CN109301833B - AC/DC series-parallel power grid power transmission section overload control method based on path stripping - Google Patents
AC/DC series-parallel power grid power transmission section overload control method based on path stripping Download PDFInfo
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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
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
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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
- H02J3/36—Arrangements for transfer of electric power between ac networks via a high-tension dc link
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- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/60—Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]
Abstract
The invention relates to an alternating current-direct current series-parallel power grid power transmission section overload control method based on path stripping, which comprises the following steps: step 1): monitoring the section tide, if the line is overloaded, carrying out direct current emergency control to provide the maximum belt transfer capacity for the overloaded line, if the belt transfer capacity is insufficient, stripping a power transmission path to obtain an upstream generator and a downstream load of the overloaded line, and judging the minimum load to be transferred or cut off when the line returns to a safe operation state; step 2): searching other power transmission paths for supplying power to the downstream load, judging whether the maximum belt-transferring capacity of the paths can meet the load requirement according to constraint conditions, if the belt-transferring capacity is insufficient, entering the step 3), and if not, turning to the step 4); step 3): judging the maximum transfer supply amount which can be satisfied, and cutting off the load which can not be supplied; step 4): constructing an objective function; step 5): and solving the objective function by using a simplex method to obtain the optimal adjustment quantity.
Description
Technical Field
The invention relates to an alternating current-direct current series-parallel power grid power transmission section overload control method based on path stripping, and relates to the technical field of power grid power supply.
Background
The power transmission section line tide crosses the line, so that large-scale cascading faults are easily caused, and serious consequences are caused. The quick and effective control measures can reduce the residual line power transmission pressure and avoid the occurrence of malignant accidents. The direct current transmission has the advantages of high power regulation speed and large regulation capacity, and can improve the power balance capability and the tide distribution characteristic of a power grid under the impact of large disturbance.
Currently, expert scholars have conducted extensive research in the area of section overload control. The existing effective control methods can be summarized into the following categories: 1. sensitivity method: the prior art documents disclose the use of node sensitivity to assess the impact of power transfer between different subnetworks on an overloaded line. And calculating the power transfer amount of the sub-network according to the pareto solution set ordering and the power transfer constraint conditions, and updating the injection power of each node until the line overload phenomenon disappears. The prior art documents disclose that a direct current model is used to obtain key loads and power generation nodes which affect the line power, and when the line power exceeds a set threshold, a control signal is sent to a corresponding load or power generation end. On the basis, the prior art documents consider the integrity of the power transmission section, construct the sensitivity indexes of the node to the overload branch and the normal branch, and reduce the total power transmission amount of the section branch on the basis of ensuring the reduction of the load flow of the overload branch. 2. And constructing an objective function by taking the minimum load shedding amount or the minimum regulating and controlling amount as a target, and solving the optimal node control amount on the basis of the system safe operation constraint. In the prior art, the aim of meeting the minimum loss is taken as a target, a penalty factor is introduced to construct a target function, a generator set is preferentially adjusted, and load shedding control is performed under the condition of no optimal solution. The prior art documents also construct a static voltage constraint and a power flow constraint function, and determine a load adjustment set by cutting a set of voltage stability margin and an active static safety domain. 3. The mixed iteration method, as indicated by the prior art literature, is based on a sensitivity method, and has a simple calculation process, but cannot realize large-scale power flow control; the control method based on the optimization process cannot be applied on line due to complex operation. Meanwhile, the prior art document also provides a line overload emergency control strategy based on a power flow tracking algorithm, the power component of the line is obtained by utilizing the power flow tracking algorithm, and a generator set and a load with larger line occupancy rate are cut off in proportion when the line is overloaded. In the prior art, a load reduction method based on power flow tracking is combined with an optimal power flow model with minimum active network loss, and a correction control measure is formed through alternative calculation. When the section is overloaded due to the tidal current transfer, the conventional method mainly takes nodes such as a generator, a load and the like as regulation and control objects, and the load tidal current on an overloaded branch is quickly reduced through a generator cutting and load cutting control measure. Although the root cause of the occurrence of the cascading trip is fundamentally eliminated, the load transfer capacity of other feasible power supply paths in the network is ignored, and unnecessary loss is caused.
