CN107785907B - Method for comparing influences of increase of horizontal and vertical connectivity of power grid on power transmission capacity - Google Patents
Method for comparing influences of increase of horizontal and vertical connectivity of power grid on power transmission capacity Download PDFInfo
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- CN107785907B CN107785907B CN201610722784.8A CN201610722784A CN107785907B CN 107785907 B CN107785907 B CN 107785907B CN 201610722784 A CN201610722784 A CN 201610722784A CN 107785907 B CN107785907 B CN 107785907B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
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- H—ELECTRICITY
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Abstract
The invention provides a method for comparing the influence of the increase of the horizontal and vertical connectivity of a power grid on the transmission capacity, which comprises the following steps: I. analyzing influence factors of the tidal current transmission capacity; II. For convenience of analysis, a power transmission network A with the transverse connectivity of 2 and the longitudinal connectivity of zero is used as an initial power transmission network, and a line is added in each of the transverse direction and the longitudinal direction to form a power transmission network B and a power transmission network C; III, respectively calculating equivalent reactance of the power transmission network A, B, C; IV, respectively comparing equivalent reactances of the power transmission network A, B, C, and comparing to obtain the influence of the increase of the horizontal and longitudinal connectivity of the power grid on the power transmission capacity; and V, building a two-end system, and carrying out power transmission between the two ends through the power transmission network A, B, C respectively to obtain the power transmission limit of the two-end system under the power transmission network A, B, C. The method can quantitatively analyze the influence degree of the increase of the horizontal and vertical connectivity of the power grid on the power transmission capacity.
Description
Technical Field
The invention relates to the field of power network analysis and power system analysis, in particular to a method for comparing the influence of the increase of the horizontal and vertical connectivity of a power grid on the power transmission capacity.
Background
Energy distribution in China is extremely uneven, so that power generation resources and the geographic distribution of a load center are unbalanced, and a lot of electric energy needs to be transmitted from an energy base to the load center in a large scale and long distance. With the continuous expansion of the scale of the power grid and the continuous increase of the social power demand, the power transmission pressure of the power grid is increased day by day, the power transmission capacity of the power grid is improved, a safe, efficient and strong power grid is constructed, and the demand of the economic and social development on the power is met, so that the development target of the power grid in China is formed.
Although the power industry in China develops rapidly, the electricity demand is increased rapidly due to rapid development of economy and increasing living standard of people, and the contradiction between power supply and demand is more and more prominent: the continuous increase of load demands forces the transmission pressure born by a transmission network to increase, and due to the consideration of land planning and environmental protection, the line construction cannot be increased proportionally along with the increase of power consumption demands and transmission pressure; due to the introduction of a competitive mechanism of the power market, in order to reduce the cost to the maximum extent, a power company needs to transmit more power on the basis of the existing network; and thirdly, the distribution of Chinese energy is extremely uneven, so that the distribution of power generation resources and the geographical distribution of a load center are unbalanced, the power must be transmitted in a long distance, and the line loss is very large. The problem causes that the power transmission pressure of a power grid in China is increased day by day, the research for improving the power transmission capacity of the power grid is imperative, the premise for improving the power transmission capacity of the power grid is to determine the factor for restricting the power transmission capacity of the power grid, and the patent starts from the aspect of a power grid topological structure and researches the influence of the power grid topological structure on the power transmission capacity of the power grid.
The power grid topology is essentially a two-dimensional graph, but different from a general two-dimensional graph, each connecting line of the power grid topology has impedance, namely the power grid topology is a two-dimensional weighted graph. Generally, a transmission network has a definite transmission direction, and if the transmission direction of a transmission network Z to be mainly studied is defined as the positive direction of an X axis on a two-dimensional plane, also called as a transverse direction, all lines directly connected from a transmitting end to a receiving end can be regarded as transverse lines, and a transmission line of the transmission network in the transverse direction is expressed by a two-dimensional vector LX, then LXZ=[(lx1,rx1),...,(lxi,rxi),...(lxn,rxn)]', n is the number of the direct connection lines of the transmission network Z in the X-axis direction, and the two-dimensional vector element (l)xi,rxi) The two components of (a) represent the length and unit reactance of the ith line (in the transmission network, the line reactance is generally far larger than the resistance, and for simple operation, the influence of the reactance is mainly analyzed).
