JPS6028224B2 - Automatic power system recovery control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic recovery control device in the event of a power system accident, and an object of the present invention is to prevent secondary power outages due to equipment overload during recovery control, and to maximize recovery of loads on the power outage side.

Conventionally, restoration control in the event of power system accidents has been performed manually, but it is difficult to coordinate time when performing integrated restoration operations at multiple substations, and it is difficult to decide and judge the content of restoration operations, making restoration control time-consuming. It took a long time (for example, 20 minutes).

Recently, recovery control is being automated with the aim of increasing speed (for example, completing recovery control within one minute), saving manpower, and increasing reliability. When one automatic system restoration control device is in charge of multiple power systems that are operated independently,
When a total power outage occurs in one of the systems, the recovery control device switches on the disconnector that connects the other healthy systems, which are always open, and performs control to retransmit power to the system where the power outage occurred. do.

This restoration control not only involves the above-mentioned paddy changing operations on the power transmission system, but also
Before the switching operation, in coordination with the protection system of the power outage system, the fault point removal operation of the power outage system, the power reception preparation operation, and the provisional configuration operation after the switching operation are performed by opening or closing the switch group related to these operations. Do it under control. Temporary configuration operation refers to an operation that temporarily closes or opens a switch that has been previously opened or closed in order to facilitate recovery control when the protection system has tripped. say. In addition, the power reception preparation operation includes opening or closing operations such as busbar shields and disconnectors, and load limiting operations in order to facilitate subsequent recovery control. The present invention relates to the above-mentioned load limiting device, which compares the predicted power flow value after a predetermined time predicted from the power flow before the occurrence of an accident with the current carrying capacity of the power equipment in the responsible system, and
In particular, restoration control will be performed within the range that does not cause overload on power transmission lines and banks. Examples of the present invention will be described in detail below.

First, the load limiting operation is generally performed by calculating the full load power PL of the outage system and the excess power supply PP of the healthy system (supply V supply capacity of the power supply, current carrying capacity of the transmission line, current carrying capacity of the bank, (remaining after subtracting the load power of the healthy system from the capacity limit), and perform an operation to disconnect a part of the power outage load commensurate with the difference Ps when PL>PP.

Ps=PL-PP......'1'Also, when the power reception capacity PP, which is limited by the current carrying capacity of the power transmission line of the power outage system or the current carrying capacity of the bank, is small compared to the above power supply surplus PP, PP is used instead of PP. Restrict.

Furthermore, when viewed on a substation-by-system basis, the total load power PL generally has a daily load pattern as shown in FIG. 1, in which the horizontal axis represents time and the vertical axis represents power. 1st
As shown in the figure, everyone's loading power P is 1 around 8 o'clock.
It will rapidly double in time. Such a sudden increase in the full load power PL immediately results in equipment overload even if the load is limited by the above-mentioned equation '1). Therefore, instead of the above m formula, the following [
Perform load limiting operation using Formula 21.

PS=PL(t)-Min{pP,SP} ……■
In the '2' formula, PL(t) is t minutes (for example, 20 minutes)
This is a predicted value of the future load PL, and in the case of a power outage during a load reduction time period, the current value is used.

Moreover, Min{PP, SP} means that the smaller of PP and SP is taken. Further, t is an operational setting value that allows control of power generation power adjustment, voltage adjustment, and power support from other routes. When the load limiting operation is performed using the formula (2) instead of the above-mentioned formula '11, the load limitation is increased in anticipation of equipment overload after t minutes, so that the power outage load relief amount is reduced.

In the present invention, in order to further increase the amount of power outage load relief, a short-time current carrying capacity larger than the fixed or continuous current carrying capacity of power equipment, particularly power transmission lines and banks, is used for load limiting operations.

Here, a short time is defined as a set value t for load limiting operation or a time slightly longer than t (for example, less than a circle), and this current carrying capacity is the amount of load that is allowable for operation when carrying out load limiting operations. It is. FIG. 2 shows the configuration of a control device for load limiting operations, with solid lines showing the flow of control and broken lines showing the flow of information.

