CN111431213A

CN111431213A - Plant network coordination method for exciting combined operation of wind power plant and pumped storage power station and combined scheduling method thereof

Info

Publication number: CN111431213A
Application number: CN202010177497.XA
Authority: CN
Inventors: 苏承国; 卢璐; 原文林; 吴洋; 周彬彬
Original assignee: Zhengzhou University
Current assignee: Zhengzhou University
Priority date: 2020-03-13
Filing date: 2020-03-13
Publication date: 2020-07-17

Abstract

The invention discloses a plant network coordination method for stimulating joint operation of a wind power plant and a pumped storage power station and a joint scheduling method thereof. By adopting the method, the combined dispatching of the wind power and the pumped storage can effectively inhibit the output fluctuation of the wind power, greatly reduce the wind abandoning risk of a power grid and obviously improve the power generation benefit of the wind power plant-pumped storage power station combination body.

Description

Plant network coordination method for exciting combined operation of wind power plant and pumped storage power station and combined scheduling method thereof

Technical Field

The invention relates to the technical field of energy, in particular to a combined dispatching method of a wind power plant and a pumped storage power station based on a plant network coordination method.

Background

Under the development mode of offshore wind power bases in eastern areas, wind power plants are built intensively, peak shaving requirements of a power grid in a local area are larger due to large-scale wind power centralized grid connection, and wind abandoning and load shedding risks of the power grid are increased greatly. And under the condition that the peak regulation capacity of the power system is insufficient, the wind power integration scale is limited to a certain extent. Although some researches optimize the cross-region and cross-provincial junctor plans, the load peak-valley difference of the provincial network is reduced, and the clean energy consumption space of the provincial network is improved. However, because different scheduling layers have priority sequences, and cross-region and cross-provincial power transmission plans cannot respond to the random fluctuation of the intra-provincial wind power in time, the peak shaving capacity of the system still needs to be further mined so as to eliminate or reduce negative effects caused by the random fluctuation of the wind power as much as possible. The pumped storage power station is used as the most flexible and economic large-scale energy storage tool in the current power system and plays an important role in system peak regulation all the time. Along with the continuous grid connection of large-scale wind power, the demand of the system on flexible peak regulation capacity is increased, and the flexible peak regulation performance of the pumped storage power station can play a greater role in reducing wind power curtailment of a power grid and promoting wind power consumption. Therefore, the inter-provincial pumped storage power station and the wind power base are considered to be interconnected, the peak regulation capacity of the pumped storage power station is utilized to compensate the wind power output, the fluctuation of the wind power is stabilized, and then the wind power output and the peak regulation capacity are connected into the power grid together to improve the controllability of the wind power and ensure the safe and stable operation of the power grid. As a perfect clean energy power market is not established in China, the wind power should be fully consumed by a power grid under the condition of ensuring the safety and stability of the power grid, so that the wind power-pumped storage power station combined dispatching strategy related in most of the current researches is difficult to be directly applied to China. In addition, the operation conditions of the pumped storage power station are complex, and besides conventional hydraulic constraints, such as upper and lower reservoir water balance constraints, reservoir capacity constraints and power generation flow constraints, the operation constraints of the units and the influence of a water head on the power generation and pumping characteristics of the units need to be considered to more accurately simulate the output plan of the pumped storage power station, so that the peak shaving effect of the pumped storage power station on wind power is better exerted.

Disclosure of Invention

The invention aims to provide a plant network coordination method and a combined dispatching method thereof for exciting combined operation of a wind power plant and a pumped storage power station.

In order to solve the technical problems, the technical scheme adopted by the invention is as follows.

A plant network coordination method for exciting combined operation of a wind power plant and a pumped storage power station is provided, which starts from stable operation of a power grid and the demand of a generator for increasing the income, promotes the coincidence of an actual total output curve and a planned output curve of a wind power-pumped storage power station combined body through multiple ways, improves the schedulability of wind power, and forms a plant network coordination mechanism for exciting the combined operation of the wind power plant and the pumped storage power station;

as a preferred technical scheme of the invention, the method specifically comprises the following steps:

(1) the wind power plant predicts the output curve of the next day according to historical operating data or weather forecast data of the next day and reports the output curve to the generator;

(2) the power supplier comprehensively considers the electricity price of the power grid, the technical characteristics of the pumped storage power station and the possible deviation factors between the actual wind power output and the predicted output, determines the output plan of the wind power plant-pumped storage power station combination in the next day, and reports the output plan to the power grid dispatching center 8-12h in advance;

(3) the power grid dispatching center corrects the output plan declared by the power generator according to the load prediction of the next day, the trans-regional and trans-provincial tie line plans issued by national and regional network dispatching, the wind power consumption capacity of the system and the transmission line capacity limit, so that the declared output curve follows the load variation trend as much as possible to relieve the peak load regulation pressure of the power generator and issues the output curve to the power generator;

(4) the power generator and the dispatching center form a power transmission contract after the output plan is agreed, and the contract simultaneously defines a power transmission plan, a power transmission price and positive and negative deviation prices between the actual power transmission output and the power transmission plan; when the actual power transmission output deviates from the reported planned output, the power grid company gives punishment feedback to the union according to the deviation amount;

(5) and the dispatching center arranges the output plans of other power stations in the power grid according to the determined output plan of the wind power-pumped storage combined body.

As a preferred technical solution of the present invention, the technical characteristics of the pumped storage power station at least include a reservoir capacity limiting characteristic, an installed capacity characteristic of a pump storage unit, and a water pump start-stop cost characteristic of the pump storage unit.

As a preferred technical scheme of the invention, under the condition of combined operation of a wind power plant and a pumped storage power station, when the actual wind power output is higher than the reported output, the excess wind power is supplied to the pumped storage power station for pumping water, and as the reversible unit pumps water from a lower reservoir to an upper reservoir of the power station continuously, the water level of the upper reservoir is higher and higher, and the redundant wind energy is converted into the potential energy of water for storage; when the actual wind power output is lower than the declared output, the pumped storage power station discharges water from the upper reservoir to drive the reversible unit to generate power and supply power grid load; in the process, the pumped storage power station effectively stabilizes the random fluctuation of wind power by using the advantages of quick start and stop, flexible working condition conversion and high load response speed, plays the roles of peak clipping and valley filling, realizes manual control of wind energy and prediction of time and space shift, and improves the schedulability of wind power so as to reduce the output deviation punishment and improve the generation benefit.

