CN108666988B - Temperature of electric transmission line security alarm and guard method during power system oscillation - Google Patents
Temperature of electric transmission line security alarm and guard method during power system oscillation Download PDFInfo
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- CN108666988B CN108666988B CN201810468871.4A CN201810468871A CN108666988B CN 108666988 B CN108666988 B CN 108666988B CN 201810468871 A CN201810468871 A CN 201810468871A CN 108666988 B CN108666988 B CN 108666988B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
- H02H7/261—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured involving signal transmission between at least two stations
- H02H7/262—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured involving signal transmission between at least two stations involving transmissions of switching or blocking orders
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Abstract
The invention discloses temperature of electric transmission line security alarm and guard methods during a kind of power system oscillation, comprising the following steps: step 1) computing electric power line initial steady state temperature；Step 2) acquires transmission line of electricity oscillating current parameter in real time；Step 3) calculates current cycle of oscillation transmission line of electricity temperature rise response；Step 4) is responded according to transmission line of electricity temperature rise determines its current security level, and is sent to scheduling system；Step 5) judges whether oscillation calms down, if it is not, step 2) is returned to, if so, obtaining transmission line of electricity in the temperature rise response curve in the entire duration of oscillation.The present invention also provides a kind of line protection methods during power system oscillation, during security alarm, when the security level of transmission line of electricity is out-of-limit grade, and starting protection measure.The present invention solves the problems, such as to ignore transmission line safety after out-of-step blocking in the prior art, can be realized security alarm, guarantees the reliable locking of protection before temperature rise is out-of-limit, protection movement tripping in time when safety limit.
Description
Technical field
The present invention relates to a kind of transmission line of electricity real time execution safety state evaluation and guard methods, refer specifically to electric system vibration
Temperature of electric transmission line security alarm and guard method, belong to Relay Protection Technology in Power System field during swinging.
Background technique
Oscillation refers to the phenomenon that system of paired running or power plant lose synchronization, destroy stable operation.In practical electricity
In Force system, oscillation repeatedly occurs in various countries' operation power.It, will be serious when vibrating as a kind of serious systematic failures
The stability of influence system and the safety of operating unit, restrict the power delivery capabilities of power grid.The further expansion of oscillation accident
Easily cause system-wide cascading trip greatly, causes large-area power-cuts, heavy losses are caused to the life and national economy of the people.
To solve oscillation problem, many experts and scholar from different angles, mechanism of production and dynamic characteristic to oscillation,
Influence and strategy etc. inhibited to carry out extensively and in-depth study, existing research be primarily upon oscillation to generating set and after
The malfunction problem of the influence of electric protection, especially duration of oscillation distance protection.Country variant and area are treated in route protection
Oscillation problem difference, for example, the distance protection of India, North America and West Europe power grid does not have effective out-of-step blocking function generally
It can, it is easy to cause false protection, accelerate mains breakdown.False protection problem of some countries and regions when coping with oscillation
On, propose the strategy of " great circle set roundlet ", however for long range heavy load route, this strategy will failure.The relay in China
Protective device has the function of good out-of-step blocking, and the function open in short-term of having in oscillatory process and break down, and realizes
Distance protection reliable locking for a long time under simple oscillatory condition, but considered to whether transmission line of electricity after protection blocking lacks safely,
For duration of oscillation protection, when matter of opening is also there is not yet research.
In consideration of it, needing to pay close attention to security performance when conducting wire during out-of-step blocking bears significantly power swing.Judge defeated
Whether electric line, which is in safe operation state, to depend on the temperature of conducting wire by some safety criterion indexs, the safety of conducting wire
One restricted at first in these three physical quantitys of degree, arc sag, tension, the temperature rise due to caused by electric current joule heat is main
The reason of, therefore in practical projects, generally uniformly considered with the maximum permissible temperature of conducting wire.Conducting wire is flowed through when system oscillation
Oscillating current amplitude be more than normal current manyfold, or even it is quite or also bigger than short-circuit current value with short-circuit current value,
But lacking the research of oscillating current effect lower wire temperature rise response at present, it is likely that route temperature rise is out-of-limit when vibrating, into
And cause arc sag out-of-limit, or accelerate the annealing of route heating power, cause tensile strength to reduce, shorten the route service life, or even for a long time
Route is caused to fuse under oscillating current effect.Therefore, it when system vibrates, needs to check conductor temperature online, provides temperature
Threshold Crossing Alert is risen, and the open distance protection being blocked in time, prevents conducting wire from damaging because of temperature overheating, ensure transmission line of electricity peace
Row for the national games.
