CN111934317A - Method for optimizing bottom-guaranteed power grid of key area under strong typhoon condition - Google Patents
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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
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/001—Methods to deal with contingencies, e.g. abnormalities, faults or failures
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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
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/04—Circuit arrangements for ac mains or ac distribution networks for connecting networks of the same frequency but supplied from different sources
- H02J3/06—Controlling transfer of power between connected networks; Controlling sharing of load between connected networks
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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
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/12—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load
- H02J3/16—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load by adjustment of reactive power
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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
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
- H02J3/48—Controlling the sharing of the in-phase component
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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
- H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/30—Reactive power compensation
Abstract
The invention provides a method for optimizing a bottom-protected power grid of a power grid in a key area under the condition of strong typhoon, which comprises the following steps: s1, selecting a connecting line for interconnecting and expanding a bottom-protecting power grid and an external power grid; s2, making measures for adjusting the active power of the generator and controlling the load according to the power control level of the tie line in the area of the bottom-protected power grid; s3, connecting the bottom-protected power grid with an external power grid, and controlling the section tide zero-crossing; s4, controlling the voltage level of a bus node in the bottom-protected power grid; s5 transient stability characteristic verification is carried out in the process of bottom-preserving power grid division through PSD-BPA equipment; and S6, verifying the transient stability characteristics of the split bottom-protected power grid and the external power grid through PSD-BPA equipment. The method provided by the invention considers the condition that a plurality of tie lines are tripped due to faults at the same time in the typhoon invasion process, and the grounding cables are increased as much as possible as the number of loops of the tie lines in the bottom-guaranteed power grid division process.
Description
Technical Field
The invention relates to the field of power grid fault maintenance, in particular to a method for optimizing a key area power grid bottom-protecting power grid under the condition of strong typhoon.
Background
In recent years, strong typhoons often abuse sea areas, and bring great threats to the safe and stable operation of a power grid in the sea areas. The Tiange typhoon which logs in the Zhuhai city in 2017 and the mangosteen typhoon which logs in the Zhuhai city in 2018 influence the safe and stable operation of the Zhuhai power grid to different degrees, cause a large number of tower collapse and disconnection faults, cause a large amount of load loss and bring adverse effects to national economy.
Due to the fact that typhoon paths and strength have great uncertainty, during typhoon abuse, the positions of overhead line falling rods and broken lines and the number of loops in a power grid have great uncertainty. In general scheduling operation, when a line has a fault, a power grid makes an operation control strategy according to the requirement of N-1, and the power flow of a key power transmission section is pre-controlled in advance. However, during the coming period of typhoon, the faulted line and the return number are not fixed, and the advanced precontrol of the power flow of the key transmission section of the power grid is difficult to be carried out according to the relevant standard and requirement of N-1 in the stable guide rule of the power system. During typhoon period, if any two or more lines break down, the power grid may have large-scale tidal current transfer to cause overload of other alternating current lines, thereby causing system transient instability and causing grid breakdown. Chinese patent CN110176767A discloses a method for constructing a bottom-protecting net rack in coastal areas, which can construct a self-balancing local power grid in typhoon disasters; but the problem that the power grid is crashed due to transient instability of the system caused by overload of other alternating current lines due to large-scale transfer of the power flow cannot be solved.
Disclosure of Invention
The invention provides a method for optimizing a power grid in a key area under the condition of strong typhoon, aiming at overcoming the problem that the power grid is broken by any two or more circuits under the condition of typhoon, so that the power grid is possible to have large-range tidal current transfer and overload other alternating current lines, thereby causing the power grid to crash due to transient instability of the system. The invention can prevent overload of other alternating current lines caused by large-scale tidal current transfer under the condition of line disconnection fault of any two or more circuits under the condition of typhoon, maintain the transient stable operation of the power grid and finally ensure that a key power supply area can effectively deal with the attack of typhoon.
