CN111371089A - Power grid dynamic equivalence quantitative evaluation method and system - Google Patents

Power grid dynamic equivalence quantitative evaluation method and system Download PDF

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CN111371089A
CN111371089A CN202010162158.4A CN202010162158A CN111371089A CN 111371089 A CN111371089 A CN 111371089A CN 202010162158 A CN202010162158 A CN 202010162158A CN 111371089 A CN111371089 A CN 111371089A
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power grid
security
equivalence
transient
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CN111371089B (en
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赵巍
侯玉强
孟鹏飞
许剑冰
李碧君
李威
张倩
李海峰
赵彦丽
陈珏
金涛
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State Grid Corp of China SGCC
State Grid Jiangsu Electric Power Co Ltd
NARI Group Corp
Nari Technology Co Ltd
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State Grid Corp of China SGCC
State Grid Jiangsu Electric Power Co Ltd
NARI Group Corp
Nari Technology Co Ltd
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    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
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Abstract

The invention discloses a quantitative evaluation method of power grid dynamic equivalence, which comprises the steps of calculating the security degree of the steady-state characteristics of a power grid after equivalence according to the steady-state characteristics of the power grid before and after equivalence; calculating the power grid transient state characteristic security degree after equivalence according to the power grid transient state characteristics before and after equivalence; calculating the key dynamic characteristic security of the power grid after equivalence according to the key dynamic characteristics of the power grid before and after equivalence; and responding to the situation that the power grid steady-state characteristic security after equivalence, the power grid transient-state characteristic security after equivalence and the power grid key dynamic characteristic security after equivalence are all larger than a threshold value, and the power grid dynamic equivalence is effective. A corresponding system is also disclosed. According to the invention, the dynamic equivalence of the power grid is evaluated from three dimensions of the steady-state characteristic, the transient characteristic and the key dynamic characteristic of the power grid, and the preservation effect of the equivalence model on different stable characteristics of the power grid can be comprehensively and objectively reflected.

Description

Power grid dynamic equivalence quantitative evaluation method and system
Technical Field
The invention relates to a quantitative evaluation method and system for power grid dynamic equivalence, and belongs to the technical field of power systems and automation thereof.
Background
For an alternating current-direct current complex power grid with tens of thousands of nodes, a full-node electromagnetic transient model is strictly established, so that the workload is huge, and the simulation speed is also sharply reduced along with the increase of the scale of the power grid. In order to effectively improve the simulation efficiency, the simplified equivalence is usually carried out on a research network, under an ideal condition, the fault responses of a system before and after the equivalence are the same, and fault simulation curves are completely overlapped. However, in the current stage, the evaluation of the dynamic equivalent effect of the power grid is not objective and comprehensive only according to comparison of simulation curves of a few fault scenes or according to local characteristics of the power grid to provide corresponding quantitative indexes.
Disclosure of Invention
The invention provides a quantitative evaluation method and system for dynamic equivalence of a power grid, which solve the problems disclosed in the background technology.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows:
a quantitative evaluation method of power grid dynamic equivalence comprises the following steps,
calculating the security of the steady-state characteristics of the power grid after equivalence according to the steady-state characteristics of the power grid before and after equivalence;
calculating the power grid transient state characteristic security degree after equivalence according to the power grid transient state characteristics before and after equivalence;
calculating the key dynamic characteristic security of the power grid after equivalence according to the key dynamic characteristics of the power grid before and after equivalence;
and responding to the situation that the power grid steady-state characteristic security after equivalence, the power grid transient-state characteristic security after equivalence and the power grid key dynamic characteristic security after equivalence are all larger than a threshold value, and the power grid dynamic equivalence is effective.
According to the steady-state characteristics of the power grid before and after equivalence, the security of the steady-state characteristics of the power grid after the equivalence is calculated,
when the power grid normally operates, acquiring active power and reactive power before and after the equivalence of each tie line, and acquiring voltage amplitude and phase angle before and after the equivalence of bus nodes at two ends of each tie line;
calculating the steady-state power security of each tie line according to the active power and the reactive power before and after the tie line is equivalent;
calculating the steady-state voltage security of each tie line according to the voltage amplitude and the phase angle before and after the bus node equivalence;
calculating the steady-state power security degree and the steady-state voltage security degree of all the tie lines according to the weight of each tie line, the steady-state power security degree of each tie line and the steady-state voltage security degree of each tie line;
and calculating the power grid steady-state feature security after equivalence according to the weight of the steady-state power security, the weight of the steady-state voltage security, the steady-state power security and the steady-state voltage security of all the connecting lines.
