且操作的顺序可以变化。一些实施方案的部分和特征可以被包括在或替换其他实施方案的部分和特征。本申请的实施方案的范围包括权利要求书的整个范围,以及权利要求书的所有可获得的等同物。在本文中,本申请的这些实施方案可以被单独地或总地用术语“发明”来表示,这仅仅是为了方便,并且如果事实上公开了超过一个的发明,不是要自动地限制该应用的范围为任何单个发明或发明构思。
实施例一、
本申请实施例提供了一种考虑柔性直流电网控制方式的,基于注入功率描述和节点电压控制的柔直电网线性潮流计算方法,其流程图如图1所 示,包括下述步骤:
S1:按定电压控制和定功率控制控制方式建立柔直电网拓扑描述:
本申请实施例以图2所示的5节点柔直电网结构图为例开展后续描述,任意节点数及任意连接方式的柔直电网可以此类推得到相应结果。柔直电网的拓扑描述与常规交流电网拓扑描述并无不同,为保证内容描述的完整性,在此依然做简要描述。
S11,对柔直电网进行节点编号,定功率控制节点编号相对于定电压控制节点编号靠前,如图2所示,节点1、2、3为定功率控制,节点4、5为定电压控制。
S12,对支路进行编号,形成支路数据集,表示为[支路编号,首端节点,末端节点,支路电阻]。对于图2中的支路1,则表示为:[1,1,2,2.35]。
S13,根据节点编号和支路数据集,形成节点导纳矩阵,节点导纳阵的形成方式及物理意义在电力系统分析书中多有介绍,在此不再赘述。对于图2所示电路,导纳矩阵如式(1)所示。
S2:定功率控制节点的注入功率变化是可以表示柔直电网支路潮流变化的。但定电压控制的节点则不行。为了能将柔直电网的支路潮流分布进行线性化表达,本申请实施例提出将支路潮流分成2个组成部分:定电压控制节点引起的潮流分布,定功率控制节点引起的潮流分布。
其中柔直电网潮流计算相关推导如下:
为了清晰的描述本申请实施例的后续内容,需要对柔直电网的潮流计算进行相关推导,推导过程如下。
柔直电网中节点i和节点j之间的支路l的功率可表示为:
P
l,ij=(V
i-V
j)·G
i,j·V
i (2)
式中,P
l,ij为支路l的潮流,V
i为节点i的电压,G
ij为节点i和节点j之间的电导值,他就是节点导纳阵中所对应的值取负。
柔直电网中节点i的注入功率可以表示成与节点i相连的所有支路的功率之和:
式中,P
i为节点i的注入功率,j∈I,表示与节点i直接相邻的节点,将式(3)进行展开分析:
式中,G
ii为节点i的自导纳,他就是节点导纳阵中所对应的值。式中第一项只与节点i自身的电压相关,而第二项则与相邻节点的电压相关。对式(4)求V
i的偏导数。再对任意支路求V
i的偏导数。
式(6)描述了任意支路功率对节点电压的偏导数,即节点电压对支路潮流的灵敏度。如果能求出式(6)右侧值,则表示支路的功率变化可以用节点的电压变化进行描述。将式(6)除以式(5)则可以得到任意支路功率对节点i注入功率的偏导数,即节点注入功率对支路功率的灵敏度。
如果能够求出式(7)右侧的值,则表示支路的功率变化可以用节点注入功率的变化进行描述。
对于式(6)和式(7)的求取,则跟节点的控制方式密切相关。首先, 任意一个节点式(6)和式(7)只需求解一个,当该节点为定电压控制时,求取式(6);当该节点为定功率控制时,需要求取式(7)。
我们首先分析式(6)的特点。由于式中既包含电压本身,又包含电压的导数,可知,只有在极小的电压变化区间内,节点电压对支路潮流的灵敏度才可以进行线性表达。因此,在此我们不计算式(6)的值,我们认为所有定电压控制的节点电压均为已知值,不做定电压控制节点电压变化对支路潮流的影响分析。
S3:将定功率控制节点的注入功率置零,将定电压控制节点置为控制值,计算由定电压控制节点引起的潮流分布:
分析式(7)的特点,柔直电网在正常运行时,无论节点是何种控制方式,各节点电压相差很小,假设各节点电压相等,则式(7)可化简为:
再对式(8)进行求解,此时式(8)中,节点k,m及与i相邻的各节点对V
i的偏导数都是待求变量。当在求
时,除了节点i我们假设其他定功率控制的节点注入功率是不变的。因此其它节点注入功率对V
