CN102540077A - Method for judging load shedding of electric power system unit on basis of local electric quantity - Google Patents
Method for judging load shedding of electric power system unit on basis of local electric quantity Download PDFInfo
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- CN102540077A CN102540077A CN2012100373667A CN201210037366A CN102540077A CN 102540077 A CN102540077 A CN 102540077A CN 2012100373667 A CN2012100373667 A CN 2012100373667A CN 201210037366 A CN201210037366 A CN 201210037366A CN 102540077 A CN102540077 A CN 102540077A
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Abstract
The invention relates to a method for judging load shedding of an electric power system unit on the basis of local electric quantity. Running current information and power information of the unit before startup are firstly preserved; through judging whether active power rapidly declines or not in a disturbing process, the absolute value of the active power after the disturbance is finished is judged, the absolute value of an active current after the disturbance is finished is judged and whether the system frequency gradually declines or not in the disturbing process is judged; if conditions of all above steps are satisfied, the unit is judged as load shedding after a time of Ts1 is delayed. According to the method, the unit is judged as load shedding by relying on the local electric quantity, so the problem that the closure of a main throttle valve of a steam turbine cannot be timely distinguished by relying on existing tripping criteria is solved, various load shedding processes such as tripping of a gate out switch of the unit, the closure of the throttle valve, and the like can be quickly distinguished, the method has strong adaptability and high reliability and can be perfectly matched with a low cycle device, and the improvement of the automaticity and the efficiency is facilitated.
Description
Technical field
The invention belongs to the power system automation technology field, relate to a kind of unit removal of load criterion, specifically is a kind of electric system unit removal of load determination methods based on local electric parameters.
Background technology
In recent years; In Hainan, outlying provinces such as Xinjiang, Tibet " the big little net of machine " electric system ubiquity still; This type net capacity is less, and texture ratio is weak, and the bigger unit of capacity is installed in the net; The safety and stability problem of system is outstanding, can not satisfy the relevant criterion requirement of " power system safety and stability guide rule ".Special, taking place often to bring the power shortage large percentage after the big unit removal of load,, cause mains breakdown easily if can not in time discern and take effective safety and stability control measure.Therefore, research electric system unit removal of load criterion is very necessary.
Cause the reason of Turbo-generator Set removal of load mainly to be divided into two types, the one, unit or main transformer gate out switch trip suddenly, and unit load can't normally be exported; The 2nd, auxiliary system faults such as coal pulverizer, excitation cause the protection action, close the steam turbine main inlet throttle-stop valve.
Along with the region security as defence line, electrical network second road is stablized greatly developing of control; Stablize aspect the control in the generating plant; To the influence control of mains frequency voltage, therefore most of stability control device has all been considered the criterion to unit tripping when generally all having considered unit tripping (first type removal of load).But often owe in consideration for unit excitation system, coal mill system and other auxiliary system accidents such as the quick removal of load of unit that causes, unit quick closing valve porthole that break down; Often think that it and unit tripping have identical transient state process, therefore to second type removal of load employing and first type the same criterion of removal of load.
Criterion to unit tripping is at present:
1, sudden change amount starts;
2, power before the accident | P_|＞Ps1 (definite value);
3, current changing rate in the accident process | Δ I|＞Δ Is (definite value);
4, power after the accident | Pt|≤Ps2 (definite value);
5, trip signal (selecting for use) is arranged;
6, biphase current effective value I≤Is1 (definite value) is arranged after the accident;
Device promptly is judged to unit tripping after starting the back and satisfying above condition Ts1 (definite value) time-delay simultaneously.
In fact, theoretical analysis and on-the-spot practical operation situation all prove, electric parameters temporal variations and tripping operation process have significantly differently in the unit quick closing valve porthole process, adopt the tripping operation criterion often can't judge unit quick closing valve porthole removal of load process.During power falls in unit quick closing valve porthole; Often because the influence of excitation system; Usually can occur the unit electric current behind the quick closing valve porthole and descend slowly even the phenomenon that goes up not down, not satisfy above-mentioned unit tripping criterion, cause device can not in time discern and take control measure.
