Transient stability regulation and control method and system for multi-device combined power transmission, terminal device and storage medium

Abstract

The invention discloses a transient stability regulation and control method and system for multi-device combined power transmission, terminal equipment and a storage medium, and the method comprises the steps: constructing a fault position equation and a motion equation of an all-round static synchronous machine, and determining the transient stability of the all-round static synchronous machine in a fault scene of combined power transmission of the all-round static synchronous machine and a current converter; the method comprises the following steps of: analyzing and determining a final expression of a current-limiting phase angle of the network-building type current converter when a fault occurs by combining an electromagnetic power expression of an all-round static synchronous machine with an equal-area rule, further calculating an optimal current-limiting current phase angle of the network-building type current converter, and finally adjusting the current-limiting current phase angle of the network-building type current converter according to the optimal current-limiting current phase angle so as to obtain the optimal current-limiting current phase angle of the network-building type current converter. The transient stability of an all-round static synchronous machine and converter combined power transmission power system in a fault is improved, and the problem that in a fault scene of all-round static synchronous machine and converter combined power transmission, large disturbance stability analysis and influence analysis of a current limiting phase angle of a converter during a fault period are lacked in the prior art is solved. And the transient stability of the power system is low.

Description

Technical Field

[0001] The present invention relates to the field of transient stability control of power systems, and in particular to a transient stability control method, system, terminal equipment and storage medium for multi-device joint power transmission. Background Art

[0002] As the global power system transforms towards flexibility and efficiency, the access to new energy sources such as wind and solar power has brought challenges to the stability and reliability of the power grid. Traditional non-synchronous power sources, whether they are grid-following or grid-building types, have certain limitations, such as limited independent operation capabilities and transient instability. Therefore, new equipment is needed to enhance the stability and reliability of the power grid.

[0003] The all-round static synchronous machine is proposed as a new type of equipment, which aims to simulate the characteristics of traditional synchronous generators to enhance the stability of the power grid. However, there are still deficiencies in the current research on the all-round static synchronous machine. In particular, in the scenario where the all-round static synchronous machine is jointly transmitted with the grid-following converter, its transient stability mechanism is still unclear, which restricts its application in new power systems. Although the control strategy of flexible DC converters has been widely studied in recent years, in the scenario of multi-device joint power transmission, most of the existing technologies are limited to considering steady-state electrical parameters and small signal stability, without involving large disturbance stability analysis, and do not consider the influence of the converter current limiting current phase angle during the fault. Therefore, in the fault scenario where the all-round static synchronous machine and the grid-following converter are jointly transmitted, the existing technology lacks consideration of large disturbance stability analysis during joint power transmission and the influence of the converter current limiting current phase angle during the fault, resulting in low transient stability of the power system. Summary of the invention

[0004] The present invention provides a transient stability control method, system, terminal device and storage medium for multi-device joint power transmission, which can solve the problem of low transient stability of the power system due to the lack of large disturbance stability analysis and analysis of the influence of the converter current limiting current phase angle during the fault scenario of the all-round static synchronous machine and the converter joint power transmission in the prior art.

[0005] In order to solve the above technical problems, an embodiment of the present invention provides a transient stability control method for multi-device joint power transmission, comprising:

[0006] Obtaining device parameters of the power system; wherein the device parameters of the power system include parameters of a grid-forming converter, parameters of a grid-following converter, parameters of an all-purpose static synchronous machine, and parameters of a transmission line;

[0007] According to the transmission line parameters of the power system, the fault location equation of the power system is constructed;

[0008] According to the parameters of the universal static synchronous machine of the power system, the motion equation of the universal static synchronous machine is constructed by using the typical second-order motion equation of the synchronous machine rotor;

[0009] According to the fault location equation of the power system and the motion equation of the universal static synchronous machine, the electromagnetic power expression of the universal static synchronous machine when the power system fails is obtained;

[0010] According to the electromagnetic power expression of the universal static synchronous machine and the equal area law when the power system fails, the acceleration area expression and constraint conditions of the equivalent rotor of the universal static synchronous machine are obtained;

[0011] Under the constraint conditions, according to the acceleration area expression of the equivalent rotor of the universal static synchronous machine, the final expression of the current limiting phase angle of the grid-type converter when the power system fails is obtained;

[0012] According to the line parameters, grid-type converter parameters and all-purpose static synchronous machine parameters, combined with the final expression of the current limiting phase angle of the grid-type converter when the power system fails, the optimal current limiting current phase angle of the grid-type converter when the power system fails is calculated, and the grid-type converter of the power system is adjusted according to the optimal current limiting current phase angle.

[0013] Furthermore, constructing the fault location equation of the power system according to the transmission line parameters of the power system includes:

[0014] According to the impedance on the transmission line of the power system, the fault location equation of the power system is constructed; wherein the transmission line includes: a first line, a second line, a third line and a transmission bus; the first line is a transmission line between a grid-type converter and a transmission bus; the second line is a transmission line between an all-purpose static synchronous machine and a transmission bus; the third line is a transmission line between a grid-type converter and a transmission bus; the first line is a transmission line between a grid-type converter and a transmission bus; the fault location equation is Said represents the impedance between the PCC point of the grid-following converter and the PCC point of the grid-forming converter; represents the impedance between the universal static synchronous machine and the PCC point of the grid-type converter; the K i (i=1 or 2) represents the fault location coefficient of the i-th line, K i ∈(0,1); represents the impedance between the fault point on the first line and the PCC point of the grid-following converter; It represents the impedance between the fault point on the second line and the PCC point of the grid-following converter.

