CN109038594B - Method and system for analyzing load shedding fixed value of stability control device - Google Patents
Method and system for analyzing load shedding fixed value of stability control device Download PDFInfo
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- H02J3/00—Circuit arrangements for ac mains or ac distribution 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
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Abstract
The invention discloses a method and a system for analyzing a load shedding fixed value of a stability control device, wherein the method comprises the following steps: selecting a key station of load shedding error prevention criteria, and determining an operation mode and a fault type of the key station to be researched; determining the number of load sections, giving the upper limit and the lower limit of each load section, and calculating the minimum load cut required for keeping stability after the selected faults occur in different downlink power; solving the base value and the excision coefficient to give a primary setting scheme, then comprehensively considering the whole setting scheme, and carrying out optimization adjustment on the base value and the excision coefficient to obtain a final setting scheme; when the power grid fails, the system can act correctly and cut off the load as little as possible, and a new fixed value meeting the requirement can be conveniently given after the state is changed.
Description
Technical Field
The invention relates to the field of power system relay protection, in particular to a method and a system for analyzing a load shedding fixed value of a stability control device.
Background
With the interconnection of power grids, the scale of power systems is increasing, and the possible stability problem is also increasing. In actual operation of a power system, an N-2 fault may occur, wherein a part of faults can cause serious consequences, a stability control technology needs to be applied to ensure the stability of the system, and the core of the stability control technology is a stability control device.
The stability control device can act to cut off loads or units under abnormal conditions, ensures the stability of the system and has the advantages of strong pertinence and high reliability. However, the exertion of the function depends on reasonable constant value setting, but at present, a systematic load shedding constant value setting method is not available, the constant value determination mainly depends on experience, no uniform standard exists, and a large amount of work needs to be carried out again after the system state is changed to obtain a new constant value.
Disclosure of Invention
The technical problem to be solved by the embodiment of the invention is to provide a method and a system for analyzing the load shedding fixed value of a stability control device, when a fault occurs, the system applying the method can correctly act and shed the load as little as possible, and a new fixed value meeting the requirement can be conveniently provided after the system state is changed.
The technical problem to be solved by the invention is realized by the following technical scheme:
a method for analyzing a load shedding fixed value of a stability control device comprises the following steps:
selecting a typical operation mode of a power grid, simulating an expected fault, analyzing a low-voltage problem highlighted site, selecting a key site of a load shedding anti-error criterion, determining an operation mode and a fault type of the key site to be researched, and then determining upper and lower limit powers of a load section of the selected key site;
on the basis of an operation mode to be researched, the descending power of the key station is gradually reduced until the system is stable after a selected fault, the number of load sections is determined on the basis of the descending power of the key station, the upper limit power and the lower limit power of each load section are given, and the minimum load cut required for keeping the stability after the selected fault occurs under each descending power is calculated by using simulation software;
according to the load shedding quantity value required by the fault when the lower power is at the upper limit power and the lower limit power of each load section, the base value and the shedding coefficient are solved, a primary setting scheme is given, then the whole setting scheme is comprehensively considered, and the base value and the shedding coefficient are optimized and adjusted to obtain a final setting scheme.
Preferably, the voltage at the time of the selected fault is checked by the key station is lower than 0.75p.u. for a time not exceeding 1s during the transient state, and the recovery voltage should be above 0.90p.u., wherein p.u. actual voltage value/reference voltage value.
Preferably, the preliminary calculation of the resection coefficient k0, k0 is (Lmax-Lmin)/(Pmax-Pmin), where Pmax is the upper power limit of the load segment of the critical station, Lmax is the minimum load shedding amount corresponding to Pmax, Pmin is the lower power limit of the load segment, and Lmin is the minimum load shedding amount corresponding to Pmin; optimizing the ablation coefficient k, k ═ min (max (k0,0.8), 1.2); the base value of the Pbase is calculated,
indicating a rounding down.
