Power electronic switching device simulation model and method for direct-current power transmission system

Abstract

The invention provides a power electronic switch device simulation model for a DC power transmission system, and the model comprises a physical process numerical calculation module which is used for calculating the current charge and current-carrying state of a device; the equivalent circuit calculation module is used for calculating impedance and current source parameters of the device simulated in real time through an equivalent circuit according to the current charge and current-carrying state of the device; the electromagnetic transient differential calculation module is used for setting an external circuit electromagnetic transient calculation matrix according to the impedance and the current source parameters; and the electromagnetic transient calculation module is used for performing electromagnetic transient calculation of the current step length on an external circuit according to the electromagnetic transient calculation matrix so as to complete simulation calculation of the current step length. According to the method, the numerical calculation result is reflected as the external electrical characteristics in a circuit equivalence form, so that accurate analogue simulation of the IGCT conversion circuit can be realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of direct current transmission, and in particular relates to a simulation model and method of a power electronic switch device for a direct current transmission system. Background Art

[0002] High-voltage direct current transmission is an important means to realize the energy channel of west-to-east power transmission. At present, my country has built and operated many high-voltage direct current transmission projects. Conventional high-voltage direct current transmission uses line commutated converters (LCCs), which have the advantages of large transmission capacity, mature engineering technology, and low cost compared to flexible direct current. However, LCC uses thyristors that can only be actively turned on and cannot be actively turned off as core switching devices, and needs to rely on the voltage of the connected AC power grid to achieve phase change. When the power grid is disturbed or the voltage drops due to a fault, there is a risk of phase change failure in LCC, which in turn causes an instantaneous reduction in DC power, a large fluctuation in the power grid flow, and problems such as overcurrent in the DC transmission system, increased grounding current, and DC bias magnetism, which endangers the safe and stable operation of the DC transmission system and the AC power grid.

[0003] To address the above problems, a new type of IGCT (Integrated Gate-Commutated Thyristor) switching device that can actively open and close is used to replace the thyristor in the LCC to form a hybrid commutated converter (HCC). While maintaining the original converter topology and commutation principle, its ability to actively shut down the current can be increased, forming a commutation mechanism that mixes grid commutation and active commutation, thereby improving the safety, stability and grid-friendliness of high-voltage direct current transmission without significantly increasing costs.

[0004] However, since the IGCT device provides the ability to actively shut off the current, it may actively shut off the bridge arm current when the bridge arm current is not zero. The internal current distribution and transient change process of the HCC when working are different from those of the LCC. In the design of the converter, these differences need to be analyzed and evaluated and targeted designs need to be made, including configuring voltage-limiting arresters for the switching devices, adjusting the transient withstand voltage design of the valve body, and transient current design. These analysis and design work require detailed simulation calculations for the transient commutation process inside the converter, and analysis of the current rise and fall characteristics of the switching devices during the opening and closing process, as well as the pressure conditions of each component during the period.

[0005] At present, there is a relatively mature LCC high-voltage direct current transmission electromagnetic transient calculation and analysis model. The thyristor device module in the existing model is modified into a switch tube device module with a shutdown function, which can realize the construction of the above simulation model. However, in the existing model, both the thyristor device module and the switch tube device module with a shutdown function are ideal resistive models. They can only represent the disconnected state with high resistance and the open state with low resistance, and the switching of the resistance value represents the device on and off behavior. It is impossible to reflect the change process of the voltage at both ends and the current flowing through the device during the opening and closing process. Including the current rise and fall slope of the device and the reverse recovery process, the transient overvoltage formed by the switching action cannot be well simulated. In the conventional LCC design, since the thyristor device is basically automatically shut down when the current passes 0, there is no active shutdown of the current, and the use of the above ideal model has little effect on the design analysis. However, in the design of HCC, in order to accurately evaluate the current and voltage stress inside the converter valve, it is necessary to simulate the behavior of the device more accurately, and the current simulation model is difficult to meet the needs.

[0006] In the more professional field of power semiconductors, the behavior of a switching device is calculated in detail using multiple physical fields such as electricity, magnetism, and force, as well as thermal effects. The field distribution model is used to simulate and calculate the physical characteristics of a device in four states: off, on, on, and off. Obviously, the scale of this type of simulation calculation is too fine, requiring too many computing resources, and the simulated processes are mostly irrelevant to converter design, so they are also not suitable for the design and analysis of HCC converters.