Disclosure of Invention
In view of the above problems, an object of the present invention is to provide an ac/dc hybrid power grid transmission section overload control method that constructs a constraint condition and an objective function by ensuring the safety of an overload section as a target and improves the margin of an ac/dc hybrid power grid transmission section under the condition of an optimal path adjustment scheme based on a path stripping concept.
In order to achieve the purpose, the invention adopts the following technical scheme: a method for controlling overload of a power transmission section of an alternating current-direct current hybrid power grid based on path stripping comprises the following steps:
step 1): monitoring the power transmission section tide of an alternating-current and direct-current series-parallel power grid, if the line is overloaded, carrying out direct-current emergency control to provide the maximum belt transfer capacity for the overloaded line, if the belt transfer capacity is insufficient, stripping a power transmission path by adopting a tide tracking algorithm to obtain an upstream generator and a downstream load of the overloaded line, and judging the minimum load to be transferred or cut when the line returns to a safe operation state;
step 2): searching other power transmission paths for supplying power to the downstream load, judging whether the maximum belt-transferring capacity of the power transmission paths can meet the load requirement according to constraint conditions, if the belt-transferring capacity is insufficient, turning to the step 3), and if not, turning to the step 4);
step 3): judging the maximum transfer supply amount which can be satisfied, cutting off the load which can not be supplied, and adjusting the output of the upstream generator;
step 4): constructing a target function based on the load demand of the belt-transferring power transmission path;
step 5): and solving the objective function by using a simplex method to obtain the optimal adjustment quantity of each path, namely obtaining the adjustment power of each generator.
Further, the dc emergency control is to increase the transmission power of the dc line by using the constant power control function of the dc line in parallel with the overload ac line and the overload capability of the dc line, and if the overload line can be eliminated by the dc power emergency support, the adjustment is finished.
Further, the constraint conditions are:
and (3) generator constraint:
in the formula, PGiThe initial power of the generator Gi; delta Pm GiThe amount of power generation adjustment for the generator Gi on the path m is positive when the generated power increases and negative when the generated power decreases, and Δ P if no adjustment is made on the pathm GiA value of 0; m is all paths containing Gi, PGi minAnd PGi maxThe upper limit and the lower limit of the active power of the generator Gi respectively; g is a generator set in the network;
direct current line constraint:
0≤PDC≤1.1PNDC
in the formula, PDCFor DC line power, PNDCRated power for direct current;
and (3) load restraint:
in the formula, PLjIs the initial power of the load Lj; delta Pn LjThe amount of power generation adjustment of the load Lj in the path n is a positive number when the load power increases and a negative number when the load power decreases, and Δ P when no adjustment is made in the pathn LjA value of 0; n is all paths containing Lj. PLj minAnd PLj maxThe upper limit and the lower limit of the active power of the load Lj respectively; l is the load set in the network;
AC line restraint:
in the formula, PTkIs the initial power of line Tk; delta Pq TkThe amount of power generation adjustment of the line Tk on the path q is positive when the load power rises and negative when the load power falls, and Δ P when no adjustment is made on the pathq TkA value of 0; q is all paths containing Tk. PTk minAnd PTk maxRespectively the upper and lower limits of the active power of path Tk.
Further, an equal proportion cutting method is adopted to cut off the load which cannot be supplied.
Further, the objective function is:
in the formula,. DELTA.PxThe amount of power adjustment for path x; t isparThe overload line of a section is influenced by the path adjustment quantity, and w is the overload line of a certain section; t isresSolving the rest lines in the network, v is a certain rest line in the network, alpha is a section margin coefficient, beta is a rest line margin coefficient, alpha is more than or equal to beta is more than or equal to 0, and calculating the optimal adjustment quantity delta P of each path by utilizing a simplex methodxAnd x is 1,2 and 3 …, and the regulated power of each generator is obtained and regulated correspondingly.
Due to the adoption of the technical scheme, the invention has the following advantages: based on a power flow tracking algorithm, a whole-network power transmission path is stripped, and the line power composition is visualized; when overload occurs, firstly, emergency control of direct current power is carried out, then load transfer is carried out, and available power analysis is carried out on the downstream load of an overload circuit by using a feasible generator and a feasible path in a system; in the control process, on the premise of ensuring the reliable reduction of section tidal current, an objective function considering the overall safety of the section and the network is constructed, an optimal regulation and control scheme is obtained by adopting a simplex method, and the safety margin of the power transmission section of the alternating current-direct current series-parallel power grid is improved.