i的偏导数等于0。即如下式所示。
在分析式(9)时,再次假设各节点电压相差不大,则式(9)可化简为:
式(10)其实是一个方程组,这个方程组中除了节点i自身,其他各节点
都是未知数。一个n节点的系统,则有n-1个未知数,假设定功率控 制的节点有a个(不含i节点),定电压控制的节点有(n-1-a)个。根据式(10)可获得a个方程,而由于剩余(n-1-a)个节点由于是定电压控制,电压不受其他节点的影响,直接可得
综合分析可知,n-1个未知数正好对应n-1个方程,可求得所有
的值。同时表明,根据式(8)则可以求得所有支路功率变化对节点i注入功率变化的比例值,这也表明支路的功率变化可以用定功率控制节点的注入功率变化进行线性表达。至此,节点注入功率对支路潮流的灵敏度计算说明结束。
步骤S3中,首先将定功率控制节点的所有注入功率设置为0;
将定电压控制节点的电压设置为已知的控制值,运用传统数值解法求解非线性方程组,求得所有支路的潮流。将此支路潮流表示为P
l,V,它表示由定电压控制节点所引起的潮流分布。
S4:计算定功率控制节点注入功率对柔直电网支路功率的灵敏度,基于灵敏度将柔直支路功率表示为注入功率的线性组合:
在此步骤中,首先按照第(2)节中求取式(8)的方式求得所有定功率控制的节点对支路l的潮流灵敏度,此时求的支路潮流表示为P
l,P,它表示由定功率控制的节点所引起的潮流分布。它的计算表达式为:
式中P
i为节点i的注入功率,λ
i,l为节点i对支路l的灵敏度。i∈A表示所有定功率控制节点。这表明,任意给定一个P
i,就可以直接线性求取对应的支路潮流P
l。
S5:叠加定电压控制节点引起的潮流分布和定功率控制节点引起的潮流分布形成最终的柔直电网线性化潮流计算结果:
结合步骤S3和步骤S4即可求得此时支路潮流的线性表达式为:
P
l=P
l,V+P
l,P (12)
实施例二、
下面以图2中5节点柔直电网示意图为例说明整个计算过程。首先以图中所示,节点1、2、3为定功率控制节点,节点4、5为定电压控制节点,节点4控制电压为319.5kv,节点5控制电压为320kv。首先根据公式(10)分别对节点1、2、3列方程组如下所示:
表1 6条支路的灵敏度
下面按照步骤S3计算的影响。计算结果如下表所示。
下面按照步骤S3计算的影响。计算结果如下表所示。
再按照步骤S4和步骤S5即可计算获得定功率控制任意注入功率后的支路潮流分布。
假设节点1注入功率260MW,节点2注入功率340MW,节点3注入功率-450,按照本申请实施例计算得到的各支路潮流如下表所示。
表3定电压控制节点和定功率控制任意注入功率后的支路潮流分布
| 支路1 | 支路2 | 支路3 | 支路4 | 支路5 | 支路6 | |
| 本申请 | -39.55 | 188.398 | 261.561 | 38.775 | 111.088 | -74.301 |
| 迭代法 | -39.3475 | 189.134 | 262.605 | 38.0196 | 110.215 | -74.3012 |
| 偏差 | 0.0051201 | -0.003907 | -0.003991 | 0.0194816 | 0.0078586 | -2.69E-06 |
对比说明,本算法计算精度是极好的。
实施例三、
基于同样的发明构思,本申请实施例还提供一种考虑直流控制方式的柔性直流电网潮流线性化计算系统,其结构框图如图3所示,包括:
分解模块301,配置为依据控制方式将柔性直流电网潮流分解为:定电压控制节点潮流分布和定功率控制节点潮流分布;
第一计算模块302,配置为计算定电压控制节点的潮流分布;
第二计算模块303,配置为计算定功率控制节点的潮流分布;
第三计算模块304,配置为叠加定电压控制节点的潮流分布和定功率控制节点的潮流分布计算最终的柔性直流电网线性化潮流结果。
所述系统还包括:柔性直流电网描述模块,配置为在将柔性直流电网 潮流按照控制方式分解之前,对柔性直流电网的节点编号,定功率控制节点编号在定电压控制节点编号之前;对柔性直流电网的支路编号,形成支路数据集,表示为[支路编号,首端节点,末端节点,支路电阻];根据节点编号和支路数据集,形成节点导纳矩阵。