A wind power-pumped storage combined dispatching method based on a plant network coordination mechanism is characterized in that wind power schedulability is achieved under the plant network coordination mechanism, on the basis, a scene analysis technology is adopted to carry out modeling analysis on uncertainty of wind power output, namely wind power uncertainty modeling analysis, then the operation characteristics of a pumped storage power station are fully considered, a mixed integer programming model of coordinated operation of the wind power-pumped storage power station with maximum united body power generation yield as a target is constructed through objective function analysis and constraint condition analysis, and then an optimization solver is used for solving the model.

As a preferred technical solution of the present invention, the wind power uncertainty modeling analysis includes:

(1) scene generation

Firstly, the predicted wind power output sequence in the dispatching period is determined as

The prediction error of the method is subject to normal distribution N (mu, sigma) in any time period t²) Where μ is the mathematical expectation and σ is the standard deviation, and satisfies

On the basis, adopting Latin Hypercube Sampling, namely L tin Hypercube Sampling-L HS method, firstly layering Sampling probability distribution, then randomly extracting samples from each layer in sequence, and improving the coverage degree of the extracted samples to the distribution space of random variables, thereby accurately reflecting the whole distribution of the random variables through Sampling for a few times;

(2) scene reduction

The method still generates more electricity price scenes through L HS, adopts a synchronous retrogradation technology based on probability distance in order to fully reflect the random change characteristics of wind power output, and reduces the number of scenes to the minimum on the premise of keeping the important characteristics of the wind power output scenes, and comprises the following specific implementation steps:

1) initializing and setting; set the original scene as

Making the iteration number k equal to 1, and collecting the residual scenes in the iteration process C^(k)C, corresponding scene set to be deleted in the iterative process

2) For any two scenes i and j (i, j ∈ C)^(k)I ≠ j), the distance between them is calculated as

Wherein

Scenes i and j, respectivelyCalculating the distance between each pair of scenes according to the represented prediction deviation sequence of the wind power output, and for the scene i, if the scene s (s ∈ C)^(k)S ≠ i) satisfies D (i, s) ═ minD (i, j),

j is not equal to i, then s is called as the scene closest to the scene i;

3) calculating a probability distance PD (i) ═ p of the scene i_i·D(i,s)，p_iRepresenting the probability of the scene i, counting the scene with the smallest probability distance, which is marked as l, that is, satisfying PD (l) ═ min PD (i),

4) deleting scene l, replacing with scene m nearest to the scene l, and correcting probability of scene m to be p_m＝p_l+p_m(ii) a Reserve scene set as

The corresponding scene set needing to be deleted is

5) If card (C)^(k+1)) If the K is not less than K, turning to the step 6), otherwise, turning to the step 2) if the K is not more than K + 1;

6) saving the scene reduction operation to obtain a scene set C^(k+1)And the probability of each scene in the remaining set occurring.

As a preferred technical solution of the present invention, the objective function analysis includes:

the model only considers the problem of joint scheduling of a single large wind power plant and a single pumped storage power station, and the purpose of wind power-pumped storage combined complex joint scheduling is to stabilize random fluctuation of wind power through peak regulation capacity of pumped storage energy, so that expected power generation benefits of the combined complex are the maximum, and therefore the objective function of the model is as follows:

max F＝max(F₁+F₂-F₃-F₄) (1)

in the formula: f is the yield of the consortium, F₁The basic income CNY obtained by the united body according to the power selling contract regulation signed with the power grid company, T is the dispatching cycle, T is the dispatching time interval h, P_wp,tPlanned outputs MW, MP submitted to the grid company for the combo_tThe internet electricity price CNY/kWh is obtained for the time period t; f₂The extra income CNY obtained when the actual transmission power of the united body exceeds the planned output part is obtained, S is the simulation scene number of the wind power sequence, S is the total number of the wind power scenes considered by the model, N is the total number of the units in the pumped storage power station, i is the number of the pumped storage units,

to send out the electricity prices CNY/kWh corresponding to the excess power portion,

respectively the power generation and the pumping power MW, PW of the pumping storage unit i in the period t_s,tWind power, p, for a time period t represented by a scene s_sIs the probability of scene s; f₃The actual transmitted power of the united body is lower than the punishment fee CNY of the planned output part,

penalty electricity price CNY corresponding to the part with insufficient transmitted power; f₄The cost is the running cost CNY of the united body, and the running cost of the wind power plant and the starting and stopping cost of the water turbine can be ignored, so the cost is mainly the starting and stopping cost of the water pump of the pumped storage unit; c_su,i、C_sd,iCost CNY, y for single starting and stopping of i water pump of pumping storage unit_i,t、y'_i,tRespectively the water pump on and off operating variables, y, of the unit i_i,t1 means that the water pump is turned on during t, otherwise y_i,t＝0，y'_i,t1 denotes shutting down the water pump during period t, otherwise y'_i,t＝0。

As a preferred technical scheme of the invention, a variable b of 0-1 is introduced_s,tAnd an auxiliary variable K_s,tAnd X_s,tEquations (3) - (4) are converted into the following mixed integer linear constraint combination, and the problem that the equations (3) - (4) are difficult to directly solve is solved:

K_s,t≥-M·b_s,t(11)

K_s,t≤M·b_s,t(12)

X_s,t≥-M·(1-b_s,t) (13)

X_s,t≤M·(1-b_s,t) (14)

in the formula: m is a sufficiently large real number, b_s,tAn indicator variable for the deviation of the transmitted power of the coupling from the planned output submitted to the grid under scene s, b _s,t1 represents that the transmitted power is lower than the planned output, b _s,t0 means that the transmitted power is higher than the planned output; when the state variable b_s,tWhen 0 is satisfied, that is, when the combined transmitted power is higher than the planned output, K is determined by the restrictions of equations (11) and (12)_s,t0, according to formula (7), when F₃The penalty cost of the combo actual transmitted power lower than the planned output part is 0, and the fact is consistent; when b is_s,tWhen the combined transmitted power is 1, i.e., when the planned output power is lower than the combined transmitted power, X is restricted by equations (13) and (14)_s,tWhen F is equal to 0₂0, formula (7) and formula (4) are equivalent; the linear constraint combinations represented by equations (6) to (14) are equivalent transformations to the nonlinear functions represented by equations (3) to (4).

