JP2011135689A - Selective load interrupting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a selective load interrupting device that, no matter how the configuration of a power system is changed, computes the load flow at a point of interest in the changed power system and determines a means for restoring power balance. <P>SOLUTION: A system data input unit 1 obtains a supply voltage, a load current, and open/close information on circuit breakers and disconnectors online. An input data memory 2 stores the obtained information in a computation database 3 by regular and periodic update. If any accident occurs, a computation equivalent circuit converter 5 computes the load flow at an optional point in the power system before the accident based on the equivalent circuit network of the power system generated in accordance with the open/close information on the circuit breakers and the disconnectors and the voltage and current stored in the computation database 3. An excess/deficiency-of-power determiner 6 takes a circuit breaker interrupted in the accident pattern determined from an input accident signal by an accident pattern input unit 4 as a point of interest and determines excess or deficiency of power from the load flow value before the accident at this point. A selective load interruption/power supply suppressor 7 determines load interruption or power supply suppression appropriate to excess or deficiency of power. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a selective load interrupting device provided for system stabilization when an accident occurs in an electric power system.

  In a power system in which multiple power generation units are operating in parallel to a load such as a factory that consumes power, when the circuit breaker trips to eliminate the accident, the power balance of the power system is unbalanced In order to stabilize the system, a method of shutting off an excess load or power supply may be used to maintain a balance of power consumption with respect to supplied power.

In an electric power system to which this selective load interruption method is applied, the selective load interruption device calculates the power flow of the electric power system and determines whether to interrupt the load or to cut off the power source in order to recover the power balance.
For example, when an accident occurs in which the circuit breaker trips in a state where power from the transmission line is received before the accident, the power supply from the transmission line is interrupted. For this reason, the power system in the station becomes short of power, and reducing the load is a means for restoring the power balance.
Conversely, if an accident occurs in which the circuit breaker trips in a state where power is being transmitted to the transmission line before the accident, the place of power sent to the transmission line disappears. For this reason, the power system in the station becomes excessive, and the power balance recovery means is to reduce or stop the output of the power generation unit.

  In the prior art, the amount of power fluctuation required for the means for recovering the power balance at the time of an accident is the amount of fluctuation obtained in units of bus groups obtained by grouping complex power grids in advance. It calculated | required and calculated | required electric energy based on the electric current amount detected with the current transformer installed in the electric power grid | system (for example, refer patent document 1).

Japanese Patent Laying-Open No. 2005-341638 (Page 5, FIGS. 1 and 3)

  In Patent Document 1 of the prior art, the power system is divided into a plurality of bus groups centering on the bus, and the predicted power flow after the occurrence of the accident is obtained by the power flow prediction calculation formula corresponding to each group to obtain the power fluctuation amount. It was. However, the power flow prediction calculation formula given in advance is effective only for a relatively simple system configuration that can be assumed. There was a problem that could not be handled if there was.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a selective load interrupting device that calculates a power flow at an arbitrary point of a power system after any change in any configuration change of the power system and obtains a means for restoring power balance.

  A selective load interrupting device according to the present invention includes a system data input means for online-acquiring power supply voltage, load current, circuit breaker and disconnector switching information in an electric power system, and a database for calculation by updating the information captured online from a fixed period Input data storage means to be stored in the power system, power system equivalent circuit network created according to the circuit breaker and disconnector switching information, and the power flow at any point before the power system accident based on the voltage and current stored in the calculation database Equivalent circuit conversion means for calculation, accident pattern input means for determining an accident pattern from an accident signal, and a circuit breaker that is interrupted by the accident pattern determined by the accident pattern input means. Power excess / deficiency determination means to determine the presence or absence of power excess / deficiency from the power flow value of the power, and power excess / deficiency determined by the power excess / deficiency determination means And a selection load shedding / power suppressing means for selecting load shedding or power suppression commensurate.

