CN105610171B - Minimum startup sequence optimization method based on unit load dynamic reactive response - Google Patents
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Abstract
The invention provides a minimum starting sequence optimization method based on unit load dynamic reactive response, which comprises the steps of determining weak points in a heavy load area in a power system; determining an electrical distance index and a dynamic reactive response quantization index; calculating response effect indexes of each generator in the power system, which influence the voltage stability of the system; determining the starting sequence of each generator according to the index value of the response effect index; and controlling the generators to start or stop according to the starting sequence, and detecting the stable state of the weak point, wherein the actual starting and stopping sequence of the generators is the minimum starting and stopping sequence when the weak point reaches the critical stable state. Compared with the prior art, the minimum startup sequence optimization method based on the unit load dynamic reactive response provided by the invention has the advantages that the influence degree of each generator on the system voltage in the shutdown process is definitely given, the generator startup sequence arrangement strategy of the minimum shutdown mode is greatly improved, and the method has stronger adaptability.
Description
Technical Field
The invention relates to the field of power systems, in particular to a minimum startup sequence optimization method based on unit load dynamic reactive response.
Background
The large receiving end system of the power system mainly realizes supply and demand balance by receiving active power input by an external power supply and a remote power supply, the installed capacity of the power supply of the receiving end system is insufficient, and the voltage stability problem of the large receiving end power grid is obvious due to the operation mode of small start and heavy load. The voltage stability belongs to the problem of local stability, and the essence lies in voltage drop caused by reactive large-range transmission, and particularly under the condition of reactive standby tension, the voltage level is generally difficult to meet the requirement, and the reactive compensation is also required to meet the principle of layered and regional local balance in the operation guide rule. Therefore, how to realize reasonable reactive power distribution is an important way for solving the problem of system voltage stability.
Generally, the voltage stability of the system is closely related to the grid structure, the reactive equipment compensation level, the dynamic reactive response of the generator and the load characteristics. With the acceleration of the construction of large power grids in China, the power grids of the same voltage class are more closely connected, and the occupation ratio of a single radiation type grid structure is reduced; the occupation ratio of the looped network power supply and the grid power supply is increased, so that the influence of the change of the net rack on the reactive power distribution after the single line is disconnected is reduced. In the case of reactive equipment determination, the reactive nature of the generator and load becomes a key factor in achieving minimum voltage stabilization at start-up. When the reactive power shortage of the receiving-end power grid is large, the excitation device of the generator can enable the generator to provide large reactive power support for the system through the rapid excitation adjusting system, and the voltage of the generator end is kept at a certain level. The load ratio of a motor in a power grid is usually over 60%, a large amount of reactive power needs to be absorbed from the power grid in the voltage recovery process after the short-circuit fault of the system, and the recovery characteristic causes serious voltage reactive shortage in a short time and deteriorates voltage stability. Therefore, considering the reactive characteristics of the generator and the load in the minimum startup mode can improve the reliability of decision.
At present, the engineering method of the minimum startup mode of a large-receiver power grid is mainly used for arranging the startup mode according to experience and performing transient stability check by applying PSD-BPA until a startup scheme with stable critical voltage is found out. Because the method has no quantitative indexes to guide the starting sequence, the time consumption is increased due to repeated adjustment, and the consideration on the dynamic reactive response of the load and the generator is insufficient. Therefore, it is important to find a minimum startup sequence optimization method capable of considering the unit load dynamic reactive response.
Disclosure of Invention
In order to meet the needs of the prior art, the invention provides a minimum startup sequence optimization method based on unit load dynamic reactive response.