所述第一计算模块包括:
设置模块,配置为将定功率控制节点的所有注入功率设置为0;
支路的潮流分布计算模块,配置为将所有将定电压控制节点的电压设置为已知的控制值,求解非线性方程组,计算所有支路的潮流分布。
所述第二计算模块包括:
灵敏度计算模块,配置为计算定功率控制节点注入功率对柔性直流电网中任意一条支路功率的灵敏度;
线性组合计算模块,配置为基于灵敏度将柔性直流电网支路功率表示为注入功率的线性组合。
在实际应用中,所述柔性直流电网潮流线性化计算系统中的各个模块所实现的功能,均可由位于柔性直流电网潮流线性化计算系统中的中央处理器(CPU,Central Processing Unit)、或微处理器(MPU,Micro Processor Unit)、或数字信号处理器(DSP,Digital Signal Processor)、或现场可编程门阵列(FPGA,Field Programmable Gate Array)等实现。
本申请实施例的技术方案,解决了传统的基于注入功率的柔直电网的潮流计算是一个非线性模型,当需要通过调整注入功率调节柔直电网支路潮流时,无法对其进行线性表达,分析存在困难。柔直电网的调度计划当考虑安全约束时,不实现柔直潮流的线性化表达则无法通过现有的线性化建模方式实现优化调度的问题。
本领域内的技术人员应明白,本申请的实施例可提供为方法、系统、或计算机程序产品。因此,本申请可采用完全硬件实施例、完全软件实施 例、或结合软件和硬件方面的实施例的形式。而且,本申请可采用在一个或多个其中包含有计算机可用程序代码的计算机可用存储介质(包括但不限于磁盘存储器、CD-ROM、光学存储器等)上实施的计算机程序产品的形式。
本申请是参照根据本申请实施例的方法、设备(系统)、和计算机程序产品的流程图和/或方框图来描述的。应理解可由计算机程序指令实现流程图和/或方框图中的每一流程和/或方框、以及流程图和/或方框图中的流程和/或方框的结合。可提供这些计算机程序指令到通用计算机、专用计算机、嵌入式处理机或其他可编程数据处理设备的处理器以产生一个机器,使得通过计算机或其他可编程数据处理设备的处理器执行的指令产生用于实现在流程图一个流程或多个流程和/或方框图一个方框或多个方框中指定的功能的装置。
这些计算机程序指令也可存储在能引导计算机或其他可编程数据处理设备以特定方式工作的计算机可读存储器中,使得存储在该计算机可读存储器中的指令产生包括指令装置的制造品,该指令装置实现在流程图一个流程或多个流程和/或方框图一个方框或多个方框中指定的功能。
这些计算机程序指令也可装载到计算机或其他可编程数据处理设备上,使得在计算机或其他可编程设备上执行一系列操作步骤以产生计算机实现的处理,从而在计算机或其他可编程设备上执行的指令提供用于实现在流程图一个流程或多个流程和/或方框图一个方框或多个方框中指定的功能的步骤。
相应地,本发明实施例还提供一种计算机存储介质,其中存储有计算机程序,该计算机程序配置为执行本发明实施例的柔性直流电网潮流线性化计算方法。
最后应当说明的是:以上实施例仅用以说明本申请的技术方案而非对 其限制,尽管参照上述实施例对本申请进行了详细的说明,所属领域的普通技术人员依然可以对本申请的具体实施方式进行修改或者等同替换,这些未脱离本申请精神和范围的任何修改或者等同替换,均在申请待批的本申请的权利要求保护范围之内。
本申请实施例的技术方案,解决了传统的基于注入功率的柔直电网的潮流计算是一个非线性模型,当需要通过调整注入功率调节柔直电网支路潮流时,无法对其进行线性表达,分析存在困难。柔直电网的调度计划当考虑安全约束时,不实现柔直潮流的线性化表达则无法通过现有的线性化建模方式实现优化调度的问题。
Claims (11)