Preferably, the optimized ablation coefficient is adjusted, kp ═ sum (ki)/n, where kp is the average ablation coefficient, ki is the optimized ablation coefficient for each load segment, n is the number of load segments, and kp is adjusted to one of 0.8 to 1.2 according to the closest principle, with an interval of 0.1; adjusting the basic value, if k0> kp, then
Otherwise
A system for analyzing a load shedding constant value of a stability control device comprises:
the selection module is used for analyzing the low-voltage problem highlighted sites, selecting key sites of load shedding anti-error criteria, determining the operation mode and the fault type of the key sites to be researched, and then determining the upper limit power and the lower limit power of the load section of the selected key sites;
the load processing module is used for determining the number of the load sections, giving the upper limit power and the lower limit power of each load section, and calculating the minimum load to be cut for keeping stable after different sending powers have selected faults;
and the analysis and calculation module is used for solving the base value and the cutting coefficient according to the relation between the upper limit power and the lower limit power of the load section and the corresponding minimum load needing to be cut, giving a primary setting scheme, and optimizing and adjusting the base value and the cutting coefficient according to the whole setting scheme to obtain a final setting scheme.
The implementation scheme has the following beneficial effects: the method comprises the steps of analyzing low-voltage problem salient sites, selecting key sites, determining the operation mode and fault type of the key sites to be researched, and then determining the upper limit power and the lower limit power of load sections, the number of the load sections and the required minimum load shedding amount corresponding to different powers of the selected key sites; and finally, primarily calculating a cutting coefficient and a base value according to the relationship between the upper limit power and the lower limit power of the load section and the corresponding minimum load quantity to be cut, comprehensively considering the whole setting scheme, and optimally adjusting the base value and the cutting coefficient to obtain a final setting scheme. When a fault occurs, the system applying the method can correctly act and cut off the load as little as possible, and a new fixed value meeting the requirement can be conveniently given after the system state is changed.
Drawings
FIG. 1 is a schematic flow chart of an embodiment of a method for analyzing a load shedding fixed value of a stability and control device according to the present invention;
FIG. 2 is a system voltage response curve under a no-load-shedding strategy when the power delivered by a key station is 3300MW in the embodiment;
FIG. 3 is a system voltage response curve under the no load shedding strategy when the power sent by the key station is 3100MW in the embodiment;
FIG. 4 is a system voltage response curve under the no load shedding strategy when the key station sends power down at 2900MW in the embodiment;
FIG. 5 is a system voltage response curve under the no-load-shedding strategy when the power sent by the key station is 2700MW in the embodiment;
FIG. 6 is a system voltage response curve under a load shedding strategy when the power delivered by a key station is 3300MW in the embodiment;
FIG. 7 is a system voltage response curve under the load shedding strategy when the power sent by the key station is 3100MW in the embodiment;
FIG. 8 is a system voltage response curve under the load shedding strategy when the key station sends power down at 2900MW in the embodiment;
fig. 9 is a schematic diagram of a setting result of an embodiment provided by the method for analyzing the load shedding fixed value of the stability and control device of the present invention.
Detailed Description
The following describes in detail a specific embodiment of the present embodiment with reference to the drawings.
In the following description, first, an example of a method for analyzing a steady-state device load shedding fixed value will be described, and then an example of a system for analyzing a steady-state device load shedding fixed value will be described.
Fig. 1 is a schematic flow chart of an embodiment of the method for analyzing the load shedding fixed value of the stability and control device according to the present invention.
As shown in fig. 1, the method for analyzing the load shedding fixed value of the stability and control device in this embodiment includes the following steps:
step S100: selecting a typical operation mode of a power grid, simulating an expected fault, analyzing a prominent station aiming at a low voltage problem, selecting a key station of a load shedding error-preventing criterion, and determining an operation mode and a fault type of the key station to be researched, wherein the specific implementation is as follows.