The formula of the steady-state feature security of the power grid after equivalence is as follows,
Figure BDA0002406180420000021
wherein the content of the first and second substances,
Csteadythe security degree of the steady-state characteristics of the power grid after equivalence is obtained;
ωPQ、ωUθrespectively is the weight of the steady-state power security and the weight of the steady-state voltage security;
Figure BDA0002406180420000022
maintaining the steady state power of all the links;
n is the number of interconnections, omegaiThe weight of the ith tie line;
Figure BDA0002406180420000023
the steady state power security of the ith connecting line is ensured;
Pi、
Figure BDA0002406180420000024
the active power, Q, before and after the i-th tie line is equivalenti、
Figure BDA0002406180420000025
The reactive power before and after the equivalence of the ith connecting line is respectively;
Figure BDA0002406180420000031
the steady state voltage safety degree of all the connecting lines is guaranteed;
σi(U,θ)＝min{σj(U,θ),σl(U, theta) } is the steady-state voltage of the ith connection lineThe degree of security;
Figure BDA0002406180420000032
the voltage safety degree of a bus node j at the two ends of the ith tie line is guaranteed;
Uj、
Figure BDA0002406180420000033
the voltage amplitudes before and after the equivalent of the bus node j are respectively;
θj、
Figure BDA0002406180420000035
the voltage phase angles before and after the equivalent of the bus node j are respectively;
Figure BDA0002406180420000036
the voltage safety degree of bus nodes l at two ends of the ith connecting line is guaranteed;
Ul、
Figure BDA0002406180420000037
respectively the voltage amplitudes before and after the equivalent of the bus node l;
θl、
Figure BDA0002406180420000038
the voltage phase angles before and after the equivalent of the bus node l are respectively.
According to the transient characteristics of the power grid before and after equivalence, the transient characteristic security of the power grid after the equivalence is calculated, the specific process is as follows,
acquiring a power grid fault set;
calculating power angle stability security of the power grid under each fault impact according to the power angle stability margins of the equivalent front and rear power grids under the fault impact;
calculating the safety security of the transient voltage of the power grid under each fault impact according to the safety margins of the transient voltage of the equivalent front and rear power grids under the fault impact;
calculating the safety security of the transient frequency of the power grid under each fault impact according to the safety margins of the transient frequency of the equivalent front and rear power grids under the fault impact;
according to the fault weight, the power angle stability and safety degree of the power grid under the fault impact, the transient voltage safety and safety degree of the power grid under the fault impact and the transient frequency safety and safety degree of the power grid under the fault impact, the power angle stability and safety degree of the power grid after the fault weight is taken into account, the transient voltage safety and safety degree of the power grid after the fault weight is taken into account and the transient frequency safety and safety degree of the power grid after the fault weight is taken into account are calculated;
and calculating equivalent power grid transient characteristic security degree according to the power grid power angle stable security degree after the fault weight is calculated, the power grid transient voltage security degree after the fault weight is calculated, the power grid transient frequency security degree after the fault weight is calculated, the power grid power angle stable security degree weight, the power grid transient voltage security degree weight and the power grid transient frequency security degree weight.
After equivalence, the power grid transient state characteristic security degree formula is as follows,
Figure BDA0002406180420000041
wherein the content of the first and second substances,
Ctranthe degree of security of the transient state characteristics of the equivalent power grid is obtained;
ωas、ωv、ωfrespectively weighing power angle stability security degree of the power grid, transient voltage safety security degree of the power grid and transient frequency safety security degree of the power grid;
Figure BDA0002406180420000042
respectively calculating power angle stability security of the power grid after the fault weight is calculated, transient voltage security of the power grid after the fault weight is calculated, and transient frequency security of the power grid after the fault weight is calculated;
Figure BDA0002406180420000043
t is the number of faults in the grid fault set, omegakIs the weight of the fault k;
Figure BDA0002406180420000044
the power angle stability and the security of the power grid under the impact of the fault k are guaranteed;
ηi(as)、
Figure BDA0002406180420000045
respectively obtaining equivalent power angle stability margins of a front power grid and a rear power grid under the impact of a fault k;
Figure BDA0002406180420000046
Figure BDA0002406180420000051
the safety degree of the transient voltage of the power grid under the impact of the fault k is ensured;
ηk(v)、
Figure BDA0002406180420000052
respectively representing the transient voltage safety margins of the equivalent front and rear power grids under the impact of the fault k;
Figure BDA0002406180420000053
Figure BDA0002406180420000054
the safety degree of the transient frequency of the power grid under the impact of the fault k is ensured;
ηk(f)、
Figure BDA0002406180420000055
and respectively representing the transient frequency safety margins of the equivalent front and rear power grids under the impact of the fault k.
Calculating the key dynamic characteristic security of the power grid after equivalence according to the key dynamic characteristics of the power grid before and after equivalence,
calculating the primary frequency modulation capability security of the equivalent back power grid according to the primary frequency modulation capability of the equivalent front and back power grids;
solving the equivalent front and rear transient signals to obtain oscillation mode vectors of the equivalent front and rear transient signals;
calculating the oscillation frequency security degree, the oscillation amplitude security degree and the damping security degree according to the oscillation mode vectors of the equivalent front and rear transient signals;
calculating the equivalent oscillation mode security degree according to the weight of the oscillation frequency security degree, the weight of the oscillation amplitude security degree, the weight of the damping security degree, the oscillation frequency security degree, the oscillation amplitude security degree and the damping security degree;
and calculating the key dynamic characteristic security of the equivalent power grid according to the weight of the equivalent power grid primary frequency modulation capability security, the weight of the equivalent post-oscillation mode security, the equivalent post-power grid primary frequency modulation capability security and the equivalent post-oscillation mode security.