The technical scheme of the invention is as follows:
the minimum boot sequence optimization method comprises the following steps:
determining a weak point in a heavy-load area in a power system, wherein the weak point is a bus on one side where the most serious fault occurs in the heavy-load area;
determining an indicator of electrical distance between each generator in the power system and the weak point after the weak point has a short-circuit fault, and a quantitative indicator of dynamic reactive response of each generator during the short-circuit fault of the weak point;
calculating response effect indexes of each generator in the power system, which influence the voltage stability of the system, according to the electric distance indexes and the dynamic reactive response quantization indexes;
determining the starting sequence of each generator according to the index value of the response effect index of each generator influencing the voltage stability of the system; and controlling the generators to start or stop according to the starting sequence, and detecting the stable state of the weak point, wherein the actual starting and stopping sequence of the generators is the minimum starting and stopping sequence when the weak point reaches the critical stable state.
The invention further provides a preferred embodiment as follows: the determining weak points within heavily loaded regions in the power system prior to the selecting a heavily loaded region of the power system comprises:
calculating the power P wagered at each high voltage class bus node in the power systemmAnd sorted, including the betting power P with larger valuemThe area of the corresponding bus is the heavy load area; wherein m is the serial number of the bus;
alternatively, the first and second electrodes may be,
calculating the power P wagered at each high voltage class bus node in the power systemmAnd the power P to be bet on the node of the bus n directly connected to the bus mmnFor said bet power PmAnd bet power PmnThe sum sorting includes the Area with the larger sum valuemnThe area of the corresponding bus is the heavy load area; wherein the content of the first and second substances,
and s is the total number of the buses directly connected with the bus m.
The invention further provides a preferred embodiment as follows: the determining a weak point in a heavily loaded area in the power system comprises:
performing N-1 transient stability calculation on all the power transmission lines in the heavy load area, wherein the short circuit fault time is T seconds;
and modifying the short-circuit fault time T according to the working state of the power transmission line after the short-circuit fault, and performing N-1 transient stability calculation again according to the modified short-circuit fault time until the voltage instability of only one power transmission line after the short-circuit fault occurs, wherein the bus at one side of the power transmission line is a weak point.
The invention further provides a preferred embodiment as follows: the modifying the short-circuit fault time T according to the working state of the power transmission line after the short-circuit fault comprises the following steps:
when all the transmission lines in the heavy load area are unstable, the short-circuit fault time is modified to be T-delta T, and N-1 pause is conducted again according to the fault short-circuit time T-delta TCalculating the state stability until the power transmission line in the heavy load area has a stable state and an unstable state at the same time; resetting the short-circuit fault time to
Performing N-1 transient stability calculation on the power transmission lines in an unstable state until voltage instability occurs on one or only one power transmission line after a short circuit fault occurs;
when all the power transmission lines in the heavy load area are stable, the short-circuit fault time is modified to be T + delta T, and N-1 transient stability calculation is carried out again according to the fault short-circuit time T + delta T until the power transmission lines in the heavy load area have a stable state and an unstable state at the same time; resetting the short-circuit fault time to
And performing N-1 transient stability calculation on the power transmission lines in the unstable state until voltage instability occurs on one or only one power transmission line after the short-circuit fault occurs, wherein delta t is a time increment.
The invention further provides a preferred embodiment as follows: the determining an electrical distance indicator between each generator and a weak point in the power system comprises:
setting the electric distance index to Xim'＝1/Iim'，Iim'Short-circuit current is provided for each generator after the short-circuit fault occurs to the weak point, i is the serial number of the generator, and m' is the weak point;
determining a weighting factor omega for the electrical distance between each generator and the point of weaknessi；
Correcting the electrical distance indicator according to the weighting factor to
The invention further provides a preferred embodiment as follows: the weight factor ωiThe calculation formula of (2) is as follows:
j is a load node of the generator, and the load node j comprises a primary load node and a secondary load node;
t is the total number of the load nodes j, XijIs the shortest electrical tree reactance between the load node j and the generator;
The invention further provides a preferred embodiment as follows: dynamic reactive response quantitative index Q of each generator during short-circuit fault at weak pointiThe calculation formula of (2) is as follows:
wherein Q isi(t) is a function of the reactive power of the generator over time, Q0iFor the initial reactive load of the generator, SBIs the reference capacity of the power system, t0For the moment of fault removal, tIThe load reactive integration time.
