WO2017084404A1

WO2017084404A1 - Method for estimating grid wind power sending capability allowing for wind farm off the system constraint

Info

Publication number: WO2017084404A1
Application number: PCT/CN2016/097019
Authority: WO
Inventors: 李惠玲; 郑超; 宋云亭; 张鑫; 吕思卓; 李顺昕; 杨金刚; 李笑蓉; 张志强; 唐晓骏; 陈得治; 陈湘; 李再华
Original assignee: 中国电力科学研究院; 国家电网公司; 国网冀北电力有限公司经济技术研究院
Priority date: 2015-11-20
Filing date: 2016-08-26
Publication date: 2017-05-26
Also published as: CN106786788A; CN106786788B

Abstract

A method for estimating a grid wind power sending capability allowing for a wind farm off the system constraint, comprising the following steps: according to alternating current and direct current grid data of an estimated area, obtaining, through calculation, a grid wind power sending ultimate parameter group of the estimated area (1); according to the grid wind power sending ultimate parameter group, establishing a grid wind power sending capability estimation model (2); and according to the grid wind power sending capability estimation model, determining the grid wind power sending capability of the estimated area (3).

Description

Method for evaluating wind power transmission capacity of grid based on wind farm out-of-network constraint

Technical field

The invention relates to the field of detecting wind power transmission capability of a power grid, and particularly relates to a method for evaluating wind power transmission capability of a power grid considering a wind power grid off constraint.

Background technique

Wind power is a clean and renewable energy source. Wind power is an important supplement to conventional energy, and it plays an important role in adjusting energy structure, protecting the environment, coping with climate change and promoting sustainable development. Vigorously developing wind power has become an important task of current energy work and the long-term direction of China's power industry development.

The power transmission capacity of regional power grids is restricted by many factors, such as low voltage ride through capability, line transmission capacity, and main transformer capacity. When large-scale wind power is connected to the regional power grid, if the wind farms of different capacities are disconnected from the network, the power transmission of the line will be reduced. If the operation of the voltage regulating equipment is not considered, the system voltage will inevitably rise, thus affecting the regional power grid. Wind power delivery capability.

Therefore, it is of great significance to study the wind power transmission capacity of regional power grids under the condition of large-scale wind farm off-grid and wind power fluctuation.

Summary of the invention

In view of this, the method for evaluating the wind power transmission capability of the power grid considering the wind power off-network constraint is provided to solve at least the above problems in the prior art.

The object of the invention is achieved by the following technical solutions:

An embodiment of the present invention provides a method for evaluating a wind power transmission capability of a power grid, which includes a wind farm off-network constraint, and the method includes:

Step 1. Calculate a grid wind power transmission limit parameter group of the assessment area according to the AC/DC grid data of the assessment area;

Step 2: Establishing a wind power transmission capability evaluation based on the grid wind power sending limit parameter group model;

Step 3: Determine, according to the grid wind power sending capability evaluation model, the grid wind power sending capability of the assessment area.

It can be seen from the above technical solution that the present invention provides a method for evaluating the wind power transmission capacity of a power grid that takes into account the wind power off-coupling constraints, and calculates the wind power transmission limit parameter group of the evaluation area according to the AC and DC power grid data in the assessment area. According to the grid wind power delivery limit parameter group, the grid wind power transmission capacity assessment model is established; according to the grid wind power delivery capability assessment model, the grid wind power delivery capability of the assessment area is determined. The method proposed by the invention can quickly and accurately find the important constraint conditions for restricting the wind power transmission capacity of the regional power grid, thereby improving the wind power transmission capability of the regional power grid and maximizing the development and utilization of the wind energy resources.

Compared with the closest prior art, the technical solution provided by the present invention has the following excellent effects:

1. In the technical solution provided by the present invention, a comprehensive evaluation model for the wind power transmission capacity of the regional power grid is established, and various factors that restrict the wind power transmission capability of the regional power grid are analyzed; and the wind power transmission capacity that restricts the regional power grid is accurately and comprehensively found. The bottleneck will improve the wind power transmission capacity of the regional power grid and maximize the utilization of wind energy resources.