In addition to the above-mentioned direct connection lines, other lines connected to the direct connection lines can be regarded as transmission lines on a Y-axis (also referred to as a longitudinal direction) perpendicular to the X-axis on a two-dimensional plane, and the transmission lines in the direction can be represented by a two-dimensional vector LYZ=[(ly1,ry1),...,(lyj,ryj),...(lym,rym)]M is the number of connecting lines of the transmission network Z in the longitudinal direction; two-dimensional vector element (l)yj,ryj) Represents the length and unit reactance of the j-th line, respectively.
Therefore, from the viewpoint of a power grid topological structure, the relevant factors influencing the power transmission capacity mainly include the number of the horizontal and longitudinal connecting lines, namely, the horizontal and longitudinal connectivity, and the corresponding reactance, namely, the connecting strength. However, for an actual power transmission network, as the topological structure of the power grid is changed, the influence of the horizontal and longitudinal connectivity on the power transmission capacity cannot be directly obtained.
Disclosure of Invention
The invention aims to provide a method for comparing the influence of the increase of the horizontal and vertical connectivity of a power grid on the power transmission capacity from the perspective of a power grid topological structure aiming at the situation that the power transmission pressure of the power grid in China is increasingly severe at present, and provides theoretical support for the construction of a power transmission channel in the future.
In order to achieve the purpose, the invention adopts the technical scheme that:
a method for comparing the influence of the increase of the horizontal and vertical connectivity of a power grid on the transmission capacity is characterized in that a two-end system is built by utilizing PSD-BPA tide and transient stability simulation software, two ends of the two-end system are connected through two transmission lines, the transmission network is called as a transmission network A, on the basis of the transmission network A, one transmission line is respectively added in the horizontal direction and the vertical direction to form a new transmission network B and a new transmission network C, and the comparison of the influence of the horizontal and vertical connectivity of the power grid on the transmission capacity is realized by comparing the transmission capacities under three transmission networks.
A method of comparing the impact of increased grid horizontal and vertical connectivity on transmission capacity, the method comprising the steps of:
step 1: and (5) providing influence factors of the tidal current transmission capacity. The calculation method of the line transmission power is shown as the following formula:
in the formula ES、ERThe voltage amplitudes of the sending end and the receiving end respectively, and delta is ESAdvance ERAngle of (A) XLIs the total impedance of the line. The influence of the power grid topological structure on the power flow transmission capacity is researched in the section, the influence of the voltage of a sending end and the voltage of a receiving end can be ignored, and the power flow transmission capacity is only related to the total impedance of the power transmission network, so that the horizontal and vertical directions of the power grid are comparedThe influence of the increase of the connectivity on the transmission capacity is actually to compare the equivalent reactance of the transmission network after the increase of the horizontal and longitudinal connectivity of the power grid;
step 2: for convenience of analysis, a power transmission network A with the transverse connectivity of 2 and the longitudinal connectivity of 0 is used as an initial power transmission network, and in order to explore the influence of the increase of the connectivity in the transverse direction and the longitudinal direction on the power transmission capacity, on the basis of the power transmission network A, a line is respectively added in the transverse direction and the longitudinal direction, that is, the connectivity on the transverse axis and the longitudinal axis of the power transmission network A are respectively increased by 1, and the lengths and unit reactances of the added lines are ensured to be consistent, so that a power transmission network B and a power transmission network C are respectively formed;
and step 3: respectively calculating equivalent reactance of the power transmission network A, the power transmission network B and the power transmission network C;
and 4, step 4: respectively comparing equivalent reactances of the transmission network A, the transmission network B and the transmission network C, and comparing the reactance to obtain the influence of the increase of the horizontal and longitudinal connectivity of the power grid on the transmission capacity;
and 5: and (3) establishing a two-end system by using PSD-BPA trend and transient stability policy software, and performing power transmission between the two ends through a power transmission network A, a power transmission network B and a power transmission network C respectively to obtain the power transmission limits of the two-end system under the power transmission network A, the power transmission network B and the power transmission network C respectively.