On-the-spot ruuning situation shows; Because the too complicated operational management regulation of being correlated with that perhaps do not meet of wiring; Safety stabilization control system often can't insert the position signalling of steam turbine protection actuating signal and main inlet throttle-stop valve for the judgement of unit removal of load, can only carry out the judgement of unit removal of load through electric parameters.
Summary of the invention
The objective of the invention is to the deficiency of prior art and a kind of electric system unit removal of load determination methods based on local electric parameters is provided; Rely on local electric parameters to judge the unit removal of load, solved existing tripping operation criterion and can't in time discern the problem of closing the steam turbine main inlet throttle-stop valve, can the outlet of quick identification unit switch trip, close various removal of load processes such as porthole; It is strong to have adaptability; Reliability is high, can realize and low all device perfect cooperations, helps improving automaticity and efficient.
The technical scheme that the present invention adopted:
A kind of electric system unit removal of load determination methods based on local electric parameters comprises the following steps:
1, at first the detection power variable quantity starts, and record starts constantly, unit operation current information, power information and system frequency information before preservation starts;
2, set active power definite value Δ Pss according to the electrical network actual conditions; Quantity of information according to the step 1) preservation; Judge whether active power the process that descends rapidly occurs in the perturbation process; If the active power slippage reaches setting value Δ Pss and then continues step 3),, then declare and removal of load do not occur if do not reach.
The minimum technology value of exerting oneself of 3, getting unit operation is set at active power absolute value definite value PS2; According to the quantity of information that step 1) is preserved, judge that disturbance finishes back active power absolute value, then continues step 4) if be less than or equal to setting value PS2; If do not reach, then declare and removal of load do not occur.
The minimum current value of exerting oneself of 4, getting unit operation is set at active current absolute value definite value IS2; Quantity of information according to the step 1) preservation; Judge that disturbance finishes back active current absolute value; If have at least two to be less than or equal to setting value IS2 mutually and then to continue step 5),, then declare and removal of load do not occur if do not reach.
5, according to electrical network actual conditions initialization system frequency definite value FGQM; According to the quantity of information that step 1) is preserved, judge system frequency in the perturbation process, if frequency progressively drops to and is less than or equal to setting value FGQM and then continues step 6); If system frequency progressively descends, then declare and removal of load do not occur.
6, satisfy above condition in steps, be judged as the unit removal of load behind the Ts1 that then delays time.
Among the present invention, if unit generation removal of load to be detected, then electric parameters should have following characteristic during the accident, and is as shown in Figure 1:
(1) in the accident process, voltage keep basically stablize constant.
(2) for first type removal of load, power moment drops near 0 about 20ms of duration in the accident process; And for second type removal of load, along with main inlet throttle-stop valve is closed, power progressively drops near 0, continues about 300～500ms, and this process is considerably slower than the tripping operation process, but faster than normal load adjustment.In fact, the unit pass porthole time to various capacity in People's Republic of China's power industry standard " Steam Turhine Adjustment control system test guide rule " has provided clear and definite requirement, and is as shown in table 1.
Table 1 unit closes the porthole time standard
(3) for first type removal of load, electric current moment drops near 0 about 20ms of duration; And for second type removal of load, electric current at first faster descends, and speed is consistent with the power decline rate, is slower than the tripping operation process, but the back is because the influence of excitation system, and electric current can slowly descend, even slowly descends after raising on the contrary again.
(4) behind the porthole of pass, because vacancy appears in system power, progressively descending has appearred in system frequency.
Under (5) two kinds of situation after the accident active current all can keep descending synchronously and maintaining a less value with power.
In view of the above, step 1) power variation startup determination methods is: detect current active power P in real time
tWith T active power P before second
1-TDifference, if its absolute value then starts decision procedure continuously for several times greater than definite value Δ PS; The setting of definite value Δ PS then should guarantee to escape under the prerequisite of normal load fluctuation and Load Regulation suitably less, to guarantee sensitivity.
Step 2) reflected the power shortage that causes after the unit removal of load, can set Δ Pss (definite value) according to the power shortage that system can bear.
Step 3), 4) reflected stable state electric parameters after the unit removal of load, theoretical value is 0, escapes the measuring error after the removal of load, and definite value PS2 can be set at 3%～5% of rated power, and corresponding definite value IS2 also can set in view of the above; Partly close for porthole, these two definite values will be set according to actual conditions.
Step 5) has reflected the influence that system is caused after the unit removal of load, can set FGQM (definite value) according to the frequency slippage that system can bear, but notes with system low all devices and match.
Step 6) has guaranteed device in the non-removal of load of unit (like oscillation of power etc.) and power zero passage and measure reliably not malfunction when disturbing, and the TSI definite value was the bigger the better in the time that system can bear, but notes with system low all devices and match.
The present invention relies on local electric parameters to judge the unit removal of load; Solve existing tripping operation criterion and can't in time discern the problem of closing the steam turbine main inlet throttle-stop valve; Can the outlet of quick identification unit switch trip, close various removal of load processes such as porthole, it is strong to have adaptability, and reliability is high; Can realize and low all device perfect cooperations, help improving automaticity and efficient.
Description of drawings
Fig. 1 is a crucial electric parameters variation diagram in the unit removal of load process.
Fig. 2 is a unit removal of load criterion logic diagram.
Fig. 3 is the dynamic simulation test illustraton of model.
Fig. 4 is record ripple figure behind the unit quick closing valve porthole.
Embodiment
2 couples of the present invention further describe below in conjunction with accompanying drawing.Find out that from accompanying drawing 2 device is gathered behind the current and voltage quantities at first electric parameters such as calculating voltage current effective value, active power, active current;
If device is not activated, then start according to T temporal power variable quantity judgment means, the difference of the power before current active power and the Ts is greater than definite value Δ Ps (generally be set at rated power 10% between), then thinks the power variation startup behind the continuous 5ms.
(keep the 5s time) behind the entering starting state, note the active power P before starting
-1s
Start the back and judge power slippage, i.e. current power P in the start-up course
kWith power P before the startup
-1sPoor | Δ P|=|P
k-P
-1s| whether does>=Δ Pss (definite value) satisfy? Then unit removal of load delay counter is not subtracted 1 if do not satisfy, jump out this and interrupt judging.
After satisfying condition, then detect electric parameters such as active current in the perturbation process, active power, if active power | P
k|＜Ps2 (definite value), two phase active currents then continue to judge the unit removal of load, otherwise unit removal of load delay counter are subtracted 1 less than IS1 (definite value), jump out this and interrupt judging.
Next whether the detection system frequency descends, and then unit removal of load delay counter is not subtracted 1 if descend, and jumps out this and interrupts judging.Then continue the unit removal of load judges if descended.
After above-mentioned condition all satisfied, unit removal of load delay counter added 1, after the removal of load time-delay is greater than Ts1 (definite value), was judged as the unit removal of load.
Test:
This criterion has been passed through dynamic simulation test, and test model is shown in accompanying drawing 3, and test unit is contained in #1 unit main transformer high-pressure side.Lift a demonstration test example description criterion mechanism.
Demonstration test example: after the quick closedown of test simulation unit main inlet throttle-stop valve; Unit active power drops to 7.894MW from 104.217MW, and A, B, C three-phase current drop to 0.086A, 0.087A and 0.063A system frequency from 0.616A, 0.587A and 0.574A respectively and drop to 49.450Hz from the normal frequency 50Hz of system.Data variation sees accompanying drawing 4 for details.
Criterion differentiation process is: after the quick closedown of unit main inlet throttle-stop valve, the detection power variable quantity starts, and record starts constantly, unit operation current information (0.616A, 0.587A and 0.574A) and power information (104.217MW) before preservation starts.Along with unit removal of load process continues to carry out, the process that descends rapidly appears in unit active power, and unit active power drops to 7.894MW from 104.217MW, and slippage reaches the total slippage setting value of power of the assembling unit Δ Pss (50MW); After the unit removal of load, the active power absolute value 7.894MW of unit is less than power definite value setting value PS2 (30MW) after the accident; And unit active current absolute value has two at least smaller or equal to setting value IS2 (0.1A); Simultaneously, the system frequency of electrical network also progressively descends, and mains frequency is lower than setting value 49.5Hz.If satisfy above condition in steps, at this moment, device is judged as the unit removal of load, and in the test, device has sent actuating signal, sees accompanying drawing 4.
Claims (1)
1. the electric system unit removal of load determination methods based on local electric parameters is characterized in that, comprises the following steps:
1), at first the detection power variable quantity starts, the record startup moment, unit operation current information, power information and system frequency information before preservation starts;
2), set active power definite value Δ Pss according to the electrical network actual conditions; Quantity of information according to the step 1) preservation; Judge whether active power the process that descends rapidly occurs in the perturbation process; If the active power slippage reaches setting value Δ Pss and then continues step 3),, then declare and removal of load do not occur if do not reach.
The minimum technology value of exerting oneself of 3), getting unit operation is set at active power absolute value definite value PS2; According to the quantity of information that step 1) is preserved, judge that disturbance finishes back active power absolute value, then continues step 4) if be less than or equal to setting value PS2; If do not reach, then declare and removal of load do not occur.
The minimum current value of exerting oneself of 4), getting unit operation is set at active current absolute value definite value IS2; Quantity of information according to the step 1) preservation; Judge that disturbance finishes back active current absolute value; If have at least two to be less than or equal to setting value IS2 mutually and then to continue step 5),, then declare and removal of load do not occur if do not reach.
5), according to electrical network actual conditions initialization system frequency definite value FGQM; According to the quantity of information that step 1) is preserved, judge system frequency in the perturbation process, if frequency progressively drops to and is less than or equal to setting value FGQM and then continues step 6); If system frequency progressively descends, then declare and removal of load do not occur.
6), satisfy above condition in steps, be judged as the unit removal of load behind the Ts1 that then delays time.
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| CN103501007A (en) * | 2013-09-30 | 2014-01-08 | 南京南瑞集团公司 | Low-frequency and low-voltage load reduction control method considering comprehensive load regulation characteristic |
| CN104748101A (en) * | 2015-02-04 | 2015-07-01 | 山东电力建设第三工程公司 | Control method for load shedding house supply |
| CN104820158A (en) * | 2015-04-30 | 2015-08-05 | 国家电网公司 | Direct-current broken-line fault determination method of flexible direct-current power transmission system |
| CN107654265A (en) * | 2017-09-22 | 2018-02-02 | 贵州电网有限责任公司电力科学研究院 | The control method of steam turbine pitch quick closing valve system based on the fault critical mute time |
| CN108390600A (en) * | 2018-02-08 | 2018-08-10 | 国家电网公司东北分部 | The guard method of power of the assembling unit bust and its application system |
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103501007A (en) * | 2013-09-30 | 2014-01-08 | 南京南瑞集团公司 | Low-frequency and low-voltage load reduction control method considering comprehensive load regulation characteristic |
| CN103501007B (en) * | 2013-09-30 | 2016-02-24 | 国家电网公司 | A kind of low-frequency and low-voltage load-reducing control method taking into account load comprehensive adjustment characteristic |
| CN104748101A (en) * | 2015-02-04 | 2015-07-01 | 山东电力建设第三工程公司 | Control method for load shedding house supply |
| CN104820158A (en) * | 2015-04-30 | 2015-08-05 | 国家电网公司 | Direct-current broken-line fault determination method of flexible direct-current power transmission system |
| CN104820158B (en) * | 2015-04-30 | 2017-11-21 | 国家电网公司 | A kind of flexible direct current power transmission system direct current disconnection fault determination methods |
| CN107654265A (en) * | 2017-09-22 | 2018-02-02 | 贵州电网有限责任公司电力科学研究院 | The control method of steam turbine pitch quick closing valve system based on the fault critical mute time |
| CN108390600A (en) * | 2018-02-08 | 2018-08-10 | 国家电网公司东北分部 | The guard method of power of the assembling unit bust and its application system |
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Effective date of registration: 20140115 Address after: 570203 No. 34, Fu Hai Road, Haikou, Hainan Applicant after: Hainan Grid Co., Ltd. Applicant after: NARI Technology Development Co., Ltd. Address before: 570203 No. 34, Fu Hai Road, Haikou, Hainan Applicant before: Hainan Grid Co., Ltd. Applicant before: State Grid Electric Power Research Insititute |
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Application publication date: 20120704 |