JPH0474930B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention provides economic load distribution control (EDC:
Economical Load Dispatching Control) method.

Economic load distribution methods have been widely used to control the balance between power consumption and power generation in power systems in real time. This economical load distribution control method deals with relatively slow load fluctuations. It predicts the day's load fluctuation pattern from past load results, and uses the predicted load fluctuation pattern to handle relatively slow load fluctuations. The next period's load is predicted, and based on the prediction result, the distributed power to each generator is calculated using the equal incremental fuel cost rule and the coordination equation, and the load generators are divided so that this distributed power is generated. Control command values are issued for each generator to control the total fuel cost of each generator to a minimum.

The economic load distribution control method described above is generally combined with a load frequency control (LFC) method. This frequency control method responds to relatively fast load changes from several seconds to several tens of seconds, and the frequency deviation Δf of the power system and the deviation from the reference value P _T of interconnection line power with other power systems. Calculate Δp _T , substitute this into the following equation (1) to calculate Area Requirement (AR), calculate the proportional part and integral part, and distribute it to each generator. be.

AR=KΔf+ΔP _T =K(f−f ₀ )+P _T −P _T0 ...Equation (1) In the above Equation (1), K is the system constant, f is the measurement frequency, f ₀ is the reference frequency, and P _T is the measured interconnection line power and P _T0 is the interconnection line reference power.

As described above, the economic load distribution control method is combined with the frequency control method to control the balance between power consumption and power generation in the power system in real time. Calculation of distributed power and generation of control command values are performed at long fixed cycles of minutes. The calculation cycle of this EDC is
During that cycle, it is desirable to have an appropriate period to bring the output of the generator as close as possible to the target value and to correct the output distribution value between each generator.
It is set to an optimal value determined based on the frequency of load fluctuations, the accuracy range of load prediction, and constraints of actual operation.

Cooperation with LFC is especially important when it comes to constraints in actual operation. EDC has a long period and its power adjustment range is wide. Compared to this, LFC has a short period (several seconds to tens of seconds)
The power adjustment range is small. Stable and economical control can be achieved through cooperation between the two, and the EDC cycle should not be too early or too slow. The current situation at electric power companies is that the EDC calculation cycle is approximately 3 to 5 minutes, and is kept at a fixed cycle due to cooperation with the LEC. On the other hand, since the fluctuating frequency component of the total power demand to be adjusted is fixed, it is necessary to take sufficient measures when the total power demand suddenly changes, such as when it rises in the morning or when it drops during the lunch break. There was a problem in that the power grid frequency and interconnection line power were disrupted. That is,
Figure 1 shows the changes in total electricity demand over a day (in Figure 1, the horizontal axis shows time and the vertical axis shows total electricity demand), and the changes can be explained by temperature, day of the week, weather, etc. Although it is influenced by Figure 2 shows how the actual load changes and how the generated power changes over time (in the figure, the horizontal axis shows the change in time, the vertical axis shows the power,
The actual load is shown at 100, the control command value based on the economic load distribution control method is shown at 102, the generated power based on the control command value 102 is shown at 104, and the power deviation to be adjusted using the frequency control method is shown at 106. ing. Since advance predictive control is performed using the economic load distribution control method, as can be understood from the figure, the generated power 104 based on the control command value 102 of the economic distribution control exceeds the change in the actual load 100, and the frequency control lowers it. It works like this. At this time, the power deviation 106, which is the difference between the power generation amount 104 and the actual load 100, should be adjusted by frequency control, but in reality, a phenomenon in which the power deviation 106 becomes large often occurs, so it is difficult to completely adjust it by frequency control. As a result, the problem arises that the frequency deviation of the power system and the interconnection line power deviation increase.

In particular, if the predicted rise in total demand deviates from the rise in actual total demand, frequency deviation and interconnection line power deviation will be greatly disturbed. This situation is shown in FIG. 3, where 108 indicates the initially predicted total demand, and it is understood that the deviation 106 becomes extremely large.

The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to reduce the frequency deviation of the grid and the interconnection line power deviation by preventing the imbalance of power supply and demand.

In order to achieve the above object, the present invention attempts to shorten the EDC calculation cycle within the above-mentioned practical operational constraints when load fluctuations are large.

In other words, the power load of the power system is predicted every predetermined cycle based on past performance, and based on the predicted power load, the power to be distributed to each generator is determined so that the total fuel cost is minimized, and the current control command is issued. In the economical load distribution control method for electricity to be determined, when the deviation between the predicted electricity load and the current actual load exceeds a predetermined value, the predetermined period, which is the timing of the next prediction and control, is set at a predetermined ratio. Further, a correction value of the predicted power load is determined from the predicted power load and the actual load according to the predetermined ratio, and the current distributed power is determined based on this correction value and a control command is output. shall be.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the economical load distribution control method according to the present invention will be described below based on the drawings.

FIG. 4 shows a system to which the present invention is applied.

In this embodiment as well, control is performed by combining the economic load distribution control method and the frequency control method, and for this reason, the system of this embodiment includes an economic load distribution control device 4 mainly composed of a computer.
and a frequency control device 2 are provided.

The total power demand measured in the power system 1 (including losses during power transmission) = total power generation ΣP is input to the load prediction device 3, which compares it with past patterns to predict the total power demand after a certain period. used for. The economical load distribution device 4 distributes this predicted load to each power plant 5 as a base output according to the fuel characteristics of each power plant 5-1, 5-2...5-N, so that the total fuel cost thereof is minimized. A control command value 102 can be output for the control command value 102.

