阅读说明：本技术 一种适用含高比例风电电力系统的暂态稳定特征保全方法 (Transient stability characteristic preservation method suitable for power system containing high-proportion wind power ) 是由 汤奕 戴剑丰 李碧君 侯玉强 *** 于 2019-10-18 设计创作，主要内容包括：本发明针对含大规模风电的电力系统提出了一种适用含高比例风电电力系统的暂态稳定特征保全方法。该方法首先推导双馈风力发电机组的等效注入电流源模型,在此基础上建立含DFIG的等值单机无穷大母线(OMIB)系统的等值功率-等值功角曲线一般形式；然后将暂态过程中一段时间内采集的机端信息投影到OMIB系统的等值功率-等值功角平面并进行拟合,通过计算加速/减速面积来预测系统的暂态稳定性。该方法能有效保全含大规模风电的电力系统的暂态稳定特征,有助于电力系统暂态稳定预测,对维持电力系统稳定运行具有重要意义。(The invention provides a transient stability characteristic preservation method suitable for a power system containing high-proportion wind power, aiming at the power system containing large-scale wind power. The method comprises the steps of firstly deducing an equivalent injection current source model of the doubly-fed wind generating set, and establishing an equivalent power-equivalent power angle curve general form of an equivalent single machine infinite bus (OMIB) system containing the DFIG on the basis; then, terminal information acquired within a period of time in the transient process is projected to an equivalent power-equivalent power angle plane of the OMIB system and is fitted, and the transient stability of the system is predicted by calculating an acceleration/deceleration area. The method can effectively preserve the transient stability characteristics of the power system containing large-scale wind power, is beneficial to predicting the transient stability of the power system, and has important significance for maintaining the stable operation of the power system.)

1. A transient stability characteristic preservation method applicable to a power system containing high-proportion wind power is characterized by comprising the following steps:

(1) establishing an equivalent single-machine infinite OMIB system model containing a high-proportion wind power system based on a classic second-order model of a synchronous generator of the power system;

(2) acquiring data of n synchronous generators of the system at m different moments after fault removal through WAMS

(3) fitting the established OMIB system model parameters;

(4) and calculating the transient stability margin of the system based on the equivalent acceleration area and the deceleration surface.

2. The method for preserving transient stability characteristics of a power system containing high-proportion wind power as claimed in claim 1, wherein the step (1) of establishing the OMIB system model of the power system containing high-proportion wind power comprises the following steps:

(11) establishing an OMIB (open multimedia interface) system model of a power system without wind power:

wherein: m_g，P_mg，P_egThe rotational inertia, mechanical power and electromagnetic power, delta, of an equivalent OMIB system_s，M_s，δ_a，M_aAre respectively critical groups S_gAnd the remaining group A_gEquivalent power angle, equivalent inertia, P, of partial inertia center_ms，P_es，P_ma，P_eaAre respectively S_gGroup A and_gequivalent mechanical power and equivalent electromagnetic power of the cluster;

(12) establishing an equivalent injection current source model of the doubly-fed wind generating set:

wherein: i is_W，I_G，I_CInjecting current column vectors into a fan node W, a generator node G and a contact node C respectively; u shape_W，U_CVoltage column vectors of the fan node and the tie node, respectively, E_GIs a potential column vector in the synchronous motor; y represents an element of the inter-node admittance matrix;

(13) obtaining generator node injection current based on double-fed wind generating set equivalent injection current source model

wherein:

(14) based on the generator node injection current expression, obtaining an ith synchronous machine electromagnetic power expression considering wind power access:

wherein: p_eiFor the electromagnetic power, Δ P, of the synchronous machine i before the wind power is switched in_ei,ΔI_i，ψ_iRespectively the electromagnetic power increment generated by the fan on the synchronous motor i and the amplitude and phase angle of the equivalent injection current;

(15) establishing an OMIB system model containing a high-proportion wind power system:

P'_eg＝P_c∑-P_max∑sin(δ_g-β)

in the formula, M_g,δ_g,P_mgDefinition is the same as in step (11), P'_egFor considering the corrected equivalent electromagnetic power and parameters after wind power accessP_c∑，P_max∑And β are each P'_egOffset, amplitude and initial phase.