2. The technical solution provided by the present invention focuses on the analysis of the effects of large-scale wind turbine off-grid and voltage deviation caused by wind power fluctuation; and can quickly and accurately find important constraints that restrict the wind power transmission capacity of the regional power grid. Thereby improving the wind power transmission capacity of the regional power grid.

3. The technical solution provided by the present invention is not only limited to the low voltage ride-through capability of the wind turbine, but also comprehensively considers the thermal stability constraint of the power grid, the safety and stability constraints, the voltage offset effect caused by the large-scale wind turbine off-grid, and the wind power. Fluctuation effects.

4. The technical solution provided by the invention has wide application and significant social and economic benefits.

DRAWINGS

1 is a flow chart of a method for evaluating a wind power output capability of a power grid considering a wind farm off-grid constraint according to the present invention;

Figure 2 is a flow chart of step 1 in the evaluation method of the present invention;

3 is a schematic diagram of a regional power grid wind farm access system according to a specific application example of a method for evaluating a wind power transmission capability of a power grid according to a wind farm off-grid constraint;

4 is a flow chart showing a specific application example of the evaluation method of the present invention.

detailed description

The technical solutions in the embodiments of the present invention are clearly and completely described in the following with reference to the accompanying drawings in the embodiments of the present invention. It is obvious that the described embodiments are only a part of the embodiments of the present invention, but not all embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without creative efforts are within the scope of the present invention.

As shown in FIG. 1 , the present invention provides a method for evaluating a wind power transmission capability of a power grid that takes into account a wind farm off-grid constraint, and includes the following steps:

Step 1: Calculate the grid wind power transmission limit parameter group of the assessment area according to the AC/DC grid data in the assessment area;

Step 2: According to the grid wind power delivery limit parameter group, establish a grid wind power delivery capability evaluation model;

Step 3: Determine the grid wind power delivery capability of the assessment area based on the grid wind power delivery capability assessment model.

As shown in Figure 2, step 1 includes:

1-1. Measure the AC/DC grid data of the assessment area, wherein the AC/DC grid data includes: the conductor type and line length of the wind power transmission channel in the assessment area, the number of wind farms of the wind power collection station, and the transformer capacity of the wind power collection station. And the number of units, the maximum allowable offset value of the transformer bus voltage of the wind power collection station, and the maximum allowable offset value of the wind turbine terminal voltage;

1-2. According to the AC and DC grid data, calculate the grid wind power transmission limit parameter group in the assessment area; wherein the grid wind power transmission limit parameter group includes: wind power collection station transformer capacity limit, wind power transmission channel thermal stability limit and transient stability The limit, the wind farm off-grid and the wind farm output after the wind farm output fluctuations limit.

Among them, 1-2 includes:

a. Calculate the transformer capacity limit of the wind power collection station P _WT :

In formula (1), P _e,i is the rated capacity of transformer i in the wind power collection station, and N _T is the number of transformers in the aggregation station;

b. According to the wire type of the wind power sending channel, respectively determine the thermal stable current value and the thermal stable power value of the T _constant and T _high wire; wherein, 20 ° ≤ T _often ≤ 30 ° and 30 ° < T _high ≤ 50 °;

The thermally stable power value, calculating the thermal stability limit T are _normally fed to the wind passage at _{a high} temperature T P _WH;

c. According to the power flow calculation and the transient stability calculation, the transient stability limit P _{WS is obtained} ;

d. According to the allowable maximum offset value of the wind turbine terminal voltage, the maximum allowable offset value of the transformer busbar voltage of the wind power collection station, and the number of wind farms of the wind power collection station, the wind power transmission limit P _{WO of the} wind farm off-grid is calculated.

e. Set the wind power fluctuation scenario and compare the grid wind power delivery limit in different scenarios, and obtain the grid wind power delivery limit P _{WV in the} assessment area when the wind power fluctuates.