After equivalence, the key dynamic characteristic security degree formula of the power grid is as follows,
Cdyna＝ωPFCA·CPFCA+ωoscil·Coscil
wherein the content of the first and second substances,
Cdynathe key dynamic characteristic security of the power grid after equivalence is achieved;
ωPFCA、ωoscilrespectively weighing the equivalent power grid primary frequency modulation capability security and the equivalent oscillation mode security;
Figure BDA0002406180420000061
the security of the primary frequency modulation capability of the power grid after equivalence is ensured;
DPFCA、
Figure BDA0002406180420000062
the equivalent front and rear power grid primary frequency modulation capacity respectively;
Figure BDA0002406180420000063
the degree of security of the oscillation mode after equivalence is ensured;
ωff、ωA、ωαrespectively is the weight of the oscillation frequency security degree, the weight of the oscillation amplitude security degree and the weight of the damping security degree;
Figure BDA0002406180420000064
respectively, the oscillation frequency security degree, the oscillation amplitude security degree and the damping security degree;
Figure BDA0002406180420000065
Figure BDA0002406180420000066
n' is the number of oscillation modes;
ωi′the weight of the ith' oscillation mode;
Emi′the energy value of the ith oscillation mode of the transient signal before equivalence;
fmi′the oscillation frequency of the ith oscillation mode of the transient signal before equivalence;
Figure BDA0002406180420000067
the oscillation frequency of the ith oscillation mode of the transient signal after equivalence is obtained;
Figure BDA0002406180420000068
Ami′、
Figure BDA0002406180420000069
respectively obtaining the oscillation amplitude of the ith oscillation mode of the transient signal before equivalence and the oscillation amplitude of the ith oscillation mode of the transient signal after equivalence;
Figure BDA0002406180420000071
αmi′、
Figure BDA0002406180420000072
the damping coefficient of the ith oscillation mode of the transient signal before equivalence and the damping coefficient of the ith oscillation mode of the transient signal after equivalence are respectively obtained.
A quantitative evaluation system for power grid dynamic equivalence comprises,
the power grid steady-state characteristic security degree calculation module: calculating the security of the steady-state characteristics of the power grid after equivalence according to the steady-state characteristics of the power grid before and after equivalence;
the power grid transient characteristic security degree calculation module: calculating the power grid transient state characteristic security degree after equivalence according to the power grid transient state characteristics before and after equivalence;
the power grid key dynamic characteristic security calculation module: calculating the key dynamic characteristic security of the power grid after equivalence according to the key dynamic characteristics of the power grid before and after equivalence;
an evaluation module: and responding to the situation that the power grid steady-state characteristic security after equivalence, the power grid transient-state characteristic security after equivalence and the power grid key dynamic characteristic security after equivalence are all larger than a threshold value, and the power grid dynamic equivalence is effective.
A computer readable storage medium storing one or more programs, the one or more programs comprising instructions, which when executed by a computing device, cause the computing device to perform a method of quantitative assessment of grid dynamics equivalence.
A computing device comprising one or more processors, memory, and one or more programs stored in the memory and configured to be executed by the one or more processors, the one or more programs including instructions for performing a method for quantitative assessment of grid dynamics equivalence
The invention achieves the following beneficial effects: according to the invention, the dynamic equivalence of the power grid is evaluated from three dimensions of the steady-state characteristic, the transient characteristic and the key dynamic characteristic of the power grid, and the preservation effect of the equivalence model on different stable characteristics of the power grid can be comprehensively and objectively reflected.
Drawings
FIG. 1 is a flow chart of the method of the present invention;
FIG. 2 is a schematic diagram of an equivalent power grid structure in a Sichuan asbestos-Jiulong area;
fig. 3 is an active power curve before and after the equivalence of the jiulong-yaan tie line.
Detailed Description
The invention is further described below with reference to the accompanying drawings. The following examples are only for illustrating the technical solutions of the present invention more clearly, and the protection scope of the present invention is not limited thereby.
As shown in fig. 1, a method for quantitatively evaluating a dynamic equivalence of a power grid includes the following steps:
step 1, calculating the security of the steady-state characteristics of the power grid after equivalence according to the steady-state characteristics of the power grid before and after equivalence.
The specific process is as follows:
11) and when the power grid normally operates, acquiring active power and reactive power before and after the equivalence of each tie line, and acquiring voltage amplitude and phase angle before and after the equivalence of bus nodes at two ends of each tie line.
When the power grid normally operates, a tie line set L and a bus set B to be evaluated in a pre-equivalence power grid and a post-equivalence power grid are determined, load flow calculation is carried out on a pre-equivalence system and a post-equivalence system, active power and reactive power before and after the equivalence of tie lines i (i is 1, 2, …, n and n are the number of the tie lines) in the set L are obtained, and voltage amplitude and phase angle before and after the equivalence of bus nodes J (J is 1, 2, …, J and J are the number of the bus nodes) in the set B are obtained.
12) Calculating the steady-state power security of each tie line according to the active power and the reactive power before and after the tie line is equivalent;
the steady state power conservation degree formula of the ith tie line is as follows:
Figure BDA0002406180420000081
wherein, Pi、
Figure BDA0002406180420000082
Before and after the i-th tie line is equivalentActive, Qi、
Figure BDA0002406180420000083
The reactive power before and after the i-th tie line is equivalent.
13) And calculating the steady-state voltage security of each tie line according to the voltage amplitude and the phase angle before and after the bus node equivalence.
