Disclosure of Invention
The invention aims to overcome the defects in the prior art and provides a reservoir optimal scheduling method based on a dynamic optimization algorithm, which comprises the following steps:
suppose that the reservoir scheduling problem needs to meet two objectives: 1. a maximum power generation target; 2. and (5) a water abandoning target of the minimum-year reservoir. In addition to satisfying two goals, set constraint adjustment, the constraint conditions need to be satisfied: 1. balance constraint of reservoir water amount; 2. reservoir capacity constraints and initial condition constraints; 3. a flow limit constraint; 4. and (5) restraining the generated output.
In order to meet the above conditions, the specific implementation steps are as follows:
s1, acquiring time period t: coefficient of generated power k
t Average discharge flow of reservoir
Average storage capacity of reservoir
Average water demand of user
Setting the collected data as an initialization population pop
t Let N be 100.
S2, carrying out mathematical modeling on each parameter of the reservoir. The reservoir needs to meet two goals, respectively: maximum annual energy production f 1 And minimum annual water reject f 2 The relation formula of the two target values and each parameter of the reservoir is as follows:
wherein the target value f
1 Represents the maximum annual energy production, f
2 Expressing the total amount of water abandoned by the minimum year reservoir, as shown in formula (1)
Respectively representing the mean water level of the reservoir at time T and the mean water level of the tailwater of the hydropower station at time T, T
t Is the length of the t period, and n is the number of the period of one year.
S3 setting the constraint condition of the reservoir. While achieving the above objective function, the reservoir still needs to satisfy the following constraints:
(1) reservoir water balance constraint
I
t The amount of the water put in the warehouse is expressed,
indicating water loss of reservoir, V
t Indicating the reservoir capacity at the end of time t.
(2) And (4) constraint of storage capacity limitation:
the maximum and minimum limits are expressed as the capacity of normal impounded water and the capacity of dead reservoir, respectively.
(3) Reservoir flow restriction:
the maximum and minimum limits are expressed as the minimum and maximum let-down flows of the plant during the time period t,
indicating the average let down flow.
(4) And (3) power generation force constraint:
the limits of the maximum value and the minimum value respectively represent the minimum power generation capacity and the maximum power generation capacity of the plant during the period t,
the average power generation force is represented.
S4, detecting the environmental change, and if the environmental change does not exist, turning to the step S16; if the environment has changed, the process goes to S5.
S5, carrying out non-domination sorting on the reservoir populations, layering the reservoir populations subjected to non-domination sorting, and selecting a first layer as a non-domination solution set pop Non Here, a good set of reservoir solutions that meet all reservoir objectives and constraints can be understood.
S6, searching edge individuals in the non-dominant solution set, finding lines or planes formed by the edge individuals, and storing the edge individuals into a plurality of B as shown in figure 1.
And S7, calculating the distance from the point to a straight line (two targets) or a plane (three targets) according to the formula (3).
S8, uniformly dividing the mth target value into k areas according to the target number M, selecting a point with the maximum distance to the line or plane in each partition as a knee point of the first target value, and if the area is empty, randomly initializing a value as the knee point selected by the area. As shown in fig. 1, the first target value is divided into 4 regions, the farthest non-dominant solutions (asterisk points) from the edge point connection line are respectively selected, then the second target value is divided into 4 regions, the farthest non-dominant solutions (dots) are also selected, and if a point (dotted line point) overlapping with the first target value appears, the second farthest non-dominant solution in the region is selected. The number of knee points obtained is m × k, and the knee points obtained are stored in several KNs.
S9, calculating a boundary reference point Q * The formula is as follows:
wherein Q i Representing the ith individual in the non-dominated solution set.
And S10, adding the calculated boundary reference points into the KN, recording the boundary reference points as updated knee points NKN, calculating the crowding degree distance of all the obtained KN individuals, sequencing, and deleting the point with the minimum crowding degree distance.
S11, predicting a new position of the knee point after the environment changes. The change in knee point is shown in fig. 2. Predicting the knee point evolution direction:
s12, obtaining a direction vector according to a formula (6)
Calculating the position of the knee point at the t +1 moment in the decision space:
wherein up i Denotes the maximum value in the i dimension, low i Denotes the minimum in the i dimension, ε t Is a gaussian perturbation.
S13, predicting the non-dominated solution set after the environmental change
S14, obtaining a new prediction population at the t +1 moment:
wherein pop
rand Is a random point when
Then it will calculate
The distance of the crowdedness degree is sorted again, the point with the minimum distance of the crowdedness degree is deleted, and the random point pop
rand For ensuring population pop
t+1 The size remains unchanged at N-100.
And S15, optimizing the whole by utilizing an optimization algorithm RM-MEDA.
And S16, finishing iteration, and outputting a final pop to obtain an optimal scheme which meets the target of the maximum power generation amount and the minimum water abandon amount and also meets all reservoir constraints.
The invention provides a reservoir optimal scheduling method based on a dynamic optimization algorithm, which has the advantages that:
the method reduces the huge calculation burden caused by the need of intensively searching a well-distributed pareto frontier in the evolution process, and realizes the good balance between the convergence and the diversity by a method of increasing the population diversity by using a special point and a prediction strategy.