Wherein step d includes:

D-1. Calculate the wind farm in the assessment area i, the other wind farms caused by the off-grid, the maximum offset value of the unit terminal voltage ΔU _GV,i and the maximum offset value of the bus voltage of the transformer of the wind power collection station ΔU _TV,i ;

D-2. Determine whether ΔU _GV,i and ΔU _TV,i exceed the limit:

In equation (2),

For the wind turbine, the terminal voltage allows the maximum offset value,

The maximum allowable offset value for the transformer bus voltage of the wind power collection station;

Determine whether ΔU _GV,i and ΔU _TV,i exceed the limit, if ΔU _GV,i and / or ΔU _TV,i exceeds the limit, adjust the wind farm off-grid output to formula (2); enter d-3; Equation (2) is established, that is, ΔU _GV,i and ΔU _TV,i are not limited, then directly enter d-3;

D-3. Count the wind farm transmission capacity P _{i of} all access to the wind power collection station, and calculate the grid wind power transmission limit P _WO,i of the assessment area when the wind farm i is off the grid:

In equation (3), N _W is the number of wind farms connected to the wind power collection station;

D-4. Repeat steps d-1 to d-3 for all wind farms connected to the wind power collection station, and compare the delivery limits of all wind farms when off-grid, and obtain the grid wind power in the assessment area when the wind farm is off-grid. Send limit P _WO :

Wherein step e includes:

E-1. Set two wind power fluctuation scenarios, including:

Scene 1: The effect of wind power fluctuation on the grid voltage when the wind power output is large;

Scenario 2: The influence of wind power fluctuation on the grid voltage when the simulated wind power output is small;

E-2. In the scene, calculate the maximum offset value ΔU _GV1,i of the other terminal of the wind farm caused by the power fluctuation of the wind farm _i, and the maximum offset value ΔU _{TV1,i of the} main transformer voltage of the main transformer _, and judge ΔU _{GV1 , i} and ΔU _{TV1, i} is the limit;

If equation (5) does not hold, adjust the wind power output to formula (5); enter e-3;

If equation (5) is established, it will enter e-3 directly;

E-3. Calculate the maximum offset of the wind power under the voltage safety boundary, count the output of each wind farm, and calculate the wind power delivery capacity P _WV1,i at this time:

E-4. Perform steps e-2 to e-3 for all wind farms connected to the substation of the wind power collection station to obtain the grid wind power transmission limit P _{WV1 of the scenario} :

E-5. Under scenario 2, calculate the maximum offset value ΔU _GV2,i of the other terminal of the wind farm caused by the power fluctuation of the wind farm _i, and the maximum offset value of the bus voltage of the main transformer ΔU _TV2,i , judge ΔU Whether _GV2,i and ΔU _TV2,i are exceeded;

If equation (8) does not hold, adjust the wind power output to formula (8); enter e-6;

If equation (8) is established, it will enter e-6 directly;

E-6. Calculate the maximum offset of the wind power under the voltage safety boundary, count the output of each wind farm, and calculate the wind power delivery capacity P _{WV2, i} :

E-7. Perform steps e-5 to e-6 for all wind farms connected to the substation of the wind power collection station to obtain the grid wind power transmission limit P _WV2 under scenario 2:

E-8. Compare scene 1 and scene 2 to obtain the wind power transmission limit P _{WV of the} regional grid when the wind power fluctuates:

P _WV =min(P _WV1 , P _WV2 ) (11)

Wherein step 2 includes:

According to the transformer capacity limit P _WT of the wind power collection station, the thermal stability limit P _{WH of the} wind power transmission channel and the transient stability limit P _WS , the wind power transmission limit P _WO and P _WV after the occurrence of the wind farm off-grid and the wind farm output fluctuation; Grid Wind Power Delivery Capability Assessment Model P _W :

P _W =min(P _WT , P _WH , P _WS , P _WO , P _WV ) (12)

Wherein step 3 includes:

The result value of the wind power transmission capacity evaluation model P _W and P _W is the power supply capacity of the grid in the assessment area.