Compared with the prior art, the invention has the beneficial effects that: a two-end system is built by utilizing PSD-BPA tide and transient stability simulation software, two ends of the two-end system are connected through two power transmission lines, the power transmission network is called as a power transmission network A, the power transmission network A is used as an initial power transmission network, one power transmission line is respectively added in the transverse direction and the longitudinal direction of the initial power transmission network to form a new power transmission network B and a new power transmission network C, and the comparison of the influence of the increase of the transverse and longitudinal connectivity of a power grid on the power transmission capacity is realized for the first time by comparing the power transmission capacities of the three power transmission networks.
Drawings
FIG. 1 is a diagram: an overall flow diagram of an embodiment of the invention.
FIG. 2 is a diagram of: the invention discloses a power transmission network A topological graph.
FIG. 3 is a diagram of: the invention discloses a power transmission network B topological graph.
FIG. 4 is a diagram of: the invention discloses a power transmission network C topological graph.
Detailed Description
The technical solution of the present invention is further explained in detail by the accompanying drawings and examples.
As shown in fig. 1, the method for comparing the influence of the increase of the horizontal and vertical connectivity of the power grid on the transmission capacity of the power grid of the invention comprises the following steps:
step 1: the influence of the increase of the horizontal and longitudinal connectivity of the power grid on the power transmission capacity is definitely compared with the equivalent reactance of the power transmission network after the increase of the horizontal and longitudinal connectivity of the power grid;
step 2: for the convenience of analysis, the power transmission network a with the transverse connectivity of 2 and the longitudinal connectivity of 0 is used as the initial power transmission network, and the lengths of the two lines of the power transmission network a in the embodiment are lx1、lx2The unit reactance is rx1、rx2As shown in fig. 2. In order to explore the influence of the increase of the connectivity in the transverse direction and the longitudinal direction on the power transmission capacity, on the basis of the power transmission network A, one line is respectively added in the transverse direction and the longitudinal direction, namely, the connectivity on the transverse axis and the longitudinal axis of the power transmission network A is respectively increased by 1, the lengths and unit reactances of the added lines are ensured to be consistent, and the power transmission network B and the power transmission network C are respectively formed; in the embodiment, the newly added line lengths of the transmission network B and the transmission network C are respectively lx3、ly1The newly added unit reactance of the line is rx3、ry1And need to guaranteex3=ly1,rx3=ry1The transmission network B and the transmission network C are shown in fig. 3 and fig. 4, respectively.
And step 3: equivalent reactance X of transmission network A, transmission network B and transmission network C in the embodimentA、XB、XCRespectively shown as the following formula:
wherein A ═ rx1lx1,B=rx2lx2,C=rx3lx3,D=ry1ly1I.e. the line s1t1、s2t2、s3t3、z1z2The impedance of (c).
And 4, step 4: comparing the equivalent reactances of the transmission network A, the transmission network B and the transmission network C respectively, wherein the system total impedance X of the transmission network CCThe calculation formula of (A) is complex and cannot directly compare XA、XB、XCThe relationship between the three can not be compared, and for the convenience of analysis, the unit reactance and the length of each line in the power transmission network A, B, C are respectively r0、l0The total system impedance of each grid is as follows:
comparison of X is required belowA、XB、XCThe relation between the three is determined, thereby determining the power transmission capacity under each power transmission networkThe influence degree of the increase of the horizontal and vertical connectivity of the power grid on the power transmission capacity can be compared. Due to XA、XBThe size relationship between the two is clear at a glance, so only X needs to be comparedCAnd XA、XBThe relationship (2) of (c). Consider 0 < k1,k2< 1, then having the formula:
x can then be obtainedC<XAWhile taking into account:
and the numerator and the denominator of the above formula are subtracted to obtain:
thereby obtaining XC>r0l0/3=XBAnd then: xB<XC<XA。
And 5: and (3) establishing a two-end system by using PSD-BPA trend and transient stability policy software, and performing power transmission between the two ends through a power transmission network A, a power transmission network B and a power transmission network C respectively to obtain the power transmission limits of the two-end system under the power transmission network A, the power transmission network B and the power transmission network C respectively.