  A selective load interrupting device according to the present invention includes a system data input means for online-acquiring power supply voltage, load current, circuit breaker and disconnector switching information in an electric power system, and a database for calculation by updating the information captured online from a fixed period Input data storage means to be stored in the power system, power system equivalent circuit network created according to the circuit breaker and disconnector switching information, and the power flow at any point before the power system accident based on the voltage and current stored in the calculation database Equivalent circuit conversion means for calculation, accident pattern input means for determining an accident pattern from an accident signal, and a circuit breaker that is interrupted by the accident pattern determined by the accident pattern input means. Power excess / deficiency determination means to determine the presence or absence of power excess / deficiency from the power flow value of the power, and power excess / deficiency determined by the power excess / deficiency determination means By providing a suitable load cut-off / power supply suppression means for selecting a suitable load cut-off or power supply suppression, any power change in the configuration of the power system can be calculated to calculate the power flow at the point of interest of the power system after the change, and to recover the power balance It is possible to provide a selective load cutoff device that demands

The processing block diagram of the selective load interrupting apparatus which shows Embodiment 1 of this invention. Explanatory drawing of the equivalent circuit conversion for a calculation which shows Embodiment 1 of this invention (the 1). Explanatory drawing of the equivalent circuit conversion for a calculation which shows Embodiment 1 of this invention (the 2). Explanatory drawing of the equivalent circuit conversion for a calculation after the accident which shows Embodiment 1 and 2 of this invention. The processing block diagram of the selective load cutoff apparatus which shows Embodiment 2 of this invention. The processing block diagram of the selective load cutoff apparatus which shows Embodiment 3 of this invention. Explanatory drawing of the database for calculation which shows Embodiment 3 of this invention.

Embodiment 1 FIG.
FIG. 1 is a processing block diagram of the selective load interrupting apparatus showing the first embodiment. 2 and 3 are explanatory diagrams (No. 1 and No. 2) of the equivalent circuit conversion for calculation showing the first embodiment. FIG. 4 is an explanatory diagram of an equivalent circuit conversion for calculation after an accident according to the first and second embodiments.
In FIG. 1, 1 is a system data input means, 2 is an input data storage means, 3 is a calculation database, 4 is an accident pattern input means, 5 is a calculation equivalent circuit conversion means, 6 is a power excess / deficiency determination means, and 7 This is a selective load cutoff / power source suppression means.
The terms used in this specification are defined below.

  Before the accident: The time before the accident occurred.

  After the accident; immediately after the accident.

  After accident control: The point at which power balance recovery means (control) is implemented after an accident and the power balance is predicted to be most stable.

  Primary accident: An accident that occurred at a certain point in time. This is called a “first accident” for a secondary accident.

  Secondary accident: The accident following the accident that occurred at a certain point in time. The primary accident is called “subsequent accident”.

  Load cut-off: Control to reduce load as a means to restore power balance, output control device information for the switch that cuts off the load group, or load cut-off amount to be reduced for the load group without shutting off the load group Control to output.

The operation of the first embodiment will be described with reference to FIG.
The system data input means 1 captures the power supply voltage, load current, circuit breaker and switchgear switching information online, and the input data storage means 2 stores the captured information in the calculation database 3 with periodic updates.

When an accident occurs, the accident pattern is determined from the accident signal input by the accident pattern input means 4. The accident signal is information on what kind of accident (part), and as an accident pattern for the information, a circuit breaker that is cut off for a part that is cut off by the accident is defined in this apparatus. For example, the transmission line is a breaker at both ends of the transmission line, and the bus is a breaker around the bus.
Further, in the accident pattern, the minimum unit divided by accident removal is divided into ranges and divided into bus groups, and a tidal current prediction calculation formula corresponding to each group is defined in this apparatus.

  Next, based on the voltage and current stored in the equivalent circuit network of the power system and the calculation database 3 created according to the switching circuit information of the circuit breaker and disconnector in the equivalent circuit converting means 5 for calculation, the power system before the accident Calculate the current at any point. With the circuit breaker interrupted by the accident pattern determined by the accident pattern input means 4 as a point of interest, the power excess / deficiency determination means 6 determines the presence / absence of power excess / deficiency from the current value before the accident at this point, and the selected load interruption / The power source suppression means 7 calculates load interruption or power source suppression corresponding to excess or shortage of power.

