CN109390977B - A wind speed characteristic analysis method supporting black start of wind farms - Google Patents

Abstract

The present invention provides a wind speed characteristic analysis method for supporting the black start of a wind farm. Under the constraints of the power demand condition of the auxiliary machines of the thermal power unit to be started, the wind speed probability density index of the lower limit wind speed of the black start and the time continuity condition is defined to describe and analyze the wind speed of the wind farm. Wind speed characteristics, evaluate the black start feasibility of different wind farms, and select the wind farm auxiliary power grid black start that meets the power requirements of the auxiliary power of the thermal power plant to be started. Guiding significance. The method is scientific and reasonable, with strong applicability and good effect.

Description

Wind speed characteristic analysis method for supporting black start of wind power plant

Technical Field

The invention relates to the technical field of black start of a power grid, in particular to a wind speed characteristic analysis method for supporting black start of a wind power plant.

Background

The power system blackout accident is an unavoidable threat and hidden danger, and meanwhile, the power system in China enters the times of high voltage, large power grid and large unit. Once the power failure accident happens, the spread range is large, and the consequences are serious. Therefore, as one of the important measures for the safe operation of the power system, a black start scheme needs to be prepared in advance. The key of the black start is the selection of a black start power supply, and the conventional hydroelectric generating set is used as the start power supply to carry out the black start, but certain limitations exist in northwest regions of China with much wind and little water. With the annual improvement of the installed capacity of wind power of a local area power grid in northwest China, the research of starting a black start scheme by taking a wind power plant as an auxiliary start power source appears.

Due to the inherent property of random fluctuation of wind resources, the research on the black start feasibility of the wind power plant is still in the demonstration stage of qualitative analysis at present, so that the wind power plant and the wind resources are required to be researched in a targeted manner in a black start mode so as to effectively evaluate the feasibility of the wind power plant as a black start power supply.

At present, the analysis of the wind speed distribution characteristics of the wind power plant mainly serves for wind power plant planning or dispatching plan. However, for the feasibility study of the wind power plant as a black-start backup power supply, under the condition of the minimum black-start power requirement, especially when the problem of the time probability of the continuous effective output of the wind turbine generator is studied, the distribution characteristics of the wind energy resources in the region should be analyzed on the basis of the installed capacity of the wind power plant in the local power grid and the output performance of the wind turbine generator to adapt to new needs.

Disclosure of Invention

The purpose of the invention is: the method for analyzing the wind speed characteristics of the wind power plant overcomes the defects of the existing wind speed characteristic analysis of the wind power plant, is scientific and reasonable, considers the influence factors of various aspects of the wind speed of the wind power plant, and is strong in applicability and good in effect.

The technical scheme adopted for achieving the purpose is that the wind speed characteristic analysis method for supporting the black start of the wind power plant is characterized by comprising the following steps of:

1) determining the auxiliary machinery demand of a unit to be started

Firstly, the power P of the auxiliary machine with the starting power plant is obtained by the superposition of the power of the auxiliary machine_M；

Determining the minimum generating power P of each wind power plant meeting the black start according to the formulas (1) to (4)_{τ_lim}And minimum output power P_lim：

P_lim＝(1+α)P_M (1)

nP_W-P_Z＞(1+α)P_M (2)

P_Wmin＝P_lim/n (3)

P_{τ_lim}＝(1+α)P_M+P_Z (4)

In the formula, n is the number of the wind power plant units; p_WThe power can be generated for a single unit; p_ZSelf-powered system power for a wind farm; p_MThe power of the auxiliary engine of the power plant is to be started; minimum generating power P of single wind turbine_Wmin(ii) a The coefficient alpha is the line loss rate, and the power grid operation standard alpha is 0.085;

2) defining an evaluation index

Thirdly, defining the black start lower limit wind speed, namely the wind speed meeting the requirement is the black start lower limit wind speed v_limThe measured v-P curve formula (5) of the wind power plant is used for obtaining,

in the formula, R is the radius of the wind wheel; ρ is the air density; c_pTaking the average wind energy utilization efficiency C of the wind power plant for the wind energy utilization coefficient and considering the wake effect_p＝0.48；

