Quantitative evaluation method and device for static voltage stability of multi-infeed system

Abstract

The invention discloses a static voltage stability quantitative evaluation method and device for a multi-infeed system, and relates to the technical field of power system online monitoring and control. According to the method, power flow mathematical models under different new energy grid-connected control strategies are constructed, and the sending-out capability and the static voltage stability boundary of the heterogeneous new energy multi-infeed system under different control modes and different operation modes are quantitatively evaluated based on the singular conditions of a power flow Jacobian matrix; the static voltage stability influence factors are analyzed from the aspects of control and system parameters, and the effectiveness of the proposed method is simulated and verified.

Description

Technical Field

[0001] The invention discloses a method and a device for quantitatively evaluating static voltage stability of a multi-feedback system, and relates to the technical field of online monitoring and control of power systems. Background Art

[0002] Static voltage stability is an important constraint for the stable operation of the system. With the rapid increase in the proportion of new energy, the proportion of conventional power sources supported by synchronous machines has gradually decreased, and the static voltage stability margin of the system has continued to decline. The safety and stability of the power system faces severe challenges. Most new energy sites use grid-following converters to connect to the AC power grid. Its external characteristics are current source characteristics. In recent years, grid-building converters with voltage source characteristics have been applied to multiple projects because of their supporting role. The coexistence of grid-following and grid-building control makes the power system present heterogeneous new energy multi-feed characteristics. For heterogeneous new energy multi-feed systems, the coupling relationship between its voltage stability and control methods, system structure and other factors is complex. Therefore, revealing the static voltage stability mechanism of heterogeneous new energy systems and providing quantitative evaluation methods are crucial to ensure the safe and stable operation of power systems.

[0003] At present, there are a lot of conclusions on the research of grid-type control in improving the active support capacity of new energy stations. However, the analysis of the mathematical model of grid-type new energy power flow is relatively lacking, which makes it an urgent problem to consider the key characteristic quantities to conduct qualitative and quantitative analysis of the static voltage stability form in heterogeneous new energy multi-feedback systems. The research on the static voltage stability problem of new energy multi-feedback systems in the existing literature lacks the consideration of multi-factor constraints such as control mode and operation mode, and there are few research conclusions obtained by quantitative analysis of the grid-connected transmission capacity of heterogeneous new energy and the static voltage stability boundary of heterogeneous new energy multi-feedback systems. In the existing technology, the minimum singular value of the Jacobian matrix is ​​used as an indicator to evaluate the static voltage stability of the system, and the applicable conditions of the voltage stability margin indicator of the new energy transmission system are disclosed, but the influence of the reactive voltage characteristics of new energy on the evaluation process under different control modes is not considered.

[0004] Therefore, a method and device for quantitatively evaluating static voltage stability of a multi-infeed system are now invented to solve the above problems. Summary of the invention

[0005] A method and device for quantitatively evaluating static voltage stability of a multi-feed system are provided, and the technical solution adopted is:

[0006] In a first aspect, a method for quantitatively evaluating static voltage stability of a multi-infeed system is provided, the method comprising:

[0007] Step 1: Establish a multi-input system model;

[0008] According to the motor power supply, a power flow model is established through a renewable energy multi-feed system;

[0009] According to the power flow model, a Jacobian matrix is ​​established at a generator node through the renewable energy multi-feed system; According to the renewable energy multi-feed system, a Jacobian matrix is ​​established at a generator node of the motor power supply;

[0010] According to the Jacobian matrix, the new energy node and the generator node are connected to the grid through the power flow model;

[0011] Step 2: Process the new energy node according to the control method;

[0012] According to the type of the new energy node, modify the corresponding elements of the Jacobian matrix;

[0013] Step 3: Quantitative evaluation of static voltage stability of multi-infeed system;

[0014] According to the matrix singular values ​​of the Jacobian matrix, a quantitative evaluation of static voltage stability is performed through the renewable energy multi-feed system to obtain a stability boundary of the static voltage.