In order to solve the technical problems, the invention adopts the technical scheme that: a method for optimizing a bottom-protected power grid of a power grid in a key area under the condition of strong typhoon comprises the following steps:
s1, selecting a connecting line for interconnecting a bottom-protecting power grid and an external power grid: preferably, the grounding cables are used as the connecting lines, when the number of the grounding cables is enough, all the grounding cables are selected as the connecting points, and when the number of the grounding cables is insufficient, the overhead lines are used for complementing.
S2, adjusting the capacity of the generator in the bottom-protected power grid defined by the tie lines to be larger than the load level, and keeping the adjustment margin with the maximum output of a single generator;
s3, carrying out zero-crossing control on the communication section tide on the connecting line of the bottom-protected power grid and the external power grid;
s4, carrying out zero-cutting control on active power of all overhead lines in the connecting section;
s5, controlling the voltage level of a bus node in the bottom-protected power grid not to exceed the limit by controlling the reactive power of the reactive power compensation device and the generator;
s6, transient stability characteristic verification is carried out one by one in the process of selecting a bottom-protected power grid through PSD-BPA simulation software;
and S7, after the selected bottom-protected power grid is disconnected with an external power grid through PSD-BPA simulation software, transient stability characteristic verification is carried out one by one, and finally the optimal bottom-protected power grid is determined.
Further, the step S2 includes: the capacity of the generator in the bottom-protection power grid is larger than the load level, the active power flow direction is that the bottom-protection power grid flows to the external power grid, the bottom-protection power grid is ensured to have power regulation margin, and the maximum power of a single generator in the bottom-protection power grid is PG Single maxThe maximum natural fluctuation amount of the single-day load of the bottom-protected power grid is delta PLmaxThe current load level of the bottom-protected power grid is delta PLThe current upper limit of the generating capacity of the generator in the bottom-protected power grid is delta PG total maxDetermining the criterion of the bottom-protected power grid as follows:
ΔPg total max>ΔPL+PG Single max+ΔPLmax。
Further, the step S3 includes: suppose a bottom-protected power grid and an external power grid are networked with N tie lines, wherein the overhead line tie lines are 1 to m, and the active power of the corresponding tie lines is Pline_1，Pline_2L Pline_m(ii) a The grounding cable tie lines are m +1 to N, and the active power of the corresponding tie lines is Pline_m+1，Pline_m+2L Pline_NIn order to ensure the minimum impact after the tripping of the fault of the connecting line, the bottom of the power grid and the outside are protectedControlling the power flow of the power grid connection section to zero; namely:
Pline_1+Pline_2+L Pline_m+Pline_m+1+L+Pline_N＝0。
further, the step S4 includes: during a typhoon attack, m overhead interconnections are likely to have faults, namely m (m-1) ((m-2) L2) (-1), any 1, any 2 and any m interconnections in the overhead interconnections have faults, the active power of the rest N-m grounding cable interconnections cannot exceed the limit, any 1, any 2 and any m interconnections in the overhead interconnections are before and after the faults, and any grounding cable interconnection has a thermal power limit, and the power after the faults of the interconnections is respectively the power after the faults, and the active power after the faults of any grounding cable is required to be smaller than the thermal stability limit value of the interconnection, namely:
P′line_i<Pline_max。
further, the step S5 includes: the upper and lower limits of the bus voltage of any node in the bottom-protected power grid are respectively Ui_maxAnd Ui_minAnd 1, 2 and m overhead connecting lines have faults, and the bus voltage U of any node in the bottom-protected power gridiWithout going beyond the limit, the following formula is specifically mentioned:
Ui_min<Ui<Ui_max。
further, the step S6 includes: 1 arbitrary in the built on stilts tie line, arbitrary 2 and arbitrary m tie line failures observe all busbar voltage curve, generator power curve and system frequency curve in the key region electric wire netting, ensure because typhoon causes the disconnected end of guaranteeing that the electric wire netting can the steady operation behind the tower falls.
