Wind power plant grouping equivalence method considering dynamic and steady state equivalence precision

Abstract

The invention discloses a wind power plant grouping equivalence method considering dynamic and steady state equivalence precision, relates to the technical field of wind power plant equivalence model construction, and aims at solving the problem that a traditional grouping equivalence method does not consider steady state difference and dynamic difference, and consequently the equivalence error is large. Obtaining a steady-state difference index and a dynamic response time difference index between every two wind turbine generator sets and an inertia time constant difference index between every two wind turbine generator sets; carrying out weighted summation on all the indexes to obtain a comprehensive difference index between every two wind turbine generator sets; and judging whether the comprehensive difference index between every two wind turbine generator sets is smaller than a preset inter-set difference limit value, if yes, dividing the two wind turbine generator sets into the same group, and if not, dividing the two wind turbine generator sets into different groups, thereby realizing grouping of the multiple wind turbine generator sets in the wind power plant. The method is used for grouping all the wind turbine generators in the wind power plant.

Description

Technical Field

[0001] The invention relates to the technical field of wind farm equivalent model construction, and belongs to a wind turbine group grouping method. Background Art

[0002] With the increasing demand for the development of new energy, the installed capacity of wind power generation is getting larger and larger, and its impact on the power system cannot be ignored. In order for the power system to correctly evaluate the impact of large-scale wind farms on the stability of the power grid in the dynamic process and improve the efficiency of the power system in the calculation and analysis process, it is of great practical significance to study effective wind farm equivalent methods and establish accurate and reliable equivalent models for the research of power systems and wind power generation technology.

[0003] However, the traditional grouping equivalence method does not take into account both steady-state differences and dynamic differences, resulting in large equivalence errors. Summary of the invention

[0004] The purpose of the present invention is to solve the problem that the traditional grouping equivalent method does not take into account both steady-state differences and dynamic differences, resulting in large equivalent errors, and proposes a wind farm grouping equivalent method that takes into account the dynamic and steady-state equivalent accuracy.

[0005] A wind farm grouping equivalent method considering dynamic and steady-state equivalent accuracy, the method comprising the following contents:

[0006] Step 1: Calculate the steady-state difference index between every two wind turbines according to the power and rated capacity of every two wind turbines in the wind farm;

[0007] Step 2: obtaining a dynamic response time difference index between every two wind turbines and an inertia time constant difference index between every two wind turbines;

[0008] Step 3: weighted sum of the steady-state difference index, dynamic response time difference index and inertia time constant difference index between every two wind turbines to obtain a comprehensive difference index between every two wind turbines;

[0009] Step 4: determine whether the comprehensive difference index between every two wind turbines is less than the preset inter-group difference limit. If yes, the two wind turbines are grouped into the same group; if not, the two wind turbines are grouped into different groups, thereby realizing the grouping of multiple wind turbines in the wind farm.

[0010] Preferably, in step 1, the steady-state difference index between every two wind turbines is:

[0011]

[0012] In the formula, A ij is the steady-state difference index between the i-th wind turbine group and the j-th wind turbine group, Pi is the power of the i-th wind turbine, P j is the power of the jth wind turbine, S ni is the rated capacity of the i-th wind turbine, S nj is the rated capacity of the jth wind turbine.

[0013] Preferably, in step 2, the dynamic response time difference index of every two wind turbines is obtained, specifically:

[0014] The dynamic response time constant of each wind turbine is obtained, and the dynamic response time constants of every two wind turbines are denormalized after being subtracted to obtain a dynamic response time difference index of every two wind turbines.

[0015] Preferably, in step 2, the dynamic response time difference index between every two wind turbines is:

[0016]

[0017] Where, B1 ij is the dynamic response time difference index between the i-th wind turbine group and the j-th wind turbine group, τ Wi is the circuit dynamic response time constant of the i-th wind turbine unit, τ Wj is the circuit dynamic response time constant of the jth wind turbine generator set, Δτ Wij is the difference in circuit dynamic response time constant between the i-th wind turbine group and the j-th wind turbine group, L i ′ is the stator transient inductance of the i-th wind turbine, R si is the stator resistance of the i-th unit, X i ′ is the stator reactance of the i-th wind turbine, ω si is the rotor angular velocity of the i-th wind turbine, L j ′ is the stator transient inductance of the j-th wind turbine, R sj is the stator resistance of the jth unit, X j ′ is the stator reactance of the jth wind turbine, ω sj is the rotor angular velocity of the jth wind turbine.

[0018] Preferably, in step 2, the inertia time constant difference index of every two wind turbines is obtained, specifically:

[0019] The inertia time constant of each wind turbine is obtained, and the inertia time constants of every two wind turbines are denormalized after the difference is taken to obtain the inertia time constant difference index of every two wind turbines.

