CN112117766A - Safety constraint optimal power flow control method and system for alternating current-direct current hybrid power grid - Google Patents

Safety constraint optimal power flow control method and system for alternating current-direct current hybrid power grid Download PDF

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CN112117766A
CN112117766A CN201910540219.3A CN201910540219A CN112117766A CN 112117766 A CN112117766 A CN 112117766A CN 201910540219 A CN201910540219 A CN 201910540219A CN 112117766 A CN112117766 A CN 112117766A
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generator
power
optimal
load
control stage
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哈坎·埃尔贡
陆晶晶
安婷
德克·范·希姆
杨杰
吴亚楠
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State Grid Corp of China SGCC
Global Energy Interconnection Research Institute
State Grid Liaoning Electric Power Co Ltd
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State Grid Corp of China SGCC
Global Energy Interconnection Research Institute
State Grid Liaoning Electric Power Co Ltd
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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
    • 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
    • H02J3/008—Circuit arrangements for ac mains or ac distribution networks involving trading of energy or energy transmission rights
    • 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
    • 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
    • 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
    • H02J3/50—Controlling the sharing of the out-of-phase component
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • 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]

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Abstract

The invention provides a safety constraint optimal power flow control method and system for an alternating current-direct current hybrid power grid, which comprises the following steps: inputting the operation data of a generator, an alternating current bus and a direct current node in an alternating current-direct current hybrid power grid into a pre-established prevention correction control safety constraint optimal power flow model to obtain the optimal re-dispatching amount of the output of the generator and the optimal re-dispatching amount of the load; and adjusting the output and the load consumption of the generator according to the optimal output rescheduling amount and the optimal load rescheduling amount. Compared with the prior art, the method and the system have the remarkable characteristics that the optimal power flow of the preventive control safety constraint and the optimal power flow of the correction control safety constraint are combined and applied to the alternating-current and direct-current hybrid power grid, and the optimal decision of the alternating-current and direct-current hybrid power grid considering both economy and reliability is realized.

Description

Safety constraint optimal power flow control method and system for alternating current-direct current hybrid power grid
Technical Field
The invention belongs to the technical field of alternating current and direct current transmission systems, and particularly relates to a safety constraint optimal power flow control method and system for an alternating current and direct current series-parallel power grid.
Background
In recent years, High Voltage Direct Current (HVDC) technology is gradually developed, and has been widely applied to modern power grids to realize long-distance transmission of large-capacity electric energy, and an alternating Current/Direct Current power grid which can run safely and stably is gradually formed.
The Security Constrained Optimal Power Flow (SCOPF) is an optimal Power Flow model considering the constraints of the Security operating conditions under the expected accident, and is an important scheduling means for realizing the safe, reliable and operating of the Power system. The existing safety constraint optimal power flow meets the safety operation constraint conditions under all expected faults and normal states only by adjusting operation points, the operation of a scheduling result is simple, and the economy is poor; or the overload tide and the out-of-limit voltage are adjusted to be within a safety range by adopting control measures such as rescheduling of the generator set, load shedding and the like after an accident, the economy is better, but the method allows the line tide to be out-of-limit after the fault, the safety is poorer, and the operation is more difficult. Aiming at the problem of safety constraint optimal power flow of an alternating current and direct current power grid, the prior art can not ensure that the alternating current and direct current power grid always runs safely, stably and economically.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention provides a safety constraint optimal power flow control method and system for an alternating current-direct current hybrid power grid. The method and the system aim to provide a method for preventing, correcting and controlling safety constraint optimal power flow applied to an alternating current and direct current power grid, which is essentially a nonlinear optimization problem containing constraint, and finally solve an optimal solution by means of an intelligent algorithm, and realize that the system always operates at an optimal operating point by adjusting the output of a generator, load reduction and other modes under the conditions that the alternating current and direct current power grid is in a heavy load, weak operating mode and the like.
The adopted solution for realizing the purpose is as follows:
the improvement of a safety constraint optimal power flow control method for an alternating current-direct current hybrid power grid is that the method comprises the following steps:
inputting the operation data of a generator, an alternating current bus and a direct current node in an alternating current-direct current hybrid power grid into a pre-established prevention correction control safety constraint optimal power flow model to obtain the optimal re-dispatching amount of the output of the generator and the optimal re-dispatching amount of the load;
adjusting the output and the load consumption of the generator according to the output optimal rescheduling quantity and the load optimal rescheduling quantity;
the preventive correction control safety constraint optimal power flow model comprises a preventive control stage and a correction control stage.
In a first preferred embodiment, the improvement of the preventive correction control safety constraint optimal power flow model includes:
constructing an objective function by taking the minimum operation risk as a target and considering the minimum power generation cost;
constructing a safety constraint optimal power flow condition for prevention, correction and control;
wherein the safety-constrained optimal power flow condition of the preventive correction control includes: preventing and correcting power balance constraints of direct current and alternating current nodes in a control stage; generator and load power constraints, node voltage constraints, and branch power flow constraints.
The improvement of the second preferred technical scheme provided by the invention is that the alternating current-direct current hybrid power grid comprises:
alternating current branch circuit, direct current branch circuit, converter transformer, wave filter, phase reactor and transverter.
In a third preferred technical solution provided by the present invention, the improvement is that the power constraint of the generator is as follows:
Figure BDA0002102320130000021
Figure BDA0002102320130000022
in the formula, Pg,o corrCorrecting the active power of the g-th generator in the control phase when the expected failure o occurs, Qg,o corrWhen the predicted fault o occurs, correcting the reactive power of the g-th generator in the control stage;
Figure BDA0002102320130000023
representing the active power of the g-th generator after the preventive control phase is completed,
Figure BDA0002102320130000024
the reactive power of the g-th generator after the prevention control stage is finished is shown;
Figure BDA0002102320130000025
indicating that the predicted fault o occurs, correcting the active power readjustment quantity of the generator in the g-th stage of control,
Figure BDA0002102320130000026
when the predicted fault o occurs, correcting the reactive power readjustment amount of the generator at the g-th stage in the control stage;
Figure BDA0002102320130000027
and
Figure BDA0002102320130000028
the constraints are respectively shown as follows:
Figure BDA0002102320130000029
Figure BDA00021023201300000210
in the formula (I), the compound is shown in the specification,
Figure BDA00021023201300000211
represents the minimum value of the active power of the g-th generator in the prevention and correction control stage,
Figure BDA00021023201300000212
representing the maximum value of the active power of the g-th generator in the prevention and correction control stage;
Figure BDA00021023201300000213
represents the reactive power minimum value of the g-th generator in the prevention and correction control stage,
Figure BDA00021023201300000214
the maximum value of the reactive power of the g-th generator in the prevention and correction control stage is shown.
