CN111130144B - Small hydropower station quick grid connection method considering deviation and trend change - Google Patents
Small hydropower station quick grid connection method considering deviation and trend change Download PDFInfo
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- CN111130144B CN111130144B CN201911285017.5A CN201911285017A CN111130144B CN 111130144 B CN111130144 B CN 111130144B CN 201911285017 A CN201911285017 A CN 201911285017A CN 111130144 B CN111130144 B CN 111130144B
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- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
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- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
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Abstract
The invention provides a small hydropower station rapid water supply considering deviation and trend changeThe grid connection method is characterized in that the small hydropower station comprises a voltage transformer and a control system, and the voltage of the small hydropower station side is acquiredy a And distribution network voltagey b Is conveyed to a control system which applies small hydropower side voltagey a And distribution network voltagey b Comparing, and controlling the reclosing of the small hydropower station to be started by the control system according to a comparison result; the acquisition points are randomly selected, so that the reliability of the method is improved; by a relatively small hydroelectric side voltagey a And distribution network voltagey b The difference between them, and then performing an operation whenY≤0.05*（|y a1|+…+|y an I) is established, and the voltage of the small hydropower side isy a Trend of change and distribution network voltagey b The variation trends of the grid-connected; at the same time by judgmenty=|y b ‑y a |＞0.05*y a Whether it is true or not, so that the voltage on the small hydropower side can be avoidedy a And distribution network voltagey b The voltage sampling value of (2) is polluted by data; and meanwhile, the step of comparing the whole trend is set, so that the reliability of the method can be improved.
Description
Technical Field
The invention relates to the field of small hydropower station grid connection, in particular to a small hydropower station quick grid connection method considering deviation and trend change.
Background
The existing closing schemes all need long waiting time, and at the cost of disconnecting all small power supplies in the area, reclosing needs to be carried out on the small hydropower stations again after the small hydropower stations are disconnected, at the moment, for the distributed small hydropower stations, more time is consumed for re-operating grid connection, the operation is also complex, the recovery of a normal power grid operation mode needs a long time, short-time power failure of a line cannot be avoided, and the requirement of a client on power supply reliability cannot be met.
The existing implementation scheme adopts the existing small hydropower grid-connected intelligent electronic equipment and a multi-purpose full-wave Fourier algorithm, at least one cycle data window (20 ms) is needed, the calculation process is complex, firstly, the full-wave Fourier calculation needs to be carried out on the collected voltages of the small hydropower side and the power distribution network side, then, three quantities of voltage amplitude, phase and frequency of the small hydropower side and the power distribution network side need to be calculated and extracted, and finally, the extracted three quantities of voltage amplitude, phase and frequency need to be compared one by one to judge whether the grid-connected requirement is met.
The method has longer fault detection time, leads to longer power restoration time, and thus leads to lower power supply reliability. Meanwhile, when a fault occurs, the power distribution network adjusts the voltage parameters by cutting off the power supply end or the load end, so that the closing time can be greatly prolonged.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides the small hydropower station quick grid-connection method which is quick in grid connection and high in data accuracy and considers deviation and trend change.