Step S101: analyzing main alternating current and direct current transmission lines of the system according to each typical operation mode and a tidal current diagram of the power grid;
step S102: setting faults of different types and different regions aiming at the line, carrying out N-2 time domain simulation on the faults, observing voltage disturbance response curves of all substations, selecting an important substation which truly reflects the transient stability characteristic of the system near the main alternating current and direct current transmission section of the power grid, and taking the voltage of the substation as a load shedding error prevention criterion;
step S103: and comparing the load shedding amount of different operation modes facing different faults, and determining the operation mode and the fault type to be researched.
Through tests, transient low-voltage instability problems exist when a Bo N-2 fault, a flower N-2 fault, a tree N-2 fault and a tree qi N-2 fault occur in the southern power grid operating mode of North Guangdong and summer, the low-voltage problem of a certain key station of 220kV is prominent, and the relation between the lower power transmission and the load shedding amount is close, so that the key station is selected as a load shedding error prevention criterion station. Compared with the traditional mode, the load cutting amount is the most when the failure occurs in the BoN-2 mode in North Guangdong, so the operation mode and the failure type which need to be researched are the BoN-2 failure and the BoN-2 failure in North Guangdong respectively.
Step S200: on the basis of an operation mode needing to be researched, the sending power of the key station is gradually reduced until the system is stable after a selected fault, the number of load sections is determined on the basis of the sending power of the key station, the upper limit and the lower limit of each load section are given, simulation software is used for calculating the minimum load cut required for keeping the stability after the selected fault occurs under each sending power, and the method is specifically implemented as follows.
Step S201: determining the maximum sending power of the key station of the current system based on the operation mode to be researched, taking the maximum sending power or the maximum sending power plus a certain margin as the upper limit of the power of a load section, and checking the minimum load to be cut when a selected fault occurs;
step S202: gradually reducing the sending power of the key station until the system can keep stable without load shedding under the selected fault, and taking the sending power without load shedding or reducing the power by a certain amount as the lower limit of the power of the load section;
step S203: selecting a proper number of load segments based on the determined upper and lower limits of the load segments;
step S204: and (3) calculating the minimum load cut-off quantity required for keeping stability after the selected fault occurs under each downlink power by using simulation software.
The maximum downward power of the kapok station in the big-sending mode in North Guangdong is 3300MW, so that the downward power is gradually reduced from 3300MW until the system can be stable even from Bon-2 fault when no load shedding strategy is carried out, and the downward power at the moment is taken as the lower limit of the load section. Fig. 2, fig. 3, fig. 4 and fig. 5 show simulated voltage curves of the critical site after bon-2 failure in the case of 3300MW, 3100MW, 2900MW and 2700MW of the above-mentioned critical site down power under the no-load-shedding strategy, respectively. After the fault is cleared for 1.0s in fig. 2, the voltage is 0.62p.u., and is lower than 0.75p.u., and the system is unstable; after the fault is cleared for 1.0s in fig. 3, the voltage is 0.68p.u., and is lower than 0.75p.u., and the system is unstable; after the fault is cleared for 1.0s in fig. 4, the voltage is 0.73p.u., and is lower than 0.75p.u., and the system is unstable; after the fault is cleared for 1.0s in fig. 5, the system is stable with a voltage of 0.84p.u., higher than 0.75p.u., and a recovery voltage of higher than 0.90 p.u.. Comparing the power with a stability criterion, the system is unstable when the N-2 fault occurs when the sending power of the key station is 3300MW, 3100MW and 2900MW, and the system is stable after the Bo N-2 fault occurs when the key station is sent at 2700 MW. Therefore, the lower limit of the load section should be set to 2700MW, the maximum power of the system is 3300MW at present, and considering the possibility of future growth, the upper limit is set to 3500MW, and the difference between the upper limit and the lower limit of each section is 200 MW.
Simulation software is used for calculating the load cut required for the fault of Bo N-2 when different sending powers occur, and the arrangement result is shown in a table 1. The effect of the system after load shedding is shown in fig. 6, 7 and 8.