3. The method for preserving transient stability characteristics of a power system containing high-proportion wind power as claimed in claim 2, wherein the step (3) of fitting the established parameters of the OMIB system model is implemented by:

(31) the OMIB system equivalent electromagnetic power P 'in the step (15)'_egWritten as follows:

P'_eg＝p₀+p₁cos(δ_g)+p₂sin(δ_g)

wherein: p is a radical of₀,p₁,p₂Is a parameter to be determined;

(32) according to the parameter equivalence method in the step (11), the method comprises the steps of

(33) Will be provided with

y＝Xp

y＝[P_eg.1P_eg.2…P_eg.m]^T

p＝[p₀p₁p₂]^T

when m is greater than or equal to 3, the parameter phasor P can be obtained by the following formula:

p＝(X^TX)^-1X^Ty。

4. the method for saving transient stability characteristics of a power system with high wind power content according to claim 1, wherein the step (4) of calculating the transient stability margin of the system based on the equivalent acceleration area and deceleration area comprises the following specific steps:

(41) solving the equivalent acceleration area S at the machine end according to the fitted equivalent electromagnetic power curve of the fault period and the fault after being removed_accAnd the deceleration area S_dec：

In the formula: p_eg.acc(δ_g)，P_eg.dec(δ_g) The equivalent electromagnetic power curve is obtained during the fault and after the fault is removed; delta₀,δ_ccThe equivalent power angle in a steady state and the equivalent power angle delta in fault removal are respectively_limFor the equivalent power angle corresponding to the right intersection point of the equivalent electromagnetic power curve and the mechanical power after the fault is removed, the equivalent power angle can be solved through the following formula:

P_mg＝P_eg.dec(δ_lim)

(42) calculating a system transient stability margin η according to the equivalent acceleration area and deceleration area:

Technical Field

The invention relates to the technical field of power system model equivalence and situation perception, in particular to a transient stability characteristic preservation method suitable for a power system containing high-proportion wind power.

Background

The world energy crisis, environmental pressures, and the low cost of wind power have prompted global power system planners to continually increase the medium proportion of wind power in the total power generation of the system. High-level wind power permeability generates economic and environmental benefits, and simultaneously, due to high randomness of wind power and reduction of effective inertia of a system caused by replacement of a synchronous motor by the wind power, great influence is also generated on transient stability of a power system.

Transient power angle instability is one of the most serious events of a power system. In the transient process after the system suffers from serious disturbance, if one or more motors lose the synchronization with the rest of the motors, power angle instability can be caused, so that cascade power failure and even large-area power failure are caused. Therefore, the method has important significance for providing early warning for emergency control by quickly predicting the transient power angle stability of the power system after suffering severe disturbance.

Although the traditional transient power angle stability prediction method based on the physical mechanism, such as a time domain simulation method and a transient energy function method, has high precision, the timeliness is poor due to large calculated amount, and the requirement of online prediction is difficult to meet; although some transient stability prediction methods based on data mining represented by trajectory fitting and artificial intelligence have great advantages in online prediction speed, ignoring the physical mechanism of the transient process may cause the prediction accuracy to be reduced. Therefore, how to simplify the equivalent power system containing large-scale wind power and retain the transient stability characteristics is the key for balancing the transient stability prediction speed and prediction accuracy.

Disclosure of Invention

The invention aims to solve the problems and provides a transient stability characteristic preservation method suitable for a power system containing high-proportion wind power.

The method comprises the steps of firstly deducing an equivalent injection current source model of the doubly-fed wind generating set, and establishing an equivalent power-equivalent power angle curve general form of an equivalent single machine infinite bus (OMIB) system containing the DFIG on the basis; then, terminal information acquired within a period of time in the transient process is projected to an equivalent power-equivalent power angle plane of the OMIB system and is fitted, and the transient stability of the system is predicted by calculating an acceleration/deceleration area. The method can effectively preserve the transient stability characteristics of the power system containing large-scale wind power, is beneficial to predicting the transient stability of the power system, and has important significance for maintaining the stable operation of the power system.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

a transient stability characteristic preservation method applicable to a power system containing high-proportion wind power comprises the following steps:

(1) establishing an equivalent single-machine infinite (OMIB) system model containing a high-proportion wind power system based on a classic second-order model of a synchronous generator of the power system;

(2) acquiring data of n synchronous generators of the system at m different moments after fault removal through WAMS

Wherein delta_i、P_eiRespectively representing the power angle and the electromagnetic power of the ith synchronous generator;

(3) fitting the established OMIB system model parameters;

(4) calculating the transient stability margin of the system based on the equivalent acceleration area and the deceleration surface;

further, the step (1) of establishing the OMIB system model including the high-proportion wind power system includes the following steps:

