A kind of method assessing wind power influence of fluctuations safe operation of electric network risk
Technical field
The invention belongs to Power System and its Automation technical field, more precisely, the present invention relates to a kind of method assessing wind power influence of fluctuations safe operation of electric network risk.
Background technology
The wave characteristic of wind power is the basic reason that it has an impact to access power network safety operation.When grid connected wind power installed capacity rises to certain scale, the fluctuation that wind power can not be controlled will work the mischief to power network safety operation.The risk of assessment wind power output power influence of fluctuations access power network safety operation, thus take prevention and control measure targetedly ensures that power grid security is reliably dissolved the basis of wind-powered electricity generation.
Mandatory power industry standard " guiding rules of power system safety and stability " specify that the basic demand of operation of power networks, and the safety and stability standard of disturbance ability is born in specification electric power system, provides principle for carrying out electricity net safety stable analytical work.On-line security and stability analysis technology is used widely, according to the power system operating mode that EMS provides, to the forecast failure of specifying, carry out the analytical calculation of safety and stability evaluation and control decision, provide important technical support for management and running personnel control electrical network.The on-line security and stability analysis of current realization is based on deterministic theory, does not take into account wind power and to fluctuate the uncertainty that causes power system operating mode to occur and the impact of wind power fluctuation to electrical network.
Wind turbines precision of prediction of exerting oneself reaches certain level, in conjunction with load prediction, conventional power unit generation schedule and maintenance scheduling, can form future time instance, have the power system operating mode of probability characteristics, can predict wind power fluctuation situation.
Therefore, assessment wind power influence of fluctuations safe operation of electric network risk, thus the technical conditions of evading wind power influence of fluctuations safe operation of electric network risk of adopting an effective measure possess.
Summary of the invention
The object of the invention is: a kind of method assessing wind power influence of fluctuations safe operation of electric network risk is provided, establish technical foundation for carrying out prevention and control wind power influence of fluctuations safe operation of electric network decision in the face of risk targetedly, thus support the safe and reliable large-scale wind power of dissolving of bulk power grid.
The present invention, according to wind power actual measurement and ultra-short term information of forecasting, for adjacent time interval, identifies wind power fluctuation status, is judged as steady fluctuation status or rapid fluctuation state.Can not meet the demands as hazard analysis and HACCP using security margin, according to wind power fluctuation status, choose the appraisal procedure of safe operation of electric network risk.If wind energy turbine set power fluctuation is in steady fluctuation status in electrical network, then only carry out the safe operation of electric network risk assessment after wind power smooth fluctuations; If wind energy turbine set power fluctuation is in rapid fluctuation state in electrical network, then carry out wind power rapid fluctuation affect safe operation of electric network risk assessment and wind power smooth fluctuations after safe operation of electric network risk assessment.Thus, realizing the comprehensive assessment to wind power influence of fluctuations safe operation of electric network risk, providing decision-making foundation for reducing wind power fluctuation to the harmful effect of operation of power networks.
Specifically, the present invention adopts following technical scheme to realize, and comprises the following steps:
1) the wind energy turbine set ultra-short term power prediction information with probability characteristics is collected in control centre, and operation of power networks real measured data, load prediction information, conventional power unit generation schedule information and maintenance scheduling information.
2) after determining to assess the initial time of wind power fluctuation, choose from this moment, continuous print two moment t
iand t
i+1, for each wind energy turbine set, according to the wind power information of actual measurement/prediction, judge wind power fluctuation status.If wind energy turbine set is in power rapid fluctuation state in electrical network, then carry out step 3).If the wind energy turbine set in electrical network is all in the mild fluctuation status of power, then first wind power rapid fluctuation is affected safe operation of electric network value-at-risk RJ
tEbe set to 0, then go to step 5).
Judge that the method for wind power fluctuation status is as follows:
(1) the wind power P in two moment is compared
iand P
i+1, with | P
i-P
i+1| be greater than threshold value ThP as criterion, determine the wind energy turbine set of wind power rapid fluctuation.
Installed capacity is less than to the wind energy turbine set of 500MW, ThP value is 25MW; For the wind energy turbine set of installed capacity more than 500MW, ThP can be taken as P
max* 5%, wherein P
maxit is the installed capacity of wind energy turbine set.