Due to transmission line of electricity over long distances, across meteorological subregion the characteristics of, different segment lines are difficult to be introduced directly into there are the temperature difference
The conductor temperature that temperature element is surveyed is as scheduling decision or protection act criterion.Dynamic thermal capacity (Dynamic Thermal
Rating, DTR) technology commented conducting wire maximum current-carrying capability and running temperature based on route real-time external weather condition
Estimate, this kind of technology can provide more objective route operation information for grid operator.The related maximum allowable current-carrying of transmission line of electricity
Amount and running temperature calculation method, more representational is that ieee standard model, CIGRE master pattern and Morgan are mentioned
Method, above-mentioned several method model is similar, and expression is different, but these methods are inherently built upon route
On equation of heat balance basis, it can be used for the running temperature of computing electric power line.
Summary of the invention
In view of the above shortcomings of the prior art, the present invention provides temperature of electric transmission line safety during a kind of power system oscillation
Alarm and guard method, when solving to occur in the prior art non-faulting oscillation, protection ignores after being oscillated lock modules locking
The technical issues of considering transmission line safety, can be realized safe early warning, can guarantee the reliable locking before temperature rise is out-of-limit, and
In route temperature rise safety limit, the open protection being blocked in time, issues trip signal, prevents conducting wire from damaging because of temperature overheating
Wound ensures transmission line safety operation.
In order to solve the above-mentioned technical problem, present invention employs the following technical solutions: during a kind of power system oscillation
Temperature of electric transmission line security alarm method, comprising the following steps:
Step 1): initial steady state temperature when computing electric power line steady-state operation: when acquisition transmission line of electricity steady-state operation
Real-time current and environment parament, weather environment ginseng when according to the conducting wire parameter of transmission line of electricity, transmission line of electricity steady-state operation
Several and real-time current, initial steady state temperature when using steady-state heat balance equation calculation transmission line of electricity steady-state operation；
Step 2): after generating system oscillation, real-time online acquires transmission line of electricity oscillating current parameter and current weather environment
Parameter；
Step 3): the cycle of oscillation number of oscillation is set as N, temperature rise response curve corresponding to current cycle of oscillation is calculated, presses
Such as under type: according to the transmission line of electricity oscillating current parameter and current weather environmental parameter acquired in step 2), and above one shakes
Initial conductor temperature of the conductor temperature as current cycle of oscillation when swinging end cycle, passes through transmission line of electricity transient state thermal balance side
Journey calculates the temperature variation Δ T of current cycle of oscillation transmission line of electricityc；According to the temperature variation Δ T of current cycle of oscillationc
And the initial conductor temperature of current cycle of oscillation, the temperature rise response curve of current cycle of oscillation is constructed, the temperature rise response is bent
Line has reacted the conductor temperature changed over time；Wherein, if current cycle of oscillation is first cycle of oscillation, with defeated in step 1)
Initial steady state temperature when electric line steady-state operation is as initial conductor temperature；
Step 4): according to temperature threshold section by security classification be following three kinds: safety level, safe early warning grade and
Safety limit grade；The security level of transmission line of electricity is judged according to the temperature rise response curve in the duration of oscillation, and transmission line of electricity is current
Security level be sent to scheduling system；
Step 5): judging whether oscillation calms down, if it is not, then returning to step 2)；If so, synchronously completing the power system oscillation phase
Between temperature of electric transmission line security alarm, and obtain transmission line of electricity in the temperature rise response curve in the entire duration of oscillation.