Fourthly, defining the wind speed probability density under the continuous time condition:

under the condition of black start lower limit wind speed, according to wind speed sampling data in a selected time scale, taking the hot start time of the thermal power generating unit as a time length standard for 30-45min, taking the lower limit wind speed probability density P of the continuous time condition as the probability density of the data subset, and expressing by an equation (6):

wherein v is the wind speed; v. of_maxIs the maximum wind speed; v. of_{τ_lim}Lower wind speed for continuous time conditions;

certain deviation can occur in the utilization of wind energy by the wind turbine generator, namely, a wind speed slightly larger than a starting lower limit is sometimes required to be reserved to ensure the output of required power, and the maximum wind speed meeting the minimum power generation power of a single unit in measured data is taken as a margin wind speed v_{σ-t_lim}If the wind speed is larger than the margin wind speed value, the executable wind speed is used, and if the wind speed is smaller than the lower limit wind speed value, the wind speed is not executable, and the probabilities are respectively an expression (7) and an expression (8);

P₊and P_-The probability of the trend executable wind speed and the probability of the trend unexecutable wind speed are respectively, the relative sizes of the two probabilities can intuitively represent the trend degree of feasibility, and the feasibility probability relative inclination eta is expressed by the formula (9):

in formula (9): when η > 1, the wind speed is relatively inclined to be executable; when η < 1, the wind speed is relatively prone to be unexecutable;

the evaluation indexes of contents 1) to 2) reflect the influence of the wind speed characteristics of the wind power plant on the black start feasibility of the wind power plant, and reflect the black start feasibility of the wind power plant expressed in different wind power places.

According to the wind speed characteristic analysis method for supporting the black start of the wind power plant, under the constraint of the power requirement condition of the auxiliary machinery of the thermoelectric power plant to be started, the wind speed probability density indexes of the black start lower limit wind speed and time continuous conditions are defined, the wind speed characteristics of the wind power plant are analyzed in a depicting manner, and the black start feasibility shown in different wind power places is evaluated, so that the wind power plant which meets the power requirement of the auxiliary machinery of the thermoelectric power plant to be started is selected to assist the black start of the power grid, and the method has important guiding significance for the black start of the wind power plant after the power failure in the area with much wind and little water. The method is scientific and reasonable, and has strong applicability and good effect.

Drawings

FIG. 1 is a flow chart of evaluation of black start feasibility of a wind farm;

FIG. 2 is a start-up wind farm geography wiring diagram;

FIG. 3 is a wind speed probability distribution diagram of each wind farm.

Detailed Description

The invention is further illustrated by the following figures and examples.

The invention discloses a wind speed characteristic analysis method for supporting black start of a wind power plant, which comprises the following steps of:

1) determining the auxiliary machinery demand of a unit to be started

Firstly, the power P of the auxiliary machine with the starting power plant is obtained by the superposition of the power of the auxiliary machine_M；

Determining the minimum generating power P of each wind power plant meeting the black start according to the formulas (1) to (4)_{τ_lim}And minimum output power P_lim：

P_lim＝(1+α)P_M (1)

nP_W-P_Z＞(1+α)P_M (2)

P_Wmin＝P_lim/n (3)

P_{τ_lim}＝(1+α)P_M+P_Z (4)

In the formula, n is the number of the wind power plant units; p_WThe power can be generated for a single unit; p_ZSelf-powered system power for a wind farm; p_MThe power of the auxiliary engine of the power plant is to be started; minimum generating power P of single wind turbine_Wmin(ii) a Coefficient alpha isAnd the line loss rate is equal to 0.085 of the operation standard alpha of the power grid.