The data collection element 21 mainly collects load flow and equipment temperature information. Note that this information is also used as a determining factor for other recovery operations. The load prediction element 22 is 2
Calculate and predict the load after t minutes from the information collected in step 1. 2
3 is a load limit determining element, and 24 is an element that generates information when the equipment is overloaded and a display alarm output element.

Reference numeral 25 denotes an information storage element, which stores information required by the load limit determining element 23, such as system connection information of the system in charge and current carrying capacity setting values of each equipment, and further stores the information required by the load limit determining element 23.
The output of is also stored and referenced during load shedding operations.

Each of these elements 21 to 25 has a hardware configuration using LSII or the like or a software configuration using a microcomputer or the like. In the above configuration, the load limit determining element 23 uses {3' instead of the above equation '2).
Use the formula.

P3=PL(t)-Min{PP(t), PP(t)}
...'31 Here, PP(t) and PP(t) are the excess power supply of a healthy system (in this case The load power of the healthy system to be subtracted is also the predicted value after t minutes) and the power receiving capacity. By determining the load limit using the above formula {3}, the difference △Ps between the restriction formula and the '2' formula is ΔPs=Min{PP(t), PP(t)}-Min{
pP, PP} ...■, and since the first term on the right side is larger than the second term, △Ps becomes a positive value.

This is the amount by which the load restriction amount is reduced when the right side of the above equation '3} takes a positive value, or in other words, the amount by which the power outage load relief amount is increased. [4' To simplify the meaning of the expression, pP<pP
(t)<FP<;P(t)...Assuming a shelf, {41 formula becomes formula ■.

△Ps=PP(t)-PP...{
6' △Ps in this {6i formula shows the effect of using short-time current carrying capacity for t minutes instead of rated suitable current capacity for the transmission line and bank of a healthy system.

For example, if the power transmission line is an eye path and it is assumed that this is an underground line, the calculation of the allowable current carrying amount of the underground line is, for example, {7'
It is determined from the continuous allowable current 1 shown in the formula and the short-time allowable current 1 (t) shown in the '8-formula. 、． =/Tc-To-Td
．． ．． ．． ...'7' 1(t) = Zoya {Rjokarashi) 1x & C} ......'8' However, Tc is the maximum allowable temperature of the conductor (e.g. 85Co), 9 is the base temperature, and Td is the underground temperature. The temperature that rises due to dielectric loss in the line, rc, is the effective conductor resistance of the underground line (e.g. 85qo
), Rth is the thermal resistance of discharge (85oo), T
, is the maximum permissible short-term temperature (e.g. 9500), L' is the conductor temperature before short-time current application (e.g. 85oo), lo is the current before short-time current application (1, value), and rc' is the underground cable temperature. The effective resistance of the conductor (95o○), Rth' is the thermal resistance of the heat radiation path (95oo), t is the duration of the short-time current, and ↑ is the time constant of the heat radiation path.

The results of the trial calculation using the 27-ball VOF cable according to the above formulas '7) and '8} are 1, = 730A, 1
(20 minutes) = 199 ships, and assuming power factor transmission of 95%, P = 330 MW, P (20 minutes) = 90 MW, and the difference of 570 MW can be said to be △Ps in formula [6].

Furthermore, since this is the amount of effect per line, if there are three lines, the power outage load relief amount will increase by 1710 MW. Similarly,
Depending on the bank, for example, you can expect an increase of 10 cents WA for one unit, or 300 MVA for three units. FIG. 3 shows an example of systems J and K handled by the device of the present invention.

G, , G2 are the respective power supplies of the J system and K system, and L's, L2
, L3, L4, L Samurai, and L56 are cables or overhead power transmission lines, CB to CB, o are line breakers representing a group of switches, C& indicates an open state, and the others indicate a closed state.

B to B indicate banks, and P and to P5 indicate loads. Note that although one line is shown in the figure for simplicity, generally n(2,3
...) line. SS to SS3 are substations of the J system, and SS4 and Smi are substations of the system. Now, J.
When a power outage occurs in the system, the open circuit breakers CB are closed from the healthy K system to automatically restore the J system.