[0015] In some implementations, in step one, the motor power supply includes an asynchronous motor power supply and a traditional synchronous motor power supply.

[0016] In some implementations, in step 2, the new energy nodes include network-following new energy nodes and network-building new energy nodes.

[0017] In some implementations, the step 2 specifically includes:

[0018] According to the load model, the grid-following new energy node is processed as a PQ node through a constant impedance model, and the corresponding elements of the Jacobian matrix are modified to obtain an element expression of the grid-following new energy node;

[0019] When the grid-type power source is in a rated working state, the grid-type new energy node is processed as a PV node, and the corresponding elements of the Jacobian matrix are modified to obtain an element expression of the grid-type new energy node;

[0020] When the potential inside the VSC of the grid-type power source reaches the limiting value, the grid-type new energy node is processed as a PQ node, and the corresponding elements of the Jacobian matrix are modified to obtain the element expression of the grid-type new energy node.

[0021] In a second aspect, an embodiment of the present invention provides a device for quantitatively evaluating static voltage stability of a multi-feed system, the device comprising:

[0022] Modeling module, used to establish multi-input system model, including:

[0023] A model unit, used for establishing a power flow model through a renewable energy multi-feed system according to a motor power supply;

[0024] A matrix unit, for establishing a Jacobian matrix at a generator node through the renewable energy multi-feed system according to the power flow model; and establishing a Jacobian matrix at a generator node of the motor power supply according to the renewable energy multi-feed system;

[0025] A node processing unit, used for performing grid connection processing on the new energy node and the generator node through the power flow model according to the Jacobian matrix;

[0026] An updating module, used for processing the new energy node according to the control mode, and modifying the corresponding elements of the Jacobian matrix according to the type of the new energy node;

[0027] The evaluation module is used for quantitatively evaluating the static voltage stability of the multi-feed system, and according to the matrix singular values ​​of the Jacobian matrix, quantitatively evaluating the static voltage stability through the renewable energy multi-feed system to obtain the stability boundary of the static voltage.

[0028] In some implementations, the motor power supply includes an asynchronous motor power supply and a conventional synchronous motor power supply.

[0029] In some implementations, the new energy nodes include network-following new energy nodes and network-building new energy nodes.

[0030] In some implementations, the update module specifically includes:

[0031] A grid-following new energy node processing unit, used to process the grid-following new energy node as a PQ node through a constant impedance model according to a load model, modify corresponding elements of the Jacobian matrix, and obtain an element expression of the grid-following new energy node;

[0032] A grid-forming new energy node processing unit, comprising a rated working subunit and a potential value subunit; wherein the rated working subunit is used to process the grid-forming new energy node as a PV node when the grid-forming power source is in a rated working state, and to modify the corresponding elements of the Jacobian matrix to obtain an element expression of the grid-forming new energy node;

[0033] The potential value subunit is used to process the grid-type new energy node as a PQ node when the potential inside the VSC of the grid-type power supply reaches the limit value, modify the corresponding elements of the Jacobian matrix, and obtain the element expression of the grid-type new energy node.

[0034] In a third aspect, an embodiment of the present invention provides an electronic device, comprising a memory and a processor, wherein the memory is used to store one or more computer instructions, wherein when the one or more computer instructions are executed by the processor, the method described in the first aspect above is implemented.

[0035] In a fourth aspect, an embodiment of the present invention provides a computer storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, it is used to implement the method described in the first aspect.