As shown in FIG. 3 and FIG. 4, the present invention provides a specific application example of a method for evaluating a wind power output capability of a power grid, which includes a wind farm off-network constraint, and includes the following steps:

(1) Collecting AC and DC grid data and establishing an evaluation model;

(2) Calculate the transformer capacity limit of the regional power grid wind power collection station P _WT ;

(3) Calculate the thermal stability limit P _{WH of the} wind power transmission channel of the regional power grid;

(4) Calculate the transient stability limit P _{WS of the} wind power transmission channel of the regional power grid;

(5) Evaluation of large-scale wind farms will affect the voltage deviation off the network, and calculates the power of wind power feed area limit in this case is P _WO;

(6) Evaluate the voltage offset effect of the wind farm output fluctuation, and calculate the regional power grid wind power transmission limit P _{WV in} this case;

(7) Through the above calculations, a comprehensive assessment of the various wind power transmission limits is carried out to determine the wind power transmission limit P _{W of the} regional power grid.

The AC grid data in step (1) includes AC transmission line parameters and transformer parameters; the DC transmission system data includes DC transmission system controller parameters.

The transformer limit of the wind power collection station in step (2) is determined by:

The thermal stability limit in step (3) is determined according to the following method:

(1) Determine the wire type of the wind power transmission channel, determine the thermal stability current and thermal stability power of the wire when the temperature is 25°; calculate the thermal stability limit of the wind power transmission channel according to the thermal stability power of the transmission line

(2) Same as above, calculate the thermal stability limit of the wind power transmission channel when the temperature is 40°.

The present invention provides a further preferred method for estimating the wind power transmission capability of a regional power grid that takes into account the wind farm off-grid constraint. The transient stability limit P _WS in the step (4) is obtained by the power flow calculation and the transient stability calculation.

The voltage deviation impact assessment caused by the large-scale wind farm off-grid in step (5) is determined by the following method:

(1) Calculate the maximum offset value of the terminal voltage of other wind farms caused by the wind farm i off-grid ΔU _GV,i and the maximum offset value of the bus voltage of the transformer of the wind power collection station ΔU _TV,i , to determine whether the voltage exceeds the limit (see Formula (14)); if the voltage exceeds the limit, adjust the output of the wind farm off-grid to not exceed the limit, and count all the wind farms that have access to the collection station to send the capacity P _i and calculate the wind farm i off the grid. The regional power grid wind power delivery limit P _WO,i (see equation (15)).

among them,

For the wind turbine, the terminal voltage allows the maximum offset value,

The maximum offset allowed for the transformer bus voltage of the aggregation station, N _W is the number of wind farms connected to the wind power collection station.

(2) Performing (1) on all wind farms connected to the wind power collection station, and comparing the delivery limits of all wind farms when they are off-grid, and finally obtaining the wind power transmission limit P _{WO of the} regional power grid when the wind farm is off-grid. which is:

The effect of wind power fluctuations in step (6) is determined by the following method:

(1) Design two wind power fluctuation scenarios, scenario 1: impact of wind power fluctuation on grid voltage when simulating wind power output is large; scenario 2: impact of wind power fluctuation on grid voltage when simulated wind power output is small.

(2) In the scene, calculate the maximum offset value ΔU _GV1,i of the other terminal of the wind farm caused by the power fluctuation of the wind farm _i, and the maximum offset value of the bus voltage of the main transformer to the main transformer ΔU _TV1,i , judge the voltage Whether to exceed the limit (see Equation 17); if the limit is exceeded, calculate the maximum offset of the wind power under the voltage safety boundary, count the wind farm output, and calculate the wind power delivery capacity P _WV1,i (see Equation 18). The above steps are performed for all wind farms connected to the substation of the aggregation station. The comparative analysis finally obtains the wind power fluctuation limit P _{WV1 of the} regional power grid (see Equation 19).

(3) Under scenario 2, calculate the maximum offset value ΔU _GV2,i of the other terminal of the wind farm caused by the power fluctuation of the wind farm _i, and the maximum offset value ΔU _TV2,i of the bus voltage of the main transformer. Whether the voltage is beyond the limit; if the limit is exceeded, the voltage safety boundary is calculated.