Further, the step S7 includes: during the typhoon attack, faults of 1 random number, 2 random numbers and m random numbers in the overhead connecting lines and overload of the remaining n-m grounding cables lead to disconnection of a bottom-protected power grid and an external power grid connecting section, so that all bus voltage curves, generator power curves and system frequency curves in a power grid of a key area are observed, and the bottom-protected power grid can stably run after the lines are broken and the tower is inverted due to typhoon.
Further, the upper limit of the generating capacity of the generator is delta PG total maxIs the sum of the current developed capacity of the generator and the upper limit of the adjustable capacity.
Further, the bus bar comprises a 220KV bus bar and a 500KV bus bar.
Compared with the prior art, the beneficial effects are:
1. the method provided by the invention considers the condition that a plurality of tie lines are tripped due to faults at the same time in the typhoon invasion process, and the grounding cables are increased as much as possible as the number of loops of the tie lines in the bottom-guaranteed power grid division process.
2. Aiming at the problem that pre-control is difficult to perform before the overhead line tripping fault is caused by typhoon between a bottom-protection power grid and an external power grid, the principle that the upper limit of the generating capacity of a generator in the range of the bottom-protection power grid is larger than the current load of the bottom-protection power grid, the maximum power of a single generator and the maximum natural fluctuation amount of a single daily load is provided, and transient stable operation of the power grid is guaranteed.
3. Aiming at the problem of tripping of any overhead line in m overhead lines of a bottom-protected power grid and an external power grid in a typhoon invasion process, m-1-2-L-2-1 fault verification is carried out on any one or more of the m overhead lines, and stable operation of a power grid in a key area can be ensured in a typhoon invasion period.
Drawings
FIG. 1 is a schematic flow diagram of the present invention.
Fig. 2 is a schematic diagram of division of the guaranteed-base power grid in embodiment 1.
Fig. 3 is a schematic diagram of the generator power verification result in embodiment 1.
Fig. 4 is a schematic diagram of the frequency verification result in embodiment 1.
Fig. 5 is a schematic diagram of division of the guaranteed-base power grid in embodiment 2.
Fig. 6 is a schematic diagram of the generator power verification result in embodiment 2.
Fig. 7 is a schematic diagram of the frequency verification result in embodiment 2.
Fig. 8 is a schematic diagram of division of the guaranteed-base power grid in embodiment 3.
Fig. 9 is a diagram showing the result of the power verification of the generator in embodiment 3.
Fig. 10 is a schematic diagram of the frequency verification result in embodiment 3.
Detailed Description
The drawings are for illustrative purposes only and are not to be construed as limiting the patent; for the purpose of better illustrating the embodiments, certain features of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product; it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted. The positional relationships depicted in the drawings are for illustrative purposes only and are not to be construed as limiting the present patent.
Example 1
The embodiment provides a method for optimizing a bottom-protected power grid of a power grid in a key area under a strong typhoon condition, as shown in fig. 1, the method comprises the following steps:
s1, selecting a connecting line for expanding a bottom-protecting power grid and an external power grid: the bottom-protecting power grid and the external power grid connecting lines are N, namely Line1 and Line2L LineN, the bottom-protecting power grid is expanded towards the external power grid, the number of the grounding cables serving as the connecting lines is the largest, and the probability and the return number of Line tripping caused by typhoon are reduced.
S2, formulating active power regulating capacity of a guaranteed-base power grid: the capacity of the generator in the bottom-protection power grid is larger than the load level, the active power flow direction is that the bottom-protection power grid flows to the external power grid, the bottom-protection power grid is ensured to have power regulation margin, and the maximum power of a single generator in the bottom-protection power grid is PG Single maxThe maximum natural fluctuation amount of the single-day load of the bottom-protected power grid is delta PLmaxThe current load level of the bottom-protected power grid is delta PLThe current upper limit of the generating capacity of the generator in the bottom-protected power grid is delta PG total maxDetermining the criterion of the bottom-protected power grid as follows:
ΔPg total max>ΔPL+PG Single max+ΔPLmax；
The meaning of this formula is: in the bottom-protected power grid, the bottom-protected power grid has active power regulation capacity due to the fact that any one generator in typhoon is in a machine regulation fault or the load naturally fluctuates according to a daily load curve.