Preferably, the expression formula of steady-state heat balance equation is as follows:
qs+qJ=qc+qr (1)
qs=α DoQssinθs (2)
qJ=I2R(Tc) (3)
qc=9.92 (VDo)0.458(Tc-Ta) (4)
qr=π DoσBε[(Tc+237)4-(Ta+237)4] (5)
In formula (1), qs, qJ, qcAnd qrThe respectively sunshine heating power of conducting wire, joule thermal power, heat loss through convection power and
Heat loss through radiation power；
In formula (2), α is conducting wire sunshine heat absorption coefficient, value 0.5~0.9, D0For conductor diameter, unit m；QsIt is conducting wire
Solar radiation power density in the height above sea level of their location, unit W/m2；θsIt is moved towards for sunlight incident direction and conducting wire
Between angle, unit be °；
In formula (3), I be transmission line of electricity steady-state operation when real-time current virtual value, R (Tc) it be conductor temperature is TcWhen
Unit length alternating current resistance value, unit are Ω/m, can be obtained by linear interpolation；
In formula (4), V is wind speed, unit m/S；TcAnd TaRespectively conductor temperature and conducting wire local environment temperature, unit
For DEG C；
In formula (5), σBIt is Stefan-Boltzmann constant, value is 5.6697 × 10-8, ε is the radiative chain of conductor material
Number；
Real-time current virtual value when transmission line of electricity steady-state operation is a fixed value, seeks the first of route in an iterative manner
Beginning steady temperature assumes that conductor temperature is (T when iteration startsa+ 10) DEG C, in each iteration if thermal balance (qs+qJ-qc-
qr) calculated result be greater than 0, then next iteration is improved on the basis of the conducting wire cut-off temperature of upper primary iteration when starting
Conducting wire assumes temperature, and vice versa, until thermally equilibrated calculated result, close to 0, iteration ends obtain transmission of electricity when steady-state operation
The initial steady state temperature of route.
Preferably, temperature variation Δ TcIt calculates as follows:
Step 301: the oscillating current virtual value I of current cycle of oscillation is calculated using numerical integratingsw, as follows:
Wherein, T is current cycle of oscillation；iswFor oscillating current instantaneous value, i.e., the transmission line of electricity oscillating current acquired in real time
Parameter；t1For the deadline of current cycle of oscillation；
Step 302: calculating the joule thermal power q of current cycle of oscillationJ, as follows:
Wherein, R (Tc) it be conductor temperature is TcWhen unit length alternating current resistance value, unit be Ω/m, be with conductor temperature
The curve that 20 DEG C and 70 DEG C of alternating current resistance value is constituted, is obtained by linear interpolation；
Step 303: the joule thermal power of current cycle of oscillation is substituted into following transmission line of electricity transient state equation of heat balance:
Wherein, m is that unit length is oriented to quality, unit kg/m；C is that the equivalent specific heat of conducting wire holds, unit J/kg
℃；ma、msThe quality of aluminium, Steel material, unit kg/m respectively in unit length conducting wire；ca、csRespectively aluminium, Steel material
Specific heat capacity, unit are J/kg DEG C；
Step 304: using current cycle of oscillation T as time interval Δ t, so that transmission line of electricity transient state equation of heat balance be changed
It is written as:
Wherein, Δ TcTemperature variation of the as current cycle of oscillation relative to a upper cycle of oscillation.
Preferably, the temperature of electric transmission line security alarm method during power system oscillation, the temperature threshold area of safety level
Between be [Ta,TN), the temperature threshold section of safe early warning grade is [TN,TE), the temperature threshold section of safety limit grade is [TE,+
∞), TaFor conducting wire local environment temperature, TNFor conducting wire longtime running maximum permissible temperature, TEFor conducting wire short-time overload temperature.
Preferably, by the current measuring element in the protective relaying device on transmission line of electricity come online real time collecting transmission of electricity
The current parameters of route.
The present invention also provides a kind of line protection methods during power system oscillation, using power train of the invention
When duration of oscillation temperature of electric transmission line security alarm method of uniting carries out security alarm, when the current security level of transmission line of electricity is peace
When complete out-of-limit grade, then show that transmission line of electricity is out-of-limit in duration of oscillation generation temperature rise, starting protection measure；At the same time, judge defeated
It is out-of-limit whether electric line in the duration of oscillation occurs impedance, as long as out-of-limit any one of out-of-limit with the impedance condition of temperature rise meets,
The open distance protection being blocked, issues trip signal.
Compared with prior art, the invention has the following advantages:
1, the present invention solves the technical issues of not solving in the prior art, i.e., how to judge electric system and non-event occurs
When barrier oscillation, the safety of the transmission line of electricity after back-up protection out-of-step blocking, and safety is classified, for different
Security level takes different measures: when the conductor temperature of transmission line of electricity falls into safe early warning threshold interval, then transmission line of electricity
Security level is safe early warning rank, and what is taken is Forewarning Measures, but does not open out-of-step blocking, ensure that duration of oscillation conducting wire temperature
The not yet out-of-limit locking reliable before of degree, realizes protection not malfunction；When the conductor temperature of transmission line of electricity falls into the out-of-limit section of temperature rise, then
The security level of transmission line of electricity is safety limit rank, and what is taken is safeguard measure, i.e., the open distance protection for being oscillated locking,
To cut off the transmission line of electricity overheated by oscillating current effect in time, avoid generation arc sag because caused by temperature is excessively high out-of-limit
And thermal ageing.