In a fourth preferred embodiment of the present invention, the improvement is that the load power constraint is as follows:
Figure BDA0002102320130000031
Figure BDA0002102320130000032
Figure BDA0002102320130000033
Figure BDA0002102320130000034
Figure BDA0002102320130000035
Figure BDA0002102320130000036
Figure BDA0002102320130000037
in the formula (I), the compound is shown in the specification,
Figure BDA0002102320130000038
representing the active power of the mth load of the preventive control phase,
Figure BDA0002102320130000039
representing the reactive power of the mth load in the preventive control phase;
Figure BDA00021023201300000310
an initial reference value representing the active power of the mth load,
Figure BDA00021023201300000311
an initial reference value representing the mth load reactive power;
Figure BDA00021023201300000312
indicating that the m-th load has active power in the control phase corrected in anticipation of the occurrence of the fault o,
Figure BDA00021023201300000313
when the predicted fault o occurs, the reactive power of the mth load in the control stage is corrected;
Figure BDA00021023201300000314
indicating that the fault o is expected, the amount of active power re-modulation of the mth load of the control stage is corrected,
Figure BDA00021023201300000315
when the predicted fault o occurs, correcting the reactive power readjustment amount of the mth load in the control stage;
Figure BDA00021023201300000316
and
Figure BDA00021023201300000317
the constraints are respectively shown as follows:
Figure BDA00021023201300000318
Figure BDA00021023201300000319
Figure BDA00021023201300000320
indicating the minimum value of the active power of the mth load in case of the expected occurrence of the fault o,
Figure BDA00021023201300000321
this indicates the minimum reactive power value of the mth load when the occurrence of the fault o is expected.
The fifth preferred technical solution provided by the present invention is improved in that the method for obtaining the generator output optimal rescheduling amount and the load optimal rescheduling amount includes the steps of inputting the operation data of the generator, the ac bus and the dc node in the ac/dc hybrid power grid into a pre-established preventive correction control safety constraint optimal power flow model, and obtaining the generator output optimal rescheduling amount and the load optimal rescheduling amount, wherein the method includes:
inputting the operation data of a generator, an alternating current bus and a direct current node in an alternating current-direct current hybrid power grid into a pre-established preventive correction control safety constraint optimal power flow model;
solving the preventive correction control safety constraint optimal power flow model by using a Matlab optimal power flow calculation program to obtain an optimal generator output rescheduling amount and an optimal load rescheduling amount;
wherein the operational data of the generator comprises: active and reactive power of the generator; the operation data of the alternating current bus comprises the voltage and the phase angle of the alternating current bus; the operational data of the DC node includes a voltage of the DC node.
The improvement of the sixth preferred technical solution provided by the present invention is that, the adjusting the output and the load consumption of the generator according to the optimal output rescheduling amount and the optimal load rescheduling amount includes:
in the prevention control stage, adjusting the active power and the reactive power of the generator according to the re-adjustment amount of the active power and the reactive power of the generator in the prevention control stage;
in the correction control stage, the active power and the reactive power of the generator are adjusted according to the active power and reactive power readjustment amount of the generator in the correction control stage, and the active power and reactive power consumed by the load are adjusted according to the load active power and reactive power readjustment amount in the correction control stage;
wherein the best output rescheduling amount comprises: preventing the generator active power and reactive power re-dispatching quantity in the control stage and correcting the generator active power and reactive power re-dispatching quantity in the control stage; the load optimal rescheduling amount comprises load active and reactive power rescheduling amounts in a correction control stage.
In a seventh preferred embodiment, the improvement is that the objective function is represented by the following formula:
Figure BDA0002102320130000041
in the formula, F represents an objective function, a superscript prev represents a prevention control stage, a superscript corr represents a correction control stage, a subscript g represents a g-th generator, and a subscript n represents an n-th generator for load shedding;
Figure BDA0002102320130000042
representing the total rescheduling cost sum of G generators in the prevention control stage;
Figure BDA0002102320130000043
representing a rescheduling cost coefficient of the g-th generator in a prevention control stage;
Figure BDA0002102320130000044
set value P representing the output of the g-th generator in the preventive control stageg prevRelative to an initial reference value Pg refThe deviation of (a) is determined,
Figure BDA0002102320130000045
calculated as follows:
Figure BDA0002102320130000046
Figure BDA0002102320130000047
representing the operation risk of the re-scheduling of the correction control phase, O is an expected fault set, O is an expected fault in the expected fault set, and poRepresenting the probability of occurrence of the expected failure o;
Figure BDA0002102320130000048
representing the total rescheduling cost sum of G generators in the correction control stage; cg corrRepresenting a rescheduling cost coefficient of the g-th generator correction control stage;
Figure BDA0002102320130000049
setting value P of g-th power generator output in correction control stage when expected failure occursg corrAnd a preventive control phase set value Pg prevThe deviation between the two or more of them,
Figure BDA00021023201300000410
calculated as follows:
Figure BDA00021023201300000411
Figure BDA0002102320130000051
the total load shedding cost of N generators which generate load shedding in the correction control stage is shown; cn corrRepresenting the load shedding cost coefficient of the nth generator in the correction control stage;
Figure BDA0002102320130000052
setting value P of nth load shedding generator output in correction control stage when expected failure o occursn,o corrWith an initial reference value Pn refThe deviation between the two or more of them,
Figure BDA0002102320130000053
calculated as follows:
Figure BDA0002102320130000054
the improvement of a safety constraint optimal power flow control system of an alternating current-direct current hybrid power grid is that the safety constraint optimal power flow control system comprises: an optimization calculation module and an execution module;
the optimization calculation module is used for inputting the operation data of the generator, the alternating current bus and the direct current node in the alternating current-direct current hybrid power grid into a pre-established prevention correction control safety constraint optimal power flow model to obtain the optimal generator output rescheduling quantity and the optimal load rescheduling quantity;
the execution module is used for adjusting the output and the load consumption of the generator according to the output optimal rescheduling quantity and the load optimal rescheduling quantity;
the preventive correction control safety constraint optimal power flow model comprises a preventive control stage and a correction control stage.
The improvement of the eighth preferred technical scheme provided by the invention is that the system further comprises a modeling module for establishing a preventive correction control safety constraint optimal power flow model, wherein the modeling module comprises an objective function unit and a constraint condition unit;
the objective function unit is used for constructing an objective function by taking the minimization of the operation risk as a target and considering the minimization of the power generation cost;
the constraint condition unit is used for constructing a safety constraint optimal power flow condition for preventive correction control;
wherein the safety-constrained optimal power flow condition of the preventive correction control includes: preventing and correcting power balance constraints of direct current and alternating current nodes in a control stage; generator and load power constraints, node voltage constraints, and branch power flow constraints.
Compared with the closest prior art, the invention has the following beneficial effects:
the method comprises the steps that operation data in an alternating current-direct current hybrid power grid are input into a pre-established prevention correction control safety constraint optimal power flow model, and the optimal generator output rescheduling amount and the optimal load rescheduling amount are obtained; adjusting the output and the load consumption of the generator according to the optimal output rescheduling amount and the optimal load rescheduling amount; compared with the prior art, the method has the remarkable characteristics that the optimal power flow of the preventive control safety constraint and the optimal power flow of the correction control safety constraint are combined and applied to the AC/DC hybrid power grid, so that the optimal decision of the AC/DC hybrid power grid considering both economy and reliability is realized.