(11) establishing an OMIB (open multimedia interface) system model of a power system without wind power:

wherein: m_g，P_mg，P_egThe rotational inertia, mechanical power and electromagnetic power, delta, of an equivalent OMIB system_s，M_s，δ_a，M_aAre respectively critical group (S)_g) And the rest group (A)_g) Equivalent power angle, equivalent inertia, P, of partial inertia center_ms，P_es，P_ma，P_eaAre respectively S_gGroup A and_gequivalent mechanical power and equivalent electromagnetic power of the cluster;

(12) establishing an equivalent injection current source model of the doubly-fed wind generating set:

wherein: i is_W，I_G，I_CInjecting current column vectors into a fan node (W), a generator node (G) and a connection node (C) respectively; u shape_W，U_CVoltage column vectors of the fan node and the tie node, respectively, E_GIs a potential column vector in the synchronous motor; y represents an element of the inter-node admittance matrix;

(13) obtaining generator node injection current based on double-fed wind generating set equivalent injection current source model

Expression (c):

wherein:

equivalent injection current is generated for wind power at each synchronous machine node;

(14) based on the generator node injection current expression, obtaining an ith synchronous machine electromagnetic power expression considering wind power access:

wherein: p_eiFor the electromagnetic power, Δ P, of the synchronous machine i before the wind power is switched in_ei,ΔI_i，ψ_iThe electromagnetic power increment generated by the fan on the synchronous motor i and the amplitude and the phase angle of the equivalent injection current are respectively.

(15) Establishing an OMIB system model containing a high-proportion wind power system:

P'_eg＝P_c∑-P_max∑sin(δ_g-β)

in the formula, M_g,δ_g,P_mgDefinition is the same as in step (11), P'_egFor considering the corrected equivalent electromagnetic power after wind power access, the parameter P_c∑，P_max∑And β are each P'_egOffset, amplitude and initial phase of (d);

further, the step (3) of fitting the established parameters of the OMIB system model includes the following specific implementation methods:

(31) mixing OMI in step (15)Equivalent electromagnetic power P 'of system B'_egWritten as follows:

P'_eg＝p₀+p₁cos(δ_g)+p₂sin(δ_g)

wherein: p is a radical of₀,p₁,p₂Is a parameter to be determined;

(32) according to the parameter equivalence method in the step (11), the method comprises the steps of

Equivalent power angle and electromagnetic power on m groups of OMIB systems

(33) Will be provided with

Substituting step (31) can result in:

y＝Xp

y＝[P_eg.1P_eg.2… P_eg.m]^T

p＝[p₀p₁p₂]^T

when m is greater than or equal to 3, the parameter phasor P can be obtained by the following formula:

p＝(X^TX)^-1X^Ty

further, the step (4) of calculating the transient stability margin of the system based on the equivalent acceleration area and the equivalent deceleration area includes the following specific steps:

(41) solving the equivalent acceleration area S at the machine end according to the fitted equivalent electromagnetic power curve of the fault period and the fault after being removed_accAnd the deceleration area S_dec：

In the formula: p_eg.acc(δ_g)，P_eg.dec(δ_g) The equivalent electromagnetic power curve is obtained during the fault and after the fault is removed; delta₀,δ_ccThe equivalent power angle in a steady state and the equivalent power angle delta in fault removal are respectively_limFor the equivalent power angle corresponding to the right intersection point of the equivalent electromagnetic power curve and the mechanical power after the fault is removed, the equivalent power angle can be solved through the following formula:

P_mg＝P_eg.dec(δ_lim)

(42) calculating a system transient stability margin η according to the equivalent acceleration area and deceleration area:

has the advantages that:

the invention provides a method for preserving transient stability characteristics of a power system containing large-scale wind power. Compared with the prior art, the equivalent injection current source model of the doubly-fed wind generating set is deduced, and on the basis, the equivalent power-equivalent power angle curve general form of the equivalent single machine infinite bus (OMIB) system containing the DFIG is established; then, terminal information acquired within a period of time in the transient process is projected to an equivalent power-equivalent power angle plane of the OMIB system and is fitted, and the transient stability of the system is predicted by calculating an acceleration/deceleration area. On the premise of reserving the transient stability characteristics of the power system, the equivalent simplification is carried out on the power system model, the contradiction between the prediction precision and the prediction speed of the transient stability of the power system is favorably balanced, and the method has important significance for maintaining the stable operation of the power system.

Drawings

FIG. 1 is a schematic flow chart of a method according to an embodiment of the present invention;

FIG. 2 is a diagram of a system for testing the nodes of New England 39 containing wind power;

Detailed Description

As shown in fig. 1, a method for preserving transient stability characteristics of a power system including a high-ratio wind power system according to an embodiment of the present invention includes:

step S1: establishing an equivalent single-machine infinite (OMIB) system model containing a high-proportion wind power system based on a classic second-order model of a synchronous generator of the power system;

step S2: acquiring data of n synchronous generators of the system at m different moments after fault removal through WAMS

Wherein delta_i、P_eiRespectively representing the power angle and the electromagnetic power of the ith synchronous generator;

step S3: fitting the established OMIB system model parameters;

step S4: and calculating the transient stability margin of the system based on the equivalent acceleration area and the deceleration surface.