The invention further provides a preferred embodiment as follows: the calculating of the response effect index of each generator in the power system influencing the voltage stability of the system comprises the following steps:
respectively carrying out standardization processing on the electrical distance index and the dynamic reactive power response quantization index to obtain an electrical distance index standard value
And dynamic reactive power response quantization index standard value
Setting the weight of the electric distance index standard value and the dynamic reactive power response quantization index standard value to obtain that the response effect index is
α and 1- α are all weights.
The invention further provides a preferred embodiment as follows: the electric distance index standard value
The calculation formula of (2) is as follows:
the standard value of the dynamic reactive response quantization index
The calculation formula of (2) is as follows:
wherein, X'im'Is an electrical distance index, Q, corrected according to a weighting factoriFor the dynamic reactive response quantization index, p is the total number of generators.
Compared with the closest prior art, the invention has the beneficial effects that:
1. the invention provides a minimum startup sequence optimization method based on unit load dynamic reactive power response, which considers the influence of load absorption reactive power on voltage stability after short circuit fault, reduces the search of a heavy load area through the partition load capacity and the bus connection state, reduces the simulation times and shortens the time for searching weak points by adjusting the short circuit fault time;
2. according to the minimum starting sequence optimization method based on the unit load dynamic reactive response, the effect of the generator on the voltage stabilization of weak points is represented by the electrical distance index of the weak points corresponding to the generator and serious faults, and the physical significance is clear; the weight factors are used for correcting the electrical distance between the generator and the weak point, so that the condition that the generator in the peripheral load center of the weak point is not started can be avoided, the load reactive condition and the electrical distribution of the load-generator are considered by the weight factors, and the index characterization accuracy can be improved;
3. the invention provides a minimum starting sequence optimization method based on unit load dynamic reactive response, which comprehensively considers the electric distance of a generator-weak point, the peripheral load dynamic reactive and distribution conditions of the generator, the dynamic reactive response of the generator and other influence factors to form a quantitative index, definitely gives the influence degree of each generator on the system voltage in the shutdown process, greatly improves the starting sequence arrangement strategy of the generator in the minimum shutdown mode, and has stronger adaptability.
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FIG. 1: the embodiment of the invention provides a minimum startup sequence optimization method based on unit load dynamic reactive power response.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The following describes a minimum startup sequence optimization method based on unit load dynamic reactive power response according to an embodiment of the present invention, with reference to the accompanying drawings.
Fig. 1 is a flowchart of a minimum startup sequence optimization method based on unit load dynamic reactive response in an embodiment of the present invention, and as shown in the figure, the method mainly includes the following steps:
step S101: and determining a weak point in a heavy-load area in the power system, wherein the weak point is a bus on one side where the most serious fault occurs in the heavy-load area.
Step S102: and determining an electrical distance index between each generator and the weak point in the power system after the short-circuit fault occurs in the weak point, and a dynamic reactive response quantitative index of each generator during the short-circuit fault occurs in the weak point.
Step S103: and calculating the response effect index of each generator in the power system influencing the voltage stability of the system according to the electrical distance index and the dynamic reactive response quantization index.
Step S104: determining the starting sequence of each generator according to the index value of the response effect index of each generator influencing the voltage stability of the system; and controlling the generators to start or stop according to the starting sequence, and detecting the stable state of the weak point, wherein the actual starting and stopping sequence of the generators is the minimum starting and stopping sequence when the weak point reaches the critical stable state.
First, the following description is made of step S101:
1. before determining weak points in a heavy load area in a power system, selecting the heavy load area of the power system comprises two methods, specifically:
the first embodiment is as follows:
calculating the power P wagered at each high voltage class bus node in the power systemmAnd sorted, including the betting power P with larger valuemThe area of the corresponding bus is a heavy load area; wherein m is the serial number of the bus. In this embodiment, the lower power is the sum of the power injected from the high-voltage side of the main transformer to the medium-voltage side and the low-voltage side.