Aiming at all possible expected accidents of the alternating current-direct current hybrid power grid, firstly, preventive control safety constraint optimal power flow calculation is adopted, the circuit power flow after the fault is effectively limited, the overload level after the fault is reduced, and then the power generator set is rescheduled or load shedding is carried out through correcting control safety constraint to solve the problems of power flow overload and voltage out-of-limit.
Drawings
Fig. 1 is a schematic flow chart of a safety constraint optimal power flow control method for an ac-dc series-parallel power grid according to the present invention;
FIG. 2(a) is a schematic diagram of an equivalent model of an AC line according to the present invention;
FIG. 2(b) is a schematic diagram of an equivalent model of a DC line according to the present invention;
FIG. 3 is a schematic diagram of an equivalent model of an AC/DC converter station according to the present invention;
FIG. 4 is a schematic diagram of an IEEE5 node test system according to an embodiment of the present invention;
fig. 5 is a schematic diagram of a basic structure of a safety constraint optimal power flow control system of an ac-dc hybrid power grid provided by the invention;
fig. 6 is a detailed structural schematic diagram of a safety constraint optimal power flow control system of an ac-dc hybrid power grid provided by the invention.
Detailed Description
The following describes embodiments of the present invention in further detail with reference to the accompanying drawings.
Example 1:
the flow diagram of the safety constraint optimal power flow control method of the alternating current-direct current hybrid power grid is shown in fig. 1, and the method comprises the following steps:
step 1: inputting the operation data of a generator, an alternating current bus and a direct current node in an alternating current-direct current hybrid power grid into a pre-established prevention correction control safety constraint optimal power flow model to obtain the optimal re-dispatching amount of the output of the generator and the optimal re-dispatching amount of the load;
step 2: adjusting the output and the load consumption of the generator according to the optimal output rescheduling amount and the optimal load rescheduling amount;
the preventive correction control safety constraint optimal power flow model comprises a preventive control stage and a correction control stage.
A safety constraint optimal power flow control method for an alternating current-direct current hybrid power grid comprises the following steps:
step 11: and establishing an objective function for preventing, correcting and controlling the optimal power flow problem of safety constraint of the alternating-current and direct-current series-parallel power grid.
In step 11, an objective function F is constructed with the aim of minimizing the operational risk and at the same time considering the minimum power generation cost, that is to say
Figure BDA0002102320130000071
In the formula (I), the compound is shown in the specification,
Figure BDA0002102320130000072
represents the sum of G generator rescheduling costs in preventive control, wherein
Figure BDA0002102320130000073
The deviation of the corresponding coefficient and the set value of the g-th generator prevention control stage relative to the initial reference value;
Figure BDA0002102320130000074
represents the operational risk of corrective control rescheduling, where O is the set of expected failures, O is a given expected failure in the set of expected failures, and poRepresenting the probability of the occurrence of the expected failure,
Figure BDA0002102320130000075
representing the sum of G generator rescheduling costs in corrective control,
Figure BDA0002102320130000076
representing the sum of costs of load shedding of N generators in the corrective control, Cg corr、Cn corrRespectively, are the corresponding coefficients of the coefficients,
Figure BDA0002102320130000077
given the expected occurrence of the fault o, the firstg, deviation of the output of the generators between the set value in the correction control stage and the set value in the prevention control stage;
Figure BDA0002102320130000078
setting value P of output of nth generator in correction control phase after expected faultn,o corrWith an initial reference value Pn refThe deviation therebetween.
Step 12: and establishing a constraint condition for safely constraining the optimal power flow problem of the AC-DC hybrid power grid prevention correction control.
Wherein, alternating current-direct current series-parallel connection electric wire netting includes: alternating current and direct current branches, a converter transformer, a filter, a phase reactor and a current converter. The converter type can be a power grid commutation converter LCC, a voltage source converter VSC or a modular multilevel converter MMC.
The constraint conditions of the fully constrained optimal power flow problem comprise: node power balance constraint, generator and load power constraint, node voltage constraint and branch load current constraint.
Step 13: and solving by using a Matlab optimal power flow calculation program aiming at the established preventive correction control safety constraint optimal power flow model, and then adjusting the output of the generator and the load shedding amount to optimal values to realize the optimal power flow of the alternating-current and direct-current series-parallel power grid.
In step 13, the established ac/dc power grid preventive correction control safety constraint optimal power flow model is a nonlinear programming with constraints, and can be solved by using intelligent algorithms such as genetic algorithm, particle swarm optimization algorithm and the like, and is implemented by computer language programming.
In step 13, the generator output adjustment includes output adjustment in a preventive control stage and output adjustment in a corrective control stage, and the load shedding amount adjustment includes shedding amount adjustment in the corrective control stage. The load shedding amount is the load readjustment amount.
Example 2:
the following describes the embodiments of the present invention in detail with reference to the attached drawings. To facilitate understanding, common letter designations that appear in the following description will first be briefly described.
And (3) labeling:
prev-represents the preventive control phase;
corr-represents the calibration control phase;
mag-represents amplitude;
ac-stands for exchange;
dc-represents direct current;
tf represents a converter transformer;
pr-stands for phase reactor;
cv-represents a converter;
f-represents a filter;
out-represents the output electrical quantity;
rated — represents a rated value;
max-represents the maximum value;
min-represents the minimum;
ref-represents an initial reference value;
loss-represents loss;
subscripts:
o — represents the expected failure o;
lij and lji represent the node from one end i to the other end j of the AC line l and the reverse direction of the AC line l respectively;
def and dfe respectively represent a node e at one end of the direct current line d to a node f at the other end of the direct current line d and the opposite direction of the direct current line d;
cie and cei respectively represent an alternating current node i from one end to a direct current node e from the other end and an alternating current node i from one end to the other end.
Specifically, the safety constraint optimal power flow control method for the alternating current-direct current hybrid power grid comprises the following steps:
step 101: and establishing an objective function for preventing, correcting and controlling the optimal power flow problem of safety constraint of the alternating-current and direct-current series-parallel power grid. Namely, establishing an objective function of the optimal power flow model for preventing, correcting and controlling safety constraint.
Constructing an objective function F by taking the minimization of the operation risk as a target and considering the minimization of the power generation cost, namely:
Figure BDA0002102320130000081
in the formula (1), the subscript g represents the g-th generator, and the subscript n represents the n-th load shedding generator.
Figure BDA0002102320130000091
Representing the sum of G generator rescheduling costs in preventive control,
Figure BDA0002102320130000092
is the rescheduling cost coefficient of the generator prevention control stage,
Figure BDA0002102320130000093
calculated according to the following formula, and the value of the calculated value depends on the set value P of the g-th generator output in the preventive control stageg prevRelative to an initial reference value Pg refHas a polynomial nature.
Figure BDA0002102320130000094
Figure BDA0002102320130000095
Representing the operational risk of corrective control rescheduling, O being the set of expected failures, O being a given expected failure of the set of expected failures, poRepresenting the probability of occurrence of the expected failure o.