(2) if having the wind power rapid fluctuation of 1 wind energy turbine set at least, then wind power rapid fluctuation state in electrical network is determined; Otherwise, determine the mild fluctuation status of wind power in electrical network.
3) using wind power rapid fluctuation as disturbance, analysis and evaluation electricity net safety stable nargin.Implementation method is as follows:
(1) according to operation of power networks real measured data, load prediction information, conventional power unit generation schedule information and maintenance scheduling information, in conjunction with wind farm power prediction information, the power system operating mode before wind power fluctuation is formed.
(2) for each wind energy turbine set of power rapid fluctuation, according to wind power P
iand P
i+1, with (P
i+1-P
i) be Power Output for Wind Power Field Sudden Changing Rate, form the forecast failure of each wind power fluctuation respectively.
(3) to each forecast failure, based on time-domain-simulation and the safety and stability quantitative analysis of the operating characteristics of considering security stabilization control device/anti-line apparatus in second and third road such as system and low-frequency low-voltage load shedding, transient state and dynamic security stability margin is calculated.
4) rapid fluctuation of analytical calculation wind power affects the value-at-risk of safe operation of electric network.Implementation method is as follows:
(1) for the forecast failure that security margin can not meet the demands, with actual security margin η J
rwith expectation security margin η J
edeviation, by formula (1) calculate affect consequence;
SJ=|ηJ
r-ηJ
e| (1)
(2) in conjunction with the probability P of wind power change
minformation of forecasting, calculates the value-at-risk of wind power rapid fluctuation by formula (2).
RJ=P
m*SJ (2)
(3) safe operation of electric network value-at-risk is affected by wind power rapid fluctuation in formula (3) statistics electrical network.
Wherein, N is the forecast failure quantity number that can not meet the demands using wind power rapid fluctuation as security margin in forecast failure.
5) the electricity net safety stable nargin of operational mode after wind power smooth fluctuations is assessed.Implementation method is as follows:
(1) according to operation of power networks real measured data, load prediction information, conventional power unit generation schedule information and maintenance scheduling information, in conjunction with wind farm power prediction information, form the power system operating mode after wind power fluctuation and probabilistic information, and analytical calculation ground state margin of safety.
(2) according to " guiding rules of power system safety and stability ", forecast failure collection is formed.
(3) to each forecast failure, the operating characteristics of considering security stabilization control device/anti-line apparatus in second and third road such as system and low-frequency low-voltage load shedding carries out time-domain-simulation, based on safety and stability quantitative analysis, calculate static state, transient state and dynamic security stability margin.
6) the safe operation of electric network value-at-risk of operational mode after wind power smooth fluctuations is calculated.Implementation method is as follows:
(1) ground state that can not meet the demands for security margin and forecast failure, with actual security margin η P
rwith expectation security margin η P
edeviation, by formula (4) calculate impact fruit.
SP=|ηP
r-ηP
e| (4)
(2) probability P of each forecast failure is formed according to historical failure statistics
f, in conjunction with the probability P of wind power change
wMinformation of forecasting, calculates the value-at-risk after wind power smooth fluctuations by formula (5).
RP=P
WM*P
F*SP (5)
If ground state margin of safety can not meet the demands, corresponding P
fbe taken as 1.
(3) by wind energy turbine set power fluctuation steadily rear safe operation of electric network value-at-risk in formula (6) statistics electrical network.
Wherein M is the forecast failure number that security margin can not meet the demands, if ground state margin of safety can not meet the demands, M is that forecast failure number adds 1.
7) add up the value-at-risk of wind power influence of fluctuations safe operation of electric network, and carry out Risk-warning.
Wind power rapid fluctuation is affected safe operation of electric network value-at-risk RP
tEwith 6) safe operation of electric network value-at-risk adds up RP after the wind power smooth fluctuations that obtains
tS, obtain wind power and to fluctuate the safe operation of electric network value-at-risk R caused
t; If R
texceed risk threshold value RTh, then carry out the early warning that wind power fluctuation causes safe operation of electric network risk.