[0020] Preferably, in step 2, the inertia time constant difference index of every two wind turbines is:

[0021]

[0022] Where, B2 ij is the difference index of the inertia time constant between the i-th wind turbine group and the j-th wind turbine group, ΔT gij is the difference in inertia time constant between the i-th wind turbine group and the j-th wind turbine group, T gi is the inertia time constant of the i-th wind turbine, T gj is the inertia time constant of the j-th wind turbine generator set, P nj is the rated power of the jth wind turbine, P ni is the rated power of the i-th wind turbine, H i is the inertia coefficient of the i-th wind turbine unit, H j is the inertia coefficient of the j-th wind turbine unit,

[0023] Preferably, in step 2, the comprehensive difference index between every two wind turbines is:

[0024]

[0025] In the formula, Q ij It is the comprehensive difference index between the i-th wind turbine unit and the j-th wind turbine unit.

[0026] The beneficial effects of the present invention are:

[0027] The present invention calculates the steady-state difference index, dynamic response time difference index and inertia time constant difference index between every two wind turbines, comprehensively evaluates the actual differences between wind turbines, groups the wind turbines, and improves the accuracy of grouping equivalence. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a flow chart of a wind farm grouping equivalent method considering the dynamic and steady-state equivalent accuracy;

[0029] Figure 2 This is the equivalent circuit diagram of the stator side of the wind turbine. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0032] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0033] Example:

[0034] Combination Figure 1 This embodiment is described as a method for grouping wind farms considering the accuracy of dynamic and steady-state equivalent values. The method includes the following contents:

[0035] Step 1: Calculate the steady-state difference index between every two wind turbines according to the power and rated capacity of every two wind turbines in the wind farm;

[0036] Step 2: obtaining a dynamic response time difference index between every two wind turbines and an inertia time constant difference index between every two wind turbines;

[0037] Step 3: weighted sum of the steady-state difference index, dynamic response time difference index and inertia time constant difference index between every two wind turbines to obtain a comprehensive difference index between every two wind turbines;

[0038] Step 4: determine whether the comprehensive difference index between every two wind turbines is less than the preset inter-group difference limit. If yes, the two wind turbines are grouped into the same group; if not, the two wind turbines are grouped into different groups, thereby realizing the grouping of multiple wind turbines in the wind farm.

[0039] Specifically, if the comprehensive difference index between every two wind turbines is less than the preset inter-group difference limit, it means that the difference between the two wind turbines is small and they can be divided into the same group for equal value calculation; if the comprehensive difference index between every two wind turbines is not less than the preset inter-group difference limit, it means that the difference between the two wind turbines is large and they cannot be divided into the same group for equal value calculation, and finally the wind farm grouping result is obtained.

[0040] The steady-state difference index between every two wind turbines is defined as follows:

[0041]

[0042] In the formula, A ij is the steady-state difference index between the i-th wind turbine group and the j-th wind turbine group, P i is the power of the i-th wind turbine, P j is the power of the jth wind turbine, S ni is the rated capacity of the i-th wind turbine, S nj is the rated capacity of the jth wind turbine.

[0043] Specifically, the steady-state difference index is calculated by dividing the square of the wind turbine power by the rated capacity:

[0044] Assume that there are n wind turbines in the wind farm, and the input wind power of the i-th wind turbine is P i , divide the wind power of the i-th wind turbine equally into N i , N i is a non-negative integer, the minimum power value of each single-pole wind turbine is P0, and the following formula is established:

[0045] P i =N i P0(i=1,2,3...n) Formula 5,

[0046] The n wind turbines are divided into N1, N2, N3...N according to their respective input wind power. n The equivalent sub-wind turbines are divided into N equivalent sub-wind turbines with power P0, and the input power value of each sub-wind turbine after the split is P0. i The parameters and states of the equivalent sub-wind turbines are exactly the same, and their equivalent parameters are:

[0047]

[0048] In the formula, is the N equally divided by the i-th wind turbine group i Impedance parameters of equivalent wind turbines; is the N equally divided by the i-th wind turbine group i The inertia time constant of an equivalent wind turbine, Z i are all resistance and reactance parameters of the i-th wind turbine, including X0, X′ and R s ;H i is the inertia coefficient of the i-th wind turbine;

[0049] Add up the mathematical models of all the wind turbine sub-units after splitting. The input wind power of these N wind turbines is P0, and each wind turbine sub-unit is connected in parallel on the same busbar, and the terminal voltage is equal. At this time, the output current of each wind turbine sub-unit is considered to be approximately equal.