Figure BDA0002102320130000096
Representing the sum of the costs of the G generators in total for corrective control, multiplied by the probability p of occurrence of the expected faultoObtaining the risk index of G generator rescheduling under the expected failure in the correction control stage, Cg corrRescheduling of the control phase for the g-th generatorThe coefficient of the coefficient is that,
Figure BDA0002102320130000097
the value of the set point P of the g-th generator output in the correction control phase is calculated according to the following formula under the condition that the expected failure o occursg corrAnd a preventive control phase set value Pg prevThe deviation between, having polynomial properties.
Figure BDA0002102320130000098
Figure BDA0002102320130000099
Representing the sum of the load shedding costs of N generators in the correction control stage, the cost function being multiplied by the probability p of occurrence of the expected faultoObtaining the risk index of load shedding of the N generators under the expected fault o in the correction control stage, Cn corrThe load shedding cost factor of the control stage is corrected for the nth generator,
Figure BDA00021023201300000910
the set value P of the output of the nth generator in the correction control stage is calculated according to the following formulan,o corrWith an initial reference value Pn refThe deviation therebetween.
Figure BDA00021023201300000911
Step 102: and establishing mathematical description of the AC-DC series-parallel power grid.
The direct current hybrid power grid comprises an alternating current branch, a direct current branch, a converter transformer, a filter, a phase reactor and a current converter; and (3) carrying out mathematical description on the structure forming the alternating current-direct current hybrid power grid based on the topological structure of the alternating current-direct current hybrid power grid.
Firstly, establishing equivalent mathematical description of an alternating current line and a direct current line of an alternating current-direct current series-parallel power grid. The ac line is mathematically described by using a pi equivalent model, and the obtained equivalent mathematical description of the ac line is shown in fig. 2 (a).
Active power P on alternating current branch l from any node i to node j of alternating current network in prevention control stagelij ac,prevAnd reactive power Qlij ac,prevIs defined as:
Figure BDA0002102320130000101
in the formula (5), g and b are respectively the series conductance and susceptance of the circuit; gfr、bfrRespectively, the parallel conductance and susceptance at the node i; u shapei mag,prev、Uj mag,prevRespectively representing the voltage amplitudes of the node i and the node j during the preventive control phase,
Figure BDA0002102320130000102
respectively representing the voltage phase angles of the node i and the node j in the preventive control phase.
In the prevention control stage, the active power P in the reverse direction from the node j to the node ilji ac,prevAnd reactive power Qlji ac,prevThen it is defined as:
Figure BDA0002102320130000103
in the formula (6), gto、btoRespectively the parallel conductance and susceptance at node j.
In the correction control phase, in the case of an expected fault o, the non-faulty ac branch i flows from node i to the active power P of node jlij,o ac,corrAnd reactive power Qlij,o ac,corrCalculated according to the following formula,
Figure BDA0002102320130000104
in formula (7), Ui mag,corr、Uj mag,corrRespectively representing the voltage amplitudes, theta, of the nodes i and j during the correction control phasei corr、θj corrWhich represent the voltage phase angles at node i and node j, respectively, during the calibration control phase.
And when the branch l has a fault, the active power P flows from the node i to the node jlij,o ac,corr,outAnd reactive power Qlij,o ac,corr,outThen is defined as zero:
Figure BDA0002102320130000111
in the preventive and corrective control phase, the active and reactive power flows in both directions should be at the apparent power rating S, whether the AC branch I flows from node i to j or from node j to il rated,acWithin the range, there are:
Figure BDA0002102320130000112
direct current line equivalent mathematical description as shown in fig. 2(b), for a monopolar loop HVDC system, the entire power flow is on one pole, while for symmetric monopolar and bipolar HVDC systems, the power flow is on the positive and negative poles, respectively. Therefore, the current of the DC line should be based on the number of poles pd(pdE {1,2}) are processed accordingly.
From fig. 2(b) it can be derived that the power flow of the dc branch is represented as follows:
Figure BDA0002102320130000113
in the formula (10), the compound represented by the formula (10),
Figure BDA0002102320130000114
and Pdfe dcRespectively represent the flow from a DC node e to a node f, and from the DC node f to the node eWork power, Pd dc,lossRepresents the loss of the DC branch d, and
Figure BDA0002102320130000115
in the preventive and corrective control phases, the power flow should be at the rated value P of the DC branchd dc,ratedWithin the range:
Figure BDA0002102320130000116
active power flow from DC node e to node f during preventive control
Figure BDA0002102320130000117
Calculated according to the following formula:
Figure BDA0002102320130000118
in formula (12), Ue dc,prev、
Figure BDA0002102320130000119
The voltages of the DC nodes e and f, g, respectively, during the preventive control phased sIs the series conductance of the dc branch d.
In the correction control phase, when the expected fault o occurs, the DC power P of the non-faulty branch ddef,o dc,corrCalculated according to the following formula:
Figure BDA0002102320130000121
in formula (13), Ue,o dc,corr、Uf,o dc,corrThe voltages at dc nodes e and f, respectively, during the calibration control phase.
When the branch d has a fault, the power flow P between the direct current nodes e and fdef,o dc,corr,outIs defined as zero, i.e.
Figure BDA0002102320130000122
According to fig. 3, an equivalent mathematical description of the ac-dc converter station is established, which includes: transformers with taps and series impedances, filters, phase reactors, power electronics ac/dc converters. Transformers, filters and phase reactors are passive components and are described using a classical power model. The converter type may be LCC, VSC or MMC and operates in an inverted or rectified state. In the figure, the position of the upper end of the main shaft,
Figure BDA0002102320130000123
represents the alternating voltage at node i, where Ui mag、θiAre respectively UiThe amplitude and phase angle of; u shapee dcRepresents the dc voltage at node e;
Figure BDA0002102320130000124
which represents the voltage of the filter and which,
Figure BDA0002102320130000125
is that
Figure BDA0002102320130000126
The amplitude and phase angle of;
Figure BDA0002102320130000127
representing the converter outlet side voltage.
Assuming that the impedance of the converter transformer is zc tf＝rc tf+jxc tfAdmittance of the form yc tf＝gc tf+jbc tf。tcIs a converter transformer tap. In the prevention control stage, the flow active power P passing through the converter transformer is calculated by taking the flow direction of the alternating current node i to the direct current node e as the positive directioncie tf,prevAnd reactive Qcie tf,prevIs composed of
Figure BDA0002102320130000128
In formula (15), Ui mag,prev、
Figure BDA0002102320130000129
Respectively representing the amplitude of the alternating voltage at node i and the amplitude of the voltage at the filter, theta, of the preventive control stagei prev、θc f,prevRespectively representing the ac voltage at node i and the voltage phase angle of the filter during the preventive control phase.
The current P passing through the converter transformer takes the flow direction of the direct current node e to the alternating current node i as the positive directioncei tf,prevAnd Qcei tf ,prevIs composed of
Figure BDA0002102320130000131
In the correction control stage, when the expected fault o occurs, the load flow flowing through the converter transformer of the non-fault branch is calculated as
Figure BDA0002102320130000132
In the formula (17), Pcie,o tf,corr、Qcie,o tf,corrRespectively representing a correction control stage, taking the flow direction of an alternating current node i to a direct current node e as a positive direction, and passing active power and reactive power of a converter transformer; pcei,o tf,corr、Qcei,o tf,corrRepresenting a correction control stage, taking the flow direction of a direct current node e to an alternating current node i as a positive direction, and passing active power and reactive power of a converter transformer; u shapei mag,corr、
Figure BDA0002102320130000141
Respectively representing the amplitude of the AC voltage at node i and the amplitude of the voltage at the filter, theta, during the correction control phasei corr、θc,o f,corrRespectively representing the ac voltage at node i and the phase angle of the voltage of the filter during the calibration control phase.