As a preferred technical solution of the present invention, the constraint analysis only considers the operation limitations of the pumped storage power station and the unit, and includes:

(1) and (3) balance constraint of water amount of upper and lower reservoirs:

the pumped storage power station is a pure pumped storage power station, and the natural inflow runoff injection of upper and lower reservoirs is not considered; the water balance constraints for the upper and lower banks are expressed as:

in the formula:

respectively the upper storage capacity m and the lower storage capacity m of the pumped storage power station at the end of the t period³；Δ_tIs a time interval step h;

respectively generating power and pumping water flow of the pumping storage unit i in a period tm³/s；

(2) And (4) library capacity constraint:

in the formula:

upper and lower limits m of upper storage capacity of pumped storage power station³；

Respectively an upper limit m and a lower limit m of the lower storage capacity of the pumped storage power station³；

(3) Limiting the initial and final storage capacity of the reservoir:

starting storage capacity m of an upper storage and a lower storage of the pumped storage power station respectively³Determined by the schedule of the previous day or by historical operating data;

controlling the storage capacity m for the target of the upper storage of the pumped storage power station at the end of the dispatching period³The scheduling personnel sets the operation requirement according to the scheduling; considering that the storage capacity of the reservoir at the end of the allowable dispatching period has certain deviation from the target control storage capacity in the actual dispatching operation process, the set allowable deviation proportion is set;

(4) unit output restraint:

when the pumped storage unit is in a power generation state, the pumped storage unit is equivalent to a water turbine, and the output force of the pumped storage unit can be adjusted at will in a feasible operation interval; in the water pumping state, the power of the water pump only runs near the maximum rated water pumping power point;

in the formula:

the maximum generating power MW of the unit i is respectively;

the maximum rated pumping power MW of the unit i;

is the generating state variable of the unit i in the time period t, if the unit i is in the generating state

Otherwise

Is the pumping state variable of the unit i in the time period t, if the unit i is in the pumping state

Otherwise

(5) Unit power generation/pumped water flow constraint:

in the formula:

maximum power generation and water pumping flow m of the unit i respectively³/)；

(6) And (3) restraining the running state of the unit:

compared with the conventional hydroelectric generating set, the pumping storage unit has three working states: power generation, water pumping and shutdown are performed, but the same unit can only be in one working state at any time; in order to ensure the operation stability of the power station, for different units of the same power station, when at least one unit is in a power generation state, all the other units can not pump water; and vice versa; the above constraints are expressed as shown in formulas (20) to (21);

the formula (21) is nonlinear constraint and needs to be subjected to linearization treatment; introduction of 0-1 integer variables

And

equation (21) can be converted to the following combination of constraints;

for the formula (23), when

When the unit i is in the pumping state during the period t, due to the equation (22),

must be 0, then for

Similarly, in the formula (24), when

When the temperature of the water is higher than the set temperature,

therefore, the formulas (22) to (24) can ensure that the working conditions of pumping water and generating electricity by the organic group do not occur in the same power station;

(7) and (3) restricting the duration of water pumping and power generation of the unit:

in the formula α_i、β_iRespectively the minimum starting time and the minimum stopping time h of the water turbine; x is the number of_i,t、x'_i,tRespectively is the starting and stopping operation variable of the water turbine i, when the water turbine i is started in the time period t, x_i,t1, otherwise x_i,t＝0，x'_i,t1 denotes shutting down turbine i during period t, otherwise x'_i,t＝0；ψ_i、φ_iThe minimum starting time and the minimum stopping time h of the water pump are respectively set;

(8) restraint of the generating water head:

in the formula: h_tThe generating head m of the unit in the time period t;

respectively as the relation function of water level and storage capacity of upper and lower storehouses;

the constraint is a nonlinear constraint, and the nonlinear constraint is subjected to linearization processing; firstly, dispersing the upper and lower library capacity intervals into J subintervals, and introducing 0-1 integer variable

And satisfies the following constraints:

in the formula (I), the compound is shown in the specification,

respectively indicating variables of an upper library and a lower library, wherein when the library capacity of the upper library or the lower library in the t period is in the jth library capacity subinterval, the indicating variable is 1, otherwise, the indicating variable is 0; uniquely determining a storage capacity subinterval in which the storage capacity is positioned in the t period through an equation (29-32); the upper and lower reservoir water levels at the end of the t period are expressed as:

the water level-storage capacity relation linearization is realized through the formulas (29) to (33);

(9) dynamic characteristics of the water turbine:

in the formula:

representing a nonlinear relation between the output of the unit and the generating flow and the generating head for a binary relation function between the output of the unit and the generating flow and the generating head; for a pumping and storage power station for stabilizing random fluctuation of wind power, the fluctuation of the water levels of an upper reservoir and a lower reservoir is severe, so that the water head of the pumping and storage power station is severely changed in a scheduling period, and the influence of the water head on the output of a unit cannot be ignored;

the formula (34) is a nonlinear relation, and the linearization is carried out on the nonlinear relation; determining a unit i water head change interval [ H ] according to the historical operating data of the pumped storage power station_i,min,H_i,max]And dividing the waterhead interval into 5 subintervals, and respectively representing 6 nodes as

Wherein

Introduction of 0-1 integer variables

The unit i is required to meet the following constraints at any time:

in the formula:

indicating the variable for discrete intervals of head when

When the temperature of the water is higher than the set temperature,

otherwise

In each water head interval, selecting one unit power characteristic curve in each subinterval to represent the power characteristic curve of the whole subinterval; at the moment, the constraint of the power characteristic of the water turbine is changed from binary nonlinear constraint to unary nonlinear constraint only related to the generated flow, and a mathematical expression of the constraint is constructed as follows:

in the formula (I), the compound is shown in the specification,

the function relation between the power characteristic of the water wheel and the power generation flow is obtained; from the formulae (36) to (37), there is one and only one

For the

Then when k is 1,2,4,5, the equation (38) is relaxed, and only k is 3, which is the effective constraint

By the formulas (35) - (38), the dynamic characteristics of the water turbine are effectively simplified;

(10) the dynamic characteristic of the water pump is as follows:

the unit pumping power is a binary function with respect to pumping flow and head, but as stated in the constraint (18), the unit operates at nominal power when pumping, and therefore the pump dynamics of the unit is actually the relationship between pumping flow and head at a fixed pumping power, as follows:

in the formula:

the water pumping flow and the water head of the unit i are a relation function.