Table 1 key sites simulate different load shedding amounts required for power delivery from bon N-2 fault occurrence:
| down power | Stable situation | Load shedding amount |
| 3500MW | Transient low voltage problem | Load of 900MW to be cut |
| 3300MW | Transient low voltage problem | Load to be cut 770MW |
| 3100MW | Transient low voltage problem | Load to be cut is 510MW |
| 2900MW | Transient low voltage problem | Load to be cut is 230MW |
| 2700MW | Transient low voltage problem | Without load shedding |
After the fault is cleared for 1.0s in fig. 6, the voltage is 0.83p.u., higher than 0.75p.u., and the recovery voltage is higher than 0.90p.u., indicating that the system is stable; fig. 7 illustrates that after the fault is cleared for 1.0s, the voltage is 0.83p.u., higher than 0.75p.u., and the recovery voltage is higher than 0.90p.u., indicating that the system is stable; fig. 8 illustrates that after the fault is cleared for 1.0s, the voltage is 0.81p.u., higher than 0.75p.u., and the recovery voltage is higher than 0.90p.u., indicating that the system is stable.
Step S300: according to the load shedding quantity value required by the fault when the lower power is at the upper limit and the lower limit of each load section, solving the base value and the cutting coefficient, giving a primary setting scheme, then comprehensively considering the whole setting scheme, and carrying out optimization adjustment on the base value and the cutting coefficient to obtain a final setting scheme, which is concretely as follows.
Step S301: the resection coefficient k0 is preliminarily calculated, k0 is (Lmax-Lmin)/(Pmax-Pmin),
wherein, the power upper limit of the load section of the key station is represented by Lmax which is the minimum load shedding amount corresponding to Pmax, Pmin which is the power lower limit of the load section is represented by Pmin;
optimizing the ablation coefficient k, k ═ min (max (k0,0.8), 1.2);
the base value of the Pbase is calculated,
step S302: adjusting the optimized ablation coefficient, judging whether the ablation coefficients k are consistent or not, if so, calculating kp which is sum (ki)/n, wherein kp is the average ablation coefficient, ki is the optimized ablation coefficient of each load section, n is the number of the load sections, kp is adjusted to be one of 0.8 to 1.2 according to the closest principle, and the interval is 0.1;
adjusting the basic value, if k0> kp, then
Otherwise
The specific process of preliminarily solving the base value and the removal coefficient according to the load shedding quantity value required by the fault of the upper limit and the lower limit of each load section of the key station is as follows, and the result is shown in table 2.
2700－2900：k0＝(Lmax－Lmin)/(Pmax－Pmin)＝(230－0)/200＝1.15
k＝min(max(k0，0.8)，1.2)＝1.15
2900－3100：k0＝(Lmax－Lmin)/(Pmax－Pmin)＝(510－230)/200＝1.4
k＝min(max(k0，0.8)，1.2)＝1.2
3100－3300：k0＝(Lmax－Lmin)/(Pmax－Pmin)＝(770－510)/200＝1.3
k＝min(max(k0，0.8)，1.2)＝1.2
3300－3500：k0＝(Lmax－Lmin)/(Pmax－Pmin)＝(900－770)/200＝0.65
k＝min(max(k0，0.8)，1.2)＝0.8
Table 2 base values and ablation coefficients of preliminary calculations for each load segment of the key site:
| load section | Pbase | k0 |
| 2700－2900 | 2700 | 1.15 |
| 2900－3100 | 2708 | 1.2 |
| 3100－3300 | 2675 | 1.2 |
| 3300－3500 | 2337 | 0.8 |
From table 2, it can be seen that the primarily calculated removal coefficients of each load segment of the key station are different, the whole setting scheme is considered integrally, the following optimization and adjustment are performed, the specific steps are shown below, and the results are shown in table 2.