The method to set up of risk threshold value RTh is as follows:
RTh=CSTh*NTh*RC (7)
Wherein CSTh is the absolute value of acceptable actual security margin and the deviation expecting security margin; NTh is acceptable actual security margin and expectation security margin number of elements devious; RC is the coefficient embodying risk-bearing degree, if can't stand risk completely, is 0, if completely can risk-bearing, is 1.0.
Beneficial effect of the present invention is as follows: the method for the assessment wind power influence of fluctuations safe operation of electric network risk that the present invention proposes, the risk of power network safety operation under operational mode after safe operation of electric network risk and wind-powered electricity generation smooth fluctuations is affected by comprehensive assessment wind power wave process, can to fluctuate the safe operation of electric network risk caused by comprehensive assessment wind power, there is provided decision-making foundation for reducing wind-powered electricity generation fluctuation to the adverse effect that security of operation causes, thus promote safe and reliable large-scale wind power of dissolving.
Accompanying drawing explanation
Fig. 1 is the flow chart of the inventive method.
Embodiment
With reference to the accompanying drawings 1 and in conjunction with example, the present invention is described in further detail.
The step 1 described in Fig. 1 is that the heart collects Back ground Information in the controlling, comprises the wind energy turbine set ultra-short term power prediction information with probability characteristics, and operation of power networks real measured data, load prediction information, conventional power unit generation schedule information and maintenance scheduling information.
The step 2 described in Fig. 1 is after the initial time determining to assess wind power fluctuation, choose from this moment, continuous print two moment t
iand t
i+1, according to the wind power information of actual measurement/prediction, judge wind energy turbine set power fluctuation state in electrical network.
If wind energy turbine set is in power rapid fluctuation state in electrical network, then carry out step 3).If the wind energy turbine set in electrical network is all in the mild fluctuation status of power, then first wind power rapid fluctuation is affected safe operation of electric network value-at-risk RJ
tEbe set to 0, then go to step 5).
Judge that the method for wind energy turbine set power fluctuation state in electrical network is as follows:
(1) the wind power P in two moment is compared
iand P
i+1, with | P
i-P
i+1| be greater than threshold value as criterion, determine the wind energy turbine set of wind power rapid fluctuation.
Installed capacity is less than to the wind energy turbine set of 500MW, ThP value is 25MW; For the wind energy turbine set of installed capacity more than 500MW, ThP can be taken as P
max* 5%, wherein P
maxit is the installed capacity of wind energy turbine set.
(2) if having the wind power rapid fluctuation of 1 wind energy turbine set at least, then wind power rapid fluctuation state in these two period electrical networks is determined; Otherwise, determine the mild fluctuation status of wind power in these two period electrical networks.
The step 3 described in Fig. 1 is using wind power rapid fluctuation as disturbance, analysis and evaluation electricity net safety stable nargin.Implementation method is as follows:
(1) according to operation of power networks real measured data, load prediction information, conventional power unit generation schedule information and maintenance scheduling information, in conjunction with wind farm power prediction information, the power system operating mode before wind power fluctuation is formed.If the impact of wind power fluctuation under assessment current state, then based on operation real measured data, form the power system operating mode before wind power fluctuation; If the impact of assessment future time instance wind power fluctuation, then according to operation of power networks load prediction information, conventional power unit generation schedule information and maintenance scheduling information, in conjunction with wind farm power prediction information, form the power system operating mode before wind power fluctuation.
(2) for each wind energy turbine set of power rapid fluctuation, according to wind power P
iand P
i+1, with (P
i+1-P
i) be Power Output for Wind Power Field Sudden Changing Rate, form the forecast failure of each wind power fluctuation respectively.
(3) to each forecast failure, based on time-domain-simulation and the safety and stability quantitative analysis of the operating characteristics of considering security stabilization control device/anti-line apparatus in second and third road such as system and low-frequency low-voltage load shedding, transient state and dynamic security stability margin is calculated.