[0015] Furthermore, the motion equation of the universal static synchronous machine is as follows:

[0016]

[0017] Wherein, δ represents the power angle of the voltage phasor at the AC side of the universal static synchronous machine relative to the voltage phasor at the PCC point of the grid-forming converter; ω δ represents the angular velocity corresponding to δ; ω0 represents the rated angular frequency of the all-round static synchronous machine; J g represents the equivalent inertia coefficient of the universal static synchronous machine; mg Represents the equivalent mechanical power of the all-purpose static synchronous machine; g represents the equivalent damping coefficient of the universal static synchronous machine; the P egi It represents the equivalent electromagnetic power of the universal static synchronous machine. i=0 means that the system is in a non-fault state. i=1 or 2 means that the fault occurs on the i-th line.

[0018] Furthermore, the electromagnetic power expression of the universal static synchronous machine when the power system fails is as follows:

[0019]

[0020] Among them, the P egl represents the electromagnetic power of the universal static synchronous machine when the fault occurs in the first line; the P eg2 represents the electromagnetic power of the universal static synchronous machine when the fault occurs in the second line; q represents the equivalent q-axis transient potential of the universal static synchronous machine; Imax Indicates the maximum current limiting current output by the grid-type converter when a fault occurs in the first line; represents the current limiting current phase angle output by the grid-type converter when a fault occurs in the first line; X1 represents the reactance value between the PCC point of the grid-type converter and the grid-type converter; X2 represents the reactance value between the AC side outlet of the universal static synchronous machine and the grid-type converter; P eglmax Indicates P eg1 The maximum amplitude; the δ represents the power angle of the voltage phasor at the AC side outlet of the universal static synchronous machine relative to the voltage phasor at the PCC point of the grid-type converter; the K1 represents the fault point location coefficient when the fault occurs in the first line.

[0021] Furthermore, according to the electromagnetic power expression of the universal static synchronous machine and the equal area law when the power system fails, the acceleration area expression and constraint conditions of the equivalent rotor of the universal static synchronous machine are obtained, including:

[0022] According to the electromagnetic power expression of the universal static synchronous machine and the device parameters of the power system when the power system fails, the initial expression of the current limiting phase angle of the grid-forming converter when the power system fails is obtained;

[0023] According to the electromagnetic power expression of the universal static synchronous machine during power system fault, the initial expression of the current limiting phase angle of the grid-forming converter during power system fault and the equal area law, the acceleration area expression and constraint conditions of the equivalent rotor of the universal static synchronous machine are obtained.

[0024] Furthermore, the initial expression of the current limiting phase angle of the grid-connected converter when the power system fails, the acceleration area expression of the equivalent rotor of the all-purpose static synchronous machine and the constraint conditions are as follows:

[0025] The initial expression of the current limiting phase angle of the grid-connected converter when the power system fails is:

[0026]

[0027] Among them, the represents the current limiting current phase angle output by the grid-type converter when the fault occurs in the first line; K1 represents the fault point location coefficient when the fault occurs in the first line; U0 represents the voltage of the grid-type converter output value PCC point; E′ q represents the equivalent q-axis transient potential of the universal static synchronous machine; Imax represents the maximum current limiting current output by the grid-type converter when a fault occurs in the first line; X1 represents the reactance value between the PCC point of the grid-type converter and the grid-type converter; X2 represents the reactance value between the AC side outlet of the universal static synchronous machine and the grid-type converter; δ SEP represents the angle corresponding to the equivalent power angle of the universal static synchronous machine at the stable equilibrium point; the P mg Indicates the equivalent mechanical power of the all-purpose static synchronous machine;

[0028] The acceleration area expression of the equivalent rotor of the all-round static synchronous machine is:

[0029]

[0030] Among them, the S + represents the acceleration area of ​​the equivalent rotor of the universal static synchronous machine; mg Represents the equivalent mechanical power of the all-purpose static synchronous machine; represents the current limiting current phase angle output by the grid-type converter when a fault occurs in the first line; the δ SEP represents the angle corresponding to the equivalent power angle of the universal static synchronous machine at the stable equilibrium point; the P egImaxrepresents the maximum amplitude of the electromagnetic power of the universal static synchronous machine when the fault occurs in the first line; q represents the equivalent q-axis transient potential of the universal static synchronous machine; Imax Indicates the maximum current limiting current output by the grid-type converter when a fault occurs in the first line; X1 indicates the reactance value between the PCC point of the grid-type converter and the grid-type converter; X2 indicates the reactance value between the AC side outlet of the all-purpose static synchronous machine and the grid-type converter;

[0031] The constraints are:

[0032]

[0033] Among them, the P mg Represents the equivalent mechanical power of the all-purpose static synchronous machine; represents the current limiting current phase angle output by the grid-type converter when a fault occurs in the first line; the δ SEP represents the angle corresponding to the equivalent power angle of the universal static synchronous machine at the stable equilibrium point; the P egImax represents the maximum amplitude of the electromagnetic power of the universal static synchronous machine when the fault occurs in the first line; T represents the fault removal angle.

[0034] Furthermore, the final expression of the current limiting phase angle of the grid-connected converter when the power system fails is as follows:

[0035]

[0036] Among them, the represents the current limiting current phase angle output by the grid-type converter when a fault occurs in the first line; the δ SEP It indicates the angle corresponding to the equivalent power angle of the universal static synchronous machine at the stable equilibrium point.