[0007] In summary, there is currently a lack of simulation models that can accurately simulate the transient electrical process of switching devices. Therefore, it is necessary to design a simulation model and method for power electronic switching devices for DC transmission systems to solve the above technical problems. Summary of the invention

[0008] In view of the above technical problems, the present invention provides a power electronic switch device simulation model for a DC power transmission system, wherein the power electronic switch device simulation model includes:

[0009] A physical process numerical calculation module, used to calculate the current charge and current carrying state of the device;

[0010] An equivalent circuit calculation module, used to calculate the impedance and current source parameters of the device through real-time simulation of the equivalent circuit according to the current charge and current carrying state of the device;

[0011] An electromagnetic transient differential calculation module, used to set an external circuit electromagnetic transient calculation matrix according to the impedance and current source parameters of the real-time simulation of the current state of the device;

[0012] The electromagnetic transient solution module is used to perform electromagnetic transient solution of the current step length on the external circuit according to the electromagnetic transient calculation matrix to complete the simulation calculation of the current step length.

[0013] In some embodiments, calculating the current charge and current carrying state of the device includes:

[0014] According to the current voltage and current states of the anode, cathode and gate of the device, the carrier distribution inside the device is calculated to obtain the current charge and current carrying state of the device.

[0015] In some embodiments, the calculating the impedance and current source parameters of the device through real-time simulation of an equivalent circuit includes:

[0016] According to the current charge and current carrying state of the device, the equivalent impedance and equivalent current source characteristics of the device relative to the external circuit are calculated, and the current state of the device is described as the impedance and power supply parameters simulated by the equivalent circuit.

[0017] In some embodiments, the step of setting an external circuit electromagnetic transient calculation matrix includes:

[0018] According to the impedance and current source parameters of the real-time simulation of the current state of the device, the node admittance and injection current of the device are calculated and filled in the electromagnetic transient calculation matrix of the external circuit.

[0019] The present invention also provides an electromagnetic transient simulation model of a converter, wherein the electromagnetic transient simulation model comprises a three-phase bridge arm, wherein the switch device on the bridge arm adopts the above-mentioned power electronic switch device simulation model.

[0020] In some embodiments, the electromagnetic transient simulation model further includes an AC power supply, a DC power supply and a transformer, wherein:

[0021] The AC power source is connected to both ends of the bridge arm, one end of the transformer is connected to the midpoint of each phase bridge arm, and the other end of the transformer is connected to the DC power source.

[0022] In some embodiments, the electromagnetic transient simulation model further includes a reactor, which is connected in series at one end of the bridge arm.

[0023] On the other hand, the present invention further provides a power electronic switch device simulation method for a DC power transmission system, wherein the power electronic switch device simulation method comprises:

[0024] Utilizing a physical process numerical calculation module, calculating the current charge and current carrying state of the device;

[0025] According to the current charge and current carrying state of the device, using an equivalent circuit calculation module, calculate the impedance and current source parameters of the device after real-time simulation by the equivalent circuit;

[0026] According to the impedance and current source parameters of the real-time simulation of the current state of the device, the electromagnetic transient difference calculation module is used to set the electromagnetic transient calculation matrix of the external circuit;

[0027] According to the electromagnetic transient calculation matrix, the electromagnetic transient solution module is used to perform electromagnetic transient solution of the current step length on the external circuit to complete the simulation calculation of the current step length.

[0028] In some embodiments, calculating the current charge and current carrying state of the device includes:

[0029] According to the current voltage and current states of the anode, cathode and gate of the device, the carrier distribution inside the device is calculated to obtain the current charge and current carrying state of the device.

[0030] In some embodiments, the calculating the impedance and current source parameters of the device through real-time simulation of an equivalent circuit includes:

[0031] According to the current charge and current carrying state of the device, the equivalent impedance and equivalent current source characteristics of the device relative to the external circuit are calculated, and the current state of the device is described as the impedance and current source parameters simulated by the equivalent circuit.

[0032] The present invention provides a power electronic switch device simulation model and method for a direct current transmission system. The model simulates the change process of the internal semiconductor physical state of a GCT device (exemplarily, a GCT device) by numerical calculation, and reflects the results of the numerical calculation into external electrical characteristics in the form of circuit equivalence, thereby realizing accurate simulation of an IGCT commutation circuit.