The maximum deviation of the downwind power, statistics of the wind farm output, and calculate the wind power transmission capacity P _{WV2, i} at this time; perform the above steps for all wind farms connected to the substation of the aggregation station, and compare and analyze the wind power fluctuation scene Second, the regional power grid wind power delivery limit P _WV2 .

(4) Compare scene 1 and scene 2 (see Equation 23), and finally obtain the wind power transmission limit of the regional grid when the wind power fluctuates.

P _WV =min(P _WV1 , P _WV2 ) (23)

The regional grid wind power transmission capability in step (7) is obtained by comprehensively comparing the thermal stability limit, the temporary stability limit, and the voltage offset level, that is,

P _W =min(P _WH , P _WS , P _WO , P _WV ) (24).

It will be understood by those skilled in the art that all or part of the steps of the foregoing embodiments may be implemented by a program to control related hardware, and the program may be stored in a computer readable storage medium, and the storage medium may be It is ROM/RAM, disk, CD, etc.

It should be understood that the above are only preferred embodiments of the present invention, and thus cannot limit the scope of the present invention. The equivalent structure or equivalent process transformations made by the present specification and the drawings are directly or indirectly applied to other related technical fields, and are included in the scope of patent protection of the present invention.

In the several embodiments provided by the present application, it should be understood that the disclosed apparatus and method may be implemented in other manners. The device embodiments described above are merely illustrative. For example, the division of the unit is only a logical function division. In actual implementation, there may be another division manner, such as: multiple units or components may be combined, or Can be integrated into another system, or some features can be ignored or not executed. In addition, the coupling, or direct coupling, or communication connection of the components shown or discussed may be indirect coupling or communication connection through some interfaces, devices or units, and may be electrical, mechanical or other forms. of.

A person skilled in the art can understand that all or part of the steps of implementing the above method embodiments may be completed by using hardware related to the program instructions. The foregoing program may be stored in a computer readable storage medium, and the program is executed when executed. The foregoing storage device includes the following steps: the foregoing storage medium includes: a mobile storage device, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk. A medium that can store program code.

The above is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily think of changes or substitutions within the technical scope of the present invention. It should be covered by the scope of the present invention. Therefore, the scope of the invention should be determined by the scope of the appended claims.

Claims

A method for evaluating a wind power output capability of a power grid considering a wind farm off-grid constraint, the method comprising:

Step 1. Calculate a grid wind power transmission limit parameter group of the assessment area according to the AC/DC grid data of the assessment area;

Step 2: establishing a wind power transmission capability evaluation model according to the grid wind power sending limit parameter group;

Step 3: Determine, according to the grid wind power sending capability evaluation model, the grid wind power sending capability of the assessment area.
The method of claim 1 wherein said step 1 comprises:

Measuring the AC/DC grid data of the evaluation area, wherein the AC/DC grid data comprises: a wire type and a line length of the wind power sending channel in the evaluation area, a wind field quantity of the wind power collecting station, and a wind power collecting station The capacity and number of transformers, the maximum allowable offset value of the transformer bus voltage of the wind power collection station, and the maximum allowable offset value of the wind turbine terminal voltage;

Calculating, according to the AC/DC power grid data, a grid wind power transmission limit parameter group of the assessment area; wherein the grid wind power transmission limit parameter group includes: the wind power collection station transformer capacity limit, and the heat of the wind power transmission channel Stability limit and transient stability limit, grid wind power transmission limit after the wind farm off-grid and wind farm output fluctuation.
The method of claim 2, wherein the calculating a grid wind power transmission limit parameter group of the evaluation area according to the AC/DC grid data comprises:

Calculating the wind power collection station transformer capacity limit P WT :

Where P e,i is the rated capacity of the transformer i in the wind power collection station, and N T is the number of transformers in the aggregation station;

The feeding passage of the wind power wire model, each constant value of T is determined with a high thermal current value of the wire and thermally stable power T; wherein, 20 ° ≤T often ≤30 ° and 30 ° <T high ≤50 °;

