CN105391036A - Power grid fault stable control method - Google Patents

Abstract

The invention provides a power grid fault stable control method. The method comprises the steps of establishing layered power grid structures, selecting an optimal control strategy, and judging and selecting a fault operation means, wherein the layered power grid structures are established under different operation modes and initial trigger fault conditions, and backbone structures required by power grid survivability are not completely the same. Key lines, which effectively support the power grid survivability, are extracted from the plurality of backbone structures under different operation modes and initial trigger fault conditions, thereby playing an import role in targetedly carrying out survivability enhancing means. According to the invention, fault points and fault types can be rapidly sought according to the grid structure of a power grid when the power grid breaks down, the optimal control strategy can be selected from control strategies, and different fault processing modes are adopted according to the different fault types, so that a protection device is prevented against non-triggering or false triggering.

Description

A kind of electric network fault stable control method

Technical field

The technical field that the stability that the present invention designs a kind of electrical network controls specifically, is a kind of electric network fault stable control method.

Background technology

Along with the expansion of interconnected network region and exchange capacity, the especially big power outage caused by interconnected network fault almost becomes social disaster to the impact of social life, and ensure the safety in operation of interconnected network, avoid the generation of great, especially big power outage but to become more and more difficult.Occurrence of large-area has a power failure often caused by multiple accidentalia, although the probability that this fault occurs is very low, consequence is abnormal serious.Therefore, need a kind of control mode extreme in electric power system seriously with when being difficult to the fault expected react in time and carry out fault reply rapidly, and frequently can not be triggered by the minor swing of electrical network.

Summary of the invention

Based on the deficiencies in the prior art, the present invention proposes a kind of electric network fault stable control method, and described electric network fault stable control method comprises sets up layering Net Frame of Electric Network, the selection of optimal control policy, and the judgement of failed operation means is selected.

Wherein, setting up layering Net Frame of Electric Network is that the bulk transmission grid needed for Grid survival is incomplete same due under different running method and initial trigger fault condition.Comform in many bulk transmission grid and extract under various operational mode and initial trigger fault condition, Grid survival being played to the critical circuits of effective supporting role, for implementing survivability enhancement measure targetedly, there is important function

Therefore, in order to can location promptly and accurately during electric network fault, need to carry out structuring to electrical network in advance, mainly in four steps.

1) with different levels structural model is set up

On the basis analysing in depth practical problem, each relevant factor is resolved into some levels according to different attribute from top to down, the factors of same layer be subordinated to last layer factor or on upper strata because have impact, simultaneously again the lower one deck of domination factor or be subject to the effect of lower layer factors.The superiors are destination layer, and usually only have 1 factor, orlop is generally scheme or object layer, and can there be one or several level centre.

2) Judgement Matricies

By structure relative Link Importance judgment matrix, determine for last layer time certain factor, the relative importance between any 2 factors of this level.The structure of this judgment matrix shows, the circuit in the larger bulk transmission grid of probability of happening has relatively larger importance degree.

3) Mode of Level Simple Sequence and consistency check thereof

For each judgment matrix, calculate Maximum characteristic root and character pair vector, utilize coincident indicator, random index and Consistency Ratio to do consistency check.If upcheck, characteristic vector (after normalization), is weight vectors: if do not pass through, and need re-construct judgment matrix.

4) total hierarchial sorting and consistency check thereof

Determine the weight vectors of each object of lowermost layer relative to top target, and do consistency check, if upcheck, then the result that can represent according to weight vectors carries out decision-making, otherwise needs rethink model or re-construct judgment matrix.

After obtaining complete divided power system structure in general, electric network composition and the ruuning situation of the known current system of the information obtained is divided, as place, the situation such as scope and the order of severity of fault and fault are normally run or be there occurs to system by failure diagnosis, Identification Division.These information are only had also to be nowhere near as the decision-making of emergency control, also will according to a large amount of metrical informations got from SCADA (supervisory control and data acquisition (SCADA)) system, as active-power P, the variable quantity △ P of active power, slip δ, the variable quantity △ δ of slip, the variable quantity △ I of electric current I and electric current, variable quantity △ U of reactive power Q and voltage U and voltage etc.