For the converter transformer with the fault branch, the output active power Pcie,o tf,corr,out、Pcei,o tf,corr,outAnd reactive power Qcie,o tf,corr,out、Qcei,o tf,corr,outUniformly defined as zero, i.e.
Figure BDA0002102320130000142
If no converter transformer is present on the line, or numerically
Figure BDA0002102320130000143
The elements that do not experience loss during the preventive and corrective control phases have the following formula:
Figure BDA0002102320130000144
in the formula (19), Pcie tfAnd Qcie tfRespectively representing active power and reactive power flowing through the converter transformer when the flow direction of the node i is a positive direction; pcei tfAnd Qcei tfRespectively representing the active power and the reactive power which flow through the converter transformer when the flow direction of the node e to the node i is a positive direction;
Figure BDA0002102320130000145
and thetaiRespectively representing the magnitude and phase angle of the voltage at node i,
Figure BDA0002102320130000146
and
Figure BDA0002102320130000147
respectively representing the voltage magnitude and phase angle of the filter.
For filters, LCC is currently mainly usedIn HVDC systems, to filter out harmonics on the line. Assuming the susceptance of the parallel capacitor as bc fReactive power Q in the preventive control phasec f,prevAnd the reactive power Q of the non-fault branch filter under the condition that the expected fault occurs in the correction control stagec,o f,corrThe calculation is as follows:
Figure BDA0002102320130000148
reactive power Q of filter for all branches with predicted faultsc,o f,corr,outIs provided with
Figure BDA0002102320130000149
For the phase reactor, assume the impedance of the phase reactor is zc pr＝rc pr+jxc prAdmittance of the form yc pr＝gc pr+jbc pr. The power flow calculation formula is consistent with the converter transformer, namely the transformer tap t in the formula (15) to the formula (17)cIs set to 1.
In the preventive and corrective control phase, the power flow between the filter capacitors, the phase reactors and the converter transformer is generally balanced, i.e. there are:
Figure BDA0002102320130000151
in the formula (22), Pcie pr、Qcie prRespectively the active power and the reactive power which take the flow direction of the node i to the node e as the positive direction and pass through the phase reactor; pcei pr、Qcei prRespectively the active power and the reactive power which take the flow direction of the node e to the node i as the positive direction and pass through the phase reactor; qc fRepresenting the filter reactive power.
For AC-DC conversionFlow device, assume Pc cv,acAnd Qc cv,acRespectively the active power exchange and the reactive power exchange at the AC outlet bus of the converter. In the preventive and corrective control phases, the active and reactive whiskers follow the following constraints:
Figure BDA0002102320130000152
in the formula (23), the superscripts prev, corr, min and max have the same meanings as described above; sc cv,ac,ratedRepresenting the apparent power rating at the ac outlet bus of the converter.
Active power P of DC side of converter in prevention and correction control stagec cv,dcThe following constraints need to be observed:
Figure BDA0002102320130000153
in the formula (24), the superscripts prev, corr, min and max have the same meanings as in the formula (23).
For converters with branch circuits expected to fail during the correction phase, the DC side power Pc.o cv,dc,corr,outIs zero, i.e.:
Figure BDA0002102320130000154
active power P at AC side of converterc cv,acActive power P on the sum DC sidec cv,dcSatisfies the following equation
Figure BDA0002102320130000155
P in formula (26)c cv,lossThe loss of the converter itself is generally calculated by the following formula:
Figure BDA0002102320130000156
wherein, ac cvRepresenting the no-load loss of the transformer and the average loss of the auxiliary equipment, bc cvRepresenting the average loss of the valve and the freewheeling diode, cc cvRepresents the conduction loss of the valve and satisfies ac cv≥0(W)，bc cv≥0(W/A)，cc cv≥0(Ω)；
Figure BDA0002102320130000161
Representing the magnitude of the current on the ac side of the converter.
Active power P at AC side of converterc cv,acAnd reactive power Qc cv,acThe following constraint should be satisfied,
Figure BDA0002102320130000162
in the formula (28), Ic cv,mag、Ic cv,ratedRespectively representing the amplitude and rated value of the current at the AC side of the converter, Uc cv、Uc cv ,min、Uc cv,maxRespectively representing the effective value, the minimum value and the maximum value of the voltage of the AC bus of the converter. For the preventive control phase, the AC side voltage U of the converterc cv,mag,prevCurrent Ic cv,mag,prevAnd correcting the AC side voltage U of the converter of the non-faulty branch in case of the expected fault in the control stagec,o cv,mag,corrCurrent Ic,o cv,mag,corrBoth need to satisfy equation (28).
Active power P on AC side of converter for predicted fault branch in correction control stagec,o cv,ac,corr,outReactive power Qc,o cv,ac,corr,outAlternating current Ic,o cv,mag,corrThen there are:
Figure BDA0002102320130000163
DC side current I of converterc cv,dcThe following constraint conditions should be satisfied
Figure BDA0002102320130000164
In the formula (29), Ic cv,dc,mag、Ic cv,dc,min、Ic cv,dc,maxRespectively representing the amplitude, the minimum value and the maximum value of the current on the direct current side of the converter.
In LCC-HVDC, in order to accurately simulate the system characteristics, a filter and a phase reactor cannot be ignored, and an active power P at the AC outlet side of a converterc cv,acAnd reactive Qc cv,acHave the following relationship
Figure BDA0002102320130000165
Wherein
Figure BDA0002102320130000166
Is a thyristor firing angle and has
Figure BDA0002102320130000167
Step 103: and establishing a constraint condition of the optimal power flow model for preventing, correcting and controlling safety constraint of the alternating-current and direct-current series-parallel power grid.
The constraint conditions include:
(1) power balance equation of each point
In the prevention and correction control stage, the direct current node e of the alternating current-direct current network has:
Figure BDA0002102320130000171
in the formula (32), E represents the number of all the inverter branches connected to the DC node E, and F represents the number of the inverter branches connected to the DC node EThe number of all DC branches connected to the node e, M, dc, represents the number of all DC loads connected to the node e, Pm dcRepresenting the active power of the mth direct current load connected with the direct current node e; pc cv,dc,prevRepresenting the active power of the direct current side of the converter in the preventive control stage;
Figure BDA0002102320130000172
representing the active power from one end node e to the other end node f of the direct current line in the prevention control stage;
Figure BDA0002102320130000173
when the expected fault o occurs, correcting the active power of the DC side of the converter in the control stage;
Figure BDA0002102320130000179
the method comprises the steps that when a fault o is expected to occur, active power from a node e at one end of a direct-current line to a node f at the other end of the direct-current line in a control stage is corrected; .