On the other hand, the frequency f and interconnection line power P _T measured in the power system 1 are supplied to the frequency control device 2 and input to the AR calculation circuit 6. this
The AR calculation circuit 6 calculates the regional required load AR, and the control command value 110 is generated for each power plant 5 via the proportional circuit 7, the integral circuit 8, and the distribution circuit 9.

The control command value 102 outputted from the economical load distribution control device and the control command value 110 outputted from the frequency control device 2 as described above are sent to the adder 10-1,
10-2...10-N are added and transmitted to each power plant 5.

As described above, the present invention is characterized in that the cycle of calculation of distributed power to each generator and generation of control command value is shortened when the predicted power load fluctuates rapidly. As shown in FIG. 5, the economic load distribution control device 4 calculates the distributed power and calculates the control command value at the normal cycle when the predicted load 108 does not change rapidly. However, when the predicted power load 108 changes rapidly, this calculation and the command value 102 are performed.
2 generation cycle is shortened.

This embodiment has the above configuration, and its operation will be explained below.

6 and 7 show the temporal changes in the total power generation amount according to this embodiment, that is, the virtual total power generation amount 104 according to the actual load 100, the predicted power load 108, and the control command value 102 only for economic load distribution control, These correspond to conventional FIGS. 2 and 3, respectively. The actual load P(t-1) (=total power generation ΣP) at time t-1 is input from the grid to the load prediction device 3, and the load prediction device 3 calculates the cycle of economic load distribution control from the past power load time pattern. △Total electricity demand after t,
That is, the predicted power load P(t) at time t is determined.
This predicted power load P(t) is compared with the actual load P(t-1) at the present time, that is, at the prediction time t-1.
Then, when α is a predetermined power deviation value, if P(t)-P(t-1)≦α, then the economic load distribution control device 4 receives this P(t) and uses the law of equal incremental fuel cost. The power distribution for each generator 5 that minimizes the total fuel cost for power generation is determined by the following, and a control command value 102 is output. The control command value 102 in the figure is the command value 102 of each generator.
-1 to 102-N is shown.

On the other hand, if P(t)-P(t-1)>α, the load prediction device 3 changes the economic load distribution control period (prediction calculation and control command value 102 generation period) △t to △t/2. And time t-1+△
The predicted power load at t/2 is calculated as P(t-1+△t/2)=P(t)+P(t-1)/2 and output to the economic load distribution control device 4, which then performs the above-mentioned process. Control command values are determined in a similar manner to control each generator.

Of course, it is also possible to calculate the deviation between the predicted power load and the actual load in the shortened period again, and if the deviation is larger than the predetermined value α, it is also possible to recalculate the period by setting the period to Δt/4.

In this way, in the present invention, when the predicted power load changes rapidly, the calculation and control command value 1
Since the period of occurrence of 02 is shortened, the deviation is 10
6 compared to the conventional cases of Fig. 2 and Fig. 3.
It decreases as shown in FIG.

In particular, as shown in Figure 3, the predicted value 108 based on the load fluctuation pattern based on past results and the actual load 10
4 is large and the prediction deviation needs to be corrected at time t, the decrease in the deviation 106 becomes significant as shown in FIG. In addition to shortening the period, this is due to △
The predicted load 106 after t/2 is P(t-1+△t/2) = {P(t)+P(t-1)}/2, and the actual load P(t-1) is the predicted value at the same time. This is because the higher the deviation from 108, the larger the value.

As described above, according to the present invention, when the predicted load suddenly changes, the difference between the amount of power generated by the economic load distribution control and the actual load (indicated by 106 in the above embodiment) is determined by the cycle of calculating the distributed power and generating the control command value. As a result, the frequency deviation of the power system and interconnection line power deviation can be reduced, and a good balance of power demand can be maintained. At this time, since the difference between the amount of power generated by the economic load distribution control and the actual load is reduced, the frequency deviation of the power system and the interconnection line power deviation are reduced by the frequency control in the above embodiment.

[Brief explanation of the drawing]

Figure 1 is a graph explaining changes in the total electricity demand in a day, Figures 2 and 3 are characteristic diagrams of conventional power supply balance, and Figure 4 is a diagram of a system to which the method of the present invention is applied. 5 is a graph showing the relationship between predicted load and calculation and periodic output in the present invention, and FIGS. 6 and 7 are power supply and demand balance characteristic diagrams in the embodiment shown in FIG. 4. 1...Power gate, 2...Frequency control device, 3
... Load prediction device, 4 ... Economic load distribution control device, 5 ... Power plant, 100 ... Actual load, 102 ...
...Control command value.

Claims (1)

[Scope of Claims] 1. Electric power that predicts the electric power load from past results every predetermined cycle, and calculates and controls the electric power distributed to each generator so that the total fuel cost is minimized based on the predicted electric power load. In the economic load distribution control method, when the deviation between the predicted power load and the current actual load exceeds a predetermined value, the predetermined period, which is the timing of the next prediction, is shortened by a predetermined ratio. Features: Economic load distribution control method for electricity. 2. An economic load distribution control method for electric power that predicts the electric power load from past performance at each predetermined cycle, and calculates and controls the distributed power of each generator so that the total fuel cost is minimized based on the predicted electric power load. When the deviation between the predicted power load and the current actual load exceeds a predetermined value, the predetermined cycle, which is the timing of the next prediction, is shortened by a predetermined ratio, and the predicted power load and the current actual load are reduced by a predetermined ratio. A method for controlling economic load distribution of electric power, characterized in that a correction value of the predicted power load is determined from the actual load according to the predetermined ratio, and the distribution power at the present moment is determined and controlled based on this correction value.