The stability contorting of electric power system according to target can be divided into two classes: a class prevents the stability of stability disruption from controlling: another kind of is prevent the correcting property of system parameters substantial deviation permissible value from controlling.The latter comprises limit frequency exception, electric voltage exception, overload and prevention out-of-step operation etc., the all corresponding good several control device of each control objectives, that is this can take different control devices to reach identical control objectives, so there is optimum selection to control device.

The optimal selection problem of control strategy is a very important problem, the effect of execution part after the quality that this part is optimized directly has influence on.It not only will consider interregional mutual coordinative role, also will consider the cooperation control etc. controlled between the degree performed, several control measure.

The preferred model of electric power system stability control optimal policy will consider the determination (comprising safety and stability evaluation and cost function) of optimal objective function and the determination (comprising the negative effect constraint etc. of stability margin, control measure) of constraints.

The preferred target function of control strategy and corresponding constraints are:

$\min J=\underset{i=1}{\overset{m}{\Σ}}\underset{j=1}{\overset{n\left(t\right)}{\Σ}}{C}_{ij}{U}_{ij}$

$s.t.\underset{j=1}{\overset{n\left(t\right)}{\mathrm{\Σ}}}{U}_{ij}={\stackrel{\‾}{\mathrm{\σ}}}_i$

U _ij≤k _ij(i＝1...m，j＝1...n(j))

F(U)＞ε

g(X，U)＝0

h(X，U)≤0

Wherein

J: operating cost minimum target function:

C _ij: the unit operation expense required for j control point taking i-th kind of control measure

U _ij: the controlled quentity controlled variable taking i-th kind of control measure j control point;

M: the control measure number that can take;

The control point number of n (i): the i-th kind of control measure;

the control total quantity of i-th kind of control measure;

K _ij: the maximum controlled quentity controlled variable taking the j control point of i-th kind of control measure;

X: the state variable of system;

U: the control variables of system;

F (U): the stability margin function of corresponding various controlled quentity controlled variable

ε: be a given little positive number;

G (X, U): trend equilibrium equation:

H (X, U): functional inequality retrains;

After fault occurs, according to the operating mode detected and fault form, or various unsafe dynamic behaviour that system occurs, automatically drop into the good optimal control policy of chosen in advance by the computer in system, communication and stability control device.For this type of controls, control time after fault is precious, control opportunity more early, control effects is better, and the Instability of system after fault occurs is very of short duration in addition, may be as short as 200ms, so the direct intervention of the execution of these class control measure no longer scheduled person, rely on various steady control equipment completely to automatically perform, be automatic control, main automatic control measure cut machine, cutting load, off-the-line, quick closing valve, resistance braking etc.

The machine of cutting is unbalanced due to resource distribution, and power center is often away from load center, and this just needs long-distance transmissions electric energy.If emerged in operation direct current locking or important fault of interconnected transmission line, just may cause the problem such as circuit overload, transient stability destruction, the machine of cutting is that the one solved the problem commonly uses measure.In system splitting or when losing a large amount of load, often cause mains frequency higher because of power surplus, at this moment need to excise a part of generated output and carry out blanketing frequency rising.In addition, when system frequency is lower than particular value, also need part of generating units to excise, to protect unit safety and the continuous power supply to important loads such as station services.

By detection failure form, or judge some quantity of state, such as important transmission line three-phase permanent short, Branch Power Flow, generator speed etc., with on the spot or the mode of remote control excise some unit preventing stability disruption, eliminate asynchronous operation mode, limit frequency raises and apparatus overload.The machine of cutting makes unit bear the unexpected change of mechanical load and electrical load, thus creates corresponding impact to generator, prime mover and energy supplying system.For generator, following three problems can be produced: the hypervelocity that (1) causes by cutting machine; (2) thermal stress of load Rapid Variable Design generation; (3) the continuous high-order shaft torque that causes of disturbance.

Cutting load is after losing large power supply suddenly in electrical network, system frequency and voltage will be caused to decline to a great extent, electric power system can be made to lose stable under serious conditions.Cutting load measure is one of the most effective Discrete Control Method of power supply and load balancing in maintenance system, when post-fault system emergent power vacancy, some load in correct excision system can solve following system problem: (1) prevents stability disruption, eliminates asynchronous operation mode; (2) limit frequency and voltage reduce; (3) limiting device overload.

Off-the-line is system when there is asynchronous oscillation, and electric current, voltage and power intense oscillations will occur, and suppress this vibration in time if fail, and just likely have a negative impact to various system equipment, even cause system break-down.Off-the-line refers to and system is divided into some parts of asynchronous operation in suitable section and time, is the important measures eliminated system oscillation and avoid power failure range to expand.

Stability contorting mainly for following system fault condition, and judges when there is following malfunction to start to perform:

(1) chugging occurring the section of contact with foreign countries, makes active power in system occur comparatively serious imbalance, is now perform unit allocation or spatial load forecasting according to the state of electrical network internal power imbalance power and walking direction;

(2) when the external transmission power of contact with foreign countries line reaches stability limit, in district, important load disconnects suddenly, and make system active power occur larger residue, now stability contorting main actions is unit allocation;

(3) when the internal input power of contact with foreign countries line reaches stability limit, in district, vital power supply disconnects suddenly, and make system active power occur larger vacancy, now the main actions of stability contorting is spatial load forecasting.

In stability contorting, other faults (as single-phase fault and reclosing process etc.) do not satisfied condition should not trigger stability contorting action, meanwhile, should arrange a valve limit value P to fault disturbance _{c, set}this considers power disturbance P _cbe less than P _{c, set}time, can not cause extreme shock to system, frequency and voltage does not have too large fluctuation, does not need to adopt stability contorting, and meanwhile, the sensitivity of restriction stability contorting triggers continually to avoid it, is also the object for reducing secondary system disturbance.Therefore, P is worked as _c> P _{c, set}time, start stability contorting, the load in controllable node in system or power supply are operated; And work as P _c> P _{c, set}time, scheduling should not send stability contorting order, should then take other stability contorting measures, P _{c, set}value should have different settings when the different system network architecture and load level, must by off-line simulation calculate provide.

Above-described a kind of stable control method can when electric network fault; in time according to the grid structure of electrical network; search out fault point and failure mode fast; and the control strategy optimizing the best in control strategy is tackled; and adopt different troubleshooting modes according to different failure modes, to prevent not triggering or false triggering of protective device.

Accompanying drawing explanation

Fig. 1 is the control flow of a kind of electric network fault stable control method of the present invention

Embodiment

A kind of electric network fault stable control method, described electric network fault stable control method comprises sets up layering Net Frame of Electric Network, the selection of optimal control policy, and the judgement of failed operation means is selected.

Wherein, setting up layering Net Frame of Electric Network is that the bulk transmission grid needed for Grid survival is incomplete same due under different running method and initial trigger fault condition.Comform in many bulk transmission grid and extract under various operational mode and initial trigger fault condition, Grid survival being played to the critical circuits of effective supporting role, for implementing survivability enhancement measure targetedly, there is important function

Therefore, in order to can location promptly and accurately during electric network fault, need to carry out structuring to electrical network in advance, mainly in four steps.

1) with different levels structural model is set up

On the basis analysing in depth practical problem, each relevant factor is resolved into some levels according to different attribute from top to down, the factors of same layer be subordinated to last layer factor or on upper strata because have impact, simultaneously again the lower one deck of domination factor or be subject to the effect of lower layer factors.The superiors are destination layer, and usually only have 1 factor, orlop is generally scheme or object layer, and can there be one or several level centre.

2) Judgement Matricies

By structure relative Link Importance judgment matrix, determine for last layer time certain factor, the relative importance between any 2 factors of this level.The structure of this judgment matrix shows, the circuit in the larger bulk transmission grid of probability of happening has relatively larger importance degree.

3) Mode of Level Simple Sequence and consistency check thereof

For each judgment matrix, calculate Maximum characteristic root and character pair vector, utilize coincident indicator, random index and Consistency Ratio to do consistency check.If upcheck, characteristic vector (after normalization), is weight vectors: if do not pass through, and need re-construct judgment matrix.

4) total hierarchial sorting and consistency check thereof

Determine the weight vectors of each object of lowermost layer relative to top target, and do consistency check, if upcheck, then the result that can represent according to weight vectors carries out decision-making, otherwise needs rethink model or re-construct judgment matrix.

After obtaining complete divided power system structure in general, electric network composition and the ruuning situation of the known current system of the information obtained is divided, as place, the situation such as scope and the order of severity of fault and fault are normally run or be there occurs to system by failure diagnosis, Identification Division.These information are only had also to be nowhere near as the decision-making of emergency control, also will according to a large amount of metrical informations got from SCADA (supervisory control and data acquisition (SCADA)) system, as active-power P, the variable quantity △ P of active power, slip δ, the variable quantity △ δ of slip, the variable quantity △ I of electric current I and electric current, variable quantity △ U of reactive power Q and voltage U and voltage etc.

The stability contorting of electric power system according to target can be divided into two classes: a class prevents the stability of stability disruption from controlling: another kind of is prevent the correcting property of system parameters substantial deviation permissible value from controlling.The latter comprises limit frequency exception, electric voltage exception, overload and prevention out-of-step operation etc., the all corresponding good several control device of each control objectives, that is this can take different control devices to reach identical control objectives, so there is optimum selection to control device.

The optimal selection problem of control strategy is a very important problem, the effect of execution part after the quality that this part is optimized directly has influence on.It not only will consider interregional mutual coordinative role, also will consider the cooperation control etc. controlled between the degree performed, several control measure.

The preferred model of electric power system stability control optimal policy will consider the determination (comprising safety and stability evaluation and cost function) of optimal objective function and the determination (comprising the negative effect constraint etc. of stability margin, control measure) of constraints.

The preferred target function of control strategy and corresponding constraints are:

$\min J=\underset{i=1}{\overset{m}{\Σ}}\underset{j=1}{\overset{n\left(t\right)}{\Σ}}{C}_{ij}{U}_{ij}$

$s.t.\underset{j=1}{\overset{n\left(t\right)}{\mathrm{\Σ}}}{U}_{ij}={\stackrel{\‾}{\mathrm{\σ}}}_i$

U _ij≤k _ij(i＝1...m，j＝1...n(j))

F(U)＞ε

g(X，U)＝0

h(X，U)≤0

Wherein

J: operating cost minimum target function:

C _ij: the unit operation expense required for j control point taking i-th kind of control measure

U _ij: the controlled quentity controlled variable taking i-th kind of control measure j control point;

M: the control measure number that can take;

The control point number of n (i): the i-th kind of control measure;

the control total quantity of i-th kind of control measure;

K _ij: the maximum controlled quentity controlled variable taking the j control point of i-th kind of control measure;

X: the state variable of system;

U: the control variables of system;

F (U): the stability margin function of corresponding various controlled quentity controlled variable

ε: be a given little positive number;

G (X, U): trend equilibrium equation:

H (X, U): functional inequality retrains;

After fault occurs, according to the operating mode detected and fault form, or various unsafe dynamic behaviour that system occurs, automatically drop into the good optimal control policy of chosen in advance by the computer in system, communication and stability control device.For this type of controls, control time after fault is precious, control opportunity more early, control effects is better, and the Instability of system after fault occurs is very of short duration in addition, may be as short as 200ms, so the direct intervention of the execution of these class control measure no longer scheduled person, rely on various steady control equipment completely to automatically perform, be automatic control, main automatic control measure cut machine, cutting load, off-the-line, quick closing valve, resistance braking etc.

The machine of cutting is unbalanced due to resource distribution, and power center is often away from load center, and this just needs long-distance transmissions electric energy.If emerged in operation direct current locking or important fault of interconnected transmission line, just may cause the problem such as circuit overload, transient stability destruction, the machine of cutting is that the one solved the problem commonly uses measure.In system splitting or when losing a large amount of load, often cause mains frequency higher because of power surplus, at this moment need to excise a part of generated output and carry out blanketing frequency rising.In addition, when system frequency is lower than particular value, also need part of generating units to excise, to protect unit safety and the continuous power supply to important loads such as station services.

By detection failure form, or judge some quantity of state, such as important transmission line three-phase permanent short, Branch Power Flow, generator speed etc., with on the spot or the mode of remote control excise some unit preventing stability disruption, eliminate asynchronous operation mode, limit frequency raises and apparatus overload.The machine of cutting makes unit bear the unexpected change of mechanical load and electrical load, thus creates corresponding impact to generator, prime mover and energy supplying system.For generator, following three problems can be produced: the hypervelocity that (1) causes by cutting machine; (2) thermal stress of load Rapid Variable Design generation; (3) the continuous high-order shaft torque that causes of disturbance.

Cutting load is after losing large power supply suddenly in electrical network, system frequency and voltage will be caused to decline to a great extent, electric power system can be made to lose stable under serious conditions.Cutting load measure is one of the most effective Discrete Control Method of power supply and load balancing in maintenance system, when post-fault system emergent power vacancy, some load in correct excision system can solve following system problem: (1) prevents stability disruption, eliminates asynchronous operation mode; (2) limit frequency and voltage reduce; (3) limiting device overload.

Off-the-line is system when there is asynchronous oscillation, and electric current, voltage and power intense oscillations will occur, and suppress this vibration in time if fail, and just likely have a negative impact to various system equipment, even cause system break-down.Off-the-line refers to and system is divided into some parts of asynchronous operation in suitable section and time, is the important measures eliminated system oscillation and avoid power failure range to expand.

Stability contorting mainly for following system fault condition, and judges when there is following malfunction to start to perform:

(1) chugging occurring the section of contact with foreign countries, makes active power in system occur comparatively serious imbalance, is now perform unit allocation or spatial load forecasting according to the state of electrical network internal power imbalance power and walking direction;

(2) when the external transmission power of contact with foreign countries line reaches stability limit, in district, important load disconnects suddenly, and make system active power occur larger residue, now stability contorting main actions is unit allocation;

(3) when the internal input power of contact with foreign countries line reaches stability limit, in district, vital power supply disconnects suddenly, and make system active power occur larger vacancy, now the main actions of stability contorting is spatial load forecasting.

In stability contorting, other faults (as single-phase fault and reclosing process etc.) do not satisfied condition should not trigger stability contorting action, meanwhile, should arrange a valve limit value P to fault disturbance _{c, set}this considers power disturbance P _cbe less than P _{c, set}time, can not cause extreme shock to system, frequency and voltage does not have too large fluctuation, does not need to adopt stability contorting, and meanwhile, the sensitivity of restriction stability contorting triggers continually to avoid it, is also the object for reducing secondary system disturbance.Therefore, P is worked as _c> P _{c, set}time, start stability contorting, the load in controllable node in system or power supply are operated; And work as P _c> P _{c, set}time, scheduling should not send stability contorting order, should then take other stability contorting measures, P _{c, set}value should have different settings when the different system network architecture and load level, must by off-line simulation calculate provide.

Above-described a kind of stable control method can when electric network fault; in time according to the grid structure of electrical network; search out fault point and failure mode fast; and the control strategy optimizing the best in control strategy is tackled; and adopt different troubleshooting modes according to different failure modes, to prevent not triggering or false triggering of protective device.

The foregoing is only of the present invention and be preferably not limited to the present invention, obviously, those skilled in the art can carry out various change and modification to the present invention and not depart from the spirit and scope of the present invention.Like this, if these amendments of the present invention and modification belong within the scope of the claims in the present invention and equivalent technologies thereof, then the present invention is also intended to comprise these change and modification.

Claims (8)

1. an electric network fault stable control method, is characterized in that, described electric network fault stable control method comprises sets up layering Net Frame of Electric Network, the selection of optimal control policy, and the judgement of failed operation means is selected.