Aiming at the alternating current side of the alternating current-direct current network, a node balance equation in a prevention control stage comprises the following steps:
Figure BDA0002102320130000174
in formula (33), Pg prev、Qg prevRespectively representing active and reactive power, P, of the generator outputm prev、Qm prevRespectively representing the active and reactive power consumed by the ac load, gi shunt、bi shuntThe current is divided by the AC bus, I represents the number of all current converter branches connected with an AC node I, J represents the number of all AC branches connected with the AC node I, G represents the number of generators connected with the AC node I, and M and ac represent the number of all AC loads connected with the AC node I;
Figure BDA0002102320130000175
indicating preventive control phaseThe flow of the alternating current node i to the direct current node e is taken as the positive direction, and through the active power of the converter transformer,
Figure BDA0002102320130000176
the reactive power of the converter transformer is passed through by taking the flow direction of an alternating current node i to a direct current node e as a positive direction in the prevention control stage;
Figure BDA0002102320130000177
representing the active power flowing on the ac line l from the ac node i to the ac node j during the preventive control phase,
Figure BDA0002102320130000178
which represents the reactive power on the ac line l flowing from the ac node i to the ac node j during the preventive control phase.
The node balance equation in the correction control stage is as follows:
Figure BDA0002102320130000181
in the formula (34), Pg,o corr、Qg,o corrRespectively representing the active and reactive power, P, output by the generator in the event of an expected fault om corr、Qm corrRespectively representing the real and reactive power consumed by the load in the case of the occurrence of the expected fault o;
Figure BDA0002102320130000182
when the expected failure o occurs, the correction control stage takes the AC node i to flow to the DC node e as the positive direction, and the active power of the converter transformer is passed,
Figure BDA0002102320130000183
when the situation that the fault o is expected to occur is shown, the correction control stage takes the flow of the alternating current node i to the direct current node e as the positive direction and passes through the reactive power of the converter transformer;
Figure BDA0002102320130000184
when the expected fault o occurs, the active power flowing from the AC node i to the AC node j on the AC line l in the control stage is corrected,
Figure BDA0002102320130000185
when the fault o is expected to occur, the reactive power flowing from the AC node i to the AC node j on the AC line l in the control stage is corrected;
Figure BDA0002102320130000186
indicating the magnitude of the voltage at ac node i during the calibration control phase.
(2) Other constraints
Prevention and correction of generator active power P in control phasegReactive PgThe force must comply with the following constraints:
Figure BDA0002102320130000187
in the formula (I), the compound is shown in the specification,
Figure BDA0002102320130000188
represents the minimum value of the active power of the g-th generator in the prevention and correction control stage,
Figure BDA0002102320130000189
representing the maximum value of the active power of the g-th generator in the prevention and correction control stage;
Figure BDA00021023201300001810
represents the reactive power minimum value of the g-th generator in the prevention and correction control stage,
Figure BDA00021023201300001811
the maximum value of the reactive power of the g-th generator in the prevention and correction control stage is shown.
Active and reactive power re-scheduling amount in prevention control stage
Figure BDA00021023201300001812
The following constraints are to be followed
Figure BDA00021023201300001813
The active power P of the g-th generator after the prevention control stage is finishedg prevAnd reactive Qg prevThe force should be set according to the following formula:
Figure BDA00021023201300001814
wherein the content of the first and second substances,
Figure BDA0002102320130000191
and
Figure BDA0002102320130000192
initial reference values of the active and reactive power of the g-th generator are respectively shown.
A correction control phase for every possible predicted fault O in the set of predicted faults O, generator active and reactive power output rescheduling quantities
Figure BDA0002102320130000193
The following constraints should be observed:
Figure BDA0002102320130000194
therefore, the generator active power P is corrected in the control phaseg,o corrAnd reactive Qg,o corrThe force should be set according to the following formula:
Figure BDA0002102320130000195
the preventive control phase does not allow load shedding, so the active load P of the phasem prevAnd is idleLoad Qm prevIs not changed, i.e.
Figure BDA0002102320130000196
Wherein the content of the first and second substances,
Figure BDA0002102320130000197
an initial reference value representing the active power of the mth load,
Figure BDA0002102320130000198
representing the initial reference value of the m-th load reactive power.
In the correction control phase, the load active power Pm,o corrReactive Qm,o corrAnd amount of rescheduling
Figure BDA0002102320130000199
The constraint condition is
Figure BDA00021023201300001910
Figure BDA00021023201300001911
Wherein the content of the first and second substances,
Figure BDA00021023201300001912
indicating the minimum value of the active power of the mth load in case of the expected occurrence of the fault o,
Figure BDA00021023201300001913
this indicates the minimum reactive power value of the mth load when the occurrence of the fault o is expected.
The load of the calibration control stage should be set according to the following equation:
Figure BDA00021023201300001914
and the values of active and reactive power Pm,o corr、Qm,o corrHas the following relation
Figure BDA00021023201300001915
During the preventive control and the correction control, the node voltage should satisfy:
Figure BDA0002102320130000201
in the formula (I), the compound is shown in the specification,
Figure BDA0002102320130000202
representing the magnitude of the voltage at the ac node i,
Figure BDA0002102320130000203
to represent
Figure BDA0002102320130000204
The minimum value of (a) is determined,
Figure BDA0002102320130000205
to represent
Figure BDA0002102320130000206
Maximum value of (d);
Figure BDA0002102320130000207
represents the voltage of the node e on the dc side,
Figure BDA0002102320130000208
to represent
Figure BDA0002102320130000209
The maximum value of (a) is,
Figure BDA00021023201300002010
to represent
Figure BDA00021023201300002011
Is measured.
In the preventive control and corrective control stages, the AC and DC branch power flow constraints are referred to above in equation (9) and equation (11)
Step 104: and (5) solving the optimal power flow model of preventive correction control safety constraint.
Aiming at the established preventive correction control safety constraint optimal power flow model, Matlab programming is adopted for realization, parameters of the active power and the reactive power of the generator, the voltage and the phase angle of an alternating current bus and a direct current node, initial set values of the active power and the reactive power of the load and the like mentioned in the description are input, a genetic algorithm is used for solving, and the optimal solution of state variables in the alternating current-direct current hybrid power grid is obtained, namely the generator output rescheduling quantity in the preventive control stage
Figure BDA00021023201300002012
Generator output rescheduling quantity in correction control stage
Figure BDA00021023201300002013
And amount of load rescheduling
Figure BDA00021023201300002014
Finally, the state variable (the generator output rescheduling quantity in the prevention control stage) in the AC-DC hybrid power grid
Figure BDA00021023201300002015
Generator output rescheduling quantity in correction control stage
Figure BDA00021023201300002016
And amount of load rescheduling
Figure BDA00021023201300002017
) And giving an optimal solution to enable the power grid to operate at an optimal operation point, and achieving the aim of minimizing the power generation cost and the system operation risk.
Step 105: and executing the obtained optimal solution.