S3, connecting the bottom-protected power grid with an external power grid, and controlling the section tide zero-crossing: suppose a bottom-protected power grid and an external power grid are networked with N tie lines, wherein the overhead line tie lines are 1 to m, and the active power of the corresponding tie lines is Pline_1，Pline_2L Pline_m(ii) a The grounding cable tie lines are m +1 to N, and the active power of the corresponding tie lines is Pline_m+1，Pline_m+2L Pline_NIn order to ensure that the impact is minimum after the fault of the connecting line is tripped, the connection section of the bottom-protected power grid and the external power grid is subjected to current control to zero; namely:
Pline_1+Pline_2+L Pline_m+Pline_m+1+L+Pline_N＝0。
s4, controlling the active power of all overhead connecting lines to reach the minimum value: during the stage of a typhoon attack, the possibility that m overhead interconnections have faults is m (m-1) ((m-2) L2) × 1, any 1 in the overhead interconnections, any 2 and any m interconnections have faults, the active power of the rest N-m grounding cable interconnections cannot exceed the limit, any 1 in the overhead interconnections, any 2 in the overhead interconnections and before and after any m interconnections have faults, the thermal power limit of any grounding cable interconnection is that, the power after the interconnection fault is respectively that the active power after any grounding cable fault is smaller than the thermal stability limit value of the interconnection after any grounding cable fault, namely:
P′line_i<Pline_max。
s5, controlling the voltage level of a bus node in the bottom-protected power grid not to exceed the limit by controlling the reactive power of the reactive power compensation device and the generator: the upper and lower limits of the bus voltage of any node in the bottom-protected power grid are respectively Ui_maxAnd Ui_minAnd 1, 2 and m overhead connecting lines have faults, and the bus voltage U of any node in the bottom-protected power gridiWithout going beyond the limit, the following formula is specifically mentioned:
Ui_min<Ui<Ui_max。
s6, transient stability characteristic verification in the process of dividing the bottom-preserving power grid is carried out through PSD-BPA equipment: 1 arbitrary in the built on stilts tie line, arbitrary 2 and arbitrary m tie line failures observe all busbar voltage curve, generator power curve and system frequency curve in the key region electric wire netting, ensure because typhoon causes the disconnected end of guaranteeing that the electric wire netting can the steady operation behind the tower falls.
S7, performing transient stability characteristic verification after the bottom-protected power grid and the external power grid are disconnected through PSD-BPA equipment: during the typhoon attack, faults of 1 random number, 2 random numbers and m random numbers in the overhead connecting lines and overload of the remaining n-m grounding cables lead to disconnection of a bottom-protected power grid and an external power grid connecting section, so that all bus voltage curves, generator power curves and system frequency curves in a power grid of a key area are observed, and the bottom-protected power grid can stably run after the lines are broken and the tower is inverted due to typhoon.
Wherein the generator upper limit of the generable capacity Δ PG total maxThe sum of the current sent capacity and the adjustable capacity upper limit of the generator; the bus comprises a 220KV bus and a 500KV bus.
In a specific case, as shown in fig. 2, a grid of an important power supply area is used as a grid system of a bottom-protected grid 1. Determining a guaranteed-base power grid 1 based on the steps S1 and S2, involving four substations and one power plant; the bottom-protecting power grid 1 and the external power grid connecting lines are seven, namely ZHH A/B/C lines, JQ A/B lines and YQ A/B lines, wherein ZHH A/B/C lines are cables; determining that the installed capacity of the WY power plant in the guaranteed-base power grid 1 is 2 x 390MW and the total load is 694MW based on the steps S3, S4 and S5; the generator capacity is larger than the load level within the range of the bottom-protected power grid 1; a guaranteed-base power grid 1 is shown in fig. 2.