Average ablation coefficient: kp ═ (1.15+1.2+1.2+0.8)/4 ═ 1.1 (after rounding)
2700－2900：
2900－3100：
3100－3300：
3300－3500：
Table 3 base values and removal coefficients of optimization calculation of each load segment of the key site:
| load section | Pbase | k |
| 2700－2900 | 2690 | 1.1 |
| 2900－3100 | 2636 | 1.1 |
| 3100－3300 | 2600 | 1.1 |
| 3300－3500 | 2600 | 1.1 |
And (3) drawing the corresponding curves of the preliminary calculated basic values and the excision coefficients of the load sections of the key sites and the optimized calculated basic values and excision coefficients into a final overall effect diagram, and referring to fig. 9. The black dots in the figure correspond to the minimum load to be cut under a given load, the blue dotted line is a preliminary fixed value setting result, and the red solid line is a final fixed value setting result after optimization. The blue dotted line can ensure that the load shedding amount meets the requirement when the given downward power is sent, but when the actual downward power sending power value is not the given power, the lower power is slightly reduced to 3299MW from 3300MW, the system operation mode is basically unchanged at the moment, the load shedding amount required cannot be obviously reduced, but the load shedding amount of the blue required line is greatly reduced at the moment, the system stability requirement cannot be met, but the final setting scheme represented by the red solid line better solves the problem. In addition, different from a plurality of k0 values existing in the primary setting scheme, the k values of all the sections of the final setting scheme are basically consistent, and the possibility that the k values of all the sections are filled by mistake by a person who sets the final setting scheme and a person who executes the final setting scheme is effectively reduced.
The system for analyzing the load shedding fixed value of the stability control device in the embodiment comprises the following steps:
step S400: the selection module is used for selecting the key station of the load shedding error-preventing criterion and determining the operation mode and the fault type of the key station to be researched, and specifically comprises the following steps:
step S401: the analysis unit is used for analyzing main alternating current and direct current transmission lines of the system according to each typical operation mode and tidal current diagram of the power grid;
step S402: the system comprises a first simulation unit, a second simulation unit and a third simulation unit, wherein the first simulation unit is used for setting faults of different types and different regions aiming at a selected line, carrying out N-2 time domain simulation on the faults, observing voltage disturbance response curves of all transformer substations, selecting an important transformer substation which truly reflects the transient stability characteristic of the system near main alternating current and direct current transmission sections of a power grid, and taking the voltage of the transformer substation as a load shedding error prevention criterion;
step S403: and the comparison unit is used for comparing the load shedding amount of different operation modes facing different faults and determining the operation mode and the fault type to be researched.
Step S500: the load processing module is used for determining the number of the load sections, giving the upper limit and the lower limit of each load section, and calculating the minimum load to be cut required for keeping stable after the selected faults occur to different downlink powers, and specifically comprises the following steps:
step S501: the upper limit power determining unit is used for determining the maximum lower power upper limit of the key station;
step S502: the lower limit power determining unit is used for determining to gradually reduce the downlink power of the key station until the system can keep stable without load shedding under the selected fault, and the downlink power without load shedding or the power reduced by a certain amount is taken as the lower limit of the power of the load section;
step S503: the load section number determining unit is used for determining the appropriate number of load sections according to the upper limit and the lower limit of the selected load sections;
step S504: and the second simulation unit is used for simulating and calculating the minimum load required to be cut for keeping stability after the selected fault occurs under different sending powers.
Step S600: the analysis and calculation module is used for solving the base value and the excision coefficient, giving a primary setting scheme, and optimizing and adjusting the base value and the excision coefficient in consideration of the whole setting scheme to obtain a final setting scheme, and the analysis and calculation module specifically comprises the following components:
step S601: a preliminary scheme determination unit for preliminarily determining the resection coefficient and the base value;
step S602: and the optimization scheme determination unit is used for optimizing the excision coefficient and the base value.
The system for analyzing the fixed value of the load shedding of the stability and control device is in one-to-one correspondence with the method for analyzing the fixed value of the load shedding of the stability and control device, and the technical characteristics and the effects thereof described in the embodiment of the method for analyzing the fixed value of the load shedding of the stability and control device are all applicable to the embodiment of the system for analyzing the fixed value of the load shedding of the stability and control device.