Giving an optimal solution to the state variable in the AC-DC hybrid power grid, namely a prevention control stage according to
Figure BDA00021023201300002018
Adjusting the output of the generator according to the correction control stage
Figure BDA00021023201300002019
Adjusting the output of the generator according to
Figure BDA00021023201300002020
And adjusting active power and reactive power consumed by the load, and realizing the aim of minimizing the generating cost and the system operation risk when the power grid operates at the optimal operating point.
Example 3:
a specific example is given below.
Based on the mathematical model provided by the invention, matlab programming language is adopted to develop optimal power flow calculation software for preventing, correcting, controlling and controlling safety constraint of the alternating current-direct current hybrid power grid, and simulation verification is carried out on an IEEE5 node test system. As shown in fig. 4, a 3-node dc grid is connected in series with an IEEE 5-node ac system through VSC, and the probability of occurrence of an expected fault is set to 1 by simulation, i.e., a typical case of the N-1 safety criterion is analyzed. The load shedding cost was set to $ 5000/MWh.
Table 1 shows the safety constraint optimal power flow result of the simulation example, and the minimum objective function value under various conditions is obtained. The first example is that the direct-current power grid is not contained, and only the expected fault occurrence situation in the alternating-current power grid is considered; the second example considers the condition that only the alternating current system in the alternating current-direct current hybrid power grid has an expected fault; and the third example is a case that only the direct current system in the alternating current and direct current hybrid power grid has an expected fault.
Table 1: safety constrained optimal power flow results
Figure BDA0002102320130000211
Example 4:
based on the same invention concept, the invention also provides a safety constraint optimal power flow control system of the alternating current-direct current hybrid power grid, and because the principle of solving the technical problems of the devices is similar to the safety constraint optimal power flow control method of the alternating current-direct current hybrid power grid, repeated parts are not repeated.
The basic structure of the system is shown in fig. 5, and comprises: an optimization calculation module and an execution module;
the optimization calculation module is used for inputting the operation data of a generator, an alternating current bus and a direct current node in the alternating current-direct current hybrid power grid into a pre-established prevention correction control safety constraint optimal power flow model to obtain an optimal generator output rescheduling quantity and an optimal load rescheduling quantity;
the execution module is used for adjusting the output and the load consumption of the generator according to the optimal output rescheduling amount and the optimal load rescheduling amount;
the preventive correction control safety constraint optimal power flow model comprises a preventive control stage and a correction control stage.
The detailed structure of the safety constraint optimal power flow control system of the alternating current-direct current hybrid power grid is shown in fig. 6.
The system also comprises a modeling module used for establishing a preventive correction control safety constraint optimal power flow model, wherein the modeling module comprises a target function unit and a constraint condition unit;
the objective function unit is used for constructing an objective function by taking the minimization of the operation risk as a target and considering the minimization of the power generation cost;
the constraint condition unit is used for constructing a safety constraint optimal power flow condition for preventive correction control;
the safety constraint optimal power flow condition for preventive correction control comprises the following steps: preventing and correcting power balance constraints of direct current and alternating current nodes in a control stage; generator and load power constraints, node voltage constraints, and branch power flow constraints.
The optimization calculation module comprises a data input unit and a solving unit;
the data input unit is used for inputting the operation data of the generator, the alternating current bus and the direct current node in the alternating current-direct current hybrid power grid into a pre-established preventive correction control safety constraint optimal power flow model;
the solving unit is used for solving a preventive correction control safety constraint optimal power flow model by utilizing a Matlab optimal power flow calculation program to obtain an optimal generator output rescheduling amount and an optimal load rescheduling amount;
wherein the operational data of the generator comprises: active and reactive power of the generator; the operation data of the alternating current bus comprises the voltage and the phase angle of the alternating current bus; the operational data of the dc node includes a voltage of the dc node.
The execution module comprises a prevention control stage execution unit and a correction control stage execution unit;
the prevention control stage execution unit is used for adjusting the active power and the reactive power of the generator according to the active power and reactive power readjustment quantity of the generator in the prevention control stage;
the correction control stage execution unit is used for adjusting the active power and the reactive power of the generator according to the active power and reactive power readjustment amount of the generator in the correction control stage and adjusting the active power and reactive power consumed by the load according to the load active power and reactive power readjustment amount in the correction control stage;
wherein the optimal output rescheduling amount comprises the following steps: preventing the generator active power and reactive power re-dispatching quantity in the control stage and correcting the generator active power and reactive power re-dispatching quantity in the control stage; the load optimal rescheduling amount comprises load active and reactive power rescheduling amounts in a correction control stage.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
It should be noted that the above-mentioned embodiments are only for illustrating the technical solutions of the present application and not for limiting the scope of protection thereof, and although the present application is described in detail with reference to the above-mentioned embodiments, those skilled in the art should understand that after reading the present application, they can make various changes, modifications or equivalents to the specific embodiments of the application, but these changes, modifications or equivalents are all within the scope of protection of the claims to be filed.

Claims (10)

1. A safety constraint optimal power flow control method of an alternating current-direct current hybrid power grid is characterized by comprising the following steps:
inputting the operation data of a generator, an alternating current bus and a direct current node in an alternating current-direct current hybrid power grid into a pre-established prevention correction control safety constraint optimal power flow model to obtain the optimal re-dispatching amount of the output of the generator and the optimal re-dispatching amount of the load;
adjusting the output and the load consumption of the generator according to the output optimal rescheduling quantity and the load optimal rescheduling quantity;
the preventive correction control safety constraint optimal power flow model comprises a preventive control stage and a correction control stage.
2. The method of claim 1, wherein the establishing of the preventive correction control safety constrained optimal power flow model comprises:
constructing an objective function by taking the minimum operation risk as a target and considering the minimum power generation cost;
constructing a safety constraint optimal power flow condition for prevention, correction and control;
wherein the safety-constrained optimal power flow condition of the preventive correction control includes: preventing and correcting power balance constraints of direct current and alternating current nodes in a control stage; generator and load power constraints, node voltage constraints, and branch power flow constraints.
3. The method of claim 1, wherein the AC/DC hybrid grid comprises:
alternating current branch circuit, direct current branch circuit, converter transformer, wave filter, phase reactor and transverter.
4. The method of claim 2, wherein the generator power constraint is expressed by:
Figure FDA0002102320120000011
Figure FDA0002102320120000012
in the formula, Pg,o corrCorrecting the active power of the g-th generator in the control phase when the expected failure o occurs, Qg,o corrWhen the predicted fault o occurs, correcting the reactive power of the g-th generator in the control stage;
Figure FDA0002102320120000013
representing the active power of the g-th generator after the preventive control phase is completed,
Figure FDA0002102320120000014
the reactive power of the g-th generator after the prevention control stage is finished is shown;
Figure FDA0002102320120000015
indicating that the predicted fault o occurs, correcting the active power readjustment quantity of the generator in the g-th stage of control,
Figure FDA0002102320120000016
when the predicted fault o occurs, correcting the reactive power readjustment amount of the generator at the g-th stage in the control stage;
Figure FDA0002102320120000017
and
Figure FDA0002102320120000018
the constraints are respectively shown as follows:
Figure FDA0002102320120000019
Figure FDA00021023201200000110
in the formula (I), the compound is shown in the specification,
Figure FDA00021023201200000111
represents the minimum value of the active power of the g-th generator in the prevention and correction control stage,
Figure FDA00021023201200000112
representing the maximum value of the active power of the g-th generator in the prevention and correction control stage;
Figure FDA0002102320120000021
represents the reactive power minimum value of the g-th generator in the prevention and correction control stage,
Figure FDA0002102320120000022
the maximum value of the reactive power of the g-th generator in the prevention and correction control stage is shown.