[0050]

[0051] Since the third-order transient model of the wind turbine is:

[0052]

[0053] Where, e′ is the transient potential of the generator; j is an imaginary unit, X0 and X′ are the stator reactance and stator transient reactance respectively; R s is the stator resistance; R s +jX′ is the input impedance of the wind turbine; T0′ is the rotor winding time constant; ω s is the synchronous angular velocity; s is the slip rate; i s is the stator current; v s is the stator voltage; H is the inertia coefficient; T t , T e are the mechanical torque of the wind turbine and the electromagnetic torque of the generator respectively; ω m is the generator rotor angular velocity, u r ' is the converted value of the rotor voltage; P w , P e are the mechanical power of the wind turbine and the electromagnetic power of the generator respectively; the · on the symbol represents the derivative;

[0054] Add the mathematical models of each wind turbine unit after splitting to obtain the detailed mathematical model of the wind farm as follows:

[0055]

[0056] In the formula, R sk is the stator resistance of the wind turbine after splitting, X k ′ is the stator transient reactance of the wind turbine after splitting, i sk is the stator current of the wind turbine sub-unit after splitting, ω mk is the angular velocity of the generator rotor of the wind turbine after splitting, e′ k is the transient potential of the generator of the wind turbine sub-unit after splitting, X 0k is the stator reactance of the wind turbine after splitting, T0′ k is the rotor winding time constant of the split sub-wind turbine, u r ' k is the converted value of the rotor voltage, P w0 , P e0 and H k are the corresponding parameters of the kth wind turbine among the N wind turbines with a power of P0 obtained by splitting; P w0 is wind power, P e0 is the electromagnetic power, and the power of N split units is equal;

[0057] Treat all wind turbines as one wind turbine:

[0058]

[0059] Where T0′ iIt is the equivalent parameter of the entire wind farm aggregated into a single unit. The superscript eq represents the equivalent unit, and the subscript i represents the parameters of the i-th unit among the n wind turbines in the original wind farm.

[0060] According to P i =N i P0, transform formula 10 into:

[0061]

[0062] It can be seen from formula 11 that the equivalent result has a strong relationship with the square of the actual power, so formula 1 is used to calculate the steady-state difference index between every two wind turbines.

[0063] The specific process of obtaining the dynamic response time difference index of every two wind turbines is defined as follows:

[0064] The dynamic response time constant of each wind turbine is obtained, and the dynamic response time constants of every two wind turbines are denormalized after being subtracted to obtain a dynamic response time difference index of every two wind turbines.

[0065] The following introduces the dynamic response time difference index of each two wind turbines:

[0066]

[0067] Where, B1 ij is the dynamic response time difference index between the i-th wind turbine group and the j-th wind turbine group, τ Wi is the circuit dynamic response time constant of the i-th wind turbine unit, τ Wj is the circuit dynamic response time constant of the jth wind turbine generator set, Δτ Wij is the difference in circuit dynamic response time constant between the i-th wind turbine group and the j-th wind turbine group, The subscript i represents the i-th wind turbine; L i ′ is the stator transient inductance of the i-th wind turbine, R si is the stator resistance of the i-th unit, The superscript j represents the jth wind turbine.

[0068] Specifically, the dynamic characteristics of each wind turbine are divided into RL input circuit characteristics and wind turbine inertia characteristics. Figure 2 The third-order transient model of the stator side equivalent circuit is obtained, and it can be seen that the input impedance of the wind turbine is R s +jX′=R s +jω s L′. According to the RL circuit dynamic response time constant τ = L / R, the circuit dynamic response time constant of the wind turbine generator set is obtained as:

[0069] The circuit dynamic response time constant of the wind turbine indicates the speed of its dynamic response. The dynamic curves of wind turbines with similar response speeds will be more fitted. Therefore, it is used as a dynamic difference reference index 1 to obtain Divide by the average value of the two to get the wind turbine dynamic difference index: Wind turbines have mechanical structures such as wind blades and transmission shafts, which have response inertia, which also affects the dynamic response speed of the wind turbine. According to the generator inertia time constant formula:

[0070]

[0071] P n is the rated power of the wind turbine, and H is the inertia coefficient of the wind turbine.

[0072] Taking it as the dynamic difference reference index 2, among the n wind turbines in the wind farm, the difference in inertia time constant between the i-th wind turbine and the j-th wind turbine is:

[0073]

[0074] Divide by the average value of the two to get the wind turbine dynamic difference index:

[0075]

[0076] The specific process of obtaining the inertia time constant difference index of each two wind turbines is defined as follows:

[0077] The inertia time constant of each wind turbine is obtained, and the inertia time constants of every two wind turbines are denormalized after the difference is taken to obtain the inertia time constant difference index of every two wind turbines.