The implementation scheme has the following beneficial effects: the method comprises the steps of analyzing low-voltage problem salient sites, selecting key sites, determining the operation mode and fault type of the key sites to be researched, and then determining the upper limit power and the lower limit power of load sections, the number of the load sections and the required minimum load shedding amount corresponding to different powers of the selected key sites; and finally, primarily calculating a cutting coefficient and a base value according to the relationship between the upper limit power and the lower limit power of the load section and the corresponding minimum load quantity to be cut, comprehensively considering the whole setting scheme, and optimally adjusting the base value and the cutting coefficient to obtain a final setting scheme. When a fault occurs, the system applying the method can correctly act and cut off the load as little as possible, and a new fixed value meeting the requirement can be conveniently given after the system state is changed.
Although the present invention has been described with reference to the preferred embodiments, it is not intended to limit the scope of the invention. It will be appreciated by those skilled in the art that changes may be made without departing from the scope of the invention, and it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.
Claims (10)
1. A method for analyzing a load shedding fixed value of a stability control device is characterized by comprising the following steps:
selecting a typical operation mode of a power grid, simulating an expected fault, analyzing a low-voltage problem highlighted site, selecting a key site of a load shedding anti-error criterion, determining an operation mode and a fault type of the key site to be researched, and then determining upper and lower limit powers of a load section of the selected key site;
on the basis of an operation mode to be researched, the descending power of the key station is gradually reduced until the system is stable after a selected fault, the number of load sections is determined on the basis of the descending power of the key station, the upper limit power and the lower limit power of each load section are given, and the minimum load cut required for keeping the stability after the selected fault occurs under each descending power is calculated by using simulation software;
according to the load shedding quantity value required by the fault when the lower power is at the upper limit power and the lower limit power of each load section, the base value and the shedding coefficient are solved, a primary setting scheme is given, then the whole setting scheme is comprehensively considered, and the base value and the shedding coefficient are optimized and adjusted to obtain a final setting scheme.
2. The method for analyzing the load shedding fixed value of the stability control device according to claim 1, wherein the step of selecting the key station of the load shedding anti-error criterion and determining the operation mode and the fault type of the key station to be researched comprises the following steps:
analyzing main alternating current and direct current transmission lines of the system according to each typical operation mode and a tidal current diagram of the power grid;
setting faults of different types and different regions aiming at the line, carrying out N-2 time domain simulation on the faults, observing voltage disturbance response curves of all substations, selecting an important substation which truly reflects the transient stability characteristic of the system near the main alternating current and direct current transmission section of the power grid, and taking the important substation as a load shedding error-preventing criterion;
and comparing the load shedding amount of different operation modes facing different faults, and determining the operation mode and the fault type to be researched.
3. The method for analyzing the load shedding fixed value of the stability control device according to claim 1, wherein the determining the number of the load segments and providing the upper and lower limit powers of each load segment comprises the following steps:
determining the maximum sending power of the key station of the current system based on the operation mode to be researched, taking the maximum sending power or the maximum sending power plus a certain margin as the upper limit of the power of a load section, and checking the minimum load to be cut when a selected fault occurs;
gradually reducing the sending power of the key station until the system can keep stable without load shedding under the selected fault, and taking the sending power when the load shedding is not needed or reducing the sending power by a certain amount as the lower limit of the power of the load section;
and selecting the proper number of the load sections based on the determined upper and lower limit powers of the load sections.
4. The method for analyzing the load shedding fixed value of the stability control device according to claim 3, wherein the judgment basis for the system to keep stable is as follows: the critical site checks that the voltage at the time of the selected fault is below 0.75p.u. for no more than 1s during the transient, and the recovery voltage should be above 0.90p.u., where p.u. = actual voltage value/reference voltage value.