Next, calculation equivalent circuit conversion will be described with reference to FIGS. 2 and the left side of FIG. 3 are the same.
In the power system shown on the left side of FIG. 2, electrical components such as a bus, a transformer, and a cable are connected to each other by a circuit breaker and a disconnector to form one power system network. An equivalent circuit network is shown on the right side of FIG. 2 in which this power system network is expressed as a circuit element with a transformer and a cable as an admittance element (H), and a circuit breaker and a disconnector as a switch (S). Used for calculation.
Next, when the equivalent network on the left side of FIG. 3 is arranged according to the open / close state of the switch (S), the connection end of each circuit element is defined as a node (N), and the switch (S) of the circuit breaker and disconnector is “closed”. In the state of FIG. 3, both ends of the switch (S) are electrically in the same state, and when the switch (S) is in the “open” state, both ends of the switch (S) are separated in circuit. This is an arithmetic equivalent circuit network composed only of nodes and admittance end nodes.

Next, in the calculation equivalent circuit network on the right side of FIG. 3, formulas for calculating each node current In with the line admittance Yj and each node voltage Vn being positive in the outflow direction from the node are as follows.
I1 = Y1 * (V1-V5) = Y1 * V1-Y1 * V5
I2 = Y2 * (V2-V5) = Y2 * V2-Y2 * V5
I3 = Y3 * (V3-V4) = Y3 * V3-Y3 * V4
I4 = Y3 * (V4-V3) + Y5 * (V4-V6) + Y4 * (V4-V5)
= -Y3 * V3 + (Y3 + Y4 + Y5) * V4-Y4 * V5-Y5 * V6
I5 = Y1 * (V5-V1) + Y2 * (V5-V2) + Y4 * (V5-V4)
= -Y1 * V1-Y2 * V2-Y4 * V4 + (Y1 + Y2 + Y4) * V5
I6 = Y5 * (V6-V4) = − Y5 * V4 + Y5 * V6
From the above formula of In and Vn, the following relational determinant is established.

  In the relational determinant of equation (1), the infinite bus at the power system end (power receiving systems 1 and 2) is treated as a known power supply voltage with a constant voltage, and the known power supply voltage and the known load current are substituted. The unknown voltage is obtained by solving the equation. When the voltage of each node (N) is obtained, the current flowing through the admittance element (H) installed at an arbitrary point and the active power are obtained.

  Next, a method for determining excess or shortage of power and obtaining load interruption or power suppression will be described with reference to FIG. In FIG. 4, when the cable is designated as an accident point F1, the circuit breakers S6 and S8 are tripped (opened), and the electric circuit of Y5 is disconnected. The tidal current that was balanced as a whole before the accident is separated into a dotted line system and a dashed line system after the accident, and a tidal current (electric power) imbalance occurs in each system.

In this apparatus, the circuit breakers S6 and S8 that are interrupted by the determined accident pattern are obtained by the accident pattern input means 4 from the accident signal that the cable is an accident (part). With these circuit breakers S6 and S8 as a point of interest, the tidal current value before the accident at this point is obtained.
In the calculation equivalent circuit converting means 5, the power flow value before the accident is I6 = −Y5 * V4 + Y5 * V6. After the circuit breakers S6 and S8 are opened, since I6 = 0, the value of I6 before the accident becomes the power excess / deficiency at the point of interest (positions S6 and S8). The power excess / deficiency determining means 6 determines whether the value of I6 is out of a predetermined range and is a positive value or a negative value, thereby obtaining the power excess / deficiency amount. In the selected load cut-off / power suppression means 7, if the calculated power excess / deficiency is a positive value, the output of the power generation unit is suppressed to match the power excess / deficiency, and if it is a negative value, the power excess / deficiency is Control to reduce the load corresponding to the amount.
In the case of FIG. 4, the current of the circuit breaker S <b> 6 in the dotted line system is a positive value, and nothing is done in the power system of FIG. 4, but the output of the power generation unit is suppressed with respect to the power receiving system 1 or 2. . The current of the circuit breaker S8 in the one-dot broken line system is a negative value, and the load group B is cut off in order to reduce the load.