[0036] One or more embodiments of the present invention can at least bring the following beneficial effects: the method of the present invention constructs a mathematical model of power flow under different renewable energy grid-connected control strategies, and quantitatively evaluates the delivery capacity and static voltage stability boundary of a heterogeneous renewable energy multi-feed system under different control modes and different operating modes based on the singular conditions of the power flow Jacobian matrix, analyzes the factors affecting static voltage stability from the aspects of control and system parameters, and simulates and verifies the effectiveness of the proposed method. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0038] Figure 1 is a simplified topological diagram of a multi-feed system provided by an embodiment of the present invention;

[0039] Figure 2 It is a topology diagram of an improved 3-machine 9-node system with multiple machines and single feed provided by an embodiment of the present invention;

[0040] Figure 3 is a relationship diagram between the output of each station in the multi-machine single-feed system and the singular criterion value of the Jacobian matrix provided by an embodiment of the present invention;

[0041] Figure 4 is a relationship diagram between the output of each station in the multi-machine multi-feed system and the singular criterion value of the Jacobian matrix provided by an embodiment of the present invention;

[0042] Figure 5 is a graph showing the relationship between the station output and the Jacobian matrix singular criterion value under different renewable energy transmission distances provided by an embodiment of the present invention;

[0043] Figure 6 It is a relationship diagram between the station output and the Jacobian matrix singular criterion value under different internal potential limit values ​​provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0044] It is worth noting that the methods used in the present invention are all conventional methods unless otherwise specified; the raw materials and devices used are all conventional commercially available products, and their sources are not specifically limited unless otherwise specified.

[0045] Embodiment 1:

[0046] This embodiment provides a method for quantitatively evaluating static voltage stability of a multi-infeed system, the method comprising:

[0047] First, follow step 1 to establish a multi-input system model, including:

[0048] S11, establishing a power flow model through a renewable energy multi-feed system based on the motor power supply;

[0049] S12, establishing a Jacobian matrix at a generator node through the new energy multi-feed system according to the power flow model; establishing a Jacobian matrix at a generator node of the motor power supply according to the new energy multi-feed system;

[0050] S13, according to the Jacobian matrix, performing grid connection processing on the new energy node and the generator node through the power flow model;

[0051] Wherein, the motor power supply includes an asynchronous motor power supply and a traditional synchronous motor power supply.

[0052] According to S11, assume that the high-proportion new energy grid has n nodes, most of which are non-synchronous power sources, and a small number of power sources are traditional synchronous power sources. The simplified topology of the system is as follows: Figure 1 shown.

[0053] The injection power corresponding to node i is denoted by P Si , Q Si The load of node i is represented by P Li , Q Li If , then the power balance equation of the i-th node in the power grid is as follows:

[0054]

[0055] Where ΔP i , ΔQ i are respectively the active and reactive unbalanced quantities of node i; U i , U j are the voltage amplitudes of nodes i and j respectively; G ij , B ij are the conductance and susceptance between nodes i and j respectively; δ ij is the phase angle difference between nodes i and j.

[0056] According to S12, the synchronous generator node is usually treated as a balance node or a PV node, and the load model adopts a constant impedance (ZIP) model, which is usually treated as a PQ node, so that the AC side Jacobian matrix is ​​obtained as follows:

[0057]

[0058] The Jacobian matrix of the renewable energy multi-feed system includes the Jacobian matrix J on the AC system side ac And the device-side Jacobian matrix J S , according to the power flow model of the multi-infeed system, it can be expanded as follows:

[0059]

[0060] Among them, J ac Contains all generators, loads and their interconnection nodes in the AC system, J S It includes all new energy nodes and the AC system-side grid-connected nodes connected to them. Figure 1 According to S13, the Jacobian matrix element expression corresponding to the new energy node is:

[0061]

[0062] Wherein, node i is the grid connection point of the equipment, and node j is the node on the AC system side connected to the equipment.

[0063] For the non-synchronous power supply node, the power injected into the AC system contains information such as controller parameters. Next, consider different types of new energy nodes and modify the elements in the corresponding Jacobian matrix.