[0078] The following defines the difference index of the inertia time constant of every two wind turbines as:

[0079]

[0080] Where, B2 ij is the difference index of the inertia time constant between the i-th wind turbine group and the j-th wind turbine group, ΔT gij is the difference in inertia time constant between the i-th wind turbine group and the j-th wind turbine group, T gi is the inertia time constant of the i-th wind turbine, T gj is the inertia time constant of the j-th wind turbine generator set, P nj is the rated power of the jth wind turbine, P ni is the rated power of the i-th wind turbine, H i is the inertia coefficient of the i-th wind turbine unit, H jis the inertia coefficient of the j-th wind turbine unit,

[0081] The comprehensive difference index between every two wind turbines is defined as follows:

[0082]

[0083] In the formula, Q ij It is the comprehensive difference index between the i-th wind turbine unit and the j-th wind turbine unit.

[0084] Although the present invention is described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. It should therefore be understood that many modifications may be made to the exemplary embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims. It should be understood that the various dependent claims and features described herein may be combined in a manner different from that described in the original claims. It should also be understood that features described in conjunction with individual embodiments may be used in other described embodiments.

Claims

1. A wind farm grouping equivalent method considering dynamic and steady state equivalent accuracy, characterized in that: The method comprises the following: Step 1: Calculate the steady-state difference index between every two wind turbines according to the power and rated capacity of every two wind turbines in the wind farm; Step 2: obtaining a dynamic response time difference index between every two wind turbines and an inertia time constant difference index between every two wind turbines; Step 3: weighted sum of the steady-state difference index, dynamic response time difference index and inertia time constant difference index between every two wind turbines to obtain a comprehensive difference index between every two wind turbines; Step 4: determine whether the comprehensive difference index between every two wind turbines is less than the preset inter-group difference limit. If yes, the two wind turbines are grouped into the same group; if not, the two wind turbines are grouped into different groups, thereby realizing the grouping of multiple wind turbines in the wind farm.

2. A wind farm grouping equivalent method considering dynamic and steady-state equivalent accuracy according to claim 1, characterized in that: In step 1, the steady-state difference index between every two wind turbines is: In the formula, A ij is the steady-state difference index between the i-th wind turbine group and the j-th wind turbine group, P i is the power of the i-th wind turbine, P j is the power of the jth wind turbine, S ni is the rated capacity of the i-th wind turbine, S nj is the rated capacity of the jth wind turbine.

3. The method for grouping wind farms considering the accuracy of dynamic and steady-state equivalent values ​​according to claim 1 is characterized in that: In step 2, the dynamic response time difference index of every two wind turbines is obtained, specifically: The dynamic response time constant of each wind turbine is obtained, and the dynamic response time constants of every two wind turbines are denormalized after being subtracted to obtain a dynamic response time difference index of every two wind turbines.

4. A wind farm grouping equivalent method considering dynamic and steady state equivalent accuracy according to claim 3, characterized in that: In step 2, the dynamic response time difference index of every two wind turbines is: Where B1 ij is the dynamic response time difference index between the i-th wind turbine group and the j-th wind turbine group, τ Wi is the circuit dynamic response time constant of the i-th wind turbine unit, τ Wj is the circuit dynamic response time constant of the jth wind turbine generator set, Δτ Wij is the difference in circuit dynamic response time constant between the i-th wind turbine group and the j-th wind turbine group, L i ′ is the stator transient inductance of the i-th wind turbine, R si is the stator resistance of the i-th unit, X i ′ is the stator reactance of the i-th wind turbine, ω si is the rotor angular velocity of the i-th wind turbine, L j ′ is the stator transient inductance of the j-th wind turbine, R sj is the stator resistance of the jth unit, X j ′ is the stator reactance of the jth wind turbine, ω sj is the rotor angular velocity of the jth wind turbine.

5. The method for grouping wind farms considering the accuracy of dynamic and steady-state equivalent values ​​according to claim 1 is characterized in that: In step 2, the inertia time constant difference index of every two wind turbines is obtained, specifically: The inertia time constant of each wind turbine is obtained, and the inertia time constants of every two wind turbines are denormalized after the difference is taken to obtain the inertia time constant difference index of every two wind turbines.

6. A wind farm grouping equivalent method considering dynamic and steady state equivalent accuracy according to claim 5, characterized in that: In step 2, the inertia time constant difference index of every two wind turbines is: Where, B2 ij is the difference index of the inertia time constant between the i-th wind turbine group and the j-th wind turbine group, ΔT gij is the difference in inertia time constant between the i-th wind turbine group and the j-th wind turbine group, T gi is the inertia time constant of the i-th wind turbine, T gj is the inertia time constant of the j-th wind turbine generator set, P nj is the rated power of the jth wind turbine, P ni is the rated power of the i-th wind turbine, H i is the inertia coefficient of the i-th wind turbine unit, H j is the inertia coefficient of the j-th wind turbine unit, 7. A wind farm grouping equivalent method considering dynamic and steady state equivalent accuracy according to claim 2, 5 or 6, characterized in that: In step 2, the comprehensive difference index between every two wind turbines is: In the formula, Q ij It is the comprehensive difference index between the i-th wind turbine unit and the j-th wind turbine unit.

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