Recording bus nodes j and l at two ends of the ith connecting line, wherein the voltage security formula of the bus node j at the two ends of the ith connecting line is as follows:
Figure BDA0002406180420000091
wherein, Uj、
Figure BDA0002406180420000092
The voltage amplitudes before and after the equivalent of the bus node j, thetaj、
Figure BDA0002406180420000093
The voltage phase angles before and after the equivalent of the bus node j are respectively.
The voltage security formula of the bus node l at the two ends of the ith tie line is as follows:
Figure BDA0002406180420000094
wherein, Ul、
Figure BDA0002406180420000095
The voltage amplitudes before and after the equivalent of the bus node l, thetal、
Figure BDA0002406180420000096
The voltage phase angles before and after the equivalent of the bus node l are respectively.
The steady state voltage security of the ith tie-line is σi(U,θ)＝min{σj(U,θ),σl(U,θ)}。
14) The steady-state power security and the steady-state voltage security of all the links (i.e., all the links in L) are calculated based on the weight of each link, the steady-state power security of each link, and the steady-state voltage security of each link.
The steady state power conservation formula for all the junctor is as follows:
Figure BDA0002406180420000097
the steady state voltage security formula of all the tie lines is as follows:
Figure BDA0002406180420000101
wherein n is the number of tie lines, ωiThe weight of the ith tie line.
15) Calculating the power grid steady-state feature security after equivalence according to the weight of the steady-state power security, the weight of the steady-state voltage security, the steady-state power security and the steady-state voltage security of all the connecting lines, wherein the specific formula is as follows:
Figure BDA0002406180420000102
wherein, CsteadyAnd the power grid steady-state characteristic security after equivalence is respectively the weight of the steady-state power security and the weight of the steady-state voltage security.
Step 2, calculating the power grid transient state characteristic security degree after equivalence according to the power grid transient state characteristics before and after equivalence; the power grid transient characteristics comprise power grid transient frequency safety, power grid power angle stability and power grid transient voltage safety.
The specific process is as follows:
21) and acquiring a power grid fault set F.
22) And calculating the power angle stability security of the power grid under each fault impact according to the power angle stability margins of the equivalent front and rear power grids under the fault impact.
By using a stability analysis quantification method proposed in the literature, "kinematic stability quantification theory", a power grid power angle stability margin, a transient voltage safety margin, and a transient frequency safety margin under the impact of a fault k (k is 1, 2, …, T is the number of faults in a power grid fault set) are calculated.
Therefore, the power angle stability security formula of the power grid under the impact of the fault k is as follows:
Figure BDA0002406180420000103
wherein, ηi(as)、
Figure BDA0002406180420000104
And respectively the power angle stability margins of the equivalent front and rear power grids under the impact of the fault k.
23) And calculating the safety security of the transient voltage of the power grid under each fault impact according to the safety margins of the transient voltage of the equivalent front and rear power grids under the fault impact.
The formula of the transient voltage safety security degree of the power grid under the impact of the fault k is as follows:
Figure BDA0002406180420000111
wherein, ηk(v)、
Figure BDA0002406180420000112
And respectively representing the transient voltage safety margins of the equivalent front and rear power grids under the impact of the fault k.
24) And calculating the safety security of the transient frequency of the power grid under each fault impact according to the safety margins of the transient frequency of the equivalent front and rear power grids under the fault impact.
The formula of the power grid transient frequency safety security under the fault k impact is as follows:
Figure BDA0002406180420000113
wherein, ηk(f)、
Figure BDA0002406180420000114
Respectively under fault k impact, etcAnd the safety margins of the transient frequency of the power grid before and after the value.
25) And calculating the power angle stability security degree of the power grid after considering the fault weight, the transient voltage security degree of the power grid after considering the fault weight and the transient frequency security degree of the power grid after considering the fault weight according to the fault weight, the power angle stability security degree of the power grid under the fault impact, the transient voltage security degree of the power grid under the fault impact and the transient frequency security degree of the power grid under the fault impact.
Calculating the power angle stability security degree of the power grid considering the fault weight, the transient voltage security degree of the power grid considering the fault weight and the transient frequency security degree of the power grid considering the fault weight, wherein the formulas are respectively as follows:
Figure BDA0002406180420000115
Figure BDA0002406180420000116
Figure BDA0002406180420000117
wherein the content of the first and second substances,
Figure BDA0002406180420000121
respectively, the power angle stability security degree of the power grid after considering the fault weight, the transient voltage security degree of the power grid after considering the fault weight, and the transient frequency security degree, omega, of the power grid after considering the fault weightkIs the weight of the fault k.
26) And calculating equivalent power grid transient characteristic security degree according to the power grid power angle stable security degree after the fault weight is calculated, the power grid transient voltage security degree after the fault weight is calculated, the power grid transient frequency security degree after the fault weight is calculated, the power grid power angle stable security degree weight, the power grid transient voltage security degree weight and the power grid transient frequency security degree weight.
The equivalent power grid transient characteristic preservation degree formula is as follows:
Figure BDA0002406180420000122
wherein, CtranFor power grid transient state feature security after equivalence, omegaas、ωv、ωfAnd respectively a power grid angle stability security weight, a power grid transient voltage security weight and a power grid transient frequency security weight.
And 3, calculating the key dynamic characteristic security of the power grid after equivalence according to the key dynamic characteristics of the power grid before and after equivalence.