In order to achieve the purpose, the technical scheme of the invention is as follows: a method for quickly connecting small hydropower station to a grid in consideration of deviation and trend change comprises the steps that the small hydropower station comprises a voltage transformer and a control system, and the voltage transformer collects the voltage of the small hydropower station sidey a And distribution network voltagey b Is conveyed to a control system which applies small hydropower side voltagey a And distribution network voltagey b Comparing, and controlling the reclosing of the small hydropower station to be started by the control system according to a comparison result;
when the small hydropower station is quickly connected to the grid, the method comprises the following steps:
a) whether the small hydropower station detects tripping; if yes, performing step b);
b) starting a control system, and randomly setting acquisition points and the number n of the acquisition points; then step c) is carried out;
c) small hydropower station side voltage with n values collected by voltage transformery a And distribution network voltagey b (ii) a And transmitting the collected data to a control system, and then performing step d);
d) the control system calculates the voltage at the small hydropower side of one of the collection pointsy a And distribution network voltagey b The difference between them, and then step e) is carried out;
e) determining noty b -y a |＞0.05*y a If yes, performing step f), and if not, performing step j);
f) proceed withY=|y b1-y a1|+…+|y bn -y an|Operation, when Y finishes the small hydropower side voltage of n acquisition pointsy a And distribution network voltagey b The difference between the two is the sum, then step g) is carried out; when Y does not finish the small hydropower side voltage of n acquisition pointsy a And distribution network voltagey b If the difference between the two points is equal to the sum, returning to the step d) to calculate another acquisition point;
g) judgment ofY≤0.05*（|y a1|+…+|y an I) whether the result is true, if true, performing step h); if the grid connection is not established, the grid connection cannot be carried out;
h) relatively small side voltage of water and electricityy a Trend of change and distribution network voltagey b The graphs are similar to the graph in step i);
i) starting a reclosing switch;
j) discarding the collection point, and randomly collecting by the voltage transformer to remove the step c)A new collection point is arranged outside, and the control system compares the voltage of the small hydropower side of the collection pointy a And distribution network voltagey b The difference between them, and then step e) is carried out;
in the method, the acquisition points are randomly selected, so that the reliability of the method is improved; by a relatively small hydroelectric side voltagey a And distribution network voltagey bIf the difference is larger than 0.05 times of the voltage value of the small hydropower side, the difference is accumulated, otherwise the collection point is abandoned and is replenished with a collection point, and then the operation is carried out, when the difference is larger than the voltage value of the small hydropower sideY≤0.05*（|y a1|+…+|y an I) is established, and the voltage of the small hydropower side isy a Trend of change and distribution network voltagey b The variation trends of the grid-connected voltage values are similar, so that grid-connected conditions are met, the grid-connected method is simple, only comparison and judgment are carried out on the voltage values, and the time required by grid connection is short; at the same time by judgmenty=|y b -y a |＞0.05*y a Whether it is true or not, so that the voltage on the small hydropower side can be avoidedy a And distribution network voltagey bThe voltage sampling value of (2) is polluted by data; and meanwhile, the step of comparing the whole trend is set, so that the reliability of the method can be improved.
Further, small hydropower side voltagey a And distribution network voltagey b The same collection quantity, the voltage mutual inductor collects the voltage of the small hydropower station side at the same pointy a And distribution network voltagey b And (5) synchronous acquisition.
Thus ensuring the voltage of the small hydropower sidey a And distribution network voltagey b The synchronism of (2).
Further, n has a value of 5.
Therefore, the condition that grid connection is sporadic due to too little data acquisition is avoided; meanwhile, the phenomenon that the grid connection time is increased due to excessive data acquisition is avoided.
Further, randomly setting the collection points is realized by randomly setting the collection time.
This improves the reliability of the method.
Drawings
FIG. 1 is a flow chart of the present invention
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
As shown in figure 1, the small hydropower station rapid grid-connected method considering deviation and trend change comprises a voltage transformer and a control system, wherein the voltage transformer collects voltage on the side of the small hydropower stationy a And distribution network voltage ybIs conveyed to a control system which applies small hydropower side voltagey a And distribution network voltagey b Comparing, and controlling the reclosing of the small hydropower station to be started by the control system according to a comparison result;
when the small hydropower station is quickly connected to the grid, the method comprises the following steps:
a) whether the small hydropower station detects tripping; if yes, performing step b);
b) starting a control system, and randomly setting acquisition points and the number n of the acquisition points; then step c) is carried out;
c) small hydropower station side voltage with n values collected by voltage transformery a And distribution network voltagey b (ii) a And transmitting the collected data to a control system, and then performing step d);
d) the control system calculates the voltage at the small hydropower side of one of the collection pointsy a And distribution network voltagey b The difference between them, and then step e) is carried out;
e) determining noty b -y a |＞0.05*y a If yes, performing step f), and if not, performing step j);
f) proceed withY=|y b1-y a1|+…+|y bn -y an I calculation, namely when Y finishes the voltage of the small hydropower side of n acquisition pointsy a And distribution network voltagey b The difference between the two is the sum, then step g) is carried out; when Y does not finish the small hydropower side voltage of n acquisition pointsy a And distribution network voltagey b If the difference between the two points is equal to the sum, returning to the step d) to calculate another acquisition point;
g) judgment ofY≤0.05*（|y a1|+…+|y an I) whether the result is true, if true, performing step h); if the grid connection is not established, the grid connection cannot be carried out;
h) relatively small side voltage of water and electricityy a Trend of change and distribution network voltagey b The graphs are similar to the graph in step i);
i) starting a reclosing switch;
j) discarding the collection point, randomly collecting a new collection point except the step c) by a voltage transformer, and comparing the small hydropower side voltage of the collection point by a control systemy a And distribution network voltagey b The difference between the voltage values is then carried out in the step e), in the invention, the acquisition points are randomly selected, and n is the voltage of the small hydropower sidey a And distribution network voltagey b The number of acquisition points; small hydropower side voltage with same acquisition quantity and acquisition points of voltage transformersy a And distribution network voltagey b Thus ensuring the voltage of the small hydropower sidey a And distribution network voltagey b The synchronism of (2). The control system compares the voltages of the same small hydropower stations at the acquisition pointsy a And distribution network voltagey b The difference between them, which is comparable.