  According to the first embodiment, it is not necessary to previously create a power flow prediction calculation formula of a system configuration limited type as in Patent Document 1 of the prior art for a specific point of the power system, and any configuration change of the power system Calculate the power flow at any point before the accident in the power system after the change, and use the circuit breaker interrupted by the accident pattern as a point of interest to determine whether there is power shortage or not from the power flow value before the accident at this point. In addition, it is possible to provide a selective load interrupting device that seeks power balance recovery means.

Embodiment 2. FIG.
FIG. 4 is an explanatory diagram of an equivalent circuit conversion for calculation after an accident according to the first and second embodiments. FIG. 5 is a processing block diagram of the selective load interrupting apparatus showing the second embodiment.
In the first embodiment, the circuit breaker that is interrupted by the accident pattern determined by the accident pattern input means 4 from the accident signal is calculated by the calculation equivalent circuit conversion means 5 by calculating the power flow at an arbitrary point before the power system accident. As a point of interest, the power excess / deficiency determination means 6 determines the presence / absence of power excess / deficiency from the current value before the accident at this point.
In the second embodiment, the arithmetic equivalent circuit converting means 5 calculates the power flow at an arbitrary point before the power system accident, and the circuit breaker is interrupted by the accident pattern determined by the accident pattern input means 4 from the accident signal. Based on the pre-accident voltage and current stored in the database 3 for calculation after the accident of the power system obtained by adding the open / close information to the switching information, and the power flow at any point after the accident of the power system With an arbitrary point of the power system as a point of interest, the power excess / deficiency determining means 6 determines the presence / absence of power excess / deficiency from the deviation in power flow before and after the accident at this point.

Next, a method for calculating the power flow at an arbitrary point after an accident in the power system and determining whether the power is excessive or insufficient will be described with reference to FIG.
In FIG. 4, when the cable is designated as an accident point F1, an equivalent circuit network for calculation after an accident with the circuit breakers S6 and S8 opened by the accident pattern determined by the accident pattern input means 4 from the accident signal is opened. When the formula for calculating each node current In is made as shown on the right side and the outflow direction from the node is positive, the following formula is obtained.
I1 = Y1 * (V1-V5) = Y1 * V1-Y1 * V5
I2 = Y2 * (V2-V5) = Y2 * V2-Y2 * V5
I3 = Y3 * (V3-V4) = Y3 * V3-Y3 * V4
I4 = Y3 * (V4-V3) + Y4 * (V4-V5)
= -Y3 * V3 + (Y3 + Y4) * V4-Y4 * V5
I5 = Y1 * (V5-V1) + Y2 * (V5-V2) + Y4 * (V5-V4)
= -Y1 * V1-Y2 * V2-Y4 * V4 + (Y1 + Y2 + Y4) * V5
I6 = 0

Taking an arbitrary point of the power system as a point of interest, the deviation of the tidal current before and after the accident at this point is obtained. In the calculation formula of each node current, the difference between the pre-accident obtained in the first embodiment and the post-accident is the following points I4 and I6. Find the deviation.
(Before the accident) I4 = −Y3 * V3 + (Y3 + Y4 + Y5) * V4-Y4 * V5-Y5 * V6
I6 = −Y5 * V4 + Y5 * V6
(After accident) I4 = −Y3 * V3 + (Y3 + Y4) * V4-Y4 * V5
I6 = 0
(Deviation: Before accident-After accident) I4 = Y5 * V4-Y5 * V6
I6 = −Y5 * V4 + Y5 * V6
The power excess / deficiency determination means 6 determines whether the deviation between I4 and I6 is outside a predetermined range and is a positive value or a negative value, thereby obtaining the power excess / deficiency amount. In the selected load cut-off / power suppression means 7, if the calculated power excess / deficiency is a positive value, the output of the power generation unit is suppressed to match the power excess / deficiency, and if it is a negative value, the power excess / deficiency is Control to reduce the load corresponding to the amount.
In the case of FIG. 4, if the deviation of I4 in the dotted line system is, for example, a positive value, nothing is done in the power system of FIG. 4, but the output of the power generation unit is suppressed with respect to the power receiving system 1 or 2. If the deviation of I6 in the one-dot broken line system is, for example, a negative value, the load group B is shut off in order to reduce the load.