The specific process is as follows:
31) and calculating the primary frequency modulation capability security of the equivalent back power grid according to the primary frequency modulation capability of the equivalent front and back power grids.
And calculating the primary frequency modulation capability of the power grid by using a mathematical expression given in the document 'online estimation of the primary frequency modulation capability of the power grid'.
The formula of the degree of security of the primary frequency modulation capability of the power grid after equivalence is as follows:
Figure BDA0002406180420000123
wherein D isPFCA、
Figure BDA0002406180420000131
The equivalent front and back power grid primary frequency modulation capacity respectively.
32) And solving the equivalent front and rear transient signals to obtain oscillation mode vectors of the equivalent front and rear transient signals.
Solving the transient signal before equivalence by using a Prony analysis method, recording amplitude values of different oscillation modes obtained by the transient signal through Prony transformation, and obtaining an oscillation amplitude vector A after sequencing from large to smallm＝[Am1,Am2,···,Amn′]. Each amplitude corresponds to an energy, an oscillation frequency and a damping coefficient, and the energy vector, the oscillation frequency vector and the damping vector of the transient signal before equivalence are as follows:
Figure BDA0002406180420000132
wherein E ismi′Is the energy value of the ith oscillation mode of the transient signal before equivalence, fmi′Is the oscillation frequency of the ith oscillation mode of the transient signal before equivalence,
Figure BDA0002406180420000133
the oscillation frequency of the ith oscillation mode of the transient signal after the equivalence.
The method is characterized in that a Prony analysis method is utilized to solve the transient signals after equivalence, the number of sinusoids analyzed by Prony before and after equivalence is the same, the number of oscillation modes obtained through Prony transformation is ensured to be the same, the oscillation modes are sequenced from large to small according to the oscillation amplitude quantity, and the oscillation mode vector of the transient signals after equivalence is as follows:
Figure BDA0002406180420000134
wherein the content of the first and second substances,
Figure BDA0002406180420000135
respectively obtaining the oscillation amplitude, the energy value, the oscillation frequency and the damping coefficient of the ith oscillation mode in the equivalent transient signal;
Figure BDA0002406180420000136
respectively an oscillation amplitude vector, an energy vector, an oscillation frequency vector and a damping vector of the transient signal after equivalence.
33) And calculating the oscillation frequency security, the oscillation amplitude security and the damping security according to the oscillation mode vectors of the equivalent front and rear transient signals.
Figure BDA0002406180420000141
Figure BDA0002406180420000142
Figure BDA0002406180420000143
Wherein the content of the first and second substances,
Figure BDA0002406180420000144
for oscillation frequency security, n' is the number of oscillation modes, ωi′Is the weight of the ith' oscillation mode, σi′(ff)The degree of oscillation frequency of the ith' oscillation mode is preserved.
Figure BDA0002406180420000145
Figure BDA0002406180420000146
Wherein the content of the first and second substances,
Figure BDA0002406180420000147
respectively, oscillation amplitude security and damping security, Ami′、
Figure BDA0002406180420000148
The oscillation amplitude of the ith oscillation mode of the transient signal before equivalence and the oscillation amplitude of the ith oscillation mode of the transient signal after equivalence, αmi′、
Figure BDA0002406180420000149
The damping coefficient of the ith oscillation mode of the transient signal before equivalence and the damping coefficient of the ith oscillation mode of the transient signal after equivalence are respectively obtained.
34) And calculating the equivalent post-oscillation mode security according to the weight of the oscillation frequency security, the weight of the oscillation amplitude security, the weight of the damping security, the oscillation frequency security, the oscillation amplitude security and the damping security.
The formula of the degree of security of the oscillation mode after equivalence is as follows:
Figure BDA00024061804200001410
wherein, ω isff、ωA、ωαThe weight of the oscillation frequency security, the weight of the oscillation amplitude security and the weight of the damping security are respectively.
35) And calculating the key dynamic characteristic security of the equivalent power grid according to the weight of the equivalent power grid primary frequency modulation capability security, the weight of the equivalent post-oscillation mode security, the equivalent post-power grid primary frequency modulation capability security and the equivalent post-oscillation mode security.
The key dynamic characteristic security formula of the power grid after equivalence is as follows:
Cdyna＝ωPFCA·CPFCA+ωoscil·Coscil
wherein, CdynaFor the security of key dynamic characteristics of equivalent power grid, omegaPFCA、ωoscilAnd respectively weighing the security of the equivalent primary frequency modulation capability of the power grid and the security of the equivalent oscillation mode.
And step 4, responding to the situation that the power grid steady-state feature preservation degree after equivalence, the power grid transient-state feature preservation degree after equivalence and the power grid key dynamic feature preservation degree after equivalence are all larger than a threshold value, and enabling the power grid dynamic equivalence to be effective.
The power grid of Sichuan province is used as a research object to perform equivalence on the generator group in the asbestos-Jiulong area. The asbestos-nine-Dragon region comprises 21 medium and small hydropower stations, 43 units and 2910MW total installed capacity, and the hydropower stations are connected with 220kV buses of the asbestos stations and the nine-Dragon stations through 220kV circuits and then connected with a Sichuan power grid through 500kV circuits. The equivalent system for the generator group in the asbestos-nine-Dragon region is shown in figure 2.