In this embodiment, n has a value of 5; small hydropower side voltagey a And distribution network voltagey b Five are provided. The condition that grid connection is sporadic due to too little data acquisition is avoided; meanwhile, the phenomenon that the grid connection time is increased due to excessive data acquisition is avoided. Acquisition points include time point T1, time point T2, time point T3, time point T4, and time point T5; small hydropower side voltagey a IncludedVoltage ofy a1Voltage ofy a2Voltage ofy a3Voltage ofy a4And voltagey a5(ii) a Distribution network voltagey b Including a voltagey b1Voltage ofy b2Voltage ofy b3Voltage ofy b4And voltagey b5。
Voltage ofy a1Voltage ofy a2Voltage ofy a3Voltage ofy a4And voltagey a5Respectively small hydroelectric side voltagey a Real-time voltages at time point T1, time point T2, time point T3, time point T4, and time point T5.
Voltage ofy b1Voltage ofy b2Voltage ofy b3Voltage ofy b4And voltagey b5Respectively the voltage of the distribution networky b Real-time voltages at time point T1, time point T2, time point T3, time point T4, and time point T5.
At time point T1, the voltage transformer couples the voltagesy a1And voltagey b1Collecting; at time point T2, the voltage transformer couples the voltagesy a2And voltagey b2Collecting; voltage transformer pair voltage at time point T3y a3And voltagey b3Collecting; at time point T4, the voltage transformer couples the voltagesy a4And voltagey b4Collecting voltage of a voltage transformer at a time point T5y a5And voltagey b5And (5) collecting.
Control system passes formulay=|y b -y a |＞0.05*y a Calculating the voltagey a1And voltagey b1Difference between themy 1When is coming into contact withy 1＞0.05* y a1If true; namely, the difference between the two voltage values is larger than half of the sampling value, and then the differences of the five acquisition points are added; calculating a difference value and Y;
y is the sum of the difference values of the n acquisition points; when Y finishes the small hydropower side voltage of n acquisition pointsy a And distribution network voltagey b Comparing the variation trend if the difference between the two is the sum; when Y finishes the small hydropower side voltage of n collection points in the futurey a And distribution network voltagey b If the difference between the two points is equal to the sum, returning to the step d) to calculate another acquisition point; for example, in this embodiment, it is assumed that the current acquisition point is time point T2, and acquisition at time point T3 is completed, since 3 time points in n acquisition points are used for operation, Y only has the accumulated sum of the difference values of T2 and T3, and the accumulated sum of 5 acquisition points is not completed, the process returns to step d) to perform difference comparison of another acquisition point except T2 and T3, and the process proceeds to the next round of operation according to the judgment of the difference values.
When true; then will compare the voltage at the relatively small hydropower sidey a Trend and distribution network voltagey b The trend of change of (c); specifically, curves are generated by corresponding a plurality of small hydropower side voltage values with time points, whether the two curves are similar or not is determined according to a curve similarity calculation algorithm such as a cosine similarity algorithm, and when the change trends of the two curves are similar, a reclosing switch is started to carry out grid connection.