The step 4 described in Fig. 1 is, can not meet the demands as hazard analysis and HACCP using security margin, and the rapid fluctuation of analytical calculation wind power affects the value-at-risk of safe operation of electric network.Implementation method is as follows:
(1) based on step 3) analysis result, for the forecast failure that security margin can not meet the demands, with actual security margin η J
rwith expectation security margin η J
edeviation, by formula (1) calculate affect consequence;
SJ=|ηJ
r-ηJ
e| (1)
(2) in conjunction with the probability P of wind power change
minformation of forecasting, calculates the value-at-risk of wind power rapid fluctuation by formula (2).Wherein P
mthat prediction wind power is by P
ibe changed to P
i+1probability.
RJ=P
m*SJ (2)
(3) safe operation of electric network value-at-risk is affected by wind power rapid fluctuation in formula (3) statistics electrical network.
Wherein, N is the forecast failure quantity number that can not meet the demands using wind power rapid fluctuation as security margin in forecast failure.
The step 5 described in Fig. 1 is, the electricity net safety stable nargin of operational mode after assessment wind power smooth fluctuations.Implementation method is as follows:
(1) according to operation of power networks real measured data, load prediction information, conventional power unit generation schedule information and maintenance scheduling information, in conjunction with wind farm power prediction information, form the power system operating mode after wind power fluctuation and probabilistic information, and analytical calculation ground state margin of safety.The state of the power system operating mode after wind power fluctuation is, the power of wind energy turbine set is the P of prediction
i+1, and no longer change.
(2) according to the three level security stability criterions of " guiding rules of power system safety and stability ", forecast failure collection is formed.
(3) to each forecast failure, the operating characteristics of considering security stabilization control device/anti-line apparatus in second and third road such as system and low-frequency low-voltage load shedding carries out time-domain-simulation, based on safety and stability quantitative analysis, calculate static state, transient state and dynamic security stability margin.
The step 6 described in Fig. 1 is, the safe operation of electric network value-at-risk of operational mode after analytical calculation wind power smooth fluctuations.Implementation method is as follows:
(1) ground state that can not meet the demands for security margin and forecast failure, with actual security margin η P
rwith expectation security margin η P
edeviation, by formula (4) calculate affect consequence.The implication that ground state security margin can not meet the demands is, for step 5) power system operating mode after the fluctuation of the wind power that formed, there is not forecast failure and just there is safety problem.
SP=|ηP
r-ηP
e| (4)
(2) probability P of each forecast failure is formed according to historical failure statistics
f, in conjunction with the probability P of wind power change
wMinformation of forecasting, calculates the value-at-risk after wind power smooth fluctuations by formula (5).
RP=P
WM*P
F*SP (5)
P
wMvalue is that the power of the wind energy turbine set that in electrical network, changed power amplitude is maximum is by P
ibe changed to P
i+1probability; If ground state margin of safety can not meet the demands, corresponding P
fbe taken as 1.
(3) by wind energy turbine set power fluctuation steadily rear safe operation of electric network value-at-risk in formula (6) statistics electrical network.
Wherein M is the forecast failure number that security margin can not meet the demands, if ground state margin of safety can not meet the demands, M is that forecast failure number adds 1.
The step 7 described in Fig. 1 is, the value-at-risk of statistics wind power influence of fluctuations safe operation of electric network, and carries out Risk-warning.
Wind power rapid fluctuation is affected safe operation of electric network value-at-risk RP
tEwith step 6) safe operation of electric network value-at-risk RP after the wind power smooth fluctuations that obtains
tSaccumulative, obtain wind power and to fluctuate the safe operation of electric network value-at-risk R caused
t; If R
texceed risk threshold value RTh, then carry out the early warning that wind power fluctuation causes safe operation of electric network risk.
The method to set up of risk threshold value RTh is as follows:
RTh=CSTh*NTh*RC (7)
Wherein CSTh is the absolute value of acceptable actual security margin and the deviation expecting security margin; NTh is acceptable actual security margin and expectation security margin number of elements devious; RC is the coefficient embodying risk-bearing degree, if can't stand risk completely, is 0, if completely can risk-bearing, is 1.0.
Although the present invention with preferred embodiment openly as above, embodiment is not of the present invention for limiting.Without departing from the spirit and scope of the invention, any equivalence change done or retouching, belong to the protection range of the present invention equally.Therefore the content that protection scope of the present invention should define with the claim of the application is standard.