A bus voltage set and a tie line power set are obtained as shown in tables 1 and 2.
TABLE 1 set of equivalent front and rear bus voltages
Figure BDA0002406180420000151
Figure BDA0002406180420000161
TABLE 2 equivalent front-to-back tie line Power sets
Serial number Section of Transmission power before equivalence Post-equivalence transmission power
1 Chuanjiulong-Chuan asbestos 1530.53-j53.6 1530.6-j53.3
2 Chuanzishi-Chuanyaan 3484.1+j142.2 3483.9+J142.5
The steady state power preservation of each tie line and the steady state voltage preservation of each bus node were calculated, and the results are shown in table 3.
TABLE 3 Steady State Power and Voltage safety
Figure BDA0002406180420000162
And the weight average of the steady-state power security and the steady-state voltage security is 0.5, and the steady-state characteristic security of the Szechuan power grid after equivalence is 0.99737.
And calculating power angle stability margin, transient voltage safety margin and transient frequency safety margin of the four-channel power grid in different fault types before and after equivalence, and counting the safety degree of each transient characteristic, wherein the results are shown in tables 4-6.
TABLE 4N-1 Fault before and after equi-valued transient safety margin
Figure BDA0002406180420000163
Figure BDA0002406180420000171
TABLE 5N-2 before and after equal transient safety margin under fault
Figure BDA0002406180420000172
TABLE 6 transient safety margin before and after equivalence under DC blocking fault
Figure BDA0002406180420000173
And the weight of the N-1, the N-2 and the direct current blocking fault is 1/3, and the weight of the power angle stability, the transient voltage safety and the transient frequency characteristic security degree is 1/3, so that the transient safety stability characteristic security degree is 0.97969 after the Szechwan power grid is equivalent.
And calculating primary frequency modulation capacity of the Sichuan power grid before and after equivalence, and ensuring the security of the primary frequency modulation capacity after the equivalence 0.98743.
A short-circuit fault is set in the main network in the Sichuan, and a power response curve on the nine-dragon-asbestos connecting line before and after the equivalence is obtained, as shown in fig. 3. And solving the oscillation model vector of the equivalent front and rear power grids by using a Prony analysis method.
After equivalence, the oscillation frequency, the oscillation amplitude and the damping security of the Szechuan power grid are 0.96560, 0.96629 and 0.95668 respectively. And the weight of the oscillation frequency, the oscillation amplitude and the damping preservation degree is 1/3, and the equivalent preservation degree of the oscillation mode of the Sichuan power grid is 0.96286.
And the weight of the primary frequency modulation capability and the oscillation mode security is 0.5, and the equivalent dynamic characteristic security of the Sichuan power grid is 0.97515.
The security threshold value of each index in the evaluation system is 0.95, and the dynamic equivalence of the power grid is effective by integrating the quantization results of the indexes.
According to the method, the dynamic equivalence of the power grid is evaluated from three dimensions of the steady-state characteristics, the transient characteristics and the key dynamic characteristics of the power grid, and the preservation effect of the equivalence model on different stable characteristics of the power grid can be comprehensively and objectively reflected.
A quantitative evaluation system for power grid dynamic equivalence comprises,
the power grid steady-state characteristic security degree calculation module: calculating the security of the steady-state characteristics of the power grid after equivalence according to the steady-state characteristics of the power grid before and after equivalence;
the power grid transient characteristic security degree calculation module: calculating the power grid transient state characteristic security degree after equivalence according to the power grid transient state characteristics before and after equivalence;
the power grid key dynamic characteristic security calculation module: calculating the key dynamic characteristic security of the power grid after equivalence according to the key dynamic characteristics of the power grid before and after equivalence;
an evaluation module: and responding to the situation that the power grid steady-state characteristic security after equivalence, the power grid transient-state characteristic security after equivalence and the power grid key dynamic characteristic security after equivalence are all larger than a threshold value, and the power grid dynamic equivalence is effective.
A computer readable storage medium storing one or more programs, the one or more programs comprising instructions, which when executed by a computing device, cause the computing device to perform a method of quantitative assessment of grid dynamics equivalence.
A computing device comprising one or more processors, memory, and one or more programs stored in the memory and configured to be executed by the one or more processors, the one or more programs including instructions for performing a method for quantitative assessment of grid dynamics equivalence.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
The present invention is not limited to the above embodiments, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention are included in the scope of the claims of the present invention which are filed as the application.

Claims (10)

1. A quantitative evaluation method for power grid dynamic equivalence is characterized by comprising the following steps: comprises the steps of (a) preparing a mixture of a plurality of raw materials,
calculating the security of the steady-state characteristics of the power grid after equivalence according to the steady-state characteristics of the power grid before and after equivalence;
calculating the power grid transient state characteristic security degree after equivalence according to the power grid transient state characteristics before and after equivalence;
calculating the key dynamic characteristic security of the power grid after equivalence according to the key dynamic characteristics of the power grid before and after equivalence;
and responding to the situation that the power grid steady-state characteristic security after equivalence, the power grid transient-state characteristic security after equivalence and the power grid key dynamic characteristic security after equivalence are all larger than a threshold value, and the power grid dynamic equivalence is effective.