Before an accident occurs, the power flow optimization control of the contact section 2 is carried out, the active power of the power grid can flow to an external power grid from a bottom-protected power grid 1, the power flow trend of an HZH line is from YSH to ZH, and the power flow is 3 multiplied by 3.0 MW; in order to ensure that the impact is minimum after the fault of the tie line is tripped, the tidal current of overhead lines of a bottom-protecting power grid 1 and an external power grid connection section 2 is controlled to be zero, wherein the tidal current of a JQ line is 2 multiplied by 2.7MW, and the tidal current of a YQ line is 2 multiplied by 0.1 MW; when the overhead connecting line fails, the tide of each line in the bottom-protecting power grid 1 is reasonably distributed, no overload line exists, and the voltage level is reasonable.
The transient stability characteristics of the guaranteed-base power grid 1 during the disconnection of the overhead tie line are verified based on the steps S6 and S7, and the corresponding results are shown in fig. 3 and 4.
Compared with the traditional control method, the embodiment comprises the following steps: firstly, in the embodiment, considering the condition that a plurality of tie lines are tripped due to faults at the same time in the typhoon invasion process, the embodiment proposes to increase the number of return cables as the tie lines as much as possible in the division process of the bottom-protected power grid 1, and the method can ensure that the impact caused by tripping of multiple loops of overhead lines due to typhoon invasion is minimum; secondly, aiming at the problem that pre-control is difficult to perform before the overhead line tripping fault is caused by typhoon between the bottom-protection power grid 1 and an external power grid, the principle that the upper limit of the generating capacity of the generator in the range of the bottom-protection power grid 1 is larger than the current load of the bottom-protection power grid 1, the maximum power of a single generator and the maximum natural fluctuation amount of a single daily load is provided, and transient stable operation of the power grid is ensured; finally, aiming at the problem that any overhead line in the m overhead lines of the bottom-protected power grid 1 and the external power grid trips in the typhoon attack process, m (m-1) m (m-2) L2 (1) fault verification is carried out on any one or more of the m overhead lines, and the power grid in the key area can be ensured to be stably operated in the typhoon attack period.
Example 2
This embodiment is similar to embodiment 1, but differs in that the use cases are different, specifically:
as shown in fig. 5, a power grid of an important power supply area and ZHH stations are used, and JD stations are used as a grid system of a bottom-guaranteeing power grid 1; determining the range of the guaranteed-base power grid 1 based on the steps S1 and S2, six transformer stations and one power plant in the guaranteed-base power grid 1; twelve connecting lines of the bottom-protecting power grid 1 and an external power grid are GZH A/B lines, JZH A/B lines, ZHF lines, JF lines, JG A/B lines, JQ A/B lines and YQ A/B lines; four cables are respectively a ZHF line, a JF line and a JG line; determining that the installed capacity of the WY power plant in the bottom-preserving power grid 1 is 2 x 390MW and the total load is 1229MW based on the steps S3, S4 and S5; the load level is greater than the generator capacity within the scope of the guaranteed-base grid 1.
Under the condition, after the range of a bottom-protection power grid 1 is set, the power flow optimization control of a contact section 2 is carried out before an accident occurs, because an ZHH station is used as an important load station of an external power grid and a provincial power supply station of a north channel for supplying power to a power grid in a heavy point region, the active power of the power grid cannot flow from the bottom-protection power grid 1 to some external power grid, and the power flow on a contact line cannot be controlled to be zero, wherein the power flow of a GZH line is 2 multiplied by 36.5MW, and the power flow of a JZH line is 2 multiplied by 186 MW.
After the overhead tie line fault occurs, because main power supply access JZH A B line and GZH A B line break off, make ZHH station need rely on 500kV GSH station to pass through FH station power supply, consequently two transformers of FH station need the operation side by side in advance before the accident, thereby rely on two cables of FZH line and FJ line to supply power to protect end electric wire netting 1, make each circuit trend in protecting end electric wire netting 1 all distribute rationally, do not have the overload circuit, voltage level is reasonable.
