JPH0614464A - Generator economic load distribution device - Google Patents

Abstract

(57) [Abstract] [Purpose] In the economic load distribution system of the generator for the total demand of the power system, find the maximum value and the minimum value based on the distribution value of the ELD, and make it the highest priority. E
Distributing LDs to eliminate tracking failures due to the restriction of change speed. Constitution: A means for detecting the maximum value and the minimum value of the distribution value of the ELD, a means for creating the upper and lower limit values in consideration of the changing speed while paying attention to the extreme value, and the ELD distribution again with the upper and lower limit values as constraint conditions. ELD composed of means for performing calculations
apparatus.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an economic load distribution device (ELD device) in generator control in a power system.

[0002]

2. Description of the Related Art The total demand in a power system changes with time in a pattern shown in FIG.
The automatic power supply system predicts the change in the total demand, and outputs a command value to cause each generator to generate power corresponding to the change. In order to determine how much power is generated by each generator, the allocation is performed so that the total power generation cost is the lowest, that is, the economic load distribution method (hereinafter referred to as ELD) is used. An economic load distribution device (hereinafter referred to as an ELD device) executes calculation using this method. The calculation method using the equal incremental fuel cost method, which is an example of the economic load distribution method, is described below.
Now, let the outputs of the n generators be P _i , P ₂ , ... P _n ,
Fuel cost is F ₁ (P ₁ ), F ₂ (P ₂ ),… F
_n (P _n ). Further, F _i (P _i ) is

[0003]

F _i (P _i ) = A _i + b _i P _i + C _i P _i ² ...... If it is expressed by (1),

[0004]

## EQU2 ## dF _i / dP _i = b _i + 2C _i P _i (2) From the law of equal incremental fuel cost, if P _{i of} each generator is determined so that this dF _i / dP _i becomes equal, the total It is known that fuel costs will be the lowest. Now, dF _i / dP _i = b _i
+ 2C _i P _i = λ

[0005]

## EQU3 ## P _i = (λ−b _i ) / 2C _i (3) and λ is

[0006]

[Equation 4] To be satisfied. That is, λ and P _i are

[0007]

[Equation 5] Substituting equation (5) into equation (3),

[0008]

[Equation 6] Is decided.

The ELD device adds the change amount of the predicted total demand to the predicted total demand of FIG. 2 with the power generation amount shared by the ELD target generator as a reference, and calculates the total ELD distribution amount ((4 ) Means P _R in the formula and corresponds to the shaded area in FIG. 2)
Decide.

Next, the ELD device calculates this ELD in one calculation.
The predicted distribution calculation is performed with the calculation step Δt in the time zone from the current distribution ts (generally coincident with the calculation start time) to the calculation end time te. As a result, the distribution value (predicted value from the present time to the future time te) as shown in FIG. 3 is obtained for the ELD target generator i (i = 1, n).

[0011]

On the other hand, a value that can change the output per unit time peculiar to the generator (hereinafter, the changing speed α [MW / MW
Minutes]). FIG. 4 shows an arbitrary time t and a range that can be changed after this time t. That is, when the generator i outputs P _o at time t, the output can be changed within the range of the following equation after (t + n · Δt) time.

[0012]

(7) (P _o −α · n · Δt) ≦ P ≦ (P _o + α · n · Δt) (7)

When a command value according to the curve in FIG. 3 is output to the generator i based on the distribution value of the conventional ELD,
As shown in (t) + (Δt), (ts + 2 · Δt) follows the distribution value according to the distribution value (ts + 3 · Δt), (t
s + 4 · Δt) may not be able to follow due to the restriction of the changing speed. In such a conventional ELD distribution value,
There are two reasons why the generator cannot follow. (1) ELD is distributed without considering the changing speed of each generator.

(2) Even if the rate of change is considered, (t
Only in the case of changing from s + (n−1) · Δt) to (ts + n · Δt), for example, in order to move from point A to point B in FIG. 3, each of ts + Δt, ts + 2 · Δt ,. Does not take into account time-of-day restrictions.

The present invention has been made in view of the above point. By finding the maximum value and the minimum value based on the distribution value of the ELD, and allocating the ELD with the finding of the maximum value and the minimum value as the highest priority. It is to eliminate the tracking failure due to the restriction of the changing speed.

[0016]

The technical means necessary for achieving the object of the present invention will be described with reference to FIG.