Adopt the produced beneficial effect of above-mentioned technical scheme to lie in: the invention explores a wind power-pumped storage power station combined dispatching strategy which is not only suitable for the current running situation of a power grid in China, but also can fully consider the running characteristics of a pumped storage power station, so as to improve the controllability of wind power and reduce the adverse effect on the system. The example analysis result shows that the combined dispatching of wind power and pumped storage can effectively restrain the output fluctuation of the wind power, greatly reduces the risk of wind abandon of a power grid, obviously improves the power generation benefit of a wind power plant-pumped storage power station combination body, and can provide reference for a wind power plant and a policy maker for the punishment coefficient of the output deviation of the power transmission and the sensitivity analysis result of a power price mechanism carried out by the power grid.

On the basis of the plant network coordination mechanism provided by the invention, a scene analysis technology of a coupled Latin hypercube sampling and synchronous back substitution technology is adopted to carry out modeling analysis on the uncertainty of the wind power output, and then a mixed integer linear programming model of the short-term joint optimization scheduling of the wind power-pumped storage power station is established with the maximum total combined generation benefit as a target. The model and the method provided by the invention are applied to the joint dispatching simulation analysis of the wind power base proposed by a certain provincial power grid in the east of China and the built pumped storage power station, and it can be seen that the negative influence of the randomness and the volatility of wind power on a power system can be effectively reduced by the joint operation of the pumped storage power station and the wind power plant, the peak load regulation pressure of the power grid is greatly relieved, and meanwhile, the income of the wind power-pumped storage power station combination is remarkably improved.

Drawings

Fig. 1 is a schematic diagram of a wind power plant-pumped storage power station combined power transmission mode.

FIG. 2 is a simplified characteristic curve diagram of a water turbine according to example 5.

Fig. 3 is a schematic diagram of the actual electric output of the combo in scenario 1 in embodiment 6.

Fig. 4 is a schematic diagram of the output of the pumped-hydro energy storage power plant in embodiment 6.

Fig. 5 is a schematic diagram of the water level process of the pumped-hydro energy storage power plant in embodiment 6.

Detailed Description

The following examples illustrate the invention in detail. The raw materials and various devices used in the invention are conventional commercially available products, and can be directly obtained by market purchase.

In the following description of embodiments, for purposes of explanation and not limitation, specific details are set forth, such as particular system structures, techniques, etc. in order to provide a thorough understanding of the embodiments of the present application. It will be apparent, however, to one skilled in the art that the present application may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present application with unnecessary detail.

It will be understood that the terms "comprises" and/or "comprising," when used in this specification and the appended claims, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

It should also be understood that the term "and/or" as used in this specification and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.

As used in this specification and the appended claims, the term "if" may be interpreted contextually as "when", "upon" or "in response to" determining "or" in response to detecting ". Similarly, the phrase "if it is determined" or "if a [ described condition or event ] is detected" may be interpreted contextually to mean "upon determining" or "in response to determining" or "upon detecting [ described condition or event ]" or "in response to detecting [ described condition or event ]".

Furthermore, in the description of the present application and the appended claims, the terms "first," "second," "third," and the like are used for distinguishing between descriptions and not necessarily for describing or implying relative importance.

Reference throughout this specification to "one embodiment" or "some embodiments," or the like, means that a particular feature, structure, or characteristic described in connection with the embodiment is included in one or more embodiments of the present application. Thus, appearances of the phrases "in one embodiment," "in some embodiments," "in other embodiments," or the like, in various places throughout this specification are not necessarily all referring to the same embodiment, but rather "one or more but not all embodiments" unless specifically stated otherwise. The terms "comprising," "including," "having," and variations thereof mean "including, but not limited to," unless expressly specified otherwise.

Example 1 technical framework

The invention aims to explore a wind power-pumped storage power station combined dispatching strategy which is applicable to the current running situation of a power grid in China and can fully consider the running characteristics of a pumped storage power station, so as to improve the controllability of wind power and reduce adverse effects on a system.

Embodiment 2, plant network coordination mechanism for promoting combined operation of wind power plant and storage power station

The embodiment provides a plant network coordination mechanism for promoting combined operation of a wind power plant and a pumped storage power station, which mainly comprises the following steps:

(2) the method comprises the following steps that a generator comprehensively considers factors such as power grid electricity price, technical characteristics of a pumped storage power station (reservoir capacity limit, pump storage unit installed capacity, pump storage unit start-stop cost and the like), possible deviation between actual wind power output and predicted output and the like, determines the output plan of the wind power plant-pumped storage power station combination on the next day, and reports the output plan to a power grid dispatching center in advance for 8-12 hours;

(3) the power grid dispatching center corrects the output plan declared by the power generator according to the next-day load prediction, the trans-regional and trans-provincial tie line plans issued by national and regional network dispatching, the wind power consumption capacity of the system, the transmission line capacity limit and the like, so that the declared output curve follows the load variation trend as much as possible to relieve the peak load regulation pressure of the power generator and is issued to the power generator;

(4) the power generator and the dispatching center can consult the output plan repeatedly until both parties can accept the output plan, and sign corresponding power transmission contracts. If the actual power transmission output deviates from the reported planned output, the grid company gives a certain punishment to the union according to the deviation. Therefore, the contract defines not only the power transmission plan and the power transmission rate but also positive and negative deviation rates between the actual power transmission output and the power transmission plan;