The transient stability characteristics of the guaranteed-base power grid 1 during the disconnection of the overhead tie line are verified based on the steps S6 and S7, and the corresponding results are shown in fig. 6 and 7.
Example 3
This embodiment is similar to embodiment 1, but differs in that the use cases are different, specifically:
as shown in fig. 8, the grid system of the key power supply area, the YD station, the NP station and the HW power plant are used as the grid structure of the bottom-guaranteed grid 1, and the bottom-guaranteed range is determined based on steps S1 and S2, wherein six transformer stations and two power plants are used in the bottom-guaranteed grid 1; the bottom-protecting power grid 1 and the external power grid connecting lines are seven, namely ZHH A/B/C lines, JQ A/B lines and JN A/B lines; wherein ZHH A/B/C line is cable. Determining that the installed capacity of a WY power plant in the bottom-protected power grid 1 is 2 x 390MW, the installed capacity of a HW power plant is 2 x 180MW, the total installed capacity is 1140MW and the total load of the power grid is 962MW based on the steps S3, S4 and S5; the generator capacity is greater than the load level within the range of the bottom-protected power grid 1.
Setting the range of a bottom-protection power grid 1 as shown in fig. 6, and performing power flow optimization control on a contact section 2 before an accident occurs, so that the active power of the power grid can flow from the bottom-protection power grid 1 to an external power grid, wherein the flow trend of an HZH line in the embodiment is YSH to ZHH, and the flow is 3 × 0.8 MW; in order to ensure that the impact is minimum after the disconnection of the interconnection line due to faults, the tidal current of overhead lines of a bottom-protecting power grid 1 and an external power grid interconnection section 2 is controlled to be zero, wherein the controllable JQ line tidal current is 2 multiplied by 3.5MW, and the JN line tidal current is 2 multiplied by 3.4 MW.
When the overhead connecting line fails, the power flow of each line in the bottom-protected power grid 1 is reasonably distributed, no overload line exists, and the voltage level is reasonable; finally, the transient stability characteristics of the guaranteed-base power grid 1 during the disconnection of the overhead tie line are verified based on the steps S6 and S7, and the corresponding results are shown in fig. 9 and 10.
It should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.
Claims (10)
1. A method for optimizing a bottom-protected power grid of a power grid in a key area under the condition of strong typhoon is characterized by comprising the following steps:
s1, selecting a connecting line for interconnecting a bottom-protecting power grid and an external power grid: preferably, the grounding cables are used as the connecting lines, when the number of the grounding cables is enough, all the grounding cables are selected as the connecting points, and when the number of the grounding cables is insufficient, the overhead lines are used for complementing.
S2, adjusting the capacity of the generator in the bottom-protected power grid defined by the tie lines to be larger than the load level, and keeping the adjustment margin with the maximum output of a single generator;
s3, carrying out zero-crossing control on the communication section tide on the connecting line of the bottom-protected power grid and the external power grid;
s4, carrying out zero-cutting control on active power of all overhead lines in the connecting section;
s5, controlling the voltage level of a bus node in the bottom-protected power grid not to exceed the limit by controlling the reactive power of the reactive power compensation device and the generator;
s6, performing transient stability characteristic verification on the defined guaranteed-base power grid through PSD-BPA simulation software;
and S7, performing transient stability characteristic verification after the defined guaranteed-base power grid and an external power grid are disconnected through PSD-BPA simulation software.
2. The method for optimizing the guaranteed-base power grid of the key area in the case of the strong typhoon according to the claim 1, wherein the step S1 comprises: the bottom-protecting power grid and the external power grid connecting lines are N, namely Line1 and Line2L LineN, the bottom-protecting power grid is expanded towards the external power grid, the number of the grounding cables serving as the connecting lines is the largest, and the probability and the return number of Line tripping caused by typhoon are reduced.