The total ELD distribution amount calculating means 1 has a function of obtaining the total ELD distribution amount PR of the ELD device. Further, the ELD distribution calculation means 2 has a distribution calculation function according to the conventional method. That is, only the upper and lower limit values are restricted by the facility capacity created by the generator upper and lower limit creating means 3. The generator command output means 4 has a function of outputting the ELD distribution result to each generator as a command value. The above is the same means as the conventional ELD device. The present invention has the following functions in addition to the conventional functions.

First, based on the calculation result of the ELD distribution calculating means 2, the extreme value detecting means 5 obtains the time and the extreme value of the inflection point of the distribution value of each generator. Next, the forward / backward upper and lower limit creating means 6 creates the generator upper and lower limit values by using this inflection point as a starting point and taking into consideration the restriction of the changing speed. Further, the ELD reallocation calculation means 7
Then, the ELD distribution calculation is performed again using the upper and lower limit values of the generator, which takes into account the constraint of the changing speed, as a constraint condition.

[0019]

The calculation result of the ELD reallocation calculation means 7 is the conventional E
Based on the calculation result value of the LD distribution calculating means 2, the distribution value is determined with the highest priority to reach the maximum and minimum values within the calculation time zone. Therefore, it is possible to prevent the tracking failure due to the restriction of the changing speed of the generator.

[0020]

EXAMPLE FIG. 9 shows an example in which the present invention is incorporated into a computer system for a power system. 9, the power system information input function 93 corresponds to the ELD distribution total amount calculation means 1 in FIG. 1, and the ELD device 95 is 2, 3, 5, 6, 7 in FIG.
Including the function of.

The data base 96 is a disk device for storing data such as the changing speed of the generator, the fuel characteristic constant, and the upper and lower limit values depending on the generator capacity, which are necessary for calculating the ELD.

FIG. 1 shows the interaction of each component in this embodiment.
9 and the program execution procedure of the ELD distribution 2, generator upper / lower limit creation 3, extreme value detection 5, forward / reverse upper / lower limit creation means 6, ELD distribution calculation means 7 in FIG. ― Described in the chart.

First, in FIG. 1, the ELD distribution total amount calculation 1 is the initial value P _o i (normal current output value) of the ELD target generator i.
Enter the ELD distribution calculation time zone (ts, ts + Δt,
.. te) has the function of obtaining the total ELD distribution amount PR. That is, as shown in FIG.

[0024]

[Equation 8] Is added to the total demand change amount in the calculation time zone to obtain the final total ELD distribution amount PR (hatched portion in the figure). The ELD distribution calculation means 2 has a distribution calculation function according to the conventional method, and determines the distribution value shown in FIG. 3 for each generator as an output. In this case, the generator upper / lower limit creating means 3
It is limited only by the output upper and lower limits determined from the installed capacity created in. Further, the generator command output means 4 is E
This is a function of outputting the LD distribution result to each generator as a command value. Further, the extreme value detection 5 is to obtain the time and the extreme value of the inflection point for the distribution value of each generator output by the ELD distribution 2. (Points B and C in FIG. 3). Next, the forward / backward upper / lower limit creating function 6 creates the upper and lower limit values in consideration of the changing speed while paying attention to this extreme value. (1) Determination of upper and lower limit values for retreat

At the extreme points B and C and the calculation end time zone D shown in FIG. 3, there is a direction in which time rises backward (backward direction).
The range that can be changed from that point (b _b , b ′ _b in the figure,
_{c b, c 'b, d} b, d' Request _b). This is called the retreat upper and lower limit values of each calculation time zone. (2) Determination of upper and lower limit values for forward movement

In general, the ELD device is shown in FIG.
In order from ts to (ts + Δt), (ts + 2 ·
The distribution calculation for each time zone of Δt), ... te is performed. The forward / lower limit value represents how much the output can change in each time zone after that in the calculation in each time zone.

[0027] a _f as the forward upper and lower limits in the point A in the example of FIG. 3, a _'f, B, respectively b _f as a forward on the lower limit at point C, b' _f, c _f, expressed in c _'f There is.
The upper and lower limit values of the forward movement change depending on how much the distribution value of the generator becomes, and are therefore recreated every time in the calculation time zone of ts, ts + Δt, ts + 2 · Δt .... As the final upper and lower limit values of the generator, a range surrounded by the upper and lower limits of the generator, the upper and lower limits of the backward movement, and the upper and lower limits of the forward movement created by the upper and lower limits of the generator (FIG. 7).
The shaded area).

Next, the ELD reallocation calculation means 7 will be described. The ELD redistribution calculating means 7 carries out the distribution calculation by the above-mentioned equal incremental fuel cost method within the range of the generator upper and lower limit values created by the forward / reverse upper and lower limit creating means 6. Next, how to improve the upper and lower limits of the generator by the combination of the upper and lower limits for forward movement and the upper and lower limits for backward movement will be described with reference to FIGS. 3, 5 and 6.