2. The quantitative evaluation method of the power grid dynamic equivalence as claimed in claim 1, wherein the method comprises the following steps: according to the steady-state characteristics of the power grid before and after equivalence, the security of the steady-state characteristics of the power grid after the equivalence is calculated,
when the power grid normally operates, acquiring active power and reactive power before and after the equivalence of each tie line, and acquiring voltage amplitude and phase angle before and after the equivalence of bus nodes at two ends of each tie line;
calculating the steady-state power security of each tie line according to the active power and the reactive power before and after the tie line is equivalent;
calculating the steady-state voltage security of each tie line according to the voltage amplitude and the phase angle before and after the bus node equivalence;
calculating the steady-state power security degree and the steady-state voltage security degree of all the tie lines according to the weight of each tie line, the steady-state power security degree of each tie line and the steady-state voltage security degree of each tie line;
and calculating the power grid steady-state feature security after equivalence according to the weight of the steady-state power security, the weight of the steady-state voltage security, the steady-state power security and the steady-state voltage security of all the connecting lines.
3. The quantitative evaluation method of the power grid dynamic equivalence as claimed in claim 2, wherein the method comprises the following steps: the formula of the steady-state feature security of the power grid after equivalence is as follows,
Figure FDA0002406180410000021
wherein the content of the first and second substances,
Csteadythe security degree of the steady-state characteristics of the power grid after equivalence is obtained;
ωPQ、ωUθrespectively is the weight of the steady-state power security and the weight of the steady-state voltage security;
Figure FDA0002406180410000022
maintaining the steady state power of all the links;
n is the number of interconnections, omegaiThe weight of the ith tie line;
Figure FDA0002406180410000023
the steady state power security of the ith connecting line is ensured;
Pi、
Figure FDA0002406180410000024
the active power, Q, before and after the i-th tie line is equivalenti、
Figure FDA0002406180410000025
The reactive power before and after the equivalence of the ith connecting line is respectively;
Figure FDA0002406180410000026
the steady state voltage safety degree of all the connecting lines is guaranteed;
σi(U,θ)＝min{σj(U,θ),σl(U, theta) } is the steady-state voltage security degree of the ith tie line;
Figure FDA0002406180410000027
the voltage safety degree of a bus node j at the two ends of the ith tie line is guaranteed;
Uj、
Figure FDA0002406180410000028
the voltage amplitudes before and after the equivalent of the bus node j are respectively;
θj、
Figure FDA0002406180410000029
the voltage phase angles before and after the equivalent of the bus node j are respectively;
Figure FDA00024061804100000210
the voltage safety degree of bus nodes l at two ends of the ith connecting line is guaranteed;
Ul、
Figure FDA00024061804100000211
respectively the voltage amplitudes before and after the equivalent of the bus node l;
θl、
Figure FDA0002406180410000031
the voltage phase angles before and after the equivalent of the bus node l are respectively.
4. The quantitative evaluation method of the power grid dynamic equivalence as claimed in claim 1, wherein the method comprises the following steps: according to the transient characteristics of the power grid before and after equivalence, the transient characteristic security of the power grid after the equivalence is calculated, the specific process is as follows,
acquiring a power grid fault set;
calculating power angle stability security of the power grid under each fault impact according to the power angle stability margins of the equivalent front and rear power grids under the fault impact;
calculating the safety security of the transient voltage of the power grid under each fault impact according to the safety margins of the transient voltage of the equivalent front and rear power grids under the fault impact;
calculating the safety security of the transient frequency of the power grid under each fault impact according to the safety margins of the transient frequency of the equivalent front and rear power grids under the fault impact;
according to the fault weight, the power angle stability and safety degree of the power grid under the fault impact, the transient voltage safety and safety degree of the power grid under the fault impact and the transient frequency safety and safety degree of the power grid under the fault impact, the power angle stability and safety degree of the power grid after the fault weight is taken into account, the transient voltage safety and safety degree of the power grid after the fault weight is taken into account and the transient frequency safety and safety degree of the power grid after the fault weight is taken into account are calculated;
and calculating equivalent power grid transient characteristic security degree according to the power grid power angle stable security degree after the fault weight is calculated, the power grid transient voltage security degree after the fault weight is calculated, the power grid transient frequency security degree after the fault weight is calculated, the power grid power angle stable security degree weight, the power grid transient voltage security degree weight and the power grid transient frequency security degree weight.
5. The quantitative evaluation method of the power grid dynamic equivalence as claimed in claim 4, wherein the method comprises the following steps: after equivalence, the power grid transient state characteristic security degree formula is as follows,
Figure FDA0002406180410000032
wherein the content of the first and second substances,
Ctranthe degree of security of the transient state characteristics of the equivalent power grid is obtained;
ωas、ωv、ωfrespectively weighing power angle stability security degree of the power grid, transient voltage safety security degree of the power grid and transient frequency safety security degree of the power grid;
Figure FDA0002406180410000041
respectively after taking into account the fault weightThe power grid power angle stability security degree, the power grid transient voltage security degree after the fault weight is taken into account, and the power grid transient frequency security degree after the fault weight is taken into account;
Figure FDA0002406180410000042
t is the number of faults in the grid fault set, omegakIs the weight of the fault k;
Figure FDA0002406180410000043
the power angle stability and the security of the power grid under the impact of the fault k are guaranteed;
ηi(as)、
Figure FDA0002406180410000044
respectively obtaining equivalent power angle stability margins of a front power grid and a rear power grid under the impact of a fault k;
Figure FDA0002406180410000045
Figure FDA0002406180410000046
the safety degree of the transient voltage of the power grid under the impact of the fault k is ensured;
ηk(v)、
Figure FDA0002406180410000047
respectively representing the transient voltage safety margins of the equivalent front and rear power grids under the impact of the fault k;
Figure FDA0002406180410000048
Figure FDA0002406180410000049
the safety degree of the transient frequency of the power grid under the impact of the fault k is ensured;
ηk(f)、
Figure FDA00024061804100000410
and respectively representing the transient frequency safety margins of the equivalent front and rear power grids under the impact of the fault k.