2, present invention employs the safeties that conductor temperature carrys out the Comprehensive Evaluation transmission line of electricity duration of oscillation, in order to overcome transmission of electricity
The route difference section temperature difference is big, and is difficult to be introduced directly into conductor temperature that temperature element is surveyed as scheduling decision or protection act
The technical issues of criterion, the present invention contribute to the calculation method of duration of oscillation transmission line of electricity temperature rise response thus, find oscillation period
Between transmission line of electricity temperature rise weak spot, compensate for deficiency in the prior art.
3, the present invention carries out the real-time acquisition of current parameters using protective relaying device original on transmission line of electricity, is not required to increase
Add individual current acquisition equipment, greatly reduces hardware cost and human cost.
4, line protection method combines impedance criterion with temperature criterion during power system oscillation of the invention,
Improve the reliability for judging safety limit rank.
Detailed description of the invention
Fig. 1 is the flow diagram of temperature of electric transmission line security alarm and guard method during merging power system oscillation；
Fig. 2 is the temperature rise response curve example of transmission line of electricity during power system oscillation under different weather environments；
Fig. 3 is the line protection logic diagram of fusion temperature Yu impedance criterion；
Fig. 4 is the line protection modeling example figure of fusion temperature Yu impedance criterion；
Fig. 5 is temperature rise response computation module；
Fig. 6 is the line protection performance chart of fusion temperature Yu impedance criterion.
Specific embodiment
The present invention is described in further detail with preferred embodiment with reference to the accompanying drawing.
As shown in Figure 1, a kind of temperature of electric transmission line security alarm method during power system oscillation, comprising the following steps:
Step 1): initial steady state temperature when computing electric power line steady-state operation: when acquisition transmission line of electricity steady-state operation
Real-time current and environment parament, according to the conducting wire parameter of transmission line of electricity, the real-time gas of power transmission line corridor institute overlay area
Real-time current when as parameter and transmission line of electricity steady-state operation utilizes steady-state heat balance equation calculation transmission line of electricity steady-state operation
When initial steady state temperature；Under steady state operating conditions, temperature of electric transmission line changes, temperature change related to running environment state
Mainly influenced by factors such as current-carrying, wind speed, wind direction, sunshine, temperature.Change environment parament, conducting wire can be obtained in difference
Steady temperature when running under weather environment, conducting wire parameter is as shown in table 1 in present embodiment:
Table 1
Environment parament is as shown in table 2 in present embodiment:
Table 2
The transmission line of electricity current parameters acquired according to conducting wire and environment parament and in real time, seek transmission line of electricity stable state
Initial steady state temperature when operation.
Step 2): after generating system oscillation, real-time online acquires transmission line of electricity oscillating current parameter and current weather environment
Parameter；
Step 3): the cycle of oscillation number of oscillation is set as N, temperature rise response curve corresponding to current cycle of oscillation is calculated, presses
Such as under type: according to the transmission line of electricity oscillating current parameter and current weather environmental parameter acquired in step 2), and above one shakes
Initial conductor temperature of the conductor temperature as current cycle of oscillation when swinging end cycle, passes through transmission line of electricity transient state thermal balance side
Journey calculates the temperature variation Δ T of current cycle of oscillation transmission line of electricityc；According to the temperature variation Δ T of current cycle of oscillationc
And the initial conductor temperature of current cycle of oscillation, the temperature rise response curve of current cycle of oscillation is constructed, the temperature rise response is bent
Line has reacted the conductor temperature changed over time；Wherein, if current cycle of oscillation is first cycle of oscillation, with defeated in step 1)
Initial steady state temperature when electric line steady-state operation is as initial conductor temperature；
Step 4): according to temperature threshold section by security classification be following three kinds: safety level, safe early warning grade and
Safety limit grade；The security level of transmission line of electricity is judged according to the temperature rise response curve in the duration of oscillation, and transmission line of electricity is current
Security level be sent to scheduling system；
Step 5): judging whether oscillation calms down, if it is not, then returning to step 2)；If so, synchronously completing the power system oscillation phase
Between temperature of electric transmission line security alarm, and obtain transmission line of electricity in the temperature rise response curve in the entire duration of oscillation.