On the other hand, when the K-lineage is stopped, the J-lineage is rescued in the same way as in this case, so the following explanation will be omitted.
When providing relief from the K system in response to a power outage in the J system, the calculation of the '3' formula by the load limit determining element 23 in FIG. 2 can be developed as follows, for example, assuming that PP(t)<SPw. 5 Ps,=i≧IPi(t)-PG2...
・Side 5Ps2koi≧IPi(t)-PL56(t)
...004. ．． ．． ．．
．． ．． (11) Ps3=i≧IP, [t)-PL45(t
)3. …． ．． (12) Ps4=i
ZIPi(t)-PL34(t)Ps5=Max{Ps
,,Ps2,Ps3,Ps4}.・・・． ...(13) The above equation ■ is the predicted load for all substations after t minutes (first term on the right side)
The power obtained by subtracting the supply capacity PG2 of power source G2 from is Ps,
.

The OQ formula is the power calculated by subtracting the current carrying capacity P side (top) for t minutes of transmission line -6 from the sum of predicted loads Pi (t) after t minutes of substation SS5 and substations on the J system side from this substation. is Ps2. Equations (11) and (12) have the same meaning. Equation (13) is the power Ps obtained from Equations '91 to (12).
, ~Ps4 to find the maximum value Ps5, and this power P
s5 is the amount of shortage when power is supplied to the J system, in other words, it is the left-hand side Ps of the above-mentioned equation 31 where the load should be limited in the J system. Next, regarding the bank, although it was omitted in Figure 3,
For example, as shown in Figure 4, substation SS3 has two J systems.
Assuming that the K system is one circuit, the primary bus is independent, and the secondary bus is operated in parallel, load restrictions may occur due to the bank current carrying capacity in the relevant substation SS3 at the time of restoration as described above. . This load limit Ps6 is based on the following equation. Ps
6=P3(t)-PB3,(t) (14) That is, Ps6 is the value obtained by subtracting the current carrying capacity of bank B31 for t minutes from the predicted load value P3(t) after t minutes.

Next, calculation of the current carrying capacity for t minutes of the power transmission line and bank according to the present invention will be explained.

In the formula (2) above, L is 1, that is, the continuous allowable current value, and To' is 1, and the temperature when energized for a long time (for example, 10 hours) is 85q0, and the result obtained is the short-time allowable current value 1. (20 minutes) = 199M, and P (20 minutes)
=90 skin W. In place of such a calculation method, the amount of load relief can be further increased by using OF cable temperature information (for example, the temperature of circulating oil) 9' and the current power flow value lo.
The above equation (8l) is simplified as, for example, (t)=J3YenK1K31Customer (15), this calculation is performed by the load limit determining element 23 in FIG. 2, and the result is expressed as P( t) and the aforementioned 00, (
11) and (12) as the value of the second term on the right side.

Note that K, , K2, and K3 in formula (15) are constants,
[The correspondence with formula 81 is as follows, K, = 3c'R ratio' (
1-e-? )K3=poisonAlso, without directly using equation (15) above, as shown in FIG.
It is also possible to make a table at intervals and use the value at the intersection of the two pieces of information (~', L) as 1(t).

Alternatively, as another calculation method, 1(t) is determined using only the current power flow value lo without using temperature information.

・(t)=KoK “Female ‐‐‐‐‐‐(17) However, K4
, K5, and average are constant values, and each is as follows.

& Targetable F City} (,8) &=T, one T.

-Td&=$-hand-rOR'th However, 1(t) obtained by this equation (17), where Rh=R ratio, is used for load limit determination in the same way as 1(t) obtained by equation (15).

1(t) obtained by the above equation (15) or (17) is smaller in the latter equation (17), but (17)
To show an example of calculation using the formula, when lo=730A (2
0) = 199 ships (converted P(20): 90 mountain MW), but for example, if the actual value lo: 36M, then 1 (2
0) = 250 ships (conversion P(20) = 112 law W), and in this example, a 25% load limit reduction is obtained. These effects also have a similar effect on banks. next,
Overload information generation and display alarm output element 2 in Figure 2
The effect of providing 4 will be explained.