3. The method for optimizing the guaranteed-base power grid of the key area in the case of the strong typhoon according to claim 2, wherein the step S2 comprises: the capacity of the generator in the bottom-protection power grid is larger than the load level, the active power flow direction is that the bottom-protection power grid flows to the external power grid, the bottom-protection power grid is ensured to have power regulation margin, and the maximum power of a single generator in the bottom-protection power grid is PG Single maxThe maximum natural fluctuation amount of the single-day load of the bottom-protected power grid is delta PLmaxThe current load level of the bottom-protected power grid is delta PLThe current upper limit of the generating capacity of the generator in the bottom-protected power grid is delta PG total maxDetermining the criterion of the bottom-protected power grid as follows:
ΔPg total max>ΔPL+PG Single max+ΔPLmax。
4. The method for optimizing the guaranteed-base power grid of the key area in the case of the strong typhoon according to the claim 3, wherein the step S3 comprises: suppose a bottom-protected power grid and an external power grid are networked with N tie lines, wherein the overhead line tie lines are 1 to m, and the active power of the corresponding tie lines is Pline_1，Pline_2L Pline_m(ii) a The grounding cable tie lines are m +1 to N, and the active power of the corresponding tie lines is Pline_m+1，Pline_m+2L Pline_NIn order to ensure the minimum impact after the tripping of the fault of the connecting line, the bottom-protecting power grid is communicated with the external power gridControlling the section current to cut zero; namely:
Pline_1+Pline_2+LPline_m+Pline_m+1+L+Pline_N＝0。
5. the method for optimizing the guaranteed-base power grid of the key area in the case of the strong typhoon according to claim 4, wherein the step S4 comprises: during the stage of the arrival of typhoon, the possibility of the failure of m overhead connecting lines is m (m-1) (m-2) L2 × 1, any 2 and any m connecting line failures in the overhead connecting lines, the active power of the rest N-m grounding cable connecting lines can not exceed the limit, and the thermal power limit of any grounding cable connecting line is P before and after the failure of any 1, any 2 and any m connecting lines in the overhead connecting linesline_maxThe power after the fault of the tie line is P'line_iIt is necessary to ensure that the active power is less than the thermal stability limit value of any grounding cable after the fault, that is:
P′line_i<Pline_max。
6. the method for optimizing the guaranteed-base power grid of the key area in the case of the strong typhoon according to the claim 5, wherein the step S5 comprises: the upper and lower limits of the bus voltage of any node in the bottom-protected power grid are respectively Ui_maxAnd Ui_minAnd 1, 2 and m overhead connecting lines have faults, and the bus voltage U of any node in the bottom-protected power gridiWithout going beyond the limit, the following formula is specifically mentioned:
Ui_min<Ui<Ui_max。
7. the method for optimizing the guaranteed-base power grid of the key area in the case of the strong typhoon according to claim 6, wherein the step S6 comprises: 1 arbitrary in the built on stilts tie line, arbitrary 2 and arbitrary m tie line failures observe all busbar voltage curve, generator power curve and system frequency curve in the key region electric wire netting, ensure because typhoon causes the disconnected end of guaranteeing that the electric wire netting can the steady operation behind the tower falls.
8. The method for optimizing the guaranteed-base power grid of the key area in the case of the strong typhoon according to claim 7, wherein the step S7 comprises: during the typhoon attack, faults of 1 random number, 2 random numbers and m random numbers in the overhead connecting lines and overload of the remaining n-m grounding cables lead to disconnection of a bottom-protected power grid and an external power grid connecting section, so that all bus voltage curves, generator power curves and system frequency curves in a power grid of a key area are observed, and the bottom-protected power grid can stably run after the lines are broken and the tower is inverted due to typhoon.
9. The method as claimed in claim 6, wherein the power generation capacity upper limit Δ P is set as the power generation capacity of the generatorG total maxIs the sum of the current developed capacity of the generator and the upper limit of the adjustable capacity.
10. The method for optimizing the bottom-protected power grid of the key area under the condition of the strong typhoon as claimed in claim 6, wherein the buses comprise 220KV buses and 500KV buses.
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