The thermal stability of the power value, calculating the thermal stability limit T are normally fed to the wind passage at a high temperature T P WH;

Determining the transient stability limit P WS ;

Calculating the wind power transmission limit P WO of the wind farm off-grid according to the maximum allowable offset value of the wind turbine terminal voltage, the maximum allowable offset value of the transformer bus voltage of the wind power collection station, and the number of wind farms of the wind power collection station ;

Set the wind power fluctuation scenario and compare the grid wind power delivery limit in different scenarios to obtain the grid wind power delivery limit P WV in the assessment area when the wind power fluctuates.
The method of claim 3, wherein said calculating a grid wind power delivery limit P WO at which said wind farm is off-network comprises:

Calculating a maximum offset value ΔU GV,i of the terminal voltage of the other wind farms caused by the wind farm i in the evaluation area , and a maximum offset value ΔU TV,i of the bus voltage of the transformer of the wind power collecting station;

Determining whether the ΔU GV,i and ΔU TV,i are exceeded:
among them,
For the wind turbine, the terminal voltage allows the maximum offset value,
The maximum offset allowed for the transformer bus voltage of the aggregation station;

If it is determined that the ΔU GV,i and ΔU TV,i are not exceeded, all the wind farm sending capacity P i connected to the wind power collecting station is counted, and the evaluation area when the wind farm i is off-network is calculated. Grid wind power delivery limit P WO,i :
Where N W is the number of wind farms that access the wind power collection station;

Repeat steps d-1 to d-3 for all wind farms connected to the wind power collection station, and compare the delivery limits of all wind farms when off-grid, and obtain the grid wind power transmission limit of the evaluation area when the wind farm is off-grid. P WO :
The method according to claim 3, wherein said setting a wind power fluctuation scenario and comparing grid wind power delivery limits in different scenarios, and obtaining a grid wind power delivery limit P WV of said evaluation region when wind power is fluctuating, comprising:

Set two wind power fluctuation scenarios, including: scenario 1: impact of wind power fluctuation on grid voltage when simulated wind power output is large; scenario 2: impact of wind power fluctuation on grid voltage when simulated wind power output is small;

In the scenario, calculate the maximum offset value ΔU GV1,i of the other wind farm terminal voltage caused by the wind power i power fluctuation and the busbar voltage maximum offset value ΔU TV1,i of the main transformer , and determine the ΔU GV1 , i and ΔU TV1, i is the limit;

If it is determined that the ΔU GV1,i and ΔU TV1,i are not exceeded, calculate the maximum offset of the wind power downwind power, calculate the wind farm output, and calculate the wind power delivery capacity P WV1,i at this time:

The wind farms connected to the substation of the wind power collection station are all calculated, and the grid wind power transmission limit P WV1 of the scene is obtained:

Under the scenario 2, calculating the maximum offset value ΔU GV2,i of the other wind farms caused by the fluctuation of the power of the wind farm i , and the maximum offset value ΔU TV2,i of the bus voltage of the main transformer, determining the ΔU Whether GV2,i and ΔU TV2,i are exceeded;

If it is determined that the ΔU GV2,i and ΔU TV2,i are not exceeded, the maximum offset of the wind power under the voltage safety boundary is calculated, the wind farm output is counted, and the wind power sending capacity P WV2,i is calculated:
Performing calculations on all the wind farms connected to the wind power collection station substation, and obtaining the grid wind power transmission limit P WV2 in the scenario 2:

Comparing scene 1 and scene 2, the wind power transmission limit P WV of the regional grid is obtained when the wind power fluctuates: P WV = min (P WV1 , P WV2 ).
The method of claim 4 wherein said step 2 comprises:

According to the wind power collection station transformer capacity limit P WT , the wind power transmission channel thermal stability limit P WH and the transient stability limit P WS , the wind farm off-grid and the wind farm output fluctuation after the grid wind power delivery limit P WO and P WV ; Establish a grid wind power transmission capacity assessment model P W :

P W =min (P WT , P WH , P WS , P WO , P WV ).