  According to the second embodiment, it is not necessary to previously create a power excess / deficiency determining means for each accident pattern as in the first embodiment, and the power flow at an arbitrary point before the power system accident is calculated and the accident signal is calculated. The pre-accident voltage stored in the calculation database and the equivalent circuit network after the accident of the power system obtained by adding to the switching information that the circuit breaker that was interrupted by the accident pattern determined by the accident pattern input means was opened Based on the current, the power flow at an arbitrary point after the accident in the power system is calculated. Since the presence / absence of power excess / deficiency is determined, it is possible to provide a selective load interrupting device that can commonly determine whether there is power excess / deficiency for any accident pattern.

Embodiment 3 FIG.
FIG. 6 is a process block diagram of the selective load cutoff device showing the third embodiment. FIG. 7 is an explanatory diagram of a calculation database according to the third embodiment.
Next, the operation will be described with reference to FIGS.
First, when a primary accident (first accident) occurs, the calculation equivalent circuit conversion means 5 calculates the power flow at an arbitrary point before the primary accident of the power system.
At this time, the calculation database 3 is in a state “before the first accident”.

The primary circuit of the electric power system obtained by adding to the switching information that the circuit breaker that has been cut off by the accident pattern determined by the accident pattern input means 4 from the accident signal of the primary accident is opened by the equivalent circuit conversion means 5 for calculation. Based on the equivalent circuit network after the accident and the voltage and current before the first accident stored in the calculation database 3, the power flow at an arbitrary point after the first accident of the power system is calculated.
At this time, the calculation database 3 is in a “after the primary accident” state.
With an arbitrary point of the power system as a point of interest, the power excess / deficiency determining means 6 determines the presence / absence of power excess / deficiency from the deviation of power flow before and after the primary accident at this point.

The selected load cut-off / power supply suppression means 7 requests load cut-off or power supply suppression in accordance with excess or shortage of power, and determines primary accident control information (cut-off switch, load cut-off amount, power supply suppression amount).
Further, in the equivalent circuit conversion means 5 for calculation, the selected load interruption / power suppression means 7 reversely converts the obtained primary accident control information (load interruption amount, power suppression amount) into voltage and current. In addition to storing in the calculation database 3, the control information (breaking switch) of the primary accident is stored in the calculation database 3.
At this point, the calculation database 3 is in the “after accident control” state.
This “after accident control” is a control based on the primary accident control information (break switch, load cutoff amount, power supply suppression amount) after the primary accident, and it is assumed that the power system behaves as it is And when the power balance of the power system is predicted to be most stable after a lapse of a certain time after control.

Next, when a secondary accident (subsequent accident) occurs, the circuit breaker that is interrupted by the accident pattern determined by the accident pattern input means 4 from the accident signal of the primary accident is opened in the calculation equivalent circuit conversion means 5 And the equivalent circuit network after the accident control of the electric power system obtained by adding the control information (breaker switch) of the primary accident to the switching information and the voltage and current after the accident control stored in the calculation database 3 Calculate the power flow at an arbitrary point before the second accident of the power system.
At this time, the calculation database 3 is in a state of “after accident control = before the accident of the secondary accident”.

The secondary circuit of the electric power system obtained by adding to the switching information that the circuit breaker that is interrupted by the accident pattern determined by the accident pattern input means 4 from the accident signal of the secondary accident is opened by the equivalent circuit conversion means 5 for calculation. Based on the equivalent network after the accident and the voltage and current after the accident control stored in the calculation database 3, the power flow at an arbitrary point after the secondary accident of the power system is calculated.
At this time, the calculation database 3 is in a “after secondary accident” state.
Taking an arbitrary point of the power system as a point of interest, the power excess / deficiency determining means 6 determines the presence / absence of power excess / deficiency from the deviation in power flow before and after the secondary accident at this point.