The transmission line of electricity oscillating current ginseng acquired based on conducting wire parameter and current weather environmental parameter and real-time online
Number, the temperature rise response changed over time for obtaining the entire duration of oscillation being made of the temperature rise response curve of each cycle of oscillation are bent
Line can obtain " conductor temperature of particular moment ", when specific temperature " reach used time " according to real-time temperature rise response curve
Etc. useful as a result, the safety analysis for transmission line of electricity or even electric system provides important support, while according to real-time online
The temperature rise response curve being calculated carries out duration of oscillation temperature of electric transmission line security alarm.
In present embodiment, the expression formula of steady-state heat balance equation is as follows:
qs+qJ=qc+qr (1)
qs=α DoQssinθs (2)
qJ=I2R(Tc) (3)
qc=9.92 (VDo)0.458(Tc-Ta) (4)
qr=π DoσBε[(Tc+237)4-(Ta+237)4] (5)
In formula (1), qs, qJ, qcAnd qrThe respectively sunshine heating power of conducting wire, joule thermal power, heat loss through convection power and
Heat loss through radiation power；
In formula (2), α is conducting wire sunshine heat absorption coefficient, value 0.5~0.9, D0For conductor diameter, unit m；QsIt is conducting wire
Solar radiation power density in the height above sea level of their location, unit W/m2；θsIt is moved towards for sunlight incident direction and conducting wire
Between angle, unit be °；
In formula (3), I be transmission line of electricity steady-state operation when real-time current virtual value, R (Tc) it be conductor temperature is TcWhen
Unit length alternating current resistance value, unit are Ω/m, can be obtained by linear interpolation；
In formula (4), V is wind speed, unit m/S；TcAnd TaRespectively conductor temperature and conducting wire local environment temperature, unit
For DEG C；
In formula (5), σBIt is Stefan-Boltzmann constant, value is 5.6697 × 10-8, ε is the radiative chain of conductor material
Number；
Real-time current virtual value when transmission line of electricity steady-state operation is a fixed value, seeks the first of route in an iterative manner
Beginning steady temperature assumes that conductor temperature is (T when iteration startsa+ 10) DEG C, in each iteration if thermal balance (qs+qJ-qc-
qr) calculated result be greater than 0, then conducting wire when starting next iteration on the basis of the conducting wire cut-off temperature of upper primary iteration
Assuming that temperature improves 0.3 DEG C, on the contrary then 0.1 DEG C of reduction, until thermally equilibrated calculated result is close to 0, iteration ends are obtained steady
The initial steady state temperature of transmission line of electricity when state is run.
In present embodiment, temperature variation Δ TcIt calculates as follows:
Step 301: the oscillating current virtual value I of current cycle of oscillation is calculated using numerical integratingsw, as follows:
Wherein, T is current cycle of oscillation；iswFor oscillating current instantaneous value, i.e., the transmission line of electricity oscillating current acquired in real time
Parameter；t1For the deadline of current cycle of oscillation；
Step 302: calculating the joule thermal power q of current cycle of oscillationJ, as follows:
Wherein, R (Tc) it be conductor temperature is TcWhen unit length alternating current resistance value, unit be Ω/m, be with conductor temperature
The curve that 20 DEG C and 70 DEG C of alternating current resistance value is constituted, is obtained by linear interpolation；
Step 303: the joule thermal power of current cycle of oscillation is substituted into following transmission line of electricity transient state equation of heat balance:
Wherein, m is that unit length is oriented to quality, unit kg/m；C is that the equivalent specific heat of conducting wire holds, unit J/kg
℃；ma、msThe quality of aluminium, Steel material, unit kg/m respectively in unit length conducting wire；ca、csRespectively aluminium, Steel material
Specific heat capacity, unit are J/kg DEG C；
Step 304: using current cycle of oscillation T as time interval Δ t, so that transmission line of electricity transient state equation of heat balance be changed
It is written as:
Wherein, Δ TcTemperature variation of the as current cycle of oscillation relative to a upper cycle of oscillation.