Example two:
calculating the power P wagered at each high voltage class bus node in the power systemmAnd the power P wagered at the node of bus n directly connected to bus mmnTo the power P of betmAnd bet power PmnThe sum sorting includes the Area with the larger sum valuemnThe area of the corresponding bus is a heavy load area; wherein the content of the first and second substances,
s is the total number of busbars directly connected to busbar m.
2. Determining weak points in heavily loaded areas in a power system includes:
and (4) performing N-1 transient stability calculation on all the power transmission lines in the heavy load area, wherein the short circuit fault time is T seconds.
And modifying the short-circuit fault time T according to the working state of the power transmission line after the short-circuit fault, and re-performing N-1 transient stability calculation according to the modified short-circuit fault time until voltage instability occurs in only one power transmission line after the short-circuit fault, wherein the bus at one side of the power transmission line is a weak point. The method for modifying the short-circuit fault time T according to the working state of the power transmission line after the short-circuit fault comprises two methods:
the first embodiment is as follows:
when all the power transmission lines in the heavy load area are unstable, the short-circuit fault time is modified to be T-delta T, and N-1 transient stability calculation is carried out again according to the fault short-circuit time T-delta T until the power transmission lines in the heavy load area have a stable state and an unstable state at the same time; resetting the short-circuit fault time to
And performing N-1 transient stability calculation on the power transmission lines in the unstable state until only one power transmission line has voltage instability after short circuit fault.
Example two:
when all the power transmission lines in the heavy load area are stable, the short-circuit fault time is modified to be T + delta T, and N-1 transient stability calculation is carried out again according to the fault short-circuit time T + delta T until the power transmission lines in the heavy load area have a stable state and an unstable state at the same time; resetting the short-circuit fault time to
And performing N-1 transient stability calculation on the power transmission lines in the unstable state until voltage instability occurs on one or only one power transmission line after the short-circuit fault occurs, wherein delta t is a time increment.
Step S102 is explained as follows:
1. determining an indicator of electrical distance between each generator and a weak point in an electrical power system
A plurality of link circuits are arranged between the generators and the weak points, the connection modes between the circuits are different, mutual coupling influence exists between different generators, and loads connected with nodes on different circuits are also different, wherein the mutual influence between the generators is mainly reflected on the action of reactive power generated by the generators on the terminal voltage of each other, and the influence of the short-circuit fault of the weak points on the reactive power of the generators is reflected on the electrical distance between the generators and the load node, and on the one hand, the dynamic reactive power response of the load node and the electrical distance between the load and the generator are reflected on the other hand. If the short-circuit current provided by the generator after the weak point is short-circuited is larger, the short-circuit current indicates that the weak point is closer to the generator, and the generator has larger influence on the fault of the weak point; when the load-generator electrical distance is slightly far but the dynamic reactive power demand of the load is large after a fault and the nodes are distributed near the generator in a concentrated manner, the effect of the generator on the voltage stabilization of the power system is large in the vicinity of the generator, and the system also has an important influence on the voltage stabilization condition of the system after a weak point short circuit. The specific steps for determining the electrical distance index between each generator and the weak point in the power system are as follows:
(1) setting an electrical distance index to Xim'＝1/Iim'，Iim'And i is the serial number of the generator, and m' is the weak point.
(2) Determining a weighting factor omega for the electrical distance between each generator and the point of weaknessi. Weight factor omegaiThe calculation formula of (2) is as follows:
wherein j is the load node of the generatorj comprises a first-level load node and a second-level load node; t is the total number of load nodes j, XijIs the shortest electrical tree reactance between the load node j and the generator;
Qj(t) is the load reactive time-varying function of the load node, Q0jIs the initial reactive load of the load node, SBIs the reference capacity of the power system, t0For the moment of fault removal, tIThe load reactive integration time. In this embodiment, the primary load node refers to a load node directly connected to the generator, the secondary load node refers to a load node connected to the primary load node, and the shortest reactance of the electrical tree refers to the smallest reactance value in a communication path between the load node and the generator.