The selected load cut-off / power supply suppression means 7 requests load cut-off or power supply suppression in accordance with excess or shortage of electric power, and determines secondary accident control information (cut-off switch, load cut-off amount, power supply suppression amount).
The control information is saved until a reset operation is performed. When it is determined that a subsequent accident (secondary accident) does not occur after a certain period of time, the control information is reset.

In the prior art, when a subsequent accident that can occur immediately after the control of the first accident occurs, the online power system is unstable due to power fluctuations, making measurement difficult and tidal current calculations can be performed using online input data. As a result, there was a problem that it was not possible to seek an appropriate power balance recovery method for subsequent accidents.
According to the third embodiment, an appropriate power balance recovery for a subsequent accident that may occur immediately after the control of the preceding accident is made based on the amount of electricity in the power system after the accident control predicted that the power balance is most stable. It is possible to provide a selective load interrupting device that seeks a means.

1. System data input means,
2 ... Input data storage means,
3 ... database for calculation,
4. Accident pattern input means,
5 ... Equivalent circuit conversion means for calculation,
6 ... Power over / under judgment means,
7 ... Selective load interrupt / power suppression means

Claims (3)

System data input means for capturing online power supply voltage, load current, circuit breaker and disconnector switching information in the power system, and input for storing information captured online from the system data input means in a calculation database by periodic update Based on the voltage and current stored in the data storage means, the equivalent circuit network of the power system and the calculation database created according to the switching information of the breaker and disconnector, the power flow at an arbitrary point before the accident of the power system Equivalent circuit conversion means for calculating
Focusing on the accident pattern input means that determines the accident pattern from the accident signal and the circuit breaker that is interrupted by the accident pattern determined by the accident pattern input means, whether or not there is an excess or deficiency of power from the tidal current value before the accident at this point Power excess / deficiency judging means for judging,
A selective load cutoff device comprising: a selected load cutoff / power source suppression means for selecting a load cutoff or a power source suppression corresponding to the power excess / deficiency determined by the power excess / deficiency determination means. The arithmetic equivalent circuit converting means calculates the power flow at an arbitrary point before the accident of the power system, and adds to the switching information that the circuit breaker that is interrupted by the accident pattern determined by the accident pattern input means is opened. Calculating the power flow at an arbitrary point after the accident of the power system based on the voltage and current before the accident stored in the calculation database and the equivalent circuit network after the accident of the power system determined as described above.
The selection load according to claim 1, wherein the power excess / deficiency determination unit determines an excess or deficiency of power from an arbitrary point of the power system as a point of interest and a deviation in power flow before and after the accident at this point. Shut-off device. The arithmetic equivalent circuit converting means stores the primary accident control information obtained by the selected load cutoff / power source suppressing means in the calculation database as the voltage and current after the accident control,
Obtained by adding to the switching information that the circuit breaker to be interrupted with the accident pattern determined by the accident pattern input means from the accident signal of the primary accident has been opened and the control information obtained by the selective load interruption / power suppression means. And calculating a power flow at an arbitrary point before the accident of the secondary accident of the power system based on the equivalent circuit network after the accident control of the power system and the voltage and current after the accident control stored in the calculation database. ,
An equivalent circuit network after the secondary accident of the electric power system obtained by adding to the switching information that the circuit breaker that is interrupted by the accident pattern determined by the accident pattern input means is opened from the accident signal of the secondary accident And calculating a power flow at an arbitrary point after the accident of the secondary accident of the power system based on the voltage and current after the accident control stored in the calculation database,
2. The power excess / deficiency determining means, taking an arbitrary point of the power system as a point of interest, and determining power excess / deficiency from a deviation in power flow before and after the secondary accident at this point. The selective load shut-off device described.

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