[0037] Based on the above method embodiment, the present invention provides a corresponding system embodiment;

[0038] An embodiment of the present invention provides a transient stability control system for multi-device joint power transmission, including: a device parameter acquisition module, a first building module, a second building module, a third building module, a fourth building module, a fifth building module and a control module;

[0039] The device parameter acquisition module is used to acquire device parameters of the power system; wherein the device parameters of the power system include parameters of a grid-forming converter, parameters of a grid-following converter, parameters of an all-purpose static synchronous machine, and parameters of a transmission line;

[0040] The first building module is used to build a fault location equation of the power system according to the transmission line parameters of the power system;

[0041] The second building module is used to build the motion equation of the universal static synchronous machine according to the universal static synchronous machine parameters of the power system and using the typical synchronous machine rotor second-order motion equation;

[0042] The third building block is used to obtain an electromagnetic power expression of the universal static synchronous machine when the power system fails according to the fault location equation of the power system and the motion equation of the universal static synchronous machine;

[0043] The fourth building block is used to obtain the acceleration area expression and constraint conditions of the equivalent rotor of the universal static synchronous machine according to the electromagnetic power expression and the equal area law of the universal static synchronous machine when the power system fails;

[0044] The fifth building block is used to obtain the final expression of the current limiting phase angle of the grid-type converter when the power system fails according to the acceleration area expression of the equivalent rotor of the universal static synchronous machine under the constraint condition;

[0045] The control module is used to calculate the optimal current limiting current phase angle of the grid-type converter when the power system fails according to the line parameters, the grid-type converter parameters and the all-purpose static synchronous machine parameters, combined with the final expression of the current limiting phase angle of the grid-type converter when the power system fails, and adjust the grid-type converter of the power system according to the optimal current limiting current phase angle.

[0046] Based on the above-mentioned method embodiment, the present invention provides a corresponding terminal device embodiment, including: a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, a transient stability control method for joint power transmission of multiple devices as described in the present invention is implemented.

[0047] Based on the above-mentioned method embodiment, the present invention provides a corresponding computer-readable storage medium embodiment, including: a stored computer program, which, when the computer program is running, controls the device where the computer-readable storage medium is located to execute a transient stability control method for multi-device joint power transmission as described in the present invention.

[0048] Compared with the prior art, the embodiments of the present invention have the following beneficial effects:

[0049] The present invention constructs a fault position equation of the power system and a motion equation of the universal static synchronous machine according to the device parameters of the power system, and obtains the electromagnetic power expression of the universal static synchronous machine when the line fault occurs according to the fault position equation and the motion equation of the universal static synchronous machine. Then, according to the electromagnetic power expression of the universal static synchronous machine when the line fault occurs and the equal area law, the acceleration area expression and constraint conditions of the equivalent rotor of the universal static synchronous machine are obtained. Then, by combining the acceleration area expression of the equivalent rotor of the universal static synchronous machine with the constraint conditions, the final expression of the current limiting phase angle of the grid-forming converter when the power system fails is obtained. Finally, according to the final expression of the current limiting phase angle, the optimal current limiting current phase angle of the grid-forming converter when the power system fails is calculated, and the grid-forming converter is adjusted according to the optimal current limiting current phase angle. That is, the present invention constructs a fault position equation and a motion equation of the all-purpose static synchronous machine to determine the electromagnetic power expression of the all-purpose static synchronous machine in the fault scenario of the all-purpose static synchronous machine and the converter jointly transmitting power, and performs stability analysis through the equal area law to determine the final expression of the current limiting phase angle of the grid-forming converter during the fault, thereby calculating the optimal current limiting current phase angle of the grid-forming converter, and achieving an improvement in the transient stability of the power system based on the joint power transmission of the all-purpose static synchronous machine and the converter when a fault occurs by adjusting the optimal current limiting current phase angle of the grid-forming converter, and solves the problem of low transient stability of the power system due to the lack of large disturbance stability analysis and analysis of the influence of the converter current limiting current phase angle during the fault in the prior art in the fault scenario of the joint power transmission of the all-purpose static synchronous machine and the converter. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 : A flowchart of the steps of a transient stability control method for multi-device joint power transmission provided by an embodiment of the present invention;

[0051] Figure 2 : A system structure diagram of a transient stability control system for multi-device joint power transmission provided by an embodiment of the present invention;

[0052] Figure 3 : A universal equivalent circuit diagram of a universal static synchronous machine and a converter combined power transmission provided by an embodiment of the present invention;

[0053] Figure 4 : A block diagram of a power synchronization loop control when fixed active power control is adopted according to an embodiment of the present invention. DETAILED DESCRIPTION

[0054] 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.

[0055] In the description of the present invention, it should be understood that the terms "first", "second", "third", "fourth" and "fifth" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features.

[0056] Embodiment 1:

[0057] Reference Figure 1 , is a flowchart of a method for transient stability control of multi-device joint power transmission provided by an embodiment of the present invention, the method comprising at least the following steps:

[0058] Step S1: obtaining device parameters of the power system; wherein the device parameters of the power system include parameters of a grid-forming converter, parameters of a grid-following converter, parameters of an all-purpose static synchronous machine, and parameters of a transmission line;

[0059] In this embodiment, the parameters of a grid-forming converter, a grid-following converter, an all-purpose static synchronous machine and transmission line parameters in the power system are obtained; wherein the parameters of the grid-forming converter include but are not limited to the output voltage and output current of the grid-forming converter; the parameters of the grid-following converter include but are not limited to the output voltage and output current of the grid-following converter; the parameters of the all-purpose static synchronous machine include but are not limited to the output potential, output current, equivalent inertia coefficient, equivalent mechanical power, equivalent damping coefficient and equivalent electromagnetic power of the all-purpose static synchronous machine; the transmission line parameters include but are not limited to the impedance on the transmission line.