2. a kind of electric network fault stable control method as claimed in claim 1, it is characterized in that, described layering Net Frame of Electric Network of setting up comprises and sets up with different levels structural model, Judgement Matricies, Mode of Level Simple Sequence and consistency check thereof and total hierarchial sorting and consistency check thereof.

3. a kind of electric network fault stable control method as claimed in claim 2, it is characterized in that, described set up with different levels structural model be analyse in depth practical problem basis on, each relevant factor is resolved into some levels according to different attribute from top to down, the factors of same layer be subordinated to last layer factor or on upper strata because have impact, simultaneously again the lower one deck of domination factor or be subject to the effect of lower layer factors.

4. a kind of electric network fault stable control method as claimed in claim 2, is characterized in that, described Judgement Matricies, by structure relative Link Importance judgment matrix, is determined for last layer time certain factor, the relative importance between any 2 factors of this level.

5. a kind of electric network fault stable control method as claimed in claim 2, it is characterized in that, described Mode of Level Simple Sequence and consistency check thereof, for each judgment matrix, calculate Maximum characteristic root and character pair vector, utilize coincident indicator, random index and Consistency Ratio to do consistency check, if upcheck, characteristic vector is weight vectors: if do not pass through, and need re-construct judgment matrix.

6. a kind of electric network fault stable control method as claimed in claim 2, it is characterized in that, described total hierarchial sorting and consistency check thereof are determine the weight vectors of each object of lowermost layer relative to top target, and do consistency check, if upcheck, the result then represented according to weight vectors carries out decision-making, otherwise needs rethink model or re-construct judgment matrix.

7. a kind of electric network fault stable control method as claimed in claim 2, is characterized in that, the selection of described optimal control policy comprises the preferred target function of control strategy and corresponding constraints:

$\min J=\underset{i=1}{\overset{m}{\Σ}}\underset{j=1}{\overset{n\left(t\right)}{\Σ}}{C}_{ij}{U}_{ij}$

$s.t.\underset{j=1}{\overset{n\left(t\right)}{\mathrm{\Σ}}}{U}_{ij}={\stackrel{\‾}{\mathrm{\σ}}}_i$

U _ij≤k _ij(i＝1…m，j＝1…n(i))

F(U)＞ε

g(X，U)＝0

h(X，U)≤0

Wherein

J: operating cost minimum target function:

C _ij: the unit operation expense required for j control point taking i-th kind of control measure

U _ij: the controlled quentity controlled variable taking i-th kind of control measure j control point;

M: the control measure number that can take;

The control point number of n (i): the i-th kind of control measure;

the control total quantity of i-th kind of control measure;

K _ij: the maximum controlled quentity controlled variable taking the j control point of i-th kind of control measure;

X: the state variable of system;

U: the control variables of system;

F (U): the stability margin function of corresponding various controlled quentity controlled variable

ε: be a given little positive number;

G (X, U): trend equilibrium equation:

H (X, U): functional inequality retrains.

8. a kind of electric network fault stable control method as claimed in claim 2, is characterized in that, described stability contorting mainly for following system fault condition, and judges when there is following malfunction to start to perform:

(1) chugging occurring the section of contact with foreign countries, makes active power in system occur comparatively serious imbalance, is now perform unit allocation or spatial load forecasting according to the state of electrical network internal power imbalance power and walking direction;

(2) when the external transmission power of contact with foreign countries line reaches stability limit, in district, important load disconnects suddenly, and make system active power occur larger residue, now stability contorting main actions is unit allocation;

(3) when the internal input power of contact with foreign countries line reaches stability limit, in district, vital power supply disconnects suddenly, and make system active power occur larger vacancy, now the main actions of stability contorting is spatial load forecasting,

In stability contorting, other faults do not satisfied condition should not trigger stability contorting action, meanwhile, arrange a valve limit value P to fault disturbance _{c, set}, work as P _c> P _{c, set}time, start stability contorting, the load in controllable node in system or power supply are operated; And work as P _c< P _{c, set}time, scheduling should not send stability contorting order, should then take other stability contorting measures, P _{c, set}value should have different settings when the different system network architecture and load level, must by off-line simulation calculate provide.