In element 24, the rated current-carrying capacity P of the power equipment, especially the transmission line and the bank, is compared with the predicted power flow value Pt after t minutes predicted from the power flow before the occurrence of the accident, and P<P
At time t, an overload display or alarm will be output after T minutes. As mentioned above, the restoration control according to the present invention uses the short-time energizing capacity as the allowable capacity of the equipment in order to reduce load shedding, but in this case, in order to avoid shortening the service life of the equipment, For example, information for determining the necessity of secondary restoration control such as changing the power transmission route is obtained from the element 24. An example of this calculation will be explained below. Assuming that the system shown in FIG. 3 is in charge and the above-mentioned restoration control is performed, the following calculations are performed for each power transmission line and each bank.

5. ．． ．． ．． ．． ．． (19) Pw,=
iZIPi(t)-PG25.
．． …． (20) Pw2=iZIPi(t)-PL564
．． ．． ．． ．． ．． ．． (21)3
．． ．． ．． ．． ．． ．． (22) Pw4=Z Pi(
t)-PL34i--1 2... ．． ．． (23) P bottle iZ
IP, (t)-PL23P ship NiP, (t)-PL. 2
...(24) Pw7=P3(t)-PB3
, ...(25) Above (19) to (25)
In the formula, the first term on the right side is the value explained in the above-mentioned formula [9}.

Also, the second term on the right side is 2, L56, L5, L fence for each equipment.
These are the supply capacity, continuous current capacity, and rated capacity of L3, L2, and B3. The left sides Pw to Pw7 are overload information corresponding to each of the above-mentioned facilities. Pw calculated in this way,
~ When Pw7 becomes a positive value, an overload is predicted after t minutes, so element 24 displays an overload with that value or outputs an alarm to prompt the second recovery control and reduce the power consumption. Make grid connection appropriate. As explained in detail above, the power system automatic restoration control device according to the present invention performs restoration control by comparing the predicted power flow value after a predetermined time predicted from the power flow before the accident with the short-term current carrying capacity of the connected equipment in charge. Since the load limit value is determined, it has the effect of increasing the amount of load relief in the power outage system.

Moreover, if the short-time current carrying capacity of the power equipment is calculated from the temperature information of the equipment and also from the current power flow value, it is possible to further increase the amount of load relief. In addition, secondary recovery control is also possible because the rated current carrying capacity of the equipment and the predicted power flow value predicted from the power flow before the accident are compared and monitored, and an overload after a predetermined time is warned and displayed.

[Brief explanation of drawings]

FIG. 1 is a diagram illustrating a daily pattern of power system load; FIG. 2 is an element configuration diagram of a control device according to the present invention; FIG. 3 is a system configuration diagram for explaining the operation of the present invention; 4
The diagram shows an example of the configuration of substation SS3 in Figure 3, and Figure 5 shows an example of the configuration of substation SS3.
FIG. 3 is a diagram illustrating a table for determining (t). 21... Data collection element, 22... Load prediction element, 23... Load limit determining element, 24
...Equipment overload information generation and display alarm output element, 25... Information storage element. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] 1. In automatic system recovery control at the time of power system accident,
The predicted power flow value after a predetermined time is calculated from the power flow before the accident in the faulty system, and the smaller of the short-term power reception capacity of the power equipment in the faulty system and the short-time power supply capacity of the power equipment in the healthy system is energized. The load relief amount of the faulty system is determined from the difference between the capacity and the predicted power flow value, and the short-time power reception capability and short-time power supply capability are determined from the temperature information of the power equipment and the current power flow value. An automatic recovery control device characterized by: 2 The above control element compares the predicted power flow value after a predetermined time predicted from the power flow before the accident with the rated current carrying capacity of the power equipment in the accident system and the healthy system, and if the predicted power flow value exceeds the rated current carrying capacity, it 2. The automatic recovery control device according to claim 1, further comprising an element for displaying a subsequent overload.