Table 1 shows the transmission limits of different line lengths in the transmission network a according to an embodiment of the present invention
Table 2 shows the transmission limits of different line lengths in the transmission network B according to an embodiment of the present invention
Table 3 shows the transmission limits of different line lengths in the transmission network C according to an embodiment of the present invention
TABLE 1
TABLE 2
TABLE 3
From the structural results, the influence degree of the increase of the horizontal and vertical connectivity of the power grid on the power transmission capacity can be quantitatively obtained by constructing the initial network A and then respectively adding one power transmission line in the horizontal and vertical directions to form the new power transmission network B and the new power transmission network C, and by comparing equivalent reactance of the power transmission network A, the power transmission network B and the power transmission network C, the influence degree of the increase of the horizontal and vertical connectivity of the power grid on the power transmission capacity can be compared by using the method provided by the patent.
Claims (1)
1. A method for comparing the influence of the increase of the horizontal and vertical connectivity of a power grid on the transmission capacity is characterized in that: the method comprises the following steps:
I. obtaining influence factors of the tidal current transmission capacity through a line transmission power model; the calculation method of the line transmission power model is shown as the following formula:
in the formula ES、ERThe voltage amplitudes of the sending end and the receiving end respectively, and delta is ESAdvance ERAngle of (A) XlNeglecting the influence of the voltage of a sending end and a receiving end for the total impedance of the line, and only relating the tidal current transmission capacity with the total impedance of the power transmission network, so that the influence of the increase of the horizontal and longitudinal connectivity of the power grid on the power transmission capacity is actually compared with the equivalent reactance of the power transmission network after the increase of the horizontal and longitudinal connectivity of the power grid, the power transmission direction of the power transmission network is specified to be the positive direction of an X axis on a two-dimensional plane, a power transmission line in the positive direction of the X axis on the two-dimensional plane is called a transverse line, a power transmission line in a Y axis in the direction vertical to the X axis on the two-dimensional plane is called a longitudinal line, the number of the transverse connecting lines is the transverse connectivity;
II. For convenience of analysis, a power transmission network A with the transverse connectivity of 2 and the longitudinal connectivity of zero is used as an initial power transmission network, and in order to explore the influence of the increase of the connectivity in the transverse direction and the longitudinal direction on the power transmission capacity, on the basis of the power transmission network A, a line is respectively added in the transverse direction and the longitudinal direction, that is, the connectivity on the transverse axis and the longitudinal axis of the power transmission network A are respectively increased by 1, and the lengths and unit reactances of the added lines are ensured to be consistent, so that a power transmission network B and a power transmission network C are respectively formed;
III, constructing a power transmission network A, a power transmission network B and a power transmission network C based on the step II, and respectively calculating equivalent reactance of the power transmission network A, the power transmission network B and the power transmission network C;
IV, respectively comparing the equivalent reactances of the transmission network A, the transmission network B and the transmission network C based on the equivalent reactances of the transmission network A, the transmission network B and the transmission network C calculated in the step III, and comparing the influence of the increase of the horizontal and longitudinal connectivity of the power grid on the transmission capacity through reactance comparison;
and V, establishing a two-end system by using PSD-BPA tide and transient stability policy software, and performing power transmission between the two ends through a power transmission network A, a power transmission network B and a power transmission network C respectively to obtain the power transmission limits of the two-end system under the power transmission network A, the power transmission network B and the power transmission network C respectively.
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Citations (3)
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CN102904246A (en) * | 2012-09-07 | 2013-01-30 | 中国电力科学研究院 | Fast calculating method of transient stability transmission limit of point to grid power transmission system |
CN103823998A (en) * | 2014-03-19 | 2014-05-28 | 国家电网公司 | Weak cross section determination method taking influence of network topology changes on power transmission capacity into consideration |
CN105046026A (en) * | 2015-08-28 | 2015-11-11 | 南方电网科学研究院有限责任公司 | Transmission capacity evaluation method considering node power injection and power grid topology |
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CN102904246A (en) * | 2012-09-07 | 2013-01-30 | 中国电力科学研究院 | Fast calculating method of transient stability transmission limit of point to grid power transmission system |
CN103823998A (en) * | 2014-03-19 | 2014-05-28 | 国家电网公司 | Weak cross section determination method taking influence of network topology changes on power transmission capacity into consideration |
CN105046026A (en) * | 2015-08-28 | 2015-11-11 | 南方电网科学研究院有限责任公司 | Transmission capacity evaluation method considering node power injection and power grid topology |
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