[0060] Step S2: constructing a fault location equation of the power system according to the transmission line parameters of the power system;

[0061] In this embodiment, refer to Figure 3: A universal equivalent circuit diagram of the all-purpose static synchronous machine and converter combined power transmission provided in an embodiment of the present invention, wherein the power system based on the all-purpose static synchronous machine and converter combined power transmission at least includes a grid-forming converter station (converter 1), a grid-following converter station (converter 2), an all-purpose static synchronous machine, and a transmission line; wherein the transmission line includes: a first line, a second line, a third line, and a transmission bus; the first line is a transmission line from the grid-following converter to the transmission bus; the second line is a transmission line from the all-purpose static synchronous machine to the transmission bus; the third line is a transmission line from the grid-forming converter to the transmission bus; the grid-forming converter adopts V / f control, that is, the voltage amplitude and frequency of the PCC point on its AC side are controlled to be constant; the PLL of the grid-following converter adopts PI control; the controller structure of the all-purpose static synchronous machine adopts an emulation synchronous machine control strategy; Figure 3 Middle Z f1 and Z f2 are the equivalent impedances of the faults occurring at the fault point f1 on the first line and the fault point f2 on the second line, respectively, both of which are determined by the actual fault type; Figure 3 Middle Z 11 and Z 12 They respectively represent the impedance between the fault point f1 and the PCC point of the grid-following converter station (converter 2) and the PCC point of the grid-forming converter station (converter 1); Figure 3 Middle Z 21 and Z 22 They represent the impedance between the fault point f2 and the PCC point of the universal static synchronous machine and the converter 1 respectively.

[0062] In this embodiment, refer to Figure 3 : is a universal equivalent circuit diagram of the all-round static synchronous machine and converter combined power transmission provided by the embodiment of the present invention, and the fault location equation of the power system is Among them, the represents the impedance between the PCC point of the grid-following converter and the PCC point of the grid-forming converter; represents the impedance between the universal static synchronous machine and the PCC point of the grid-type converter; the K i (i=1 or 2) represents the fault location coefficient of the i-th line, K i ∈(0,1); represents the impedance between the fault point on the first line and the PCC point of the grid-following converter; It represents the impedance between the fault point on the second line and the PCC point of the grid-following converter.

[0063] Step S3: constructing the motion equation of the universal static synchronous machine according to the universal static synchronous machine parameters of the power system and using the typical synchronous machine rotor second-order motion equation;

[0064] In this embodiment, the motion equation of the universal static synchronous machine is as follows:

[0065]

[0066] Wherein, δ represents the power angle of the voltage phasor at the AC side of the universal static synchronous machine relative to the voltage phasor at the PCC point of the grid-forming converter; ω δ represents the angular velocity corresponding to δ; ω0 represents the rated angular frequency of the all-round static synchronous machine; J g represents the equivalent inertia coefficient of the universal static synchronous machine; mg Represents the equivalent mechanical power of the all-purpose static synchronous machine; g represents the equivalent damping coefficient of the universal static synchronous machine; the P egi It represents the equivalent electromagnetic power of the universal static synchronous machine. i=0 means that the system is in a non-fault state. i=1 or 2 means that the fault occurs on the i-th line.

[0067] In this embodiment, when the control target of the all-purpose static synchronous machine is a fixed active power During control, the input of the power synchronization loop is the active power command value When the operation of a universal static synchronous machine is simulated by the second-order motion equation of the synchronous machine rotor, the corresponding substitution can be completed when designing the controller structure, that is, the active power command value Mechanical power P of all-purpose static synchronous machine mg , using the actual power P s Replacement of electromagnetic power P of all-purpose static synchronous machine egi The equations on which this control method is based are also applicable to the universal static synchronous machine under fault conditions. According to the second-order motion equation of the equivalent rotor of the universal static synchronous machine, the PSL control process using fixed active power control is as follows: Figure 4 As shown, Figure 4 A block diagram of a power synchronization loop control when fixed active power control is adopted according to an embodiment of the present invention. Figure 4 In, θ g It is the output phase angle of the all-round static synchronous machine synchronization unit.

[0068] Step S4: according to the fault position equation of the power system and the motion equation of the universal static synchronous machine, an electromagnetic power expression of the universal static synchronous machine when the power system fails is obtained;

[0069] In this embodiment, the electromagnetic power expression of the universal static synchronous machine when the power system fails is as follows:

[0070]

[0071] Among them, the P eg1 represents the electromagnetic power of the universal static synchronous machine when the fault occurs in the first line; the P eg2 represents the electromagnetic power of the universal static synchronous machine when the fault occurs in the second line; q represents the equivalent q-axis transient potential of the universal static synchronous machine; 1max Indicates the maximum current limiting current output by the grid-type converter when a fault occurs in the first line; represents the current limiting current phase angle output by the grid-type converter when a fault occurs in the first line; X1 represents the reactance value between the PCC point of the grid-type converter and the grid-type converter; X2 represents the reactance value between the AC side outlet of the universal static synchronous machine and the grid-type converter; P eglmax Indicates P eg1 The maximum amplitude; the δ represents the power angle of the voltage phasor at the AC side outlet of the universal static synchronous machine relative to the voltage phasor at the PCC point of the grid-type converter; the K1 represents the fault point location coefficient when the fault occurs in the first line.