(3) Correcting the electrical distance index according to the weighting factor to
2. Determining dynamic reactive response quantitative indexes of each generator during short-circuit fault of weak points
The capacity and the excitation system of different generators are different, the dynamic reactive response to the weak point short-circuit fault is different, and if the generator can rapidly provide large reactive support during the weak point short-circuit fault, the voltage of the power system is easy to recover and stabilize. The reactive support effect of the generator can be represented by the dynamic reactive increment per unit value and the time integral of the generator within a period of time after the short-circuit fault, the larger the index is, the more obvious the voltage stabilization support effect is, and the closer the generator is to the post-shutdown group. Dynamic reactive response quantitative index Q of each generator during short-circuit fault of weak pointiThe calculation formula of (2) is as follows:
wherein Q isi(t) is the reactive power of the generator as a function of time, Q0iBeing the initial reactive load of the generatorLotus, SBIs the reference capacity of the power system, t0For the moment of fault removal, tIThe load reactive integration time.
3. The step of calculating the response effect indexes of each generator in the power system, which influence the voltage stability of the system, comprises the following steps:
(1) respectively standardizing the electric distance index and the dynamic reactive power response quantization index to obtain an electric distance index standard value
And dynamic reactive power response quantization index standard value
Both are values between 0 and 1.
Electric distance index standard value
The calculation formula of (2) is as follows:
the standard value of the dynamic reactive response quantization index
The calculation formula of (2) is as follows:
wherein, X'im'Is an electrical distance index, Q, corrected according to a weighting factoriThe index is a dynamic reactive response quantification index and is the total number of p generators.
(2) Setting the standard value of the electrical distance index
And dynamic reactive power response quantization index standard value
The weight of (1) is obtained as a response effect index
α and 1- α can be weights, in the embodiment, the smaller the response effect index is, the more favorable the voltage stabilization of the power system is, the corresponding generator should be stopped later, and the larger the response effect index is, the more unfavorable the voltage stabilization of the power system is, the corresponding generator should be stopped first.
The method for optimizing the minimum startup sequence based on the unit load dynamic reactive response provided by the invention is described below for the Hunan power grid. The method specifically comprises the following steps:
first, weak points in heavy load areas in the Hunan power grid are determined
According to the betting power of 500kV bus of the Hunan power grid shown in Table 1, it can be determined that the betting power of bus nodes of Aries, the age of the Crane, the ancient cooking power, the sandlevel and the mountain is larger, the betting power of areas of the Star city, the age of the Crane, the Aries and the sandlevel is larger, and the area range in the embodiment is counted according to the 500kV nodes and the contact nodes.