Drawings
FIG. 1 is a flow chart of an overload control method for a power transmission section of an AC/DC hybrid power grid based on path stripping, disclosed by the invention;
FIG. 2 is a schematic diagram of a topology of an east grid according to an embodiment of the invention;
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 obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
As shown in fig. 1, the method for controlling overload of the transmission section of the alternating current/direct current hybrid power grid based on path stripping provided by the invention comprises the following steps:
step 1: monitoring the power transmission section tide of an alternating current-direct current hybrid power grid, if a line overload condition occurs, firstly, utilizing emergency control of direct current power to promote the direct current power to carry out power support to provide the maximum transfer capacity for an overload line, and confirming whether the overload line can be eliminated (namely, the overload circuit can be eliminated if the maximum carrying capacity of the line is smaller than the maximum carrying capacity of the line). If the belt transfer capability is insufficient (the belt transfer capability is the belt transfer capability of direct current to alternating current circuit, namely the direct current bears the tide of an overload alternating current line, the belt transfer capability can be understood as the tide transfer from the overload circuit to the direct current), stripping is carried out on a power transmission path of the power system based on the existing tide tracking algorithm, and the conditions of an upstream generator and a downstream load of the overload circuit are obtained. And judging the minimum load quantity required to be transferred or cut off when the line returns to the safe operation state through the line overload capacity (the generator with the rotary standby power can be fully started during actual operation, and if the overload line is still overloaded, the load is cut off at this time, so that the minimum load cutting quantity is ensured).
Step 2: other power transmission paths are sought for powering downstream loads. According to the constraint condition, whether the maximum belt-rotating capacity of the path can meet the load requirement is judged, namely: if most of the generator sets in the power grid are in a full-load state and the rotary standby is few, the generator rotary standby cannot be used for adjustment, an overload circuit is eliminated, and if the belt rotating capacity is considered to be insufficient, the step 3 is carried out, otherwise, the step 4 is carried out; the constraint conditions of the invention are respectively as follows:
(1) and (3) generator constraint:
in the formula, PGiThe initial power of the generator Gi; delta Pm GiThe amount of power generation adjustment for the generator Gi on the path m is positive when the generated power increases and negative when the generated power decreases, and Δ P if no adjustment is made on the pathm GiA value of 0; m is all the bagsPaths containing Gi, PGi minAnd PGi maxThe upper limit and the lower limit of the active power of the generator Gi respectively; g is a generator set in the network;
(2) direct current line constraint:
0≤PDC≤1.1PNDC (2)
in the formula, PDCFor DC line power, PNDCRated power for direct current;
(3) and (3) load restraint:
in the formula, PLjIs the initial power of the load Lj; delta Pn LjThe amount of power generation adjustment of the load Lj in the path n is a positive number when the load power increases and a negative number when the load power decreases, and Δ P when no adjustment is made in the pathn LjA value of 0; n is all paths containing Lj. PLj minAnd PLj maxThe upper limit and the lower limit of the active power of the load Lj respectively; l is the load set in the network;
(4) AC line restraint:
in the formula, PTkIs the initial power of line Tk; delta Pq TkThe amount of power generation adjustment of the line Tk on the path q is positive when the load power rises and negative when the load power falls, and Δ P when no adjustment is made on the pathq TkA value of 0; q is all paths containing Tk. PTk minAnd PTk maxRespectively the upper and lower limits of the active power of path Tk.
And step 3: and judging the maximum transfer supply which can be satisfied (the capacity of the rotary backup of the generator is the transfer supply), and adjusting the path (full generation of all generator sets) according to the maximum load transfer scheme. Meanwhile, the load which can not be supplied is cut off, and the output of the upstream generator is adjusted according to the power supply proportion of the power supply to the load (the output of the upstream unit is reduced). In the prior art, a cutting machine and a load cutting method are explained in detail, and the invention adopts an equal proportion cutting method, so that the specific process is not described any more.
And 4, step 4: the belt-rotating power transmission path can meet the load requirement, and even under the condition of remaining margin, path adjustment planning is carried out. Suppose that the power variation of each path is Δ PxAnd x is 1,2,3 …, and the path adjustment objective function is obtained according to equation (8).