In the embodiment, a new england 39 node testing system containing wind power is taken as an example for analysis, and the model structure is shown in fig. 2. The test system is built in PSCAD/EMTDC, the total load is 6150.5MW, the wind turbine generator adopts a double-fed fan, and the permeability is 32.52%.

Further, in this embodiment, the step S1 of establishing the OMIB system model of the high-ratio wind power system includes the following steps:

step S11: OMIB system model of the power system containing wind power:

wherein: m_g，P_mg，P_egThe rotational inertia, mechanical power and electromagnetic power, delta, of an equivalent OMIB system_s，M_s，δ_a，M_aAre respectively critical group (S)_g) And the rest group (A)_g) In part of inertiaEquivalent power angle, equivalent inertia, P, of the heart_ms，P_es，P_ma，P_eaAre respectively S_gGroup A and_gequivalent mechanical power and equivalent electromagnetic power of the cluster;

step S12: establishing an equivalent injection current source model of the doubly-fed wind generating set:

wherein: i is_W，I_G，I_CInjecting current column vectors into a fan node (W), a generator node (G) and a connection node (C) respectively; u shape_W，U_CVoltage column vectors of the fan node and the tie node, respectively, E_GIs a potential column vector in the synchronous motor; y represents an element of the inter-node admittance matrix;

step S13: obtaining generator node injection current based on double-fed wind generating set equivalent injection current source model

Expression (c):

wherein:

equivalent injection current is generated for wind power at each synchronous machine node;

step S14: based on the generator node injection current expression, obtaining an ith synchronous machine electromagnetic power expression considering wind power access:

wherein: p_eiFor the electromagnetic power, Δ P, of the synchronous machine i before the wind power is switched in_ei,ΔI_i，ψ_iThe electromagnetic power increment generated by the fan on the synchronous motor i and the amplitude and the phase angle of the equivalent injection current are respectively.

Step S15: establishing an OMIB system model containing a high-proportion wind power system:

P'_eg＝P_c∑-P_max∑sin(δ_g-β)

in the formula, M_g,δ_g,P_mgP 'is defined as in step S11'_egFor considering the corrected equivalent electromagnetic power after wind power access, the parameter P_c∑，P_max∑And β are each P'_egOffset, amplitude and initial phase of (d);

in this embodiment, the step S3 of fitting the established parameters of the OMIB system model includes:

s31: the OMIB system equivalent electromagnetic power P 'in the step S15'_egWritten as follows:

wherein: p is a radical of₀,p₁,p₂Is a parameter to be determined;

s32: according to the parameter equivalence method in step S11, the method will

Equivalent power angle and electromagnetic power on m groups of OMIB systems

S33: will be provided with

Substituting step S31, we can obtain:

y＝Xp

y＝[P_eg.1P_eg.2… P_eg.m]^T

p＝[p₀p₁p₂]^T

when m is greater than or equal to 3, the parameter phasor P can be obtained by the following formula:

p＝(X^TX)^-1X^Ty

further, in this embodiment, the specific implementation step of calculating the transient stability margin of the system based on the equivalent acceleration area and the equivalent deceleration area in step S4 is as follows:

step S41: solving the equivalent acceleration area S at the machine end according to the fitted equivalent electromagnetic power curve of the fault period and the fault after being removed_accAnd the deceleration area S_dec：

In the formula: p_eg.acc(δ_g)，P_eg.dec(δ_g) The equivalent electromagnetic power curve is obtained during the fault and after the fault is removed; delta₀,δ_ccThe equivalent power angle in a steady state and the equivalent power angle delta in fault removal are respectively_limFor the equivalent power angle corresponding to the right intersection point of the equivalent electromagnetic power curve and the mechanical power after the fault is removed, the equivalent power angle can be solved through the following formula:

P_mg＝P_eg.dec(δ_lim)

and step S42, calculating a transient stability margin η of the system according to the equivalent acceleration area and the equivalent deceleration area:

in this embodiment, to verify the validity of the transient stability feature preservation method, the results of comparing the stability discrimination effects at different fault clearing times are shown in table 1.

TABLE 1 Stable discrimination under different Fault clearing time

According to data in the table, the method can effectively judge the transient stability of the system after the fault.