[0064] Next, according to step 2, the new energy node is processed according to the control method;

[0065] According to the type of the new energy node, the corresponding elements of the Jacobian matrix are modified; wherein the new energy node includes a network-following new energy node and a network-building new energy node, specifically including:

[0066] S21, according to the load model, the grid-connected new energy node is processed as a PQ node through a constant impedance model, and the corresponding elements of the Jacobian matrix are modified to obtain an element expression of the grid-connected new energy node;

[0067] S22, when the grid-forming power source is in a rated working state, the grid-forming new energy node is processed as a PV node, and the corresponding elements of the Jacobian matrix are modified to obtain an element expression of the grid-forming new energy node;

[0068] S23, when the potential inside the VSC of the grid-type power source reaches the limiting value, the grid-type new energy node is processed as a PQ node, and the corresponding elements of the Jacobian matrix are modified to obtain the element expression of the grid-type new energy node.

[0069] For grid-connected new energy nodes, currently, grid-connected units basically operate at unity power factor. When connected to the grid, they are equivalent to current sources and treated as PQ nodes. Assume that the active power and reactive power injected into the AC system by the new energy node are P S , Q S , expressed in complex power form; U S is the bus voltage amplitude at the PCC grid connection point, δ S is the voltage phase angle; X T The equivalent reactance of the grid-connected line including the connected transformer is included, and the line resistance and ground capacitance are ignored. The output active and reactive power are:

[0070]

[0071] Let the reactive power in the above formula be 0 to obtain the relationship between the grid connection point voltage amplitude, phase angle and node injected active power:

[0072] (P S X T ) 2 +U S 4 =U S 2 U g 2 (9)

[0073]

[0074] The effective value of the grid connection point voltage is solved as follows:

[0075]

[0076] Substituting formula (11) into the Jacobian matrix element expression, we have:

[0077]

[0078] Modifying the corresponding elements in the Jacobian matrix yields:

[0079]

[0080] The grid-connected new energy nodes under constant voltage control are treated as PV nodes, which are the same as generator nodes. The relationship between the grid-connected point voltage amplitude, phase angle and node injected active power is the same as equation (8). Substituting into the Jacobian matrix element expression, we have:

[0081]

[0082] When modifying the corresponding elements in the Jacobian matrix, only the elements related to the active power output of the new energy node need to be modified to:

[0083]

[0084] Where:

[0085]

[0086] The elements related to the reactive power output of the new energy node are 0, and the processing of the remaining elements is the same as that of formula (13), thereby obtaining the reduced-order Jacobian matrix.

[0087]

[0088] For grid-building new energy nodes, the grid-building power source has voltage source characteristics under rated working conditions and is treated as a PV node, and P Si =f(U Si ), the modification of the Jacobian matrix elements is the same as that of equation (15).

[0089] If the active output of the grid-forming power source continues to increase or the external circuit fails, causing the current to over-current, the converter will reach the upper limit of modulation. After the potential inside the VSC reaches the limit value, the grid-forming new energy node type is converted to a PQ node, and P Si =f(U Si ),

[0090] Q Si =f(U Si ). The elements related to the reactive power output of the new energy node are modified as follows:

[0091]

[0092] The processing of the remaining elements is the same as that of equation (15). Thus, the element expressions of the new energy node part in the Jacobian matrix of the multi-feedback system power flow under different control modes are obtained.

[0093] Next, according to step 3, the static voltage stability of the multi-infeed system is quantitatively evaluated;

[0094] According to the matrix singular values ​​of the Jacobian matrix, a quantitative evaluation of static voltage stability is performed through the renewable energy multi-feed system to obtain a stability boundary of the static voltage.

[0095] In step 2, the Jacobian matrix of the system power flow under different renewable energy control modes is obtained, in which the main diagonal elements and off-diagonal elements directly related to the renewable energy grid connection point contain the transmission power P Si , QSi , node voltage V Ti ,δ Si The main diagonal elements in the system power flow Jacobian matrix It represents the self-feedback term in the system and reflects the power balance and transmission capacity of the system. Since the necessary and sufficient condition for a matrix to be singular is that it is a suspended matrix, that is, the sum of its diagonal elements and non-diagonal elements is zero, if the non-diagonal elements are close to the diagonal elements, the matrix may have linear correlation, which will cause the Jacobian matrix singular value to be zero or close to zero, indicating that the matrix may be singular and the system is close to an unstable state.