When in usey 1＞0.05*y a1If not, the time point T1 is discarded; the abandoned time points are not put into the difference value and Y formula for calculation; the voltage transformer collects a new collecting point which is a time point T6, and the calculated voltage collected at the time point T6 is calculatedy a6And voltagey b6Difference between themy 6And make a judgment ony 6＞0.05*y a6Whether the result is true or not; if true, willy 6Added to the difference and Y equations, the number of n is unchanged. The difference sum Y at this time is:
if it isy 6＞0.05*y a6If the time point T6 is not the same, the time point T6 is abandoned, the voltage transformer acquires a new acquisition point, and the new acquisition point is the time point T7 and is calculated.
In the method, the acquisition points are randomly selected, so that the reliability of the method is improved; by a relatively small hydroelectric side voltagey a And distribution network voltagey b The difference between them, and then performing an operation whenY≤0.05*（|y a1|+…+|y an I) is established, and the small hydropower side voltage y a Trend of change and distribution network voltagey b The variation trends of the grid-connected; at the same time by judgmenty=|y b -y a |＞0.05*y a Whether it is true or not, so that the voltage on the small hydropower side can be avoidedy a And distribution network voltagey b The voltage sampling value of (2) is polluted by data; and meanwhile, the step of comparing the whole trend is set, so that the reliability of the method can be improved.
Claims (3)
1. A small hydropower station quick grid-connection method considering deviation and trend change is characterized in that: the small hydropower station comprises a voltage transformer and a control system, wherein the voltage transformer collects the voltage of the small hydropower station sidey a And distribution network voltage ybIs conveyed to a control system which applies small hydropower side voltagey a And distribution network voltagey b Comparing, and controlling the reclosing of the small hydropower station to be started by the control system according to a comparison result;
when the small hydropower station is quickly connected to the grid, the method comprises the following steps:
a) whether the small hydropower station detects tripping; if yes, performing step b);
b) starting a control system, and randomly setting acquisition points and the number n of the acquisition points; then step c) is carried out; the acquisition point is a sampling time point;
c) voltage to voltage converterSmall hydropower station side voltage with n numerical values acquired by sensory a And distribution network voltagey b (ii) a And transmitting the collected data to a control system, and then performing step d); small hydropower side voltagey a And distribution network voltagey bThe same collection quantity, the voltage mutual inductor collects the voltage of the small hydropower station side at the same pointy a And distribution network voltagey bSynchronously collecting;
d) the control system calculates the voltage at the small hydropower side of one of the collection pointsy a And distribution network voltagey b The difference between them, and then step e) is carried out;
e) determining noty b -y a |＞0.05*y a If yes, performing step f); if not, step j);
f) proceed withY=|y b1-y a1|+…+|y nb-y an I calculation, namely when Y finishes the voltage of the small hydropower side of n acquisition pointsy a And distribution network voltagey b The difference between the two is the sum, then step g) is carried out; when Y does not finish the small hydropower side voltage of n acquisition pointsy a And distribution network voltagey b If the difference between the two points is equal to the sum, returning to the step d) to calculate another acquisition point;
g) judgment ofY≤0.05*（|y a1|+…+|y an I) whether the result is true, if true, performing step h); if the grid connection is not established, the grid connection cannot be carried out;
h) relatively small side voltage y of water and electricity a Trend of change and distribution network voltagey bThe graphs are similar to the graph in step i); if not, go to step j);
i) starting a reclosing switch;
j) discarding the collection point, randomly collecting a new collection point except the step c) by a voltage transformer, and comparing the small hydropower side voltage of the collection point by a control systemy a And distribution networkVoltage ofy b The difference between them, and then step e) is performed.
2. The small hydropower station rapid grid connection method considering deviation and trend change as claimed in claim 1, is characterized in that: n has a value of 5.
3. The small hydropower station rapid grid connection method considering deviation and trend change as claimed in claim 1, is characterized in that: the random setting of the acquisition points is realized by randomly setting the acquisition time.
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| CN201911285017.5A CN111130144B (en) | 2019-12-13 | 2019-12-13 | Small hydropower station quick grid connection method considering deviation and trend change |
| PCT/CN2020/116365 WO2021114804A1 (en) | 2019-12-13 | 2020-09-21 | Small hydropower station rapid grid connection method considering deviation and trend changes |
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