The objective function is:
in the formula,. DELTA.PxThe amount of power adjustment for path x; t isparThe overload line of a section is influenced by the path adjustment quantity, and w is the overload line of a certain section; t isresSolving the rest lines in the network, v is a certain rest line in the network, alpha is a section margin coefficient, beta is a rest line margin coefficient, alpha is more than or equal to beta is more than or equal to 0, and calculating the optimal adjustment quantity delta P of each path by utilizing a simplex methodxAnd x is 1,2 and 3 …, and the regulated power of each generator is obtained and regulated correspondingly.
And 5: solving the objective function by using the existing simplex method, calculating the optimal adjustment quantity of each path, obtaining the adjustment power of each generator, and performing corresponding adjustment.
Step 6: and after the adjustment is finished, returning to the tide monitoring link again, and continuing to monitor and ensure the safe and stable operation of the power system.
The method for controlling overload of the transmission section of the alternating current-direct current hybrid power grid based on path stripping is described in detail through specific embodiments.
As shown in fig. 2, in this embodiment, a grid geographical connection diagram of a certain eastern region is adopted, a total number of 15 nodes of the grid geographical connection diagram are obtained by analyzing a bus, and lines L4, L5 and L6 form a power transmission section of a generator G1 to a load area. When a certain tie line is overhauled, the line L5 is accidentally broken, the power of the line L6 on the same section is increased and crossed, and the stability of the system is influenced, at the moment, the overload line can be eliminated and the stability of the system can be maintained by adopting the overload control method of the power transmission section of the alternating current-direct current hybrid power grid based on path stripping, and the specific control process is as follows:
step 1: in the case of a line overload on the line L6, first, dc emergency support boost by 130MW is performed (the dc emergency power boost can be realized by a corresponding control strategy, and the implementation object of this embodiment is the dc of the line L4, which is adjusted according to the maximum capacity of the dc), if it is found that the overload line cannot be eliminated. Then, the transmission line is stripped based on a power flow tracking algorithm (each transmission path is stripped from the generator to the load according to the principle of stripping in the embodiment), and the conditions of the generator at the upstream and the load at the downstream of the overload line are analyzed. Through the line overload capacity, the minimum load quantity (the line is overloaded and is switched off again after the full power generation of the generator, and the load quantity is less than that of the direct load switching) required to be transferred or switched off when the line returns to the safe operation state is judged, the active power and the maximum bearable power on each line are shown in table 1 at this time, and the power transmission path stripping result is shown in table 2:
TABLE 1 line active power and maximum bearable power
TABLE 2 Path peeling results
Step 2: the upstream generator of the overload path is G1, and the downstream loads are P1, P2, P3, and P4. Line L6 should also be reduced by 100MW if the power is restored to within the line capability. And searching other power transmission paths for supplying power to the downstream load, and judging whether the maximum belt transferring capacity of the paths can meet the load requirement or not according to the constraint condition.
And step 3: and judging the maximum transfer supply which can be satisfied, and adjusting the path according to the maximum load transfer scheme.
Assuming that the generators G1, G3, G4 and G5 in the network are all fully loaded, the active power generation amounts are 1016MW, 242.2MW, 250MW and 480MW respectively. Generator G2 generates 350MW active, reserving a 60MW quick start power margin. The load transfer capability of the remaining paths can be derived directly from the constraints, i.e. G2 can provide more than 60MW of active power to P3 via the transmission paths 22, 23. This carousel capability does not meet the cross-section overload line L6 power reduction requirements. At this time, path adjustment is directly carried out according to the maximum rotating belt scheme (load cutting is carried out after rotary standby is put in), and meanwhile, a load cutting machine cutting plan is executed. In this embodiment, downstream loads are directly cut off in equal proportion, the total cut load is 40MW, and the cut load amounts of the loads P1, P2, P3 and P4 are 12.3MW, 5.6MW, 8.4MW and 13.6MW, respectively, after the control flow is finished, the overload disappears, and the power values of the lines after cutting are shown in table 3:
TABLE 3 line active Power
And 4, step 4: and aiming at the condition of optimizing and adjusting the load transfer path.