Acquire the oscillation electricity of transmission line of electricity in real time by the current measuring element in the protective relaying device on transmission line of electricity
Parameter is flowed, and acts on lower transmission line of electricity temperature rise method of response calculation using oscillating current of the invention, to acquire general oscillation
It transmits electricity under situation (two sides system oscillation angle variation range is smaller, and hunting angle changes between 0 °~60 °) and serious oscillatory condition
Route is 1) and 2) shown in the temperature rise response curve such as Fig. 2 under different weather environments.As it can be seen that being suitable for either temperature in spring and autumn
Under (20 DEG C) or summer high temperature (40 DEG C) environmental condition, conducting wire temperature rise is very fast when system oscillation；In summer calm situation very
It is extremely more than conducting wire maximum permissible temperature (100 DEG C) in short-term.In a practical situation, the duration of oscillation may be than 60S long, conducting wire
Temperature can reach higher value.Therefore under the action of oscillating current, conductor temperature will be more than safe temperature quickly, if vibration
It swings and continues, then conductor temperature will continue to rise, ultimately cause transmission line malfunction.
In present embodiment, temperature of electric transmission line security alarm method during power system oscillation, safety level
Temperature threshold section is [Ta,TN), the temperature threshold section of safe early warning grade is [TN,TE), the temperature threshold area of safety limit grade
Between be [TE,+∞), TaFor conducting wire local environment temperature, TNFor conducting wire longtime running maximum permissible temperature, TEFor conducting wire mistake in short-term
Carry temperature.
The present invention also provides a kind of line protection method during power system oscillation, relay protective scheme block diagram such as Fig. 3
Shown, protection modeling exemplary diagram such as Fig. 4, the temperature rise response computation module in protection modeling example is as shown in figure 5, using the present invention
Power system oscillation during temperature of electric transmission line security alarm method carry out security alarm when, when the current safety of transmission line of electricity
When rank is safety limit grade, then show that transmission line of electricity is out-of-limit in duration of oscillation generation temperature rise, starting protection measure；It is same with this
When, judge whether transmission line of electricity occurs that impedance is out-of-limit in the duration of oscillation, i.e. the I section of distance protection on transmission line of electricity and II sections are
No generation impedance is out-of-limit, as long as meeting in out-of-limit any one of out-of-limit with the impedance condition of temperature rise, the open distance being blocked
Protection issues trip signal.
Known to:
1) electric current of duration of oscillation protection installation place with the change generating period of frequency variation, such as 1) institute in figure
Show, the amplitude of oscillating current is almost twice of rated current, or even suitable with short-circuit current value, therefore under oscillating current effect
The temperature rise response of conducting wire can not be ignored.
2) since the duration of oscillation protects the variation of voltage and current all generating periods of installation place, the period of impedance
Property variation cause the variation of the action signal of distance relay also generating period to illustrate not take oscillation as shown in figure 2)
Locking, distance protection will malfunction, this is consistent with theory analysis.
3) to prevent duration of oscillation false protection, out-of-step blocking module is added to realize the protection in the duration of oscillation firmly
Locking realizes duration of oscillation protection not malfunction as shown in figure 3).
4) however under the collective effect of oscillating current and outside weather environment, it is more likely that duration of oscillation power transmission line occur
Road temperature rise is out-of-limit, and then causes arc sag out-of-limit, accelerates the annealing of route heating power, largely effects on the service life of transmission line of electricity, unfavorable
It is run in transmission line safety.From in figure 4) it is found that be under the weather environment of summer calm high temperature due to transmission line of electricity, due to
The joule heating effect of oscillating current, conductor temperature are permitted more than transmission line of electricity longtime running highest in a relatively short period of time (7.297S)
Perhaps temperature TN(70 DEG C), in 45.35S more than the short-time overload temperature T of transmission line of electricityE(100 DEG C), if oscillation continues,
It very likely will cause route damage.
5) line protection method during application power system oscillation proposed by the invention, as shown in figure 5), online
Protection is firmly latched by road temperature before being not up to its short-time overload temperature, the snap action if route temperature rise is out-of-limit, in time
The excision out-of-limit route of temperature rise, protection circuit due to oscillating current effect are not damaged by hyperthermia and superheating.Meanwhile the present invention is mentioned
Temperature rise response computation speed can meet the requirement of protection act time limit, demonstrate the feasibility and validity of proposed method.