As shown in fig. 1, under the condition of combined operation of a wind farm and a pumped storage power station, when the actual wind power output is higher than the reported output, the excess wind power is supplied to the pumped storage power station to pump water, and as the reversible units pump water from the lower reservoir to the upper reservoir of the power station continuously, the water level in the upper reservoir is higher and higher, the excess wind energy is converted into the potential energy of water to be stored; when the actual wind power output is lower than the declared output, the pumped storage power station discharges water from the upper reservoir to drive the reversible unit to generate power and supply power grid load. In the process, the pumped storage power station can utilize the advantages of quick start and stop, flexible working condition conversion and high load response speed to effectively stabilize the random fluctuation of wind power, play the roles of peak clipping and valley filling, realize the 'soaring and moving' of wind energy in time, and remarkably improve the schedulability of wind power so as to reduce the output deviation punishment and improve the generation yield.

The plant network coordination mechanism aims to stimulate the actual total output curve of the wind power-pumped storage power station combination to be matched with the submitted planned output curve by virtue of the political and economic means, so that the wind power schedulability is improved, and the peak regulation pressure of a power grid is reduced. It should be noted that the wind power plant and the pumped storage power station are assumed to belong to the same power generator, and the scheduling right is given by provincial dispatching, so as to ensure that the joint scheduling of the wind power plant and the pumped storage power station can be smoothly implemented.

Example 3 wind Power uncertainty modeling

The wind power output has certain randomness, and because of the limitation of the current wind power prediction technical level, certain deviation is always inevitable between the predicted value and the actual value of the wind power output, so the uncertainty of the wind power output is modeled and analyzed by adopting a scene analysis technology.

(1) Scene generation

The predicted wind power output sequence in the dispatching cycle is assumed to be

The prediction error of the method is subject to normal distribution N (mu, sigma) in any time period t²) Where μ is a mathematical expectation, σ is a standard deviation, and μ ═ 0 is satisfied,

therefore, the invention adopts a Latin hypercube Sampling (L hyper cube Sampling, L HS) method, the core technology of the method is to firstly layer Sampling probability distribution and then randomly extract samples from each layer in sequence, so that the coverage degree of the extracted samples to the distribution space of random variables can be effectively improved, and the L HS method can accurately reflect the whole distribution of the random variables through less times of Sampling.

(2) Scene reduction

In order to fully reflect the random change characteristics of wind power output, more electricity price scenes can still be generated through L HS, the invention adopts a synchronous retrogradation technology based on probability distance, and reduces the number of scenes as much as possible on the premise of keeping the important characteristics of the wind power output scenes.

1) And (5) initializing the setting. Set the original scene as

(

Respectively, the predicted deviation sequences of the wind power output represented by the scenes i and j), calculating the distance between each pair of scenes, and for the scene i, if the scene s (s ∈ C)^(k)S ≠ i) satisfies D (i, s) ═ min D (i, j),

j is not equal to i, then s is called as the scene closest to the scene i;

3) calculating a probability distance PD (i) ═ p of the scene i_i·D(i,s)(p_iThe probability of the scene i) is calculated, the scene with the smallest probability distance is recorded as l, that is, the PD (i) satisfies PD (l) ═ min,

4) deleting scene l, replacing with scene m nearest to the scene l, and correcting probability of scene m to be p_m＝p_l+p_m. Reserve scene set as

The corresponding scene set needing to be deleted is

Example 4 analysis of objective function

The model only considers the joint scheduling problem of 1 large wind farm and 1 pumped storage power station. For a wind power-pumped storage combined body, the purpose of combined scheduling is to stabilize random fluctuation of wind power through peak shaving capacity of pumped storage energy, so that the expected yield of power generation of the combined body is the maximum, and therefore an objective function of a model is as follows:

max F＝max(F₁+F₂-F₃-F₄) (1)

in the formula: f is the yield of the consortium, F₁Defining the obtained basic income (CNY) for the united body according to the electricity selling contract signed with the power grid company, T is the dispatching cycle, T is the dispatching time interval (h), P_wp,tPlanned output (MW), MP submitted to grid company for combo_tThe internet electricity price (CNY/kWh) is obtained for the time period t; f₂Extra earnings (CNY) obtained when the actual transmission power of the united body exceeds the planned output part, S is the simulation scene number of the wind power sequence, S is the total number of wind power scenes considered by the model, N is the total number of units in the pumped storage power station, i is the number of the pumped storage units,

to send out the electricity prices (CNY/kWh) corresponding to the excess power portion,

respectively the power generation and pumping power (MW) and PW of the pumping and storage unit i in the period t_s,tWind power, p, for a time period t represented by a scene s_sIs the probability of scene s; f₃The actual delivered power for the combo is lower than the penalty Cost (CNY) of the planned output portion,

a punished electricity price (CNY) corresponding to the part of the shortage of the transmitted power; f₄The cost is the running Cost (CNY) of a united body, and the running cost of a wind farm and the starting and stopping cost of a water turbine are negligible, so the cost is mainly the starting and stopping cost of a water pump of a pumped storage unit; c_su,i、C_sd,iCosts (CNY) and y for starting and stopping the pump of the storage unit i and water pump once respectively_i,t、y'_i,tRespectively the water pump on and off operating variables, y, of the unit i_i,t1 means that the water pump is turned on during t, otherwise y_i,t＝0，y'_i,t1 denotes shutting down the water pump during period t, otherwise y'_i,t＝0。

The non-linear terms in the equations (3) to (4) are difficult to directly use the existing solving tool. Thus, the variable b of 0 to 1 is introduced_s,tAnd an auxiliary variable K_s,tAnd X_s,tEquations (3) - (4) can be converted to mixed integer linear constraint combinations of:

K_s,t≥-M·b_s,t(11)

K_s,t≤M·b_s,t(12)

X_s,t≥-M·(1-b_s,t) (13)

X_s,t≤M·(1-b_s,t) (14)

in the formula: m is an especially large real number, b_s,tAn indicator variable for the deviation of the transmitted power of the coupling from the planned output submitted to the grid under scene s, b _s,t1 represents that the transmitted power is lower than the planned output, b _s,t0 indicates that the transmitted power is higher than the planned output. When the state variable b_s,tWhen 0 is satisfied, that is, when the combined transmitted power is higher than the planned output, K is determined by the restrictions of equations (11) and (12)_s,t0, according to formula (7), when F₃The penalty cost of the combo actual transmitted power lower than the planned output part is 0, and the fact is consistent; when b is_s,tWhen the combined transmitted power is 1, i.e., when the planned output power is lower than the combined transmitted power, X is restricted by equations (13) and (14)_s,tWhen F is equal to 0₂0, formula (7) and formula (4) are equivalent. It can be seen that the linear constraint combinations represented by equations (6) - (14) are equivalent transformations to the nonlinear functions represented by equations (3) - (4).