5. The method of claim 2, wherein the load power constraint is as follows:
Figure FDA0002102320120000023
Figure FDA0002102320120000024
Figure FDA0002102320120000025
Figure FDA0002102320120000026
Figure FDA0002102320120000027
Figure FDA0002102320120000028
Figure FDA0002102320120000029
in the formula (I), the compound is shown in the specification,
Figure FDA00021023201200000210
representing the active power of the mth load of the preventive control phase,
Figure FDA00021023201200000211
representing the reactive power of the mth load in the preventive control phase;
Figure FDA00021023201200000212
an initial reference value representing the active power of the mth load,
Figure FDA00021023201200000213
an initial reference value representing the mth load reactive power;
Figure FDA00021023201200000214
indicating that the m-th load has active power in the control phase corrected in anticipation of the occurrence of the fault o,
Figure FDA00021023201200000215
correcting the expected failureControlling reactive power of the mth load in the stage;
Figure FDA00021023201200000216
indicating that the fault o is expected, the amount of active power re-modulation of the mth load of the control stage is corrected,
Figure FDA00021023201200000217
when the predicted fault o occurs, correcting the reactive power readjustment amount of the mth load in the control stage;
Figure FDA00021023201200000218
and
Figure FDA00021023201200000219
the constraints are respectively shown as follows:
Figure FDA00021023201200000220
Figure FDA00021023201200000221
Figure FDA00021023201200000222
indicating the minimum value of the active power of the mth load in case of the expected occurrence of the fault o,
Figure FDA00021023201200000223
this indicates the minimum reactive power value of the mth load when the occurrence of the fault o is expected.
6. The method of claim 1, wherein the step of inputting the operation data of the generator, the ac bus and the dc node in the ac/dc hybrid power grid into a pre-established preventive correction control safety constraint optimal power flow model to obtain an optimal generator output rescheduling amount and an optimal load rescheduling amount comprises:
inputting the operation data of a generator, an alternating current bus and a direct current node in an alternating current-direct current hybrid power grid into a pre-established preventive correction control safety constraint optimal power flow model;
solving the preventive correction control safety constraint optimal power flow model by using a Matlab optimal power flow calculation program to obtain an optimal generator output rescheduling amount and an optimal load rescheduling amount;
wherein the operational data of the generator comprises: active and reactive power of the generator; the operation data of the alternating current bus comprises the voltage and the phase angle of the alternating current bus; the operational data of the DC node includes a voltage of the DC node.
7. The method of claim 1, wherein said adjusting the generator contribution and load consumption based on the optimal amount of contribution and optimal amount of load rescheduling comprises:
in the prevention control stage, adjusting the active power and the reactive power of the generator according to the re-adjustment amount of the active power and the reactive power of the generator in the prevention control stage;
in the correction control stage, the active power and the reactive power of the generator are adjusted according to the active power and reactive power readjustment amount of the generator in the correction control stage, and the active power and reactive power consumed by the load are adjusted according to the load active power and reactive power readjustment amount in the correction control stage;
wherein the best output rescheduling amount comprises: preventing the generator active power and reactive power re-dispatching quantity in the control stage and correcting the generator active power and reactive power re-dispatching quantity in the control stage; the load optimal rescheduling amount comprises load active and reactive power rescheduling amounts in a correction control stage.
8. The method of claim 2, wherein the objective function is expressed as:
Figure FDA0002102320120000031
in the formula, F represents an objective function, a superscript prev represents a prevention control stage, a superscript corr represents a correction control stage, a subscript g represents a g-th generator, and a subscript n represents an n-th generator for load shedding;
Figure FDA0002102320120000032
representing the total rescheduling cost sum of G generators in the prevention control stage;
Figure FDA0002102320120000033
representing a rescheduling cost coefficient of the g-th generator in a prevention control stage;
Figure FDA0002102320120000034
set value P representing the output of the g-th generator in the preventive control stageg prevRelative to an initial reference value Pg refThe deviation of (a) is determined,
Figure FDA0002102320120000035
calculated as follows:
Figure FDA0002102320120000036
Figure FDA0002102320120000037
representing the operation risk of the re-scheduling of the correction control phase, O is an expected fault set, O is an expected fault in the expected fault set, and poRepresenting the probability of occurrence of the expected failure o;
Figure FDA0002102320120000041
indicating corrective control phasesG generators share the total rescheduling cost; cg corrRepresenting a rescheduling cost coefficient of the g-th generator correction control stage;
Figure FDA0002102320120000042
setting value P of g-th power generator output in correction control stage when expected failure occursg corrAnd a preventive control phase set value Pg prevThe deviation between the two or more of them,
Figure FDA0002102320120000043
calculated as follows:
Figure FDA0002102320120000044
Figure FDA0002102320120000045
the total load shedding cost of N generators which generate load shedding in the correction control stage is shown; cn corrRepresenting the load shedding cost coefficient of the nth generator in the correction control stage;
Figure FDA0002102320120000046
setting value P of nth load shedding generator output in correction control stage when expected failure o occursn,o corrWith an initial reference value Pn refThe deviation between the two or more of them,
Figure FDA0002102320120000047
calculated as follows:
Figure FDA0002102320120000048
9. the safety constraint optimal power flow control system of the alternating current-direct current hybrid power grid is characterized by comprising the following components: an optimization calculation module and an execution module;
the optimization calculation module is used for inputting the operation data of the generator, the alternating current bus and the direct current node in the alternating current-direct current hybrid power grid into a pre-established prevention correction control safety constraint optimal power flow model to obtain the optimal generator output rescheduling quantity and the optimal load rescheduling quantity;
the execution module is used for adjusting the output and the load consumption of the generator according to the output optimal rescheduling quantity and the load optimal rescheduling quantity;
the preventive correction control safety constraint optimal power flow model comprises a preventive control stage and a correction control stage.
10. The system of claim 9, further comprising a modeling module for building a preventive correction control safety constrained optimal power flow model, the modeling module comprising an objective function unit and a constraint condition unit;
the objective function unit is used for constructing an objective function by taking the minimization of the operation risk as a target and considering the minimization of the power generation cost;
the constraint condition unit is used for constructing a safety constraint optimal power flow condition for preventive correction control;
wherein the safety-constrained optimal power flow condition of the preventive correction control includes: preventing and correcting power balance constraints of direct current and alternating current nodes in a control stage; generator and load power constraints, node voltage constraints, and branch power flow constraints.
CN201910540219.3A 2019-06-21 2019-06-21 Safety constraint optimal power flow control method and system for alternating current-direct current hybrid power grid Pending CN112117766A (en)

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