Temperature of electric transmission line security alarm and guard method, utilize conducting wire during power system oscillation provided by the present invention
Temperature is observed and judges to the security performance of transmission line of electricity, is based on transient state equation of heat balance real-time online computing electric power line
Running temperature combines temperature criterion with impedance criterion, can both be become according to the variation of temperature rise response prediction conducting wire security performance
Gesture, and the ability of transmission line of electricity tolerance overcurrent can be sufficiently excavated, decision-making foundation is provided for protection act and system call, guarantees line
Action message is protected when the failure of road, is guaranteed the not yet out-of-limit locking reliable before of duration of oscillation conductor temperature, is realized protection not malfunction；
The route that timely excision is overheated by oscillating current effect if route temperature rise is out-of-limit, protection circuit are not damaged.
Claims (6)
1. a kind of temperature of electric transmission line security alarm method during power system oscillation, it is characterised in that: the following steps are included:
Step 1): initial steady state temperature when computing electric power line steady-state operation: real-time when acquisition transmission line of electricity steady-state operation
Electric current and environment parament, environment parament when according to the conducting wire parameter of transmission line of electricity, transmission line of electricity steady-state operation with
Real-time current, initial steady state temperature when using steady-state heat balance equation calculation transmission line of electricity steady-state operation；
Step 2): after generating system oscillation, real-time online acquires transmission line of electricity oscillating current parameter and current weather environmental parameter；
Step 3): setting the cycle of oscillation number of oscillation as N, calculate temperature rise response curve corresponding to current cycle of oscillation, by as follows
Mode: according to the transmission line of electricity oscillating current parameter and current weather environmental parameter acquired in step 2), and the above oscillation is all
Initial conductor temperature of the conductor temperature as current cycle of oscillation at the end of phase passes through transmission line of electricity transient state equation of heat balance, meter
Calculate the temperature variation Δ T of current cycle of oscillation transmission line of electricityc；According to the temperature variation Δ T of current cycle of oscillationcAnd
The initial conductor temperature of current cycle of oscillation, constructs the temperature rise response curve of current cycle of oscillation, the temperature rise response curve is anti-
The conductor temperature changed over time is answered；Wherein, if current cycle of oscillation is first cycle of oscillation, with power transmission line in step 1)
Initial steady state temperature when the steady-state operation of road is as initial conductor temperature；
Step 4): according to temperature threshold section by security classification be following three kinds: safety level, safe early warning grade and safety
Out-of-limit grade；Judge the security level of transmission line of electricity according to the temperature rise response curve of duration of oscillation transmission line of electricity, and by transmission line of electricity
Current security level is sent to scheduling system；
Step 5): judging whether oscillation calms down, if it is not, then returning to step 2)；If so, defeated during synchronously completing power system oscillation
The alarm of electric line temperature safety, and transmission line of electricity is obtained in the temperature rise response curve in the entire duration of oscillation.
2. temperature of electric transmission line security alarm method during power system oscillation according to claim 1, it is characterised in that:
The expression formula of steady-state heat balance equation is as follows:
qs+qJ=qc+qr (1)
qs=α D0Qssinθs (2)
qJ=I2R(Tc) (3)
qc=9.92 (VD0)0.458(Tc-Ta) (4)
qr=π D0σBε[(Tc+237)4-(Ta+237)4] (5)
In formula (1), qs, qJ, qcAnd qrThe respectively sunshine heating power of conducting wire, joule thermal power, heat loss through convection power and radiation
Heat radiation power；
In formula (2), α is conducting wire sunshine heat absorption coefficient, value 0.5~0.9, D0For conductor diameter, unit m；QsIt is locating for conducting wire
Solar radiation power density in regional height above sea level, unit W/m2；θsIt is pressed from both sides between sunlight incident direction and conducting wire trend
Angle, unit are °；
In formula (3), I be transmission line of electricity steady-state operation when real-time current virtual value, R (Tc) it be conductor temperature is TcWhen unit
Length alternating current resistance value, unit are Ω/m, can be obtained by linear interpolation；
In formula (4), V is wind speed, unit m/S；TcAnd TaRespectively conductor temperature and conducting wire local environment temperature, unit are DEG C；
In formula (5), σBIt is Stefan-Boltzmann constant, value is 5.6697 × 10-8, ε is the radiation coefficient of conductor material；
Real-time current virtual value when transmission line of electricity steady-state operation is a fixed value, seeks the initial steady of route in an iterative manner
State temperature assumes that conductor temperature is (T when iteration startsa+ 10) DEG C, in each iteration if thermal balance (qs+qJ-qc-qr)
Calculated result is greater than 0, then conducting wire when next iteration starts is improved on the basis of the conducting wire cut-off temperature of upper primary iteration
Assuming that temperature, vice versa, until thermally equilibrated calculated result, close to 0, iteration ends obtain transmission line of electricity when steady-state operation
Initial steady state temperature.
3. temperature of electric transmission line security alarm method during power system oscillation according to claim 1, it is characterised in that:
Temperature variation Δ TcIt calculates as follows:
Step 301: the oscillating current virtual value I of current cycle of oscillation is calculated using numerical integratingsw, as follows:
Wherein, T is current cycle of oscillation；iswFor oscillating current instantaneous value, i.e., the transmission line of electricity oscillating current parameter acquired in real time；
t1For the end time of current cycle of oscillation；
Step 302: calculating the joule thermal power q of current cycle of oscillationJ, as follows:
Wherein, R (Tc) it be conductor temperature is TcWhen unit length alternating current resistance value, unit be Ω/m, with conductor temperature be 20 DEG C
With the curve of 70 DEG C of alternating current resistance value composition, obtained by linear interpolation；
Step 303: the joule thermal power of current cycle of oscillation is substituted into following transmission line of electricity transient state equation of heat balance:
Wherein, m is that unit length is oriented to quality, unit kg/m；C is that the equivalent specific heat of conducting wire holds, and unit is J/kg DEG C；ma、
msThe quality of aluminium, Steel material, unit kg/m respectively in unit length conducting wire；ca、csThe respectively specific heat capacity of aluminium, Steel material,
Unit is J/kg DEG C；
Step 304: using current cycle of oscillation T as time interval Δ t, so that transmission line of electricity transient state equation of heat balance be rewritten
Are as follows:
Wherein, Δ TcTemperature variation of the as current cycle of oscillation relative to a upper cycle of oscillation.
4. temperature of electric transmission line security alarm method during power system oscillation according to claim 1, it is characterised in that:
The temperature threshold section of safety level is [Ta,TN), the temperature threshold section of safe early warning grade is [TN,TE), the temperature of safety limit grade
Degree threshold interval is [TE,+∞), TaFor conducting wire local environment temperature, TNFor conducting wire longtime running maximum permissible temperature, TETo lead
Line short-time overload temperature.
5. temperature of electric transmission line security alarm method during power system oscillation according to claim 1, it is characterised in that:
The current parameters of transmission line of electricity are acquired by the current measuring element real-time online in the protective relaying device on transmission line of electricity.
6. a kind of line protection method during power system oscillation, it is characterised in that: using institute in Claims 1-4
When temperature of electric transmission line security alarm method during the power system oscillation stated carries out security alarm, when transmission line of electricity is current
When security level is safety limit grade, then show that transmission line of electricity is out-of-limit in duration of oscillation generation temperature rise, then starting protection measure；With
It is out-of-limit to judge whether transmission line of electricity in the duration of oscillation occurs impedance simultaneously for this, if temperature rise it is out-of-limit it is out-of-limit with impedance in it is any one
Item condition meets, then the open distance protection being blocked, issues trip signal.
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| CN102313853A (en) * | 2011-08-02 | 2012-01-11 | 广东电网公司电力科学研究院 | System for measuring and calculating dynamic transmission capacity of high voltage transmission line and method thereof |
| CN105449669A (en) * | 2015-12-04 | 2016-03-30 | 国网山东省电力公司电力科学研究院 | Power system emergency control optimization method considering power transmission line temperature characteristic |
| CN107196277A (en) * | 2017-06-02 | 2017-09-22 | 重庆大学 | The active heat protection method of transmission line of electricity predicted based on electric current tolerance time |
| CN107863756A (en) * | 2017-09-29 | 2018-03-30 | 西安工程大学 | The rotation-clogging protection method of high-tension switch cabinet electric chassis in-car direct current generator |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102313853A (en) * | 2011-08-02 | 2012-01-11 | 广东电网公司电力科学研究院 | System for measuring and calculating dynamic transmission capacity of high voltage transmission line and method thereof |
| CN105449669A (en) * | 2015-12-04 | 2016-03-30 | 国网山东省电力公司电力科学研究院 | Power system emergency control optimization method considering power transmission line temperature characteristic |
| CN107196277A (en) * | 2017-06-02 | 2017-09-22 | 重庆大学 | The active heat protection method of transmission line of electricity predicted based on electric current tolerance time |
| CN107863756A (en) * | 2017-09-29 | 2018-03-30 | 西安工程大学 | The rotation-clogging protection method of high-tension switch cabinet electric chassis in-car direct current generator |
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