TABLE 1
| Site | Lower power Pm(MW) | Areamn | Lower power sum (MW) |
| Ai Jia Chong | 1330 | Region of star city | 3700 |
| Crane ridge | 1060 | Region of Crane Green | 3680 |
| Dinggong (ancient cooking vessel) | 1010 | Ai Jia Chong district | 3160 |
| Sand terrace | 980 | Sandlevel area | 3110 |
| Ship mountain | 870 | Region of long yang | 3010 |
| Cloud field | 830 | Ding Gong region | 2990 |
| Ancient pavilion | 470 | Area of revival | 2630 |
| Star city | 420 | Cloud field area | 2040 |
| Long Yang | 310 | Ship mountain area | 1990 |
| Fuxing (Chinese character of' Fuxing | 130 | Ancient pavilion area | 880 |
A line connected between a node with a large bet power and a node included in a large bet power area is selected, a three-phase short-circuit fault is set, short-circuit fault time T is 0.1s, and time increment Δ T is 0.002s, and simulation results are shown in table 2:
TABLE 2
| Short circuit time (seconds) | 0.102 | 0.1025 | 0.103 | 0.104 | 0.106 |
| Boat mountain-Hunan pond head | Stabilization | Stabilization | Voltage instability | ||
| Jiling-Xiangtan head | Stabilization | Stabilization | Voltage instability | Voltage instability | Voltage instability |
| Ancient pavilion-Hunan pond head | Stabilization | Stabilization | Voltage instability | ||
| Ancient pavilion-star city head | Stabilization | Stabilization | Voltage instability | ||
| Yuntian-He Ling head | Stabilization | Stabilization | Voltage instability | Voltage instability | |
| Crane-mugwort head | Stabilization | Voltage instability | Voltage instability | Voltage instability | Voltage instability |
| Head of the Star City-Yunnan | Stabilization | Stabilization | Voltage instability | Voltage instability | Voltage instability |
| Fuxing-ai Jia head | Stabilization | Stabilization | Voltage instability |
The crane age-aijia line crane age side bus can be determined as a weak point through table 2.
And secondly, determining an electrical distance index between each generator and the weak point in the power system after the short-circuit fault occurs in the weak point, and a dynamic reactive response quantification index of each generator during the short-circuit fault occurs in the weak point.
1. Determining an indicator of electrical distance between each generator and a weak point in an electrical power system after a short-circuit fault at the weak point
Crane age-aijia three-phase short circuit is a serious fault, a crane age bus is a weak point, and after the weak point bus is short-circuited, the per unit value of short-circuit current of part of the generators is shown in table 3:
TABLE 3
After the weak point short circuit fault occurs, calculating the reactive response and time integral of a primary load node and a secondary load node of the generator within 1 s:
using QiAnd XijThe sum of the ratios of the two-stage node of the generator is used as a weight factor in the range of the two-stage node of the generator,
wherein Q isi(t) is the reactive power of the generator as a function of time, Q0iFor the initial reactive load of the generator, SBIs the reference capacity of the power system, t0For the moment of fault removal, tILoad reactive integration time; j is a load node of the generator, and the load node j comprises a primary load node and a secondary load node; t is the total number of load nodes j, XijThe shortest electrical tree reactance between load node j and the generator.
The product of the reciprocal of the weighting factor and the electrical distance index is used to represent the corrected electrical distance, and the corrected electrical distance index in this embodiment is shown in table 4:
TABLE 4
| Machine set | Leishui B0 | Tanzhou 04 | Yang tonifying 02 | Xiangtan B3 | Stone door 02 | Ripple source 01 | Golden bamboo 1 |
| ωi | 59.24 | 270.76 | 27.78 | 65.06 | 28.74 | 128.49 | 196.30 |
| X′im' | 0.0030 | 0.00059 | 0.00664 | 0.00198 | 0.00864 | 0.00130 | 0.0006 |
2. Determining dynamic reactive response quantitative indexes of each generator during short-circuit fault of weak points
The dynamic reactive power response quantization index obtained by using the per unit value of the dynamic reactive power increment of the generator within 1s after the short-circuit fault is changed and the time integral is shown as a formula (8), and in the embodiment, the dynamic reactive power response quantization index of the generator is shown as a table 5:
wherein Q isi(t) is the reactive power of the generator as a function of time, Q0iFor the initial reactive load of the generator, SBIs the reference capacity of the power system, t0For the moment of fault removal, tIThe load reactive integration time.
TABLE 5
| Machine set | Leishui B0 | Tanzhou 04 | Yang tonifying 02 | Xiangtan B3 | Stone door 02 | Ripple source 01 | Golden bamboo 1 |
| Qi | 1.85 | 1.96 | 1.39 | 3.22 | 1.12 | 1.76 | 2.30 |
| 1/Qi | 0.54 | 0.51 | 0.72 | 0.31 | 0.89 | 0.56 | 0.43 |
And thirdly, calculating response effect indexes of each generator in the power system influencing the voltage stability of the system according to the electrical distance indexes and the dynamic reactive response quantization indexes.
In this embodiment, the electric distance index and the dynamic reactive response quantization index are respectively normalized, and the weight α is 0.5, and the obtained response effect indexes are shown in table 6:
TABLE 6
Fourthly, determining the starting sequence of each generator according to the index value of the response effect index of each generator influencing the voltage stability of the system; and controlling the generators to start or stop according to the starting sequence, and detecting the stable state of the weak point, wherein the actual starting and stopping sequence of the generators is the minimum starting and stopping sequence when the weak point reaches the critical stable state.
Table 7 in this example shows the weak point limit cut-off times for different generator combinations at three capacities of 600MW, 900MW and 1200MW respectively:
TABLE 7
It can be found from table 7 that the limit cutting times of different generator combination modes at each shutdown capacity are sequentially reduced, which indicates that under the same power receiving proportion, the generator at the front of the close sequence result has less influence on voltage stabilization than the generator at the same capacity at the back of the close sequence result, so that the importance of the goalkeeper, the sun, the Leishang, the ripple source, the Tankian, the Hunan and the golden bamboo on system voltage stabilization gradually rises, and the result is consistent with the response effect index. The result shows that if the power generator is shut down according to the sequence of the sequencing results of the power generator, under the same power receiving condition, the power generator is shut down according to the sequence of the response effect indexes, and the system voltage stabilization is facilitated. Therefore, the voltage stability condition under the minimum startup mode is optimized through the response effect index.
It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by a computer program, which can be stored in a computer-readable storage medium, and when executed, can include the processes of the embodiments of the methods described above. The storage medium may be a magnetic disk, an optical disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), or the like.
According to the minimum starting sequence optimization method based on the unit load dynamic reactive response, influence factors such as the electric distance of a generator-weak point, the dynamic reactive power of loads around the generator, the distribution condition of the loads around the generator, the dynamic reactive power response of the generator and the like are comprehensively considered to form a quantitative index, the influence degree of each generator on the system voltage in the shutdown process is definitely given, the generator starting sequence arrangement strategy of the minimum shutdown mode is greatly improved, and the method has strong adaptability.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.
Claims (8)
1. A minimum startup sequence optimization method based on unit load dynamic reactive response is characterized by comprising the following steps:
determining a weak point in a heavy-load area in a power system, wherein the weak point is a bus on one side where the most serious fault occurs in the heavy-load area;
determining an indicator of electrical distance between each generator in the power system and the weak point after the weak point has a short-circuit fault, and a quantitative indicator of dynamic reactive response of each generator during the short-circuit fault of the weak point;
calculating response effect indexes of each generator in the power system, which influence the voltage stability of the system, according to the electric distance indexes and the dynamic reactive response quantization indexes;
determining the starting sequence of each generator according to the index value of the response effect index; controlling the generators to start or stop according to the starting sequence, and detecting the stable state of the weak points, wherein the actual starting and stopping sequence of the generators is the minimum starting and stopping sequence when the weak points reach the critical stable state;
the determining weak points within heavily loaded regions in the power system prior to the selecting a heavily loaded region of the power system comprises:
calculating the power P wagered at each high voltage class bus node in the power systemmAnd is sequenced to include the power P to be betmThe area of the corresponding bus is the heavy load area; wherein m is the serial number of the bus;
alternatively, the first and second electrodes may be,
calculating the power P wagered at each high voltage class bus node in the power systemmAnd the power P to be bet on the node of the bus n directly connected to the bus mmnFor said bet power PmAnd bet power PmnThe sum sorting is performed, and the sum Area is includedmnThe area of the corresponding bus is the heavy load area; wherein the content of the first and second substances,
and s is the total number of the buses directly connected with the bus m.
2. The method according to claim 1, wherein the determining the weak points in the heavy load area of the power system comprises:
performing N-1 transient stability calculation on all the power transmission lines in the heavy load area, wherein the short circuit fault time is T seconds;
and modifying the short-circuit fault time T according to the working state of the power transmission line after the short-circuit fault, and performing N-1 transient stability calculation again according to the modified short-circuit fault time until the voltage instability of only one power transmission line after the short-circuit fault occurs, wherein the bus at one side of the power transmission line is a weak point.
3. The method according to claim 2, wherein the modifying the short-circuit fault time T according to the operating state of the transmission line after the short-circuit fault comprises:
when all the power transmission lines in the heavy load area are unstable, the short-circuit fault time is modified to be T-delta T, and N-1 transient stability calculation is carried out again according to the fault short-circuit time T-delta T until the power transmission lines in the heavy load area have a stable state and an unstable state at the same time; resetting the short-circuit fault time to
Performing N-1 transient stability calculation on the power transmission lines in an unstable state until voltage instability occurs on one or only one power transmission line after a short circuit fault occurs;
when all the transmission lines in the heavy load area are stable, the short-circuit fault time is modified to be T + delta T, and N-1 transient stability calculation is carried out again according to the fault short-circuit time T + delta T until the heavy load areaThe transmission lines in the domain have a stable state and an unstable state at the same time; resetting the short-circuit fault time to
And performing N-1 transient stability calculation on the power transmission lines in the unstable state until voltage instability occurs on one or only one power transmission line after the short-circuit fault occurs, wherein delta t is a time increment.
4. The method of claim 1, wherein the determining an indicator of electrical distance between each generator and a weak point in the power system comprises:
setting the electric distance index to Xim'＝1/Iim'，Iim'Short-circuit current is provided for each generator after the short-circuit fault occurs to the weak point, i is the serial number of the generator, and m' is the weak point;
determining a weighting factor omega for the electrical distance between each generator and the point of weaknessi；
Correcting the electrical distance indicator according to the weighting factor to
5. The method as claimed in claim 4, wherein the weight factor ω is a weight factor of a minimum startup sequence optimization method based on a unit load dynamic reactive responseiThe calculation formula of (2) is as follows:
j is a load node of the generator, and the load node j comprises a primary load node and a secondary load node;
t is the total number of the load nodes j, XijIs the shortest electrical tree reactance between the load node j and the generator;
6. The method for optimizing the minimum startup sequence based on the unit load dynamic reactive response according to claim 1, wherein the dynamic reactive response quantitative index Q of each generator during the short-circuit fault of the weak pointiThe calculation formula of (2) is as follows:
wherein Q isi(t) is a function of the reactive power of the generator over time, Q0iFor the initial reactive load of the generator, SBIs the reference capacity of the power system, t0For the moment of fault removal, tIThe load reactive integration time.
7. The method according to claim 1, wherein the calculating response effect indicators of the generators in the power system affecting the voltage stability of the system comprises:
respectively carrying out standardization processing on the electrical distance index and the dynamic reactive power response quantization index to obtain an electrical distance index standard value
And dynamic reactive power response quantization index standard value
Setting the standard value of the electrical distance index
And dynamic reactive power response quantization index standard value
The obtained response effect index is
α and 1- α are all weights.
8. The method according to claim 7, wherein the electrical distance index standard value is the minimum startup sequence optimization method based on the unit load dynamic reactive response
The calculation formula of (2) is as follows:
the standard value of the dynamic reactive response quantization index
The calculation formula of (2) is as follows:
wherein, X'im'Is an electrical distance index, Q, corrected according to a weighting factoriFor the dynamic reactive response quantization index, p is the total number of generators.
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| CN110718912B (en) * | 2019-11-11 | 2020-09-18 | 广东电网有限责任公司电网规划研究中心 | Method and device for determining optimal electrical distance of power grid |
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