- 一种柔性直流电网潮流线性化计算方法,所述计算方法包括下述步骤:将柔性直流电网潮流分解为:定电压控制节点潮流分布和定功率控制节点潮流分布;将定功率控制节点的注入功率置零,将定电压控制节点置为控制值,计算定电压控制节点的潮流分布;基于注入功率对柔性直流电网支路功率的灵敏度,计算定功率控制节点的潮流分布;叠加定电压控制节点的潮流分布和定功率控制节点的潮流分布计算最终的柔性直流电网线性化潮流结果。
- 如权利要求1所述的柔性直流电网潮流线性化计算方法,其中,在将柔性直流电网潮流按照控制方式分解之前,所述方法还包括:对柔性直流电网的节点编号,定功率控制节点编号在定电压控制节点编号之前;对柔性直流电网的支路编号,形成支路数据集,表示为[支路编号,首端节点,末端节点,支路电阻];根据节点编号和支路数据集,形成节点导纳矩阵。
- 如权利要求1或2所述的柔性直流电网潮流线性化计算方法,其中,所述计算定电压控制节点的潮流分布,包括:将定功率控制节点的所有注入功率设置为零;将定电压控制节点的电压设置为已知的控制值,求解非线性方程组,得到所有支路定电压控制节点的潮流分布P l,V。
- 如权利要求1或2所述的柔性直流电网潮流线性化计算方法,其中,所述计算定功率控制节点的潮流分布,包括:计算定功率控制节点注入功率对柔性直流电网支路功率的灵敏度;基于灵敏度将柔性直流电网支路功率表示为注入功率的线性组合。
- 如权利要求4所述的柔性直流电网潮流线性化计算方法,其中,所有定功率控制节点对柔性直流电网中任意一条支路的潮流灵敏度,根据下式计算得到:将柔性直流电网支路功率P l,P表示为注入功率的线性组合,根据下式计算得到:式中:P l,km为节点k、m所在支路的注入功率,P i为节点i的注入功率,λ i,l为节点i对支路l的灵敏度,i∈A表示所有定功率控制节点,V i为节点i的电压,V k为节点k的电压,,V m为节点m的电压,G ij为节点i和节点j之间的电导值,对应所述节点导纳矩阵的值取负,j∈I,表示与节点i直接相邻的节点,G ii为节点i的自导纳;P l,P为定功率控制节点的潮流分布,i、j、k、m均为定功率控制节点。
- 如权利要求2或5中任一项所述的柔性直流电网潮流线性化计算方法,其中,当柔性直流电网各节点电压相等时,所述柔性直流电网线性化潮流结果,根据下式计算得到:P l=P l,V+P l,P式中:P l,V表示定电压控制节点的潮流分布,P l,P为柔性直流电网支路功率,P l为柔性直流电网线性化潮流结果。
- 一种柔性直流电网潮流线性化计算系统,所述系统包括:分解模块,配置为将柔性直流电网潮流分解为:定电压控制节点潮 流分布和定功率控制节点潮流分布;第一计算模块,配置为计算定电压控制节点的潮流分布;第二计算模块,配置为计算定功率控制节点的潮流分布;第三计算模块,配置为叠加定电压控制节点的潮流分布和定功率控制节点的潮流分布计算最终的柔性直流电网线性化潮流结果。
- 如权利要求7所述的柔性直流电网潮流线性化计算系统,其中,所述第一计算模块包括:设置模块,配置为将定功率控制节点的所有注入功率设置为0;支路的潮流分布计算模块,配置为将所有将定电压控制节点的电压设置为已知的控制值,求解非线性方程组,计算所有支路的潮流分布P l,V。
- 如权利要求7所述的柔性直流电网潮流线性化计算系统,其中,所述系统还包括:柔性直流电网描述模块,配置为在将柔性直流电网潮流按照控制方式分解之前,对柔性直流电网的节点编号,定功率控制节点编号在定电压控制节点编号之前;对柔性直流电网的支路编号,形成支路数据集,表示为[支路编号,首端节点,末端节点,支路电阻];根据节点编号和支路数据集,形成节点导纳矩阵。
- 如权利要求7所述的柔性直流电网潮流线性化计算系统,其中,所述第二计算模块包括:灵敏度计算模块,配置为计算定功率控制节点注入功率对柔性直流电网中任意一条支路功率的灵敏度;线性组合计算模块,配置为基于灵敏度将柔性直流电网支路功率表示为注入功率的线性组合。
- 一种计算机存储介质,所述计算机存储介质中存储有计算机可执行指令,该计算机可执行指令配置为执行权利要求1-6任一项所述的柔性直流电网潮流线性化计算方法。
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