Example 5 analysis of constraint conditions

Because the wind power is fully connected, the constraint condition only considers the operation limit of the pumped storage power station and the unit.

(1) Balance constraint of water amount of upper reservoir and lower reservoir

The pumped storage power station in the model is a pure pumped storage power station, namely the natural inflow runoff injection of an upper reservoir and a lower reservoir is not considered. The water balance constraints for the upper and lower banks can be expressed as:

in the formula:

respectively the upper storage capacity and the lower storage capacity (m) of the pumped storage power station at the end of the t period³)；Δ_tIs a period step (h);

are respectively a drawerGenerating and pumping flow (m) of storage unit i in t period³/s)。

(2) Capacity constraint

In the formula:

respectively an upper limit and a lower limit (m) of the upper storage capacity of the pumped storage power station³)；

Respectively an upper limit and a lower limit (m) of the lower storage capacity of the pumped storage power station³)。

(3) Reservoir initial and final storage capacity limitation

Initial storage capacities (m) of an upper storage and a lower storage of a pumped storage power station, respectively³) Typically determined by a dispatch plan of the previous day or by historical operating data;

controlling the storage capacity (m) for the target of the storage on the pumped storage power station at the end of the dispatching period³) Generally, the scheduling personnel sets the operation according to the scheduling requirement. Considering that the storage capacity of the reservoir at the end of the allowable dispatching period has certain deviation from the target control storage capacity in the actual dispatching operation process, the allowable deviation ratio is set.

(4) Unit output constraint

When the pumped storage unit is in a power generation state, the pumped storage unit is equivalent to a water turbine, and the output force of the pumped storage unit can be adjusted at will in a feasible operation interval. In the pumping state, the power of the pump is generally only operated near the maximum (rated) pumping power point.

In the formula:

the maximum generating power (MW) of the unit i is respectively;

the maximum (rated) pumping power (MW) for the unit i;

Otherwise

Otherwise

(5) Unit power generation/pumped water flow restriction

In the formula:

the maximum power generation and water pumping flow (m) of the unit i³/s)。

(6) Constraint of unit running state

Compared with the conventional hydroelectric generating set, the pumping storage unit has three working states: power generation, water pumping and shutdown are performed, but the same unit can only be in one working state at any time; in order to ensure the operation stability of the power station, for different units of the same power station, when at least one unit is in a power generation state, all the other units can not pump water; and vice versa. The above constraints are expressed as shown in formulas (20) to (21).

Equation (21) is a nonlinear constraint and requires linearization processing. Introduction of 0-1 integer variables

And

equation (21) can be converted to the following combination of constraints.

For the formula (23), when

must be 0, then for

Similarly, in the formula (24),when in use

When the temperature of the water is higher than the set temperature,

thus, equations (22) - (24) ensure that neither pumping nor generating occurs in the same power plant.

(7) Unit pumping and generating duration constraint

In the formula α_i、β_iRespectively the minimum starting time and the minimum stopping time (h) of the water turbine; x is the number of_i,t、x'_i,tRespectively is the starting and stopping operation variable of the water turbine i, when the water turbine i is started in the time period t, x_i,t1, otherwise x_i,t＝0，x'_i,t1 denotes shutting down turbine i during period t, otherwise x'_i,t＝0；ψ_i、φ_iRespectively the minimum on and off duration (h) of the water pump.

(8) Power generation head restraint

In the formula: h_tThe generating head m of the unit in the time period t;

respectively the water level-storage capacity relation function of the upper storage and the lower storage.

The constraint is a non-linear constraint and requires linearization. Firstly, dispersing the upper and lower library capacity intervals into J subintervals, and introducing 0-1 integer variable

And satisfies the following constraints:

in the formula (I), the compound is shown in the specification,

respectively indicating variables of an upper library and a lower library, wherein when the library capacity of the upper library or the lower library in the t period is located in the jth library capacity subinterval, the indicating variable is 1, otherwise, the indicating variable is 0. The subinterval of the storage capacity in the t period can be uniquely determined by the formulas (29-32). Then the upper and lower reservoir levels at the end of the t period may be expressed as:

the water level-storage capacity relation linearization can be realized through the formulas (29) to (33).

(9) Power characteristics of water wheel

In the formula:

and characterizing the nonlinear relation among the unit output, the generating flow and the generating head for the binary relation function among the generating output, the generating flow and the generating head of the unit i. For a pumping and storage power station for stabilizing random fluctuation of wind power, the fluctuation of the water levels of an upper reservoir and a lower reservoir is severe, so that the water head of the pumping and storage power station is further caused to be changed severely in a scheduling period, and the influence of the water head on the output of a unit is generally not negligible.