[0072] In this embodiment, since the resistance component in the high-voltage AC transmission line is much smaller than the reactance component, the resistance component of the transmission line is ignored when studying the transient stability of the all-purpose static synchronous machine, and when a fault occurs in the second line, the all-purpose static synchronous machine is decoupled from other equipment. Therefore, when a fault occurs in the second line, the electromagnetic power of the all-purpose static synchronous machine is 0.

[0073] Step S5: according to the electromagnetic power expression of the universal static synchronous machine when the power system fails and the equal area law, the acceleration area expression and constraint conditions of the equivalent rotor of the universal static synchronous machine are obtained;

[0074] In this embodiment, the acceleration area expression and constraint conditions of the equivalent rotor of the universal static synchronous machine are obtained according to the electromagnetic power expression of the universal static synchronous machine and the equal area law when the power system fails, including:

[0075] According to the electromagnetic power expression of the universal static synchronous machine and the device parameters of the power system when the power system fails, the initial expression of the current limiting phase angle of the grid-forming converter when the power system fails is obtained;

[0076] According to the electromagnetic power expression of the universal static synchronous machine during power system fault, the initial expression of the current limiting phase angle of the grid-forming converter during power system fault and the equal area law, the acceleration area expression and constraint conditions of the equivalent rotor of the universal static synchronous machine are obtained.

[0077] In this embodiment, the expression of the equal area law is as follows:

[0078]

[0079] Among them, the δ max It indicates the maximum power angle of the equivalent rotor swing of the all-round static synchronous machine.

[0080] In this embodiment, the initial expression of the current limiting phase angle of the grid-connected converter when the power system fails is:

[0081]

[0082] Among them, the represents the current limiting current phase angle output by the grid-type converter when the fault occurs in the first line; K1 represents the fault point location coefficient when the fault occurs in the first line; U0 represents the voltage of the grid-type converter output value PCC point; E′ q represents the equivalent q-axis transient potential of the universal static synchronous machine; Imax represents the maximum current limiting current output by the grid-type converter when a fault occurs in the first line; X1 represents the reactance value between the PCC point of the grid-type converter and the grid-type converter; X2 represents the reactance value between the AC side outlet of the universal static synchronous machine and the grid-type converter; δ SEP represents the angle corresponding to the equivalent power angle of the universal static synchronous machine at the stable equilibrium point; the P mg Indicates the equivalent mechanical power of an all-round static synchronous machine.

[0083] In this embodiment, the acceleration area expression of the equivalent rotor of the all-purpose static synchronous machine is:

[0084]

[0085] Among them, the S + represents the acceleration area of ​​the equivalent rotor of the universal static synchronous machine; mg Represents the equivalent mechanical power of the all-purpose static synchronous machine; represents the current limiting current phase angle output by the grid-type converter when a fault occurs in the first line; the δ SEP represents the angle corresponding to the equivalent power angle of the universal static synchronous machine at the stable equilibrium point; the P egImax represents the maximum amplitude of the electromagnetic power of the universal static synchronous machine when the fault occurs in the first line; q represents the equivalent q-axis transient potential of the universal static synchronous machine; Imax It represents the maximum current limiting current output by the grid-type converter when a fault occurs in the first line; X1 represents the reactance value between the PCC point of the grid-type converter and the grid-type converter; X2 represents the reactance value between the AC side outlet of the all-purpose static synchronous machine and the grid-type converter.

[0086] In this embodiment, the constraint conditions are:

[0087]

[0088] Among them, the P mg Represents the equivalent mechanical power of the all-purpose static synchronous machine; represents the current limiting current phase angle output by the grid-type converter when a fault occurs in the first line; the δ SEP represents the angle corresponding to the equivalent power angle of the universal static synchronous machine at the stable equilibrium point; the P egImax represents the maximum amplitude of the electromagnetic power of the universal static synchronous machine when the fault occurs in the first line; T represents the fault removal angle.

[0089] Step S6: Under the constraint conditions, according to the acceleration area expression of the equivalent rotor of the universal static synchronous machine, the final expression of the current limiting phase angle of the grid-connected converter when the power system fails is obtained;

[0090] In this embodiment, after a fault occurs, the current limiting phase angle of the grid-type converter is It is necessary to simultaneously satisfy the requirement at a certain cutting angle δ T Under this condition, the acceleration area S of the equivalent rotor of the universal static synchronous machine + For different The minimum value under the resection angle δ T For The limiting resection angle δ CCA and constraints.

[0091] In this embodiment, the final expression of the current limiting phase angle of the grid-connected converter when the power system fails is as follows:

[0092]

[0093] Among them, the represents the current limiting current phase angle output by the grid-type converter when a fault occurs in the first line; the δ SEP It indicates the angle corresponding to the equivalent power angle of the universal static synchronous machine at the stable equilibrium point.

[0094] Step S7: Calculate the optimal current limiting current phase angle of the grid-type converter when the power system fails according to the line parameters, the grid-type converter parameters and the all-purpose static synchronous machine parameters, combined with the final expression of the current limiting phase angle of the grid-type converter when the power system fails, and adjust the grid-type converter of the power system according to the optimal current limiting current phase angle.

[0095] In this embodiment, in order to verify the effectiveness of the method of the present invention, the system is now established in PSCAD for time domain simulation analysis, wherein the converter 1, converter 2 and the all-purpose static synchronous machine all use MMC. In the test system, the active power output of the all-purpose static synchronous machine and converter 2 is 400MW and 250MW respectively. The rated frequency of the test system is 50Hz, and the main circuit parameters of the system are shown in Table 1 below:

[0096] Table 1

[0097]

[0098] The simulation verification process of this embodiment is described as follows:

[0099] Before the fault occurred, converter 1 controlled the voltage frequency of its PCC point to be 50Hz and the voltage amplitude to be 1.0pu. The active power command values ​​of the universal static synchronous machine and converter 2 were 400MW and 250MW respectively. At t=7.0s, a metallic three-phase grounding fault occurred at the midpoint of line 1, i.e., K1=0.5. At t=7.1s, the three-phase short-circuit fault was cleared. During the fault, converter 1 entered the current limiting mode, and the amplitude of the current limiting current was 1.2pu, i.e., |I 1max |=1.2. According to the proposed transient stability improvement strategy, this test system The optimal value of is 237.9827°. To verify the effectiveness of the proposed strategy, the present invention performs The CCT under the given value is simulated, and the system response simulation results under the given conditions are shown in Table 2 below:

[0100] Table 2

[0101]

[0102] The simulation results show that the CCT after adopting the proposed strategy is greater than that of other The CCT under the value of The selected value is more beneficial to improving the transient stability of line 1 when it fails, which verifies the effectiveness of the proposed strategy.

[0103] Embodiment 2:

[0104] Reference Figure 2 , which is a system structure diagram of a transient stability control system for multi-device joint power transmission provided by an embodiment of the present invention, the system includes: a device parameter acquisition module, a first building module, a second building module, a third building module, a fourth building module, a fifth building module and a control module;

[0105] The device parameter acquisition module is used to acquire device parameters of the power system; wherein the device parameters of the power system include parameters of a grid-forming converter, parameters of a grid-following converter, parameters of an all-purpose static synchronous machine, and parameters of a transmission line;

[0106] The first building module is used to build a fault location equation of the power system according to the transmission line parameters of the power system;

[0107] The second building module is used to build the motion equation of the universal static synchronous machine according to the universal static synchronous machine parameters of the power system and using the typical synchronous machine rotor second-order motion equation;

[0108] The third building block is used to obtain an electromagnetic power expression of the universal static synchronous machine when the power system fails according to the fault location equation of the power system and the motion equation of the universal static synchronous machine;

[0109] The fourth building block is used to obtain the acceleration area expression and constraint conditions of the equivalent rotor of the universal static synchronous machine according to the electromagnetic power expression and the equal area law of the universal static synchronous machine when the power system fails;

[0110] The fifth building block is used to obtain the final expression of the current limiting phase angle of the grid-type converter when the power system fails according to the acceleration area expression of the equivalent rotor of the universal static synchronous machine under the constraint condition;

[0111] The control module is used to calculate the optimal current limiting current phase angle of the grid-type converter when the power system fails according to the line parameters, the grid-type converter parameters and the all-purpose static synchronous machine parameters, combined with the final expression of the current limiting phase angle of the grid-type converter when the power system fails, and adjust the grid-type converter of the power system according to the optimal current limiting current phase angle.

[0112] Based on the above method embodiment, another embodiment is provided;

[0113] Another embodiment of the present invention provides a terminal device for transient stability control of multi-device joint power transmission, including a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, it implements a method for transient stability control of multi-device joint power transmission described in any one of the above method embodiments of the present invention.

[0114] Exemplarily, the computer program may be divided into one or more modules / units, which are stored in the memory and executed by the processor to complete the present invention. The one or more modules / units may be a series of computer program instruction segments capable of completing specific functions, which are used to describe the execution process of the computer program in the transient stability control terminal device for multi-device joint power transmission.

[0115] The terminal device for transient stability control of multi-device joint power transmission can be a computing device such as a desktop computer, a notebook, a PDA, and a cloud server. The terminal device for transient stability control of multi-device joint power transmission can include, but is not limited to, a processor and a memory. Those skilled in the art can understand that, for example, the terminal device for transient stability control of multi-device joint power transmission can also include input and output devices, network access devices, buses, etc.

[0116] The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor, etc. The processor is the control center of the transient stability control terminal device for the combined power transmission of multiple devices, and uses various interfaces and lines to connect the various parts of the entire transient stability control terminal device for the combined power transmission of multiple devices.

[0117] The memory can be used to store the computer program and / or module, and the processor realizes various functions of the transient stability control terminal device for multi-device joint power transmission by running or executing the computer program and / or module stored in the memory, and calling the data stored in the memory. The memory can mainly include a program storage area and a data storage area, wherein the program storage area can store an operating system, an application required for at least one function (such as a sound playback function, an image playback function, etc.), etc.; the data storage area can store data created according to the use of the mobile phone (such as audio data, a phone book, etc.), etc. In addition, the memory can include a high-speed random access memory, and can also include a non-volatile memory, such as a hard disk, a memory, a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) card, a flash card (Flash Card), at least one disk storage device, a flash memory device, or other volatile solid-state storage devices.

[0118] Based on the above method embodiment, another embodiment is provided;

[0119] A storage medium provided in another embodiment of the present invention includes a stored computer program, wherein when the computer program is running, the device where the storage medium is located is controlled to execute a transient stability control method for joint power transmission of multiple devices as described in any one of the above method embodiments of the present invention.

[0120] Wherein, the above-mentioned storage medium is a computer-readable storage medium. The module / unit integrated in the transient stability control system / terminal equipment for the combined power transmission of multiple devices can be stored in a computer-readable storage medium if it is implemented in the form of a software functional unit and sold or used as an independent product. Based on such an understanding, the present invention implements all or part of the processes in the above-mentioned embodiment method, and can also be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium. When the computer program is executed by the processor, the steps of the above-mentioned method embodiments can be implemented. Wherein, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable medium can include: any entity or device capable of carrying the computer program code, recording medium, U disk, mobile hard disk, disk, optical disk, computer memory, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), electric carrier signal, telecommunication signal and software distribution medium, etc.

[0121] It should be noted that the above-mentioned terminal device may include, but is not limited to, a processor and a memory. Those skilled in the art will understand that the above-mentioned terminal device is merely an example and does not constitute a limitation on the terminal device. It may include more or fewer components, or a combination of certain components, or different components.

[0122] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. It is particularly pointed out that for those skilled in the art, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. A transient stability control method for multi-device joint power transmission, characterized in that: include: Obtaining device parameters of the power system; wherein the device parameters of the power system include parameters of a grid-forming converter, parameters of a grid-following converter, parameters of an all-purpose static synchronous machine, and parameters of a transmission line; According to the transmission line parameters of the power system, the fault location equation of the power system is constructed; According to the parameters of the universal static synchronous machine of the power system, the motion equation of the universal static synchronous machine is constructed by using the typical second-order motion equation of the synchronous machine rotor; According to the fault location equation of the power system and the motion equation of the universal static synchronous machine, the electromagnetic power expression of the universal static synchronous machine when the power system fails is obtained; According to the electromagnetic power expression of the universal static synchronous machine and the equal area law when the power system fails, the acceleration area expression and constraint conditions of the equivalent rotor of the universal static synchronous machine are obtained; Under the constraint conditions, according to the acceleration area expression of the equivalent rotor of the universal static synchronous machine, the final expression of the current limiting phase angle of the grid-type converter when the power system fails is obtained; According to the line parameters, grid-type converter parameters and all-purpose static synchronous machine parameters, combined with the final expression of the current limiting phase angle of the grid-type converter when the power system fails, the optimal current limiting current phase angle of the grid-type converter when the power system fails is calculated, and the grid-type converter of the power system is adjusted according to the optimal current limiting current phase angle.

2. A transient stability control method for multi-device joint power transmission according to claim 1, characterized in that: The method of constructing a fault location equation of the power system according to the transmission line parameters of the power system includes: According to the impedance on the transmission line of the power system, the fault location equation of the power system is constructed; wherein the transmission line includes: a first line, a second line, a third line and a transmission bus; the first line is a transmission line between a grid-type converter and a transmission bus; the second line is a transmission line between an all-purpose static synchronous machine and a transmission bus; the third line is a transmission line between a grid-type converter and a transmission bus; the first line is a transmission line between a grid-type converter and a transmission bus; the fault location equation is Said represents the impedance between the PCC point of the grid-following converter and the PCC point of the grid-forming converter; represents the impedance between the universal static synchronous machine and the PCC point of the grid-type converter; the K i (i=1 or 2) represents the fault location coefficient of the i-th line, K i ∈(0,1); represents the impedance between the fault point on the first line and the PCC point of the grid-following converter; It represents the impedance between the fault point on the second line and the PCC point of the grid-following converter.

3. A transient stability control method for multi-device joint power transmission according to claim 2, characterized in that: The motion equation of the universal static synchronous machine is as follows: Wherein, δ represents the power angle of the voltage phasor at the AC side of the universal static synchronous machine relative to the voltage phasor at the PCC point of the grid-forming converter; ω δ represents the angular velocity corresponding to δ; ω0 represents the rated angular frequency of the all-round static synchronous machine; J g represents the equivalent inertia coefficient of the universal static synchronous machine; mg Represents the equivalent mechanical power of the all-purpose static synchronous machine; g represents the equivalent damping coefficient of the universal static synchronous machine; egi It represents the equivalent electromagnetic power of the universal static synchronous machine. i=0 means that the system is in a non-fault state. i=1 or 2 means that the fault occurs on the i-th line.

4. A transient stability control method for multi-device joint power transmission according to claim 3, characterized in that: The electromagnetic power expression of the universal static synchronous machine when the power system fails is as follows: Among them, the P eg1 represents the electromagnetic power of the universal static synchronous machine when the fault occurs in the first line; the P eg2 represents the electromagnetic power of the universal static synchronous machine when the fault occurs in the second line; q represents the equivalent q-axis transient potential of the universal static synchronous machine; 1max Indicates the maximum current limiting current output by the grid-type converter when a fault occurs in the first line; represents the current limiting current phase angle output by the grid-type converter when a fault occurs in the first line; X1 represents the reactance value between the PCC point of the grid-type converter and the grid-type converter; X2 represents the reactance value between the AC side outlet of the universal static synchronous machine and the grid-type converter; P eg1max Indicates P eg1 The maximum amplitude; the δ represents the power angle of the voltage phasor at the AC side outlet of the universal static synchronous machine relative to the voltage phasor at the PCC point of the grid-type converter; the K1 represents the fault point location coefficient when the fault occurs in the first line.

5. A transient stability control method for multi-device joint power transmission according to claim 4, characterized in that: According to the electromagnetic power expression of the universal static synchronous machine and the equal area law when the power system fails, the acceleration area expression and constraint conditions of the equivalent rotor of the universal static synchronous machine are obtained, including: According to the electromagnetic power expression of the universal static synchronous machine and the device parameters of the power system when the power system fails, the initial expression of the current limiting phase angle of the grid-forming converter when the power system fails is obtained; According to the electromagnetic power expression of the universal static synchronous machine during power system fault, the initial expression of the current limiting phase angle of the grid-forming converter during power system fault and the equal area law, the acceleration area expression and constraint conditions of the equivalent rotor of the universal static synchronous machine are obtained.

6. A transient stability control method for multi-device joint power transmission according to claim 4, characterized in that: The initial expression of the current limiting phase angle of the grid-type converter when the power system fails, the acceleration area expression of the equivalent rotor of the all-purpose static synchronous machine and the constraint conditions are as follows: The initial expression of the current limiting phase angle of the grid-connected converter when the power system fails is: Among them, the represents the current limiting current phase angle output by the grid-type converter when the fault occurs in the first line; K1 represents the fault point location coefficient when the fault occurs in the first line; U0 represents the voltage of the grid-type converter output value PCC point; E′ q represents the equivalent q-axis transient potential of the universal static synchronous machine; 1max represents the maximum current limiting current output by the grid-type converter when a fault occurs in the first line; X1 represents the reactance value between the PCC point of the grid-type converter and the grid-type converter; X2 represents the reactance value between the AC side outlet of the universal static synchronous machine and the grid-type converter; δ SEP represents the angle corresponding to the equivalent power angle of the universal static synchronous machine at the stable equilibrium point; the P mg Indicates the equivalent mechanical power of the all-purpose static synchronous machine; The acceleration area expression of the equivalent rotor of the all-round static synchronous machine is: Among them, the S + represents the acceleration area of ​​the equivalent rotor of the universal static synchronous machine; mg Represents the equivalent mechanical power of the all-purpose static synchronous machine; represents the current limiting current phase angle output by the grid-type converter when a fault occurs in the first line; the δ SEP represents the angle corresponding to the equivalent power angle of the universal static synchronous machine at the stable equilibrium point; the P eg1max represents the maximum amplitude of the electromagnetic power of the universal static synchronous machine when the fault occurs in the first line; q represents the equivalent q-axis transient potential of the universal static synchronous machine; 1max Indicates the maximum current limiting current output by the grid-type converter when a fault occurs in the first line; x1 indicates the reactance value between the PCC point of the grid-type converter and the grid-type converter; X2 indicates the reactance value between the AC side outlet of the all-purpose static synchronous machine and the grid-type converter; The constraints are: Among them, the P mg Represents the equivalent mechanical power of the all-purpose static synchronous machine; represents the current limiting current phase angle output by the grid-type converter when a fault occurs in the first line; the δ SEP represents the angle corresponding to the equivalent power angle of the universal static synchronous machine at the stable equilibrium point; the P eg1max represents the maximum amplitude of the electromagnetic power of the universal static synchronous machine when the fault occurs in the first line; T represents the fault removal angle.

7. A transient stability control method for multi-device joint power transmission according to claim 6, characterized in that: The final expression of the current limiting phase angle of the grid-type converter when the power system fails is as follows: Among them, the represents the current limiting current phase angle output by the grid-type converter when a fault occurs in the first line; the δ SEP It indicates the angle corresponding to the equivalent power angle of the universal static synchronous machine at the stable equilibrium point.

8. A transient stability control system for multi-device joint power transmission, characterized in that: include: A device parameter acquisition module, a first building module, a second building module, a third building module, a fourth building module, a fifth building module and a control module; The device parameter acquisition module is used to acquire device parameters of the power system; wherein the device parameters of the power system include parameters of a grid-forming converter, parameters of a grid-following converter, parameters of an all-purpose static synchronous machine, and parameters of a transmission line; The first building module is used to build a fault location equation of the power system according to the transmission line parameters of the power system; The second building module is used to build the motion equation of the universal static synchronous machine according to the universal static synchronous machine parameters of the power system and using the typical synchronous machine rotor second-order motion equation; The third building block is used to obtain an electromagnetic power expression of the universal static synchronous machine when the power system fails according to the fault location equation of the power system and the motion equation of the universal static synchronous machine; The fourth building block is used to obtain the acceleration area expression and constraint conditions of the equivalent rotor of the universal static synchronous machine according to the electromagnetic power expression and the equal area law of the universal static synchronous machine when the power system fails; The fifth building block is used to obtain the final expression of the current limiting phase angle of the grid-type converter when the power system fails according to the acceleration area expression of the equivalent rotor of the universal static synchronous machine under the constraint condition; The control module is used to calculate the optimal current limiting current phase angle of the grid-type converter when the power system fails according to the line parameters, the grid-type converter parameters and the all-purpose static synchronous machine parameters, combined with the final expression of the current limiting phase angle of the grid-type converter when the power system fails, and adjust the grid-type converter of the power system according to the optimal current limiting current phase angle.

9. A transient stability control terminal device for multi-device joint power transmission, comprising a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein when the processor executes the computer program, it implements a transient stability control method for multi-device joint power transmission as described in any one of claims 1 to 7.

10. A storage medium, characterized in that: The storage medium includes a stored computer program, wherein when the computer program is running, the device where the storage medium is located is controlled to execute a transient stability control method for multi-device joint power transmission as described in any one of claims 1 to 7.

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