Assuming that only generators G4, G5 are fully loaded in the network, the active power production is 250MW and 480MW, respectively. The generator G2 has an active power output of 350MW, and a quick start power margin of 200MW is reserved. The generator G3 has an active power output of 155MW, and a quick start power margin of 160MW is reserved. The load transfer capacity can meet the power reduction requirement of the overload line of the section according to the path constraint condition. The power adjustment amounts for the respective paths are Δ Pi, i is 1,2,3 … 23, i is a path number, Δ P1, Δ P2, Δ P5, Δ P6, Δ P11, Δ P12, and Δ P14 are down-adjustment amounts, and the rest are up-adjustment amounts. Considering the safety performance of the section, let α be 1.5 and β be 1, construct an objective function, and then arrange:
max.G＝0.017236(ΔP1+ΔP2)+0.016285(ΔP5+ΔP6)
+0.015887(ΔP11+ΔP12)+0.002609ΔP14
-0.007274(ΔP15+ΔP16)-0.012183ΔP17
-0.010305ΔP18-0.003125ΔP20-0.002174ΔP21
-0.002915(ΔP22+ΔP23)-0.0011249(ΔP24+ΔP25)
-0.009354(ΔP26+ΔP27)+3.4355 (9)
s.t.-72.4≤ΔP1+ΔP5-ΔP15-ΔP16-ΔP24-ΔP26≤168.6 (10)
-72.4≤ΔP2+ΔP6-ΔP17-ΔP18-ΔP11-ΔP25-ΔP27≤168.6 (11)
-40.6≤ΔP1+ΔP2+ΔP5≤135 (12)
100≤ΔP1+ΔP2+ΔP5+ΔP6+ΔP11+ΔP12+ΔP14≤575 (13)
-57.8≤ΔP9+ΔP10+ΔP11+ΔP12≤193 (14)
-96≤ΔP1+ΔP2-ΔP15-ΔP16-ΔP17-ΔP18-ΔP20≤320 (15)
-138≤ΔP5+ΔP6-ΔP21-ΔP24-ΔP25-ΔP26-ΔP27≤460 (16)
-103≤ΔP9+ΔP11-ΔP22≤343 (17)
-103≤ΔP10+ΔP12-ΔP23≤343 (18)
-61≤-ΔP15-ΔP17-ΔP24-ΔP25≤203 (19)
ΔP19＝0 (20)
ΔP20+ΔP21＝0 (21)
ΔP22+ΔP23≤200 (22)
ΔP15+ΔP16+ΔP17+ΔP18≤160 (23)
-ΔP1-ΔP2-ΔP3-ΔP4+ΔP15+ΔP16+ΔP19+ΔP20＝0 (24)
-ΔP5-ΔP6-ΔP7-ΔP8+ΔP17+ΔP18+ΔP21＝0 (25)
-ΔP9-ΔP10-ΔP11-ΔP12+ΔP22+ΔP23＝0 (26)
ΔP13＝0 (27)
ΔP14＝0 (28)
in the formula, each Δ P is an adjustment amount of the line active power.
In the above constraint conditions, equations (10) to (19) are path constraints, equations (20) to (23) are active constraints of each generator, and equations (24) to (28) are load constraints;
and 5: the linear programming problem is solved by a simplex method.
Wherein, 4 paths need to be power-adjusted, and the calculation result is as follows: Δ P11 ═ Δ P12 ═ Δ P22 ═ Δ P23 ═ 87.75. The amount of power adjustment is: the power of the generator G1 is reduced by 175.5MW, and the power of the generator G2 is increased by 175.5 MW. After the adjustment is finished, the line power variation in the network is as follows:
TABLE 4 line active power variation
Step 6: after adjustment, the power of the overload line is obviously reduced, and the active power of the line is restored to 501.4MW, which is lower than the maximum power that the line can bear. The lines with large power variation are L4, L7 and L8. Analysis shows that the power supply ends of the circuits are single, namely, the generator G1 supplies power to the load area. When the section coefficient is higher than the non-section coefficient, the section power flow is obviously reduced, and the circuit in the downstream area of the section is also obviously influenced. The result of the adjusted margin objective function calculation is 5.7121, and the power required by the load region is changed from that provided by the generator G1 to that provided by the generator G2. After the adjustment, the control system returns to the tide monitoring link again to continue monitoring and ensure the safe and stable operation of the system.