Since equation (34) is characterized by a non-linear relationship, it needs to be linearized. Determining a unit i water head change interval [ H ] according to the historical operating data of the pumped storage power station_i,min,H_i,max]And dividing the waterhead interval into 5 subintervals, and respectively representing 6 nodes as

As shown in FIG. 2, wherein

Introduction of 0-1 integer variables

The unit i is required to meet the following constraints at any time:

in the formula:

indicating the variable for discrete intervals of head when

When the temperature of the water is higher than the set temperature,

otherwise

In each head interval, one train power characteristic curve in each subinterval is selected to represent the power characteristic curve of the whole subinterval, as shown by the dotted line in fig. 2. At the moment, the constraint of the power characteristic of the water turbine is changed from binary nonlinear constraint to unary nonlinear constraint only related to the generated flow, and a mathematical expression of the constraint is constructed as follows:

in the formula (I), the compound is shown in the specification,

is the functional relation between the power characteristic of the water wheel and the power generation flow. From the formulae (36) to (37), there is one and only one

To be provided with

For example, if

By the formulas (35) to (38), the dynamic characteristics of the water turbine are effectively simplified. The simplified characteristic curve of the water turbine still has the characteristic of unitary nonlinearity, and aiming at the problem, the water turbine is processed by adopting the method for linearizing the water level-reservoir capacity relation curve in the power generation water head constraint, and the specific process is not repeated.

(10) Dynamic characteristics of water pump

The unit pumping power is also a binary function with respect to pumping flow and head, but as stated in the constraint (18), the unit operates at nominal power when pumping, and therefore the pump dynamics of the unit are actually the relationship between pumping flow and head at a fixed pumping power, as follows:

in the formula:

the water pumping flow and the water head of the unit i are a relation function. Aiming at the nonlinear problem, the method for linearizing the relation curve between the water level and the reservoir capacity in the constraint of the generating head is adopted for processing, and the specific process is not repeated.

Example 6 example analysis

In order to verify the effectiveness of the on-demand model construction method provided by the invention, a simulation joint scheduling composed of a 3200MW wind power base which is planned and constructed by a certain provincial power grid in east China and a 612MW pumped storage power station which is already constructed in the province is taken as an example. And taking 1d as a scheduling cycle and 1h as a scheduling time interval. Since the power market has not been developed completely in China, peak-to-valley electricity prices (time-of-use electricity prices) are assumed to be applied to the power generation side. If the actual output of the united body is not equal to the declared planned output, the power grid punishs the deviation part, and the method is embodied in that

Generating 300 scenes by adopting a Latin hypercube sampling method, and then samplingThe scenes are reduced to 50 with the synchronous banding technique. The results and analysis are shown below:

TABLE 1 comparison of independent and Combined run results

The result shows that when the wind power plant operates alone, the wind power plant has strong fluctuation, so that the actual output of the wind power plant is greatly deviated from the declaration plan, and the negative deviation penalty reaches 4916 × 10 due to the double leverage of peak-valley electricity price and penalty coefficient³CNY, and positive bias extra revenue is only 697 × 10³CNY, plus the base revenue specified by the electricity sales contract, the wind farm total can achieve 29068 × 10³Expected revenue from CNY, and the pumped-storage power station can deliver 885 × 10 to the grid by pumping water to store electrical energy during low tariff periods and delivering power to the grid during high tariff periods³Expected profit of CNY, total profit of the generator 29953 × 10³CNY, when the wind power plant and the pumped storage power station jointly operate, the output negative deviation penalty is only 1742 × 10³CNY, reduced by 64.6%, available from the generator as 31534 × 10³The expected yield of CNY is increased by 5.28%. Therefore, the output fluctuation of the spontaneous compensation wind power plant of the pumped storage power station can be fully exerted by combined operation, and the expected income of a power generator is remarkably improved.

Detailed analysis is performed in scene 1.

Fig. 3 is a comparison between the actual power transmission power of the united body and the declared output power in the scenario 1, and it can be seen that the wind power plant and the pumped storage combined operation can smooth the wind power output power, improve the controllability of the wind power, improve the inverse peak regulation performance of the wind power in the independent operation, reduce the instability of the power grid operation, and greatly reduce the peak regulation pressure of the system.

Fig. 4 is a graph showing the output of the pumped storage power station, and it can be seen that, in a period of 1 to 8, the output of the wind farm is greater than the planned output declared by the complex, at this time, the grid-connected electricity price of the wind power is lower, and the wind power is in a valley price area, and the extra benefit of the positive output deviation is lower due to the action of the price penalty coefficient, so that the working condition of the reversible unit in this period is a pumped state, and the pumped storage power station stores water and energy by using redundant wind power; in the 9-11 period, the deviation of the wind power and the planned output declared by the united body is not large, and the wind power and the planned output declared by the united body are in the flat price area of the electricity price at the moment, the deviation punishment is not large, so that the pumped storage power station is in a shutdown state in the period; in the period of 12-22, the output of the wind power plant is small, the output power is far lower than the planned output, the grid-connected electricity price is in a high price area, the penalty cost of negative deviation is extremely high, and at the moment, the pumped storage power station starts to enter a power generation state to compensate the wind power output deviation. In the 23 th-24 th time period, the electricity price is reduced to enter the flat price area, at the moment, although the output of the wind power plant is smaller than the planned output, the pumped storage power station cannot continue to discharge water to generate electricity to compensate the negative output deviation because the upper reservoir water level of the pumped storage power station reaches the target control water level at the end of the 22 th time period, and therefore the pumped storage power station is in a shutdown state.

FIG. 5 is a water level process of the upper and lower banks of the pumped storage power station, and it can be seen that the water levels of the upper and lower banks of the power station both satisfy the upper and lower limit constraints, and the water level of the upper bank at the end of the scheduling period also meets the control requirements; the water level fluctuation of the power station in the dispatching cycle is large, so that the water head is changed drastically in the range of 133m-149m, the fluctuation range is large, and the influence of the water head change on the power generation and water pumping of the storage unit is not negligible.

TABLE 2 Start-stop state of each unit of pumped storage power station

Note that "×" indicates that the unit is in a water pumping state, "√" indicates that the unit is in a power generating state, and "○" indicates that the unit is in a shutdown state.

As shown in table 2, each unit satisfies the minimum duration constraint of minimum pumping, power generation and shutdown, and neither the water turbine nor the water pump is frequently started or stopped, nor is the existing unit in the same power station pump water and generate power. And because the start-stop cost of the water pump is considered in the model, the total times of starting and stopping all the water pumps in the whole scheduling period do not exceed 3 times, and are far lower than the times of starting and stopping the water turbine with lower cost.