[0096] In the multi-machine single feed scenario, in J S In the example, the matrix block corresponding to the voltage phase angle and amplitude information of the node on the AC system side and the node is J1, the matrix block corresponding to the information of the node on the AC system side and the new energy node is J2, the matrix block corresponding to the new energy node and the node information on the AC system side is J3, and the matrix block corresponding to the new energy node's own information is J4. Take the Jacobian matrix of the external device side of the grid-type power supply as an example:

[0097]

[0098] The general expression of the Jacobian matrix on the external device side of the multi-machine single-feed system is obtained as follows:

[0099]

[0100] Where i and j represent different new energy stations. And J2 and J3 satisfy J2=J3 T , that is, for a multi-machine single-feed renewable energy system, its Jacobian matrix is ​​still a symmetric matrix. The main diagonal elements directly related to the renewable energy output power and grid connection point voltage are The off-diagonal elements are max{P Si ,P Sj}, we can obtain the simplified condition that the system power flow Jacobian matrix is ​​close to singularity:

[0101]

[0102] For the multi-machine single-feed renewable energy system, due to the short electrical distance between stations, there is a node voltage and power coupling relationship, which may restrict its renewable energy transmission capacity. The following will analyze it in the multi-machine multi-feed system.

[0103] In a multi-machine multi-feed scenario, follow these steps to Figure 1 The multi-machine multi-feed system shown in the figure is analyzed, and the general expression of the Jacobian matrix of the external device side of the multi-machine multi-feed system is derived by analogy with formula (20):

[0104]

[0105] According to the general properties of the power flow Jacobian matrix in AC systems, J ij and J ji Meet J ij =J ji T Therefore, the Jacobian matrix block in the upper left corner of the AC system autocorrelation is a symmetric matrix, and the matrix block in the lower right corner of the new energy node autocorrelation is a diagonal matrix. Considering the characteristics of the external device side, the singularity condition of the Jacobian matrix of the system is:

[0106] min{J 4i |,J 4j}→0 (23)

[0107] Equation (23) is essentially a simplified generalization of equation (21), and its external device side can be equivalent to a single-point power supply.

[0108] The critical points discussed here refer to the operating boundaries when the system reaches the static voltage stability limit. In fact, the active output of new energy units with a certain low voltage ride-through capability decreases rapidly in the low voltage ride-through state. After the low voltage ride-through state ends, the active output will slowly recover, and the system operates within the static stability limit boundary; units without low voltage ride-through capability will trip when the voltage is lower than 0.9pu, and also operate within the static stability limit boundary. At the same time, in the actual system, the system power flow may not converge before the Jacobian matrix on the external device side reaches the singular condition. Taking the load node near the new energy feed-in point as an example, its nonlinear equation is:

[0109]

[0110] Where P W , Q W The power injected into the load node for renewable energy, P L , Q L are the active and reactive parameters of the load. It can be seen that the self-feedback item of the load node is affected by the transmission power of the external device. In a multi-machine multi-feed system, the number of nodes connected to the new energy source increases, and the parameter information in formula (24) will be incorporated into the Jacobian matrix on the external device side, which increases the dimension of the matrix order described in formula (22) and increases the complexity of the singularity analysis. In order to obtain the relationship between the power flow convergence and the degree of new energy penetration in a multi-machine multi-feed system, the load node voltage sensitivity is introduced to indicate the response of the voltage at this point when the external device changes. In the multi-machine multi-feed scenario, the voltage sensitivity distribution range of each load node is large, indicating that the nodes in the system are more susceptible to the power fluctuations of the external device at this time, and the system has run to a critical state before the singular criterion tends to 0.

[0111] Since the power and voltage of the nodes related to the Jacobian matrix on the external device side will cause changes in the overall AC system, the voltage weak nodes in the system (such as heavy load nodes) will first drop to the voltage collapse state, causing the system to become unstable before the Jacobian matrix becomes singular. This characteristic will be more obvious in multi-machine and multi-feed systems with high penetration of new energy. Therefore, the stability boundary calculated by the method proposed in this patent is more conservative than the actual working conditions and has a wider applicability.

[0112] Embodiment 2:

[0113] Based on the first embodiment, the new energy delivery capacity of the multi-feed system is verified:

[0114] This example is based on an improved three-machine system, where generator G3 is replaced by a new energy station with grid-following and grid-building control. Figure 2 As shown, the transmission distance of the new energy station is set to 100km.

[0115] Set the station output growth and perform multiple simulations to derive the relationship between the new energy output and the main and secondary diagonal elements of the Jacobian matrix on the external equipment side. Figure 3 As the station output increases, the voltage related to the new energy node drops significantly until the system becomes unstable, the main diagonal elements continue to decrease, and when approaching the maximum value of the secondary diagonal elements, the maximum transmission power is 4.8pu; if the same experiment is carried out in a station with only grid-connected new energy, the grid connection point voltage will continue to decrease with the increase of the station output, and the corresponding maximum transmission power when the system becomes unstable is 3.52pu, which verifies the effectiveness of the method in step three.

[0116] By analyzing the station output of various configurations in the multi-machine single-feed scenario and the results of the Jacobian matrix singular criterion, it can be obtained that when the system critical point is reached, its Jacobian matrix tends to be singular and does not fully meet the singularity condition, that is, the main diagonal elements are still slightly larger than the sub-diagonal elements. This also proves that in the actual operation process proposed in step three, there is a complex coupling mechanism between the renewable energy and the AC system, which may cause the system to become unstable before reaching the static voltage stability critical point.

[0117] The three-machine and nine-node system was further transformed, and the heterogeneous new energy stations were distributed and connected to nodes 5 and 9 in the system. The system parameters were kept unchanged, and the above theoretical analysis was simulated based on the constructed multi-machine and multi-feedback system to simulate the new energy distributed grid-connected scenario.

[0118] Similarly, the station output growth was set and multiple groups of experiments were conducted to obtain the relationship between the total output and the determinant of the Jacobian matrix on the external equipment side: Figure 4As shown, the minimum singular value of the Jacobian matrix is ​​introduced as an auxiliary criterion. In the distributed grid-connected scenario, the station output continues to increase, the voltage related to the new energy node begins to decrease, the determinant of the Jacobian matrix decreases, and the minimum singular value will approach 0, and the obtained new energy limit output is 5.04pu. If the same experiment is carried out in a station with only grid-connected new energy, the corresponding limit output power when the system is unstable is 3.62pu, which also verifies the effectiveness of the method in step three.

[0119] However, in the distributed grid-connected scenario, the corresponding difference in the singular criterion of the Jacobian matrix on the external device side when the voltage is unstable will be larger, which also verifies the proposal in step three that in a multi-machine and multi-feedback system with a high penetration rate of renewable energy, the impact of renewable energy on the grid-connected system will be more significant, and the system will be more likely to become unstable before reaching the critical point of static voltage stability.

[0120] The influencing factors are simulated and verified based on a heterogeneous renewable energy multi-feedback system.

[0121] Keeping other system parameters unchanged, set the transmission distance to 100km, 130km, and 160km respectively. The corresponding line impedance is X T is 0.06pu, 0.08pu, 0.10pu, and the relationship between the total output of the station and the determinant of the Jacobian matrix of the external equipment side is obtained as follows: Figure 5 shown.

[0122] It can be seen from the simulation results that as the transmission distance increases, the station output limit value continues to decrease, that is, the method proposed in this patent still has good applicability under different system structures.

[0123] Based on the influence of the modulation parameters of the grid-type power supply controller, keeping other system parameters unchanged, the Vq limit values ​​are set to 1.00pu, 1.25pu, and 1.50pu respectively, and the relationship between the total output of the station and the determinant of the Jacobian matrix on the external device side is obtained as follows: Figure 6 shown.

[0124] It can be seen from the simulation results that increasing the upper limit value of the controller modulation link can improve the power transmission limit of the new energy station to a certain extent. The static stability limit point shifts to the left with the increase of control parameters, which also verifies that the method proposed in this patent still has good applicability under different new energy controller parameters.

[0125] Embodiment three:

[0126] An embodiment of the present invention provides a device for quantitatively evaluating static voltage stability of a multi-infeed system, the device comprising:

[0127] Modeling module, used to establish multi-input system model, including:

[0128] A model unit, used for establishing a power flow model through a renewable energy multi-feed system according to a motor power supply;

[0129] A matrix unit, for establishing a Jacobian matrix at a generator node through the renewable energy multi-feed system according to the power flow model; and establishing a Jacobian matrix at a generator node of the motor power supply according to the renewable energy multi-feed system;

[0130] A node processing unit, used for performing grid connection processing on the new energy node and the generator node through the power flow model according to the Jacobian matrix;

[0131] An updating module, used for processing the new energy node according to the control mode, and modifying the corresponding elements of the Jacobian matrix according to the type of the new energy node;

[0132] The evaluation module is used for quantitatively evaluating the static voltage stability of the multi-feed system, and according to the matrix singular values ​​of the Jacobian matrix, quantitatively evaluating the static voltage stability through the renewable energy multi-feed system to obtain the stability boundary of the static voltage.

[0133] Specifically, the motor power supply includes an asynchronous motor power supply and a traditional synchronous motor power supply.

[0134] Specifically, the new energy nodes include network-following new energy nodes and network-building new energy nodes.

[0135] Specifically, the update module includes:

[0136] A grid-following new energy node processing unit, used to process the grid-following new energy node as a PQ node through a constant impedance model according to a load model, modify corresponding elements of the Jacobian matrix, and obtain an element expression of the grid-following new energy node;

[0137] A grid-forming new energy node processing unit, comprising a rated working subunit and a potential value subunit; wherein the rated working subunit is used to process the grid-forming new energy node as a PV node when the grid-forming power source is in a rated working state, and to modify the corresponding elements of the Jacobian matrix to obtain an element expression of the grid-forming new energy node;

[0138] The potential value subunit is used to process the grid-type new energy node as a PQ node when the potential inside the VSC of the grid-type power supply reaches the limit value, modify the corresponding elements of the Jacobian matrix, and obtain the element expression of the grid-type new energy node.

[0139] Embodiment 4:

[0140] This embodiment further provides an electronic device, including a memory and a processor, wherein the memory is used to store one or more computer instructions, wherein the one or more computer instructions implement the method of embodiment 1 when executed by the processor;

[0141] In practical applications, the processor can be an application specific integrated circuit (ASIC), a digital signal processor (DSP), a digital signal processing device (DSPD), a programmable logic device (PLD), a field programmable gate array (FPGA), a controller, a microcontroller unit (MCU), a microprocessor or other electronic components to execute the methods in the above embodiments.

[0142] The method implemented in this embodiment is as described in the first embodiment.

[0143] Embodiment five:

[0144] This embodiment further provides a computer storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by one or more processors, the method of the first embodiment is implemented;

[0145] Among them, the computer-readable storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, disk or optical disk.

[0146] The method implemented in this embodiment is as described in the first embodiment.

[0147] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention by ordinary technicians in this field do not deviate from the essence and scope of the technical solution of the present invention.

Claims

1. A method for quantitatively evaluating static voltage stability of a multi-infeed system, characterized in that: The method comprises: Step 1: Establish a multi-input system model; According to the motor power supply, a power flow model is established through a renewable energy multi-feed system; According to the power flow model, a Jacobian matrix is ​​established at a generator node through the renewable energy multi-feed system; According to the renewable energy multi-feed system, a Jacobian matrix is ​​established at a generator node of the motor power supply; According to the Jacobian matrix, the new energy node and the generator node are connected to the grid through the power flow model; Step 2: Process the new energy node according to the control method; According to the type of the new energy node, modify the corresponding elements of the Jacobian matrix; Step 3: Quantitative evaluation of static voltage stability of multi-infeed system; According to the matrix singular values ​​of the Jacobian matrix, a quantitative evaluation of static voltage stability is performed through the renewable energy multi-feed system to obtain a stability boundary of the static voltage.

2. The method according to claim 1, characterized in that In step one, the motor power supply includes an asynchronous motor power supply and a traditional synchronous motor power supply.

3. The method according to claim 2, characterized in that In step 2, the new energy nodes include network-following new energy nodes and network-building new energy nodes.

4. The method according to claim 3, characterized in that The step 2 specifically includes: According to the load model, the grid-following new energy node is processed as a PQ node through a constant impedance model, and the corresponding elements of the Jacobian matrix are modified to obtain an element expression of the grid-following new energy node; When the grid-type power source is in a rated working state, the grid-type new energy node is processed as a PV node, and the corresponding elements of the Jacobian matrix are modified to obtain an element expression of the grid-type new energy node; When the potential inside the VSC of the grid-type power source reaches the limiting value, the grid-type new energy node is processed as a PQ node, and the corresponding elements of the Jacobian matrix are modified to obtain the element expression of the grid-type new energy node.

5. A static voltage stability quantitative evaluation device for a multi-feed system, characterized in that: The device comprises: Modeling module, used to establish multi-input system model, including: A model unit, used for establishing a power flow model through a renewable energy multi-feed system according to a motor power supply; A matrix unit, for establishing a Jacobian matrix at a generator node through the renewable energy multi-feed system according to the power flow model; and establishing a Jacobian matrix at a generator node of the motor power supply according to the renewable energy multi-feed system; A node processing unit, used for performing grid connection processing on the new energy node and the generator node through the power flow model according to the Jacobian matrix; An updating module, used for processing the new energy node according to the control mode, and modifying the corresponding elements of the Jacobian matrix according to the type of the new energy node; The evaluation module is used for quantitatively evaluating the static voltage stability of the multi-feed system, and according to the matrix singular values ​​of the Jacobian matrix, quantitatively evaluating the static voltage stability through the renewable energy multi-feed system to obtain the stability boundary of the static voltage.

6. The device according to claim 5, characterized in that The motor power supply includes an asynchronous motor power supply and a traditional synchronous motor power supply.

7. The device according to claim 6, characterized in that The new energy nodes include network-following new energy nodes and network-building new energy nodes.

8. The device according to claim 7, characterized in that The update module specifically includes: A grid-following new energy node processing unit, used to process the grid-following new energy node as a PQ node through a constant impedance model according to a load model, modify corresponding elements of the Jacobian matrix, and obtain an element expression of the grid-following new energy node; A grid-forming new energy node processing unit, comprising a rated working subunit and a potential value subunit; wherein the rated working subunit is used to process the grid-forming new energy node as a PV node when the grid-forming power source is in a rated working state, and to modify the corresponding elements of the Jacobian matrix to obtain an element expression of the grid-forming new energy node; The potential value subunit is used to process the grid-type new energy node as a PQ node when the potential inside the VSC of the grid-type power supply reaches the limit value, modify the corresponding elements of the Jacobian matrix, and obtain the element expression of the grid-type new energy node.

9. An electronic device, characterized in that: The invention comprises a memory and a processor, wherein the memory is used to store one or more computer instructions, wherein the one or more computer instructions, when executed by the processor, implement the method as described in any one of claims 1 to 4.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, it is used to implement the method as described in any one of claims 1 to 4 above.

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