Detailed Description
In order that the process of the invention may be more readily understood, the invention will now be described in detail with reference to the examples.
The invention provides a reservoir optimal scheduling method based on a dynamic optimization algorithm, aiming at overcoming the defects in the prior art, and the method comprises the following steps:
suppose that the reservoir scheduling problem needs to meet two objectives: 1. a maximum power generation target; 2. and (5) a water abandoning target of the minimum-year reservoir. In addition to satisfying two goals, set constraint adjustment, the constraint conditions need to be satisfied: 1. balance constraint of reservoir water amount; 2. reservoir capacity constraints and initial condition constraints; 3. a flow limit constraint; 4. power generation output constraint; 5. and (4) final storage capacity constraint.
In order to meet the above conditions, the specific implementation steps are as follows:
s1, acquiring time period t: coefficient of generated power k
t Average discharge flow of reservoir
Average storage capacity of reservoir
Average water demand of user
Setting the collected data as an initialization population pop
t Let N be 100.
S2, carrying out mathematical modeling on each parameter of the reservoir. The reservoir needs to meet two goals, respectively: maximum annual energy production f 1 And minimum annual water reject f 2 The relation formula of the two target values and each parameter of the reservoir is as follows:
wherein the target value f
1 Represents the maximum annual energy production, f
2 Expressing the total amount of water abandoned by the minimum year reservoir, as shown in formula (1)
Respectively representing the mean water level of the reservoir at time T and the mean water level of the tailwater of the hydropower station at time T, T
t Is the length of the t period, and n is the number of the period of one year.
S3 setting the constraint condition of the reservoir. While achieving the above objective function, the reservoir still needs to satisfy the following constraints:
(1) reservoir water balance constraint
I
t The amount of the water put in the warehouse is expressed,
indicating water loss of reservoir, V
t Indicating the reservoir capacity at the end of time t.
(5) And (4) constraint of storage capacity limitation:
the maximum and minimum limits are expressed as the capacity of normal impounded water and the capacity of dead reservoir, respectively.
(6) Reservoir flow restriction:
the maximum and minimum limits are expressed as the minimum and maximum let-down flows of the plant during the time period t respectively,
indicating the average let down flow.
(7) And (3) power generation force constraint:
the limits of the maximum and minimum values represent the minimum and maximum power generation forces of the plant during the period t respectively,
the average power generation force is represented.
S4, detecting the environmental change, and if the environmental change does not exist, turning to the step S16; if the environment has changed, go to S5.
S5, performing non-dominated sorting on the population, layering the population, and selecting a first layer as a non-dominated solution set pop Non Here, a good set of reservoir solutions that meet all reservoir objectives and constraints can be understood.
S6, searching edge individuals in the non-dominated solution set, finding lines or planes formed by the edge individuals, and storing the edge individuals into a plurality of B as shown in figure 1.
And S7, calculating the distance from the point to a straight line (two targets) or a plane (three targets) according to the formula (3).
S8, uniformly dividing the mth target value into k areas according to the target number M, selecting a point with the maximum distance to the line or plane in each partition as a knee point of the first target value, and if the area is empty, randomly initializing a value as the knee point selected by the area. As shown in fig. 1, the first target value is divided into 4 regions, the farthest non-dominant solutions (asterisk points) from the connecting line of the edge points are respectively selected, then the second target value is divided into 4 regions, the farthest non-dominant solution (circular point) is also selected, and if a point (dotted line point) overlapping with the first target value appears, the second farthest non-dominant solution in the region is selected. The number of knee points obtained is m × k, and the knee points obtained are stored in several KNs.
S9, calculating a boundary reference point Q * The formula is as follows:
wherein Q i Representing the ith individual in the non-dominated solution set.
And S10, adding the calculated boundary reference points into the KN, recording the boundary reference points as updated knee points NKN, calculating the crowding degree distance of all the obtained KN individuals, sequencing, and deleting the point with the minimum crowding degree distance.
S11, predicting a new position of the knee point after the environment changes. The change in knee point is shown in fig. 2. Predicting the knee point evolution direction:
s12, obtaining a direction vector according to a formula (6)
Calculating the position of the knee point at the t +1 moment in the decision space:
wherein up i Denotes the maximum value in the i dimension, low i Denotes the minimum in the i dimension, ε t Is a gaussian perturbation.
S13, predicting the non-dominated solution set after the environmental change
S14, obtaining a new prediction population at the t +1 moment:
wherein pop
rand Is a random point when
Then it will calculate
The distance of the crowdedness degree is sorted again, the point with the minimum distance of the crowdedness degree is deleted, and the random point pop
rand For ensuring population pop
t+1 The size remains unchanged at N-100.
And S15, optimizing the whole by utilizing an optimization algorithm RM-MEDA.
And S16, finishing iteration, and outputting a final pop to obtain an optimal scheme which meets the target of the maximum power generation amount and the minimum water abandon amount and also meets various reservoir constraints.
The embodiments described in this specification are merely illustrative of implementations of the inventive concept and the scope of the present invention should not be considered limited to the specific forms set forth in the embodiments but rather by the equivalents thereof as may occur to those skilled in the art upon consideration of the present inventive concept.