First, as in the conventional case, E
The distribution value of the generator i when the LDs are distributed is shown in FIG. Even if the distribution value is output as a command value as it is as described above, the actual output value of the generator is as shown in FIG. 5 if the change speed is restricted. In the conventional ELD distribution,
Even if only the upper and lower limits of the forward movement are incorporated and the distribution calculation is performed, the result cannot be obtained as the distribution value of FIG. On the other hand, the operation when the present invention is applied will be described with reference to FIG. The broken curve in FIG. 6 is the same as the curve in FIG. 3 (allocation value without consideration of change speed).

Now, assuming that the distribution value A at ts is (ts +
At Δt), neither the forward nor backward limits are applied, so the distribution value is point A. (Ts + 2 · Δt) to (t
In the case of s + 4 · Δt), the conventional values are b ′, h ′, and d ′, but since they fall on the lower limit of retreat, they are distribution values of b, h, and d. As described above, it is possible to cope with a sudden change in the distribution value by considering the upper and lower limit constraints for reaching the extreme point depending on the changing speed during distribution calculation.

As described above, according to the present embodiment, when a sudden change in the distribution value is expected in the ELD distribution calculation within the calculation time zone, the distribution value is corrected in advance in the time zone before the time zone. By doing so, it is possible to deal with a sudden change in the time zone.

Next, another embodiment will be described. In the above embodiment, the upper and lower limits of the generator are set as the upper and lower limits of the forward and backward movements (see FIG. 7).
Although an example of constructing the shaded portion) is given, another embodiment will be described in which measures are taken as a function when the generator upper / lower limit area cannot be constructed in the first place as shown in FIG.

As shown in FIG. 8, when it is determined that the point B cannot be reached at the time of calculating the time zone A, A-af
Adopt a distribution value along the line and have a function to output an alarm to the operator. Based on the number of times this alarm is output, the operator can determine whether or not this ELD device is operating at the minimum fuel cost according to the original equal incremental fuel cost method.

[0034]

As described above, according to the present invention, it is possible to economically distribute ELDs of generators with the constraint that the extreme value within the calculation time zone is reached and within that range. As a result, an ELD device that can withstand a sudden change in the total ELD distribution can be supplied.

[Brief description of drawings]

FIG. 1 is a functional configuration diagram of the device of the present invention,

FIG. 2 is a diagram showing total demand and total ELD allocation,

FIG. 3 is a diagram showing a distribution value of a generator i and forward and backward upper and lower limits and backward and forward upper and lower limits when distributed by a conventional method;

FIG. 4 is a conceptual diagram of a changing range of a generator in consideration of a changing speed,

FIG. 5 is a conceptual diagram showing the actual movement of the generator when distributed by the conventional method,

FIG. 6 is a diagram showing distribution values of generators i when the system of the present invention is used,

FIG. 7 is a diagram showing the upper and lower limit values of the generator used in the distribution calculation according to the present invention;

FIG. 8 is a diagram showing a change with time of a generator distribution value when a generator upper / lower limit area cannot be configured;

FIG. 9 is a diagram showing a configuration of an embodiment of the present invention,

FIG. 10 is a flowchart showing a processing flow of the present invention.
To.

[Explanation of symbols]

 1 ... ELD distribution total amount calculation means 2 ... ELD distribution calculation means 3 ... Generator upper / lower limit value creation means 4 ... Generator command output means 5 ... Extreme value detection means 6 ... Forward / reverse upper / lower limit value creation means 7 ... ELD redistribution Calculation method

Claims (1)

[Claims] 1. A means for calculating a total ELD distribution amount by adding a change amount of the predicted total demand to the predicted total demand based on the power generation amount shared by the ELD target generator, and equipment. From the ELD distribution calculation means, a means for creating a generator upper / lower limit value determined based on the capacity, an ELD distribution calculation means for calculating the ELD distribution value with the constraint of the generator upper / lower limit value on the total ELD distribution amount, An extreme value detecting means for obtaining the time and the extreme value of the inflection point for the output distribution value of each generator, and an advance for creating upper and lower limit values in consideration of the changing speed by paying attention to the extreme value obtained by this detecting means / Reverse upper and lower limit value creating means, ELD redistribution calculating means for performing allocation calculation by the equal incremental fuel cost method within the range of the generator upper and lower limit values created by the forward / reverse upper and lower limit value creating means, and this ELD Based on the output of the reallocation calculation means An economic load distribution device for a generator, which comprises means for outputting a command to each generator.