Appropriate changes and modifications to the embodiments described above will become apparent to those skilled in the art from the disclosure and teachings of the foregoing description. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and variations of the present invention should fall within the scope of the claims of the present invention. Furthermore, although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.
Claims (4)
1. A method for controlling overload of a power transmission section of an alternating current-direct current hybrid power grid based on path stripping is characterized by comprising the following steps:
step 1): monitoring the power transmission section tide of an alternating-current and direct-current series-parallel power grid, if the line is overloaded, carrying out direct-current emergency control to provide the maximum belt transfer capacity for the overloaded line, if the belt transfer capacity is insufficient, stripping a power transmission path by adopting a tide tracking algorithm to obtain an upstream generator and a downstream load of the overloaded line, and judging the minimum load to be transferred or cut when the line returns to a safe operation state;
step 2): searching other power transmission paths for supplying power to the downstream load, judging whether the maximum belt-transferring capacity of the power transmission path can meet the load requirement according to a constraint condition, if the belt-transferring capacity is insufficient, turning to the step 3), otherwise, turning to the step 4), wherein the constraint condition is as follows:
and (3) generator constraint:
in the formula, PGiThe initial power of the generator Gi; delta Pm GiThe amount of power generation adjustment for the generator Gi on the path m is positive when the generated power increases and negative when the generated power decreases, and Δ P if no adjustment is made on the pathm GiA value of 0; m is all paths containing Gi, PGi minAnd PGi maxThe upper limit and the lower limit of the active power of the generator Gi respectively; g is a generator set in the network;
direct current line constraint:
0≤PDC≤1.1PNDC
in the formula, PDCFor DC line power, PNDCRated power for direct current;
and (3) load restraint:
in the formula, PLjIs the initial power of the load Lj; delta Pn LjThe amount of power generation adjustment of the load Lj in the path n is a positive number when the load power increases and a negative number when the load power decreases, and Δ P when no adjustment is made in the pathn LjA value of 0; n is all paths containing Lj; pLj minAnd PLj maxThe upper limit and the lower limit of the active power of the load Lj respectively; l is the load set in the network;
AC line restraint:
in the formula, PTkIs the initial power of line Tk; delta Pq TkAdjusting the amount of power generation in path q for line Tk as load workWhen the rate increases, the adjustment amount is positive and decreases to negative, and if no adjustment is made in the path, Δ Pq TkA value of 0; q is all paths containing Tk; pTk minAnd PTk maxThe upper and lower limits of the active power of the path Tk respectively;
step 3): judging the maximum transfer supply amount which can be satisfied, cutting off the load which can not be supplied, and adjusting the output of the upstream generator;
step 4): constructing a target function based on the load demand of the belt-transferring power transmission path;
step 5): and solving the objective function by using a simplex method to obtain the optimal adjustment quantity of each path, namely obtaining the adjustment power of each generator.
2. The method for controlling overload of the transmission section of the alternating current-direct current hybrid power grid based on path stripping as claimed in claim 1, wherein the direct current emergency control is to utilize the constant power control function of the direct current line parallel to the overload alternating current line and the overload capacity of the direct current line to increase the transmission power of the direct current line, and if the overload line can be eliminated by the direct current emergency support, the adjustment is finished.
3. The method for controlling the overload of the transmission section of the alternating current-direct current hybrid power grid based on the path stripping as claimed in claim 1 or 2, wherein an equal proportion cutting method is adopted for cutting off the loads which cannot be supplied.
4. The method for controlling overload of the transmission section of the alternating current-direct current hybrid power grid based on path stripping as claimed in claim 1 or 2, wherein the objective function is as follows:
in the formula,. DELTA.PxThe amount of power adjustment for path x; t isparFor section-overload lines affected by path adjustments, TwFor an overload line of a certain section, TresIs a netAnd solving the rest lines in the network, wherein Tv is a certain rest line in the network, alpha is a section margin coefficient, beta is a rest line margin coefficient, alpha is more than or equal to beta is more than or equal to 0, and the optimal adjustment quantity delta P of each path is calculated by utilizing a simplex method to solve in matlabxAnd x is 1,2 and 3 …, and the regulated power of each generator is obtained and regulated correspondingly.
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