5. The method for analyzing the fixed value of the cutting load of the stability and control device according to claim 1 or 3, wherein the step of solving the basic value and the cutting coefficient comprises the following steps:
preliminary calculation of the ablation coefficients k0, k0= (Lmax-Lmin)/(Pmax-Pmin),
wherein Pmax is the upper limit of the power of the load section of the key station, Lmax is the minimum load shedding amount corresponding to Pmax, Pmin is the lower limit of the power of the load section, and Lmin is the minimum load shedding amount corresponding to Pmin;
optimizing the ablation coefficient k, k = min (max (k0,0.8), 1.2);
the base value Pbase was calculated, Pbase = ⌊ Pmin-Lmin/k ⌋, ⌊ ⌋ indicating rounding down.
6. The method for analyzing the fixed value of the cutting load of the stability control device according to claim 5, wherein the optimization adjustment comprises the optimized adjustment of the cutting coefficient and the adjustment of the basic value, and the method comprises the following steps:
adjusting the optimized ablation coefficient, wherein kp = sum (ki)/n, wherein kp is the average ablation coefficient, ki is the optimized ablation coefficient of each load section, n is the number of load sections, kp is adjusted to be one of 0.8 to 1.2 according to the closest principle, and the interval is 0.1;
adjusting the basic value, if k0> kp, Pbase = ⌊ Pmax-Lmax/kp ⌋, otherwise Pbase = ⌊ Pmin-Lmin/kp ⌋.
7. A system for analyzing a load shedding fixed value of a stability control device is characterized by comprising:
the selection module is used for analyzing the low-voltage problem highlighted sites, selecting key sites of load shedding anti-error criteria, determining the operation mode and the fault type of the key sites to be researched, and then determining the upper limit power and the lower limit power of the load section of the selected key sites;
the load processing module is used for determining the number of the load sections, giving the upper and lower limit power of each load section, and calculating the minimum load to be cut for keeping stable after the selected faults occur to different downlink powers;
and the analysis and calculation module is used for solving the base value and the cutting coefficient according to the relation between the upper limit power and the lower limit power of the load section and the corresponding minimum load needing to be cut, giving a primary setting scheme, and optimizing and adjusting the base value and the cutting coefficient according to the whole setting scheme to obtain a final setting scheme.
8. The system for analyzing the load shedding fixed value of the stability control device according to claim 7, wherein the selecting module comprises:
the analysis unit is used for analyzing main alternating current and direct current transmission lines of the system according to each typical operation mode and tidal current diagram of the power grid;
the first simulation unit is used for setting faults of different types and different regions aiming at a selected line, carrying out N-2 time domain simulation on the faults, observing voltage disturbance response curves of all substations, selecting an important substation which truly reflects the transient stability characteristic of the system near main alternating current and direct current transmission sections of a power grid, and taking the important substation as a load shedding error prevention criterion;
and the comparison unit is used for comparing the load shedding amount of different operation modes facing different faults and determining the operation mode and the fault type to be researched.
9. The system for analyzing the load shedding constant value of the stability control device according to claim 7, wherein the load processing module comprises:
the upper limit power determining unit is used for determining the maximum lower power upper limit of the key station;
the lower limit power determining unit is used for determining to gradually reduce the downlink power of the key station until the system can keep stable without load shedding under the selected fault, and the downlink power when the load shedding is not needed or the downlink power is reduced by a certain amount to be used as the lower limit of the power of the load section;
the load segment number determining unit is used for determining the appropriate number of load segments according to the upper and lower limit power of the selected load segments;
and the second simulation unit is used for simulating and calculating the minimum load required to be cut for keeping stability after the selected fault occurs under different sending powers.
10. The system for analyzing the load shedding fixed value of the stability control device according to claim 7, wherein the analyzing and calculating module comprises:
a preliminary scheme determination unit for preliminarily determining the resection coefficient and the base value;
and the optimization scheme determination unit is used for optimizing the excision coefficient and the base value.
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