2) Defining an evaluation index

Thirdly, defining the black start lower limit wind speed, namely the wind speed meeting the requirement is the black start lower limit wind speed v_limThe measured v-P curve formula (5) of the wind power plant is used for obtaining,

in the formula, R is the radius of the wind wheel; ρ is the air density; c_pTaking the average wind energy utilization efficiency C of the wind power plant for the wind energy utilization coefficient and considering the wake effect_p＝0.48；

Fourthly, defining the wind speed probability density under the continuous time condition:

under the condition of black start lower limit wind speed, according to wind speed sampling data in a selected time scale, taking the hot start time of the thermal power generating unit as a time length standard for 30-45min, taking the lower limit wind speed probability density P of the continuous time condition as the probability density of the data subset, and expressing by an equation (6):

wherein v is the wind speed; v. of_maxIs the maximum wind speed; v. of_{τ_lim}Lower wind speed for continuous time conditions;

certain deviation can occur in the utilization of wind energy by the wind turbine generator, namely, a wind speed slightly larger than a starting lower limit is sometimes required to be reserved to ensure the output of required power, and the maximum wind speed meeting the minimum power generation power of a single unit in measured data is taken as a margin wind speed v_{σ-t_lim}If the wind speed is larger than the margin wind speed value, the executable wind speed is used, and if the wind speed is smaller than the lower limit wind speed value, the wind speed is not executable, and the probabilities are respectively an expression (7) and an expression (8);

P₊and P_-The probability of the trend executable wind speed and the probability of the trend unexecutable wind speed are respectively, the relative sizes of the two probabilities can intuitively represent the trend degree of feasibility, and the feasibility probability relative inclination eta is expressed by the formula (9):

in formula (9): when η > 1, the wind speed is relatively inclined to be executable; when η < 1, the wind speed is relatively prone to be unexecutable;

the contents 1) to 2) reflect the influence of the wind speed characteristics of the wind power plant on the black start feasibility of the wind power plant, and reflect the black start feasibility of the wind power plant expressed in different wind power places.

The calculation conditions of the specific examples are illustrated below:

(a) part of auxiliary machine parameters are shown in the table 1;

(b) the wind farm parameters are as in table 2;

(c) the feasibility evaluation flow of the wind power plant is shown in figure 1;

(d) the starting type wind farm geographical wiring diagram is shown in FIG. 2;

table 1: partial auxiliary machine parameters:

table 2: wind power plant parameters:

according to the embodiment, conditions (a) to (d) are calculated, and the black start evaluation result of each wind power plant by applying the method is as follows:

1. determining auxiliary machine demand

The auxiliary machine power P of the electric heating unit with the capacity of 300MW to be started is calculated by an attached table 1 and formulas (1) to (4)_M＝25.5MW；

Minimum generating power P when each wind power plant meets the minimum starting power of black start_{τ_lim}It was 28.67 MW.

2. Feasibility of black start of each wind farm

According to a v-P curve formula (5) of a unit installed in a wind power station, obtaining relative inclination characteristics of black start lower limit wind speed and execution probability corresponding to the minimum output of each wind power station as shown in the following table 3:

table 3: black start feasibility wind speed feature of each wind power plant

Referring to fig. 3, it can be seen from comparison of table 3 that the lower limit wind speed under the black start time condition of each wind farm decreases as the installed capacity of the wind farm increases. Under the condition of certain starting power requirement, the utilization range of the 4# wind power plant with the largest installed capacity to the wind speed is larger; when the wind speed conditions are approximately equal, the 3# and 4# wind power plants with larger installed capacity have larger relative inclination compared with the 1# and 2# wind power plants, and show stronger support to black start; and when the installed capacity is the same, the relative inclination of the 1# and 2# with the large power unit is larger than that of the 5# wind power plant.

According to the black-start wind speed characteristic index, when a single wind power plant is used as the auxiliary power supply for the black-start of the local area power grid, the feasibility probability of each wind power plant can be obtained as shown in table 4.