6. The quantitative evaluation method of the power grid dynamic equivalence as claimed in claim 1, wherein the method comprises the following steps: calculating the key dynamic characteristic security of the power grid after equivalence according to the key dynamic characteristics of the power grid before and after equivalence,
calculating the primary frequency modulation capability security of the equivalent back power grid according to the primary frequency modulation capability of the equivalent front and back power grids;
solving the equivalent front and rear transient signals to obtain oscillation mode vectors of the equivalent front and rear transient signals;
calculating the oscillation frequency security degree, the oscillation amplitude security degree and the damping security degree according to the oscillation mode vectors of the equivalent front and rear transient signals;
calculating the equivalent oscillation mode security degree according to the weight of the oscillation frequency security degree, the weight of the oscillation amplitude security degree, the weight of the damping security degree, the oscillation frequency security degree, the oscillation amplitude security degree and the damping security degree;
and calculating the key dynamic characteristic security of the equivalent power grid according to the weight of the equivalent power grid primary frequency modulation capability security, the weight of the equivalent post-oscillation mode security, the equivalent post-power grid primary frequency modulation capability security and the equivalent post-oscillation mode security.
7. The quantitative evaluation method of the power grid dynamic equivalence as claimed in claim 6, wherein the method comprises the following steps: after equivalence, the key dynamic characteristic security degree formula of the power grid is as follows,
Cdyna＝ωPFCA·CPFCA+ωoscil·Coscil
wherein the content of the first and second substances,
Cdynathe key dynamic characteristic security of the power grid after equivalence is achieved;
ωPFCA、ωoscilrespectively weighing the equivalent power grid primary frequency modulation capability security and the equivalent oscillation mode security;
Figure FDA0002406180410000051
the security of the primary frequency modulation capability of the power grid after equivalence is ensured;
DPFCA、
Figure FDA0002406180410000052
the equivalent front and rear power grid primary frequency modulation capacity respectively;
Figure FDA0002406180410000053
the degree of security of the oscillation mode after equivalence is ensured;
ωff、ωA、ωαrespectively is the weight of the oscillation frequency security degree, the weight of the oscillation amplitude security degree and the weight of the damping security degree;
Figure FDA0002406180410000061
respectively, the oscillation frequency security degree, the oscillation amplitude security degree and the damping security degree;
Figure FDA0002406180410000062
Figure FDA0002406180410000063
n' is the number of oscillation modes;
ωi′the weight of the ith' oscillation mode;
Emi′the energy value of the ith oscillation mode of the transient signal before equivalence;
fmi′the oscillation frequency of the ith oscillation mode of the transient signal before equivalence;
Figure FDA0002406180410000064
the oscillation frequency of the ith oscillation mode of the transient signal after equivalence is obtained;
Figure FDA0002406180410000065
Ami′、
Figure FDA0002406180410000066
respectively obtaining the oscillation amplitude of the ith oscillation mode of the transient signal before equivalence and the oscillation amplitude of the ith oscillation mode of the transient signal after equivalence;
Figure FDA0002406180410000067
αmi′、
Figure FDA0002406180410000068
the damping coefficient of the ith oscillation mode of the transient signal before equivalence and the damping coefficient of the ith oscillation mode of the transient signal after equivalence are respectively obtained.
8. A quantitative evaluation system of power grid dynamic equivalence is characterized in that: comprises the steps of (a) preparing a mixture of a plurality of raw materials,
the power grid steady-state characteristic security degree calculation module: calculating the security of the steady-state characteristics of the power grid after equivalence according to the steady-state characteristics of the power grid before and after equivalence;
the power grid transient characteristic security degree calculation module: calculating the power grid transient state characteristic security degree after equivalence according to the power grid transient state characteristics before and after equivalence;
the power grid key dynamic characteristic security calculation module: calculating the key dynamic characteristic security of the power grid after equivalence according to the key dynamic characteristics of the power grid before and after equivalence;
an evaluation module: and responding to the situation that the power grid steady-state characteristic security after equivalence, the power grid transient-state characteristic security after equivalence and the power grid key dynamic characteristic security after equivalence are all larger than a threshold value, and the power grid dynamic equivalence is effective.
9. A computer readable storage medium storing one or more programs, characterized in that: the one or more programs include instructions that, when executed by a computing device, cause the computing device to perform any of the methods of claims 1-7.
10. A computing device, characterized by: comprises the steps of (a) preparing a mixture of a plurality of raw materials,
one or more processors, memory, and one or more programs stored in the memory and configured to be executed by the one or more processors, the one or more programs including instructions for performing any of the methods of claims 1-7.
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