[0033] Other features and advantages of the present invention will be described in the following description, and partly become obvious from the description, or be understood by implementing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, a brief introduction is given below to 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 any creative work.

[0035] Figure 1 A schematic diagram of the structure of a power electronic switch device simulation model for a DC power transmission system according to an embodiment of the present invention is shown;

[0036] Figure 2 A flow chart of a method for simulating a power electronic switch device in a DC power transmission system according to an embodiment of the present invention is shown;

[0037] Figure 3 A topology of an electromagnetic transient simulation model for an HCC converter according to an embodiment of the present invention is shown;

[0038] Figure 4 A flowchart of solving the GCT device simulation model at each step length calculated in step 2 according to an embodiment of the present invention is shown;

[0039] Figure 5 An equivalent impedance characteristic diagram according to an embodiment of the present invention is shown;

[0040] Figure 6 A schematic diagram showing current and admittance parameters of an implementation example according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are 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.

[0042] The present invention provides a power electronic switch device simulation model and method for a DC power transmission system, such as Figure 1 The figure shows a schematic diagram of a structure of a power electronic switch device simulation model for a DC power transmission system, wherein the power electronic switch device simulation model includes:

[0043] A physical process numerical calculation module, used to calculate the current charge and current carrying state of the device (power electronic switching device, generally referred to as a switching device or device);

[0044] An equivalent circuit calculation module, used to calculate the impedance and current source parameters of the device through real-time simulation of the equivalent circuit according to the current charge and current carrying state of the device;

[0045] An electromagnetic transient differential calculation module, used to set an external circuit electromagnetic transient calculation matrix according to the impedance and current source parameters of the real-time simulation of the current state of the device;

[0046] The electromagnetic transient solution module is used to perform electromagnetic transient solution of the current step length on the external circuit to complete the simulation calculation of the current step length.

[0047] like Figure 2 FIG. 1 is a flow chart of a method for simulating a power electronic switch device for a DC power transmission system, wherein the method for simulating a power electronic switch device comprises:

[0048] Utilizing a physical process numerical calculation module, calculating the current charge and current carrying state of the device;

[0049] According to the current charge and current carrying state of the device, using an equivalent circuit calculation module, calculate the impedance and current source parameters of the device after real-time simulation by the equivalent circuit;

[0050] According to the impedance and current source parameters of the real-time simulation of the current state of the device, the electromagnetic transient difference calculation module is used to set the electromagnetic transient calculation matrix of the external circuit;

[0051] According to the electromagnetic transient calculation matrix, the electromagnetic transient solution module is used to perform electromagnetic transient solution of the current step length on the external circuit to complete the simulation calculation of the current step length.

[0052] The power electronic switch device simulation model of the present invention is described in detail below.

[0053] In some embodiments of the present invention, the specific execution steps of the physical process numerical calculation module to calculate the current charge and current carrying state of the device include:

[0054] According to the current voltage and current states of the anode, cathode and gate of the device, the carrier distribution inside the device is calculated to obtain the current charge and current carrying state of the device.

[0055] In some embodiments of the present invention, the specific execution steps of the equivalent circuit calculation module calculating the impedance and current source parameters of the device after real-time simulation of the equivalent circuit include:

[0056] Based on the current charge and current carrying state of the device, the equivalent impedance and equivalent current source characteristics of the device relative to the external circuit are calculated, and the current state of the device is described as the impedance and current source parameters simulated by an equivalent circuit (an equivalent circuit composed of an equivalent impedance and an equivalent current source, referred to as "equivalent circuit").

[0057] In some embodiments of the present invention, the specific execution steps of the electromagnetic transient difference calculation module to set the electromagnetic transient calculation matrix of the external circuit include:

[0058] According to the impedance and current source parameters of the real-time simulation of the current state of the device, the node admittance and injection current of the device are calculated and filled in the electromagnetic transient calculation matrix of the external circuit.

[0059] In some embodiments of the present invention, in view of the current lack of an electromagnetic transient simulation model that can accurately simulate the transient electrical process of switching devices and can be used for the design, analysis and calculation of HCC converters, the present invention provides an electromagnetic transient simulation model of a converter, which is based on an electromagnetic transient simulation model for an HCC converter.

[0060] The electromagnetic transient simulation model for the HCC converter mentioned above is briefly described below.

[0061] like Figure 3 The topology of the electromagnetic transient simulation model for the HCC converter is shown. In the topology of the electromagnetic transient simulation model for the HCC converter, a three-phase bridge arm is included, and each phase bridge arm has a plurality of switching devices connected in series. Each switching device is connected in parallel with a metal oxide varistor MOV (used to limit the overvoltage generated when the switching device is turned off and absorb the turn-off energy). The voltage passing through it is U_I, for example Figure 3 In the figure, the voltage of each switching device is U_I1, U_I2, U_I3, U_I4, U_I5 and U_I6, and the current flowing through each switching device is I_I1, I_I2, I_I3, I_I4, I_I5 and I_I6, respectively. The control signal given by each switching device is FP_I1_gct, FP_I2_gct, FP_I3_gct, FP_I4_gct, FP_I5_gct and FP_I6_gct, respectively.

[0062] And in Figure 3 In the electromagnetic transient simulation model for the HCC converter, the reactor is further connected in series at one end of the bridge arm (ie, one end of the reactor is connected to one end of the bridge arm).

[0063] And in Figure 3 In the present invention, an electromagnetic transient simulation model for an HCC converter also includes an AC power supply, a DC power supply and a transformer, wherein the AC power supply is connected to both ends of the bridge arm, one end of the transformer is connected to the midpoint of each phase bridge arm, and the other end of the transformer is connected to the DC power supply.

[0064] The above is an introduction to the topology of an electromagnetic transient simulation model for HCC converters. Figure 3 A case based on the topology and a simulation method of power electronic switching devices for DC transmission system is illustrated.

[0065] exist Figure 3 In the present invention, based on the above-mentioned electromagnetic transient simulation model for HCC converter, the switching devices on the bridge arm in the electromagnetic transient simulation model are replaced by the above-mentioned power electronic switching device simulation model to form an electromagnetic transient simulation model of the converter of the present invention.

[0066] During the simulation calculation, the electromagnetic transient simulation solver Figure 3 The transformer, switch device, AC power supply, DC power supply, reactor and other components and the circuit topology composed of these components are simulated step by step. Each component calculates its admittance contribution and current injection contribution in its respective circuit node at each step. After collecting the data of each component, the electromagnetic transient simulation solver calculates the voltage and current of the circuit as a whole. Among them, transformers, AC power supplies, DC power supplies, reactors and other components currently have mature calculation models.

[0067] Based on the above-mentioned power electronic switch device simulation method for DC transmission system, the solution process of the power electronic switch device simulation model at each step is given below (such as Figure 4 The GCT device simulation model shown in the figure is a flow chart of the solution at each step length), as follows:

[0068] S1: simulation starts calculation;

[0069] S2: Set the initial value of each variable;

[0070] S3: Obtain the voltage and current of the anode, cathode and gate nodes after the previous step length solution;

[0071] S4: Numerical calculation of the internal physical processes of GCT;

[0072] S5: Equivalent circuit (i.e. equivalent circuit), equivalent impedance (i.e. equivalent impedance) and current source calculation;

[0073] S6: Electromagnetic transient differential calculation to obtain the admittance and injection current of the three nodes of anode, cathode and gate;

[0074] S7: Fill in the electromagnetic transient solution matrix, and the solver (electromagnetic transient solver) performs the solution for this step;

[0075] S8: The simulation calculation ends.

[0076] Taking the IGCT device (the power electronic switch device is the IGCT device, which is just an example) as an example, the equivalent impedance characteristic calculated in step S5 is as follows: Figure 5 For example, Figure 5 In the figure, the horizontal and vertical axes are the voltage values ​​v Aand the current value i A , where when the IGCT device is in the on state, its v A -i A The relationship (V-I characteristic relationship) is I H to I A segment; when the IGCT device is in the forward blocking state, its v A -i A Relationship from 0 to V AS When the IGCT device is triggered to turn on, its v A -i A The relationship switches from the forward blocking state to the conducting state through the conductivity modulation process.

[0077] Figure 6 This illustrates the purpose of the node admittance parameter and the injection current parameter formed in step S6. Figure 6 In the figure, the anode A, cathode K and gate G of the IGCT device correspond to the three nodes of the equivalent circuit respectively; the admittance Y AG , admittance Y KG and admittance Y AK They are the mutual admittances between different nodes, connecting the three nodes A, G, and K in a triangle form; IA is the equivalent injection current of the A node, IG is the equivalent injection current of the G node, and IK is the equivalent injection current of the K node.

[0078] According to the equivalent circuit parameters calculated in step S5, step S6 performs differential calculation to fill in the entire solution matrix solved by the electromagnetic transient simulation solver. Figure 6 The current and admittance parameters shown are used to complete the simulation calculation of the switching device in this step.

[0079] In summary, the present invention simulates the change process of the physical state of the semiconductor inside the GCT device by means of numerical calculation through the model, and reflects the results of the numerical calculation into external electrical characteristics in the form of circuit equivalence, thereby realizing accurate simulation of the IGCT commutation circuit.

[0080] The above is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A simulation model of power electronic switch devices for DC transmission system, wherein: include: A physical process numerical calculation module, used to calculate the current charge and current carrying state of the device; An equivalent circuit calculation module, used to calculate the impedance and current source parameters of the device through real-time simulation of the equivalent circuit according to the current charge and current carrying state of the device; An electromagnetic transient differential calculation module, used to set an external circuit electromagnetic transient calculation matrix according to the impedance and the current source parameters; The electromagnetic transient solution module is used to perform electromagnetic transient solution of the current step length on the external circuit according to the electromagnetic transient calculation matrix to complete the simulation calculation of the current step length.

2. A power electronic switch device simulation model for a DC power transmission system according to claim 1, wherein: The calculating the current charge and current carrying state of the device comprises: According to the current voltage and current states of the anode, cathode and gate of the device, the carrier distribution inside the device is calculated to obtain the current charge and current carrying state of the device.

3. A power electronic switch device simulation model for a DC power transmission system according to claim 2, wherein: The calculating of the impedance and current source parameters of the device through real-time simulation of an equivalent circuit includes: According to the current charge and current carrying state of the device, the equivalent impedance and equivalent current source characteristics of the device relative to the external circuit are calculated, and the current state of the device is described as the impedance and power supply parameters simulated by the equivalent circuit.

4. A power electronic switch device simulation model for a DC power transmission system according to any one of claims 1 to 3, wherein: The setting of the external circuit electromagnetic transient calculation matrix includes: According to the impedance and current source parameters of the real-time simulation of the current state of the device, the node admittance and injection current of the device are calculated and filled in the electromagnetic transient calculation matrix of the external circuit.

5. An electromagnetic transient simulation model of a converter, wherein: The electromagnetic transient simulation model includes a three-phase bridge arm, wherein the switch device on the bridge arm adopts the power electronic switch device simulation model as described in any one of claims 1-5.

6. The electromagnetic transient simulation model of a converter according to claim 5, wherein: The electromagnetic transient simulation model also includes an AC power supply, a DC power supply and a transformer, wherein: The AC power source is connected to both ends of the bridge arm, one end of the transformer is connected to the midpoint of each phase bridge arm, and the other end of the transformer is connected to the DC power source.

7. The electromagnetic transient simulation model of a converter according to claim 5, wherein: The electromagnetic transient simulation model also includes a reactor, which is connected in series at one end of the bridge arm.

8. A method for simulating power electronic switch devices for a DC power transmission system, wherein: The power electronic switch device simulation method comprises: Utilizing a physical process numerical calculation module, calculating the current charge and current carrying state of the device; According to the current charge and current carrying state of the device, using an equivalent circuit calculation module, calculate the impedance and current source parameters of the device after real-time simulation by the equivalent circuit; According to the impedance and the current source parameters, using the electromagnetic transient differential calculation module, setting the external circuit electromagnetic transient calculation matrix; According to the electromagnetic transient calculation matrix, the electromagnetic transient solution module is used to perform electromagnetic transient solution of the current step length on the external circuit to complete the simulation calculation of the current step length.

9. A method for simulating power electronic switch devices for a DC power transmission system according to claim 8, wherein: The calculating the current charge and current carrying state of the device comprises: According to the current voltage and current states of the anode, cathode and gate of the device, the carrier distribution inside the device is calculated to obtain the current charge and current carrying state of the device.

10. A method for simulating power electronic switch devices for a DC power transmission system according to claim 8, wherein: The calculating of the impedance and current source parameters of the device through real-time simulation of an equivalent circuit includes: According to the current charge and current carrying state of the device, the equivalent impedance and equivalent current source characteristics of the device relative to the external circuit are calculated, and the current state of the device is described as the impedance and current source parameters simulated by the equivalent circuit.

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