Table 4: probability of feasibility of black start of each wind power plant

Accordingly, when evaluating the black start scheme of the local area power grid assisted by the wind power plant, the following principles can be referred to:

wind speed is used as an energy source for wind power generation, and a wind power plant with good wind speed condition is preferably taken as an alternative starting power source.

And (II) under the condition of similar wind speed conditions, preferentially selecting a wind power plant with large installed capacity as an alternative power source.

And (III) selecting the wind power plants with the same installed capacity, preferably selecting the wind power plants with high installed proportion of high-power units.

The terms, diagrams, tables and the like in the embodiments of the present invention are used for further description, are not exhaustive, and do not limit the scope of the claims, and those skilled in the art can conceive of other substantially equivalent alternatives without inventive step in light of the teachings of the embodiments of the present invention, which are within the scope of the present invention.

Wang xiaohai, hou you hua, qijun, zhang hong, li army badge, zhang jiaxing, zhang shi ning, yangzhou, hong you fei, yu zheng and kongming.

Claims (1)

1. A wind speed characteristic analysis method for supporting black start of a wind power plant is characterized by comprising the following steps:

1) determining the auxiliary machinery demand of a unit to be started

Firstly, the power P of the auxiliary machine with the starting power plant is obtained by the superposition of the power of the auxiliary machine_M；

Determining the minimum generating power P of each wind power plant meeting the black start according to the formulas (1) to (4)_{τ_lim}And minimum output power P_lim：

P_lim＝(1+α)P_M (1)

nP_W-P_Z＞(1+α)P_M (2)

P_Wmin＝P_lim/n (3)

P_{τ_lim}＝(1+α)P_M+P_Z (4)

In the formula, n is the number of the wind power plant units; p_WThe power can be generated for a single unit; p_ZSelf-powered system power for a wind farm; p_MThe power of the auxiliary engine of the power plant is to be started; minimum generating power P of single wind turbine_Wmin(ii) a The coefficient alpha is the line loss rate, and the power grid operation standard alpha is 0.085;

2) defining an evaluation index

Thirdly, defining the black start lower limit wind speed, namely the wind speed meeting the requirement is the black start lower limit wind speed v_limThe measured v-P curve formula (5) of the wind power plant is used for obtaining,

in the formula, R is the radius of the wind wheel; ρ is the air density; c_pTaking the average wind energy utilization efficiency C of the wind power plant for the wind energy utilization coefficient and considering the wake effect_p＝0.48；

Fourthly, defining the wind speed probability density under the continuous time condition:

under the condition of black start lower limit wind speed, according to wind speed sampling data in a selected time scale, taking the hot start time of the thermal power generating unit as a time length standard for 30-45min, taking the lower limit wind speed probability density P of the continuous time condition as the probability density of the data subset, and expressing by an equation (6):

wherein v is the wind speed; v. of_maxIs the maximum wind speed; v. of_{τ_lim}Lower wind speed for continuous time conditions;

certain deviation can occur in the utilization of wind energy by the wind turbine generator, namely, a wind speed slightly larger than a starting lower limit is sometimes required to be reserved to ensure the output of required power, and the maximum wind speed meeting the minimum power generation power of a single unit in measured data is taken as a margin wind speed v_{σ-t_lim}Wind speed value greater than the marginThe executable wind speed is used, the wind speed which is smaller than the lower limit wind speed value is the non-executable wind speed, and the probability of the wind speed is respectively an expression (7) and an expression (8);

P₊and P_-The probability of the trend executable wind speed and the probability of the trend unexecutable wind speed are respectively, the relative sizes of the two probabilities can intuitively represent the trend degree of feasibility, and the feasibility probability relative inclination eta is expressed by the formula (9):

in formula (9): when η > 1, the wind speed is relatively inclined to be executable; when η < 1, the wind speed is relatively prone to be unexecutable;

the evaluation indexes of contents 1) to 2) reflect the influence of the wind speed characteristics of the wind power plant on the black start feasibility of the wind power plant, and reflect the black start feasibility of the wind power plant expressed in different wind power places.

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