In summary, the invention provides a plant network coordination mechanism aiming at exciting combined dispatching of wind power and pumped storage power stations and improving wind power schedulability, on the basis, a scene analysis technology of a coupled latin hypercube sampling and synchronous back substitution technology is adopted to carry out modeling analysis on uncertainty of wind power output, and then a mixed integer linear programming model of short-term combined optimized dispatching of the wind power-pumped storage power station is established with the maximum combined total power generation benefit as a target. The model and the method provided by the invention are applied to the joint dispatching simulation analysis of the wind power base proposed by a certain provincial power grid in the east of China and the built pumped storage power station; the combined operation of the pumped storage power station and the wind power plant can effectively reduce the negative influence of the randomness and the fluctuation of wind power on a power system, greatly relieve the peak load regulation pressure of a power grid, and obviously improve the yield of the wind power-pumped storage power station combination. Compared with independent operation of a wind power plant and a pumped storage power station, the total power generation yield of combined operation is improved by 5.28%.

The above-mentioned embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not substantially depart from the spirit and scope of the embodiments of the present invention, and are intended to be included within the scope of the present invention.

Claims

1. A plant network coordination method for exciting combined operation of a wind power plant and a pumped storage power station is characterized by comprising the following steps: according to the method, starting from the requirements of stable operation of a power grid and improvement of profits of power generators, matching of an actual total output curve and a planned output curve of a wind power-pumped storage power station combination is promoted through multiple ways, the schedulability of wind power is improved, and a plant and grid coordination mechanism for exciting combined operation of a wind power plant and a pumped storage power station is formed.

2. The method of claim 1 for coordinating a grid for stimulating the combined operation of a wind farm and a pumped storage power plant, wherein the method comprises the steps of: the method specifically comprises the following steps:

3. The method of claim 1 for coordinating a grid for stimulating the combined operation of a wind farm and a pumped storage power plant, wherein the method comprises the steps of: the technical characteristics of the pumped storage power station at least comprise a reservoir capacity limiting characteristic, a pump storage unit installed capacity characteristic and a pump storage unit water pump starting and stopping cost characteristic.

4. The method of claim 1 for coordinating a grid for stimulating the combined operation of a wind farm and a pumped storage power plant, wherein the method comprises the steps of: under the condition that a wind power plant and a pumped storage power station are operated in a combined mode, when the actual wind power output is higher than the reported output, the excess wind power is supplied to the pumped storage power station to pump water, the water level of the upper reservoir is higher and higher along with the continuous pumping from the lower reservoir to the upper reservoir of the power station by the reversible unit, and redundant wind energy is converted into potential energy of water to be stored; when the actual wind power output is lower than the declared output, the pumped storage power station discharges water from the upper reservoir to drive the reversible unit to generate power and supply power grid load; in the process, the pumped storage power station effectively stabilizes the random fluctuation of wind power by using the advantages of quick start and stop, flexible working condition conversion and high load response speed, plays the roles of peak clipping and valley filling, realizes manual control of wind energy and prediction of time and space shift, and improves the schedulability of wind power so as to reduce the output deviation punishment and improve the generation benefit.

5. A wind power-pumped storage combined dispatching method based on the plant network coordination mechanism of claim 1, characterized in that: firstly, wind power schedulability is realized under a plant network coordination mechanism, on the basis, a scene analysis technology is adopted to carry out modeling analysis on uncertainty of wind power output, namely wind power uncertainty modeling analysis, then the operation characteristics of the pumped storage power station are fully considered, a mixed integer programming model of coordinated operation of the wind power-pumped storage power station with the maximum united body power generation yield as a target is constructed through objective function analysis and constraint condition analysis, and then an optimization solver is used for solving the model.

6. The method of claim 5, wherein: the wind power uncertainty modeling analysis comprises:

(1) scene generation

(2) scene reduction

1) initializing and setting; set the original scene as

Wherein

Respectively calculating the distance between each pair of scenes for the predicted deviation sequences of the wind power output represented by the scenes i and j, and determining the distance between each pair of scenes if the scene s is the scene i (s ∈ C)^(k)S ≠ i) satisfies

S is called as the scene closest to the scene i;

3) calculating a probability distance PD (i) ═ p of the scene i_i·D(i,s)，p_iRepresenting the probability of the scene i, counting the scene with the minimum probability distance, and recording as l, namely satisfying

The corresponding scene set needing to be deleted is

7. The method of claim 5, wherein:

the objective function analysis includes:

max F＝max(F₁+F₂-F₃-F₄) (1)

8. The method of claim 7, wherein:

introduction of the variable b from 0 to 1_s,tAnd an auxiliary variable K_s,tAnd X_s,tEquations (3) - (4) are converted into the following mixed integer linear constraint combination, and the problem that the equations (3) - (4) are difficult to directly solve is solved:

K_s,t≥-M·b_s,t(11)

K_s,t≤M·b_s,t(12)

X_s,t≥-M·(1-b_s,t) (13)

X_s,t≤M·(1-b_s,t) (14)

in the formula: m is a sufficiently large real number, b_s,tAn indicator variable for the deviation of the transmitted power of the coupling from the planned output submitted to the grid under scene s, b_s,t1 represents that the transmitted power is lower than the planned output, b_s,t0 means that the transmitted power is higher than the planned output; when the state variable b_s,tWhen 0 is satisfied, that is, when the combined transmitted power is higher than the planned output, K is determined by the restrictions of equations (11) and (12)_s,t0, according to formula (7), when F₃The penalty cost of the combo actual transmitted power lower than the planned output part is 0, and the fact is consistent; when b is_s,tWhen the combined transmitted power is 1, i.e., when the planned output power is lower than the combined transmitted power, X is restricted by equations (13) and (14)_s,tWhen F is equal to 0₂0, formula (7) and formula (4) are equivalent; the linear constraint combinations represented by equations (6) to (14) are equivalent transformations to the nonlinear functions represented by equations (3) to (4).

9. The method of claim 5, wherein:

the constraint analysis only considers the operation limits of the pumped storage power station and the unit, and comprises the following steps:

(1) and (3) balance constraint of water amount of upper and lower reservoirs: