Key parameter setting method and system for average electromagnetic transient model of flexible straight valve body

Abstract

The present invention discloses a method and system for adjusting key parameters of an average electromagnetic transient model of a flexible direct current valve body, belonging to the field of electromagnetic transient simulation technology. The method of the present invention comprises: obtaining key parameter information of a flexible direct current transmission system, and determining the voltage fluctuation characteristics and charge-discharge process characteristics of the submodule of the flexible direct current transmission system based on the key parameter information; building an average electromagnetic transient model of a flexible direct current valve body based on the voltage fluctuation characteristics and charge-discharge process characteristics, and determining the model structure of the average electromagnetic transient model of the flexible direct current valve body; and adjusting the key parameters of the average electromagnetic transient model of the flexible direct current valve body based on the model structure. The present invention has the ability to simulate the entire process including charging and unlocking.

Description

Technical Field

[0001] The present invention relates to the technical field of electromagnetic transient simulation, and more particularly to a method and system for adjusting key parameters of an average electromagnetic transient model of a flexible straight valve body. Background Art

[0002] Flexible direct current transmission technology is a new generation of transmission technology. Compared with traditional grid-commutated converter-based transmission technology, it has the advantages of flexibility, controllability, high reliability, and island power supply. It is suitable for regional power transmission in large cities and islands and the construction of efficient flexible direct current transmission systems. It is also regarded as an important way to realize large-scale renewable energy power transmission.

[0003] The flexible DC valve body based on modular multilevel converters is one of the most important components of flexible DC transmission projects. Modeling the flexible DC valve body is the foundation for simulating and analyzing the operational characteristics of flexible DC transmission projects connected to the grid. The accuracy of the model determines the accuracy of the simulation results. The simulation accuracy and efficiency of the flexible DC valve body modeled using different modeling methods vary. For different research purposes and scenarios, a model that balances both accuracy and efficiency is the most appropriate and efficient choice.

[0004] There are currently three main approaches to modeling flexible direct-flow valves: a detailed switching device modeling method that focuses on the internal characteristics of the submodule, a Thevenin equivalent modeling method that focuses on the external characteristics of the submodule, and a bridge arm average value modeling method that focuses on the bridge arm voltage output characteristics.

[0005] The detailed valve body model based on switching devices uses semiconductor switching devices to build a flexible direct-flow valve body primary main circuit according to the sub-module topology structure. This model can accurately reflect the impact of the equalizing pressure modulation strategy on the valve body in the valve control and protection system. When the number of sub-modules is large, the calculation amount is large, the simulation speed is extremely slow, and high computing power is required of the computer.

[0006] Based on the valve body model of Thevenin equivalence, the semiconductor switching device is equivalent to large and small resistors, and then the sub-modules are simulated using a controlled voltage source and a variable resistor. The sub-modules are subjected to Thevenin equivalence and algebraic superposition, so that each bridge arm of the flexible direct current valve body is equivalent to a Thevenin equivalent branch with a voltage source and a resistor in series. This can take into account both simulation accuracy and simulation efficiency, but cannot simulate the charging process of the flexible direct current valve body.

[0007] The bridge arm average value valve body model decouples the DC side and AC side of the flexible direct current valve body according to the principle of power conservation, and equates the sub-module of each bridge arm to a series circuit of a voltage source and a diode. At the same time, the influence of voltage balancing sorting and circulating current suppression is ignored. It is believed that the internal variables of the sub-module have been well controlled, and the capacitor voltages of all sub-modules are completely balanced. At the same time, the double frequency current in each phase is also effectively suppressed. It has the advantages of small calculation amount and simple valve control, but it cannot accurately reflect the sub-module capacitor voltage and switch action characteristics, and cannot accurately simulate the sub-module capacitor voltage charging and discharging process. Summary of the Invention

[0008] To address the above problems, the present invention proposes a method for adjusting key parameters of an average electromagnetic transient model of a flexible straight valve body, comprising:

[0009] Acquiring key parameter information of a flexible direct current transmission system, and determining voltage fluctuation characteristics and charging and discharging process characteristics of submodules of the flexible direct current transmission system based on the key parameter information;

[0010] Based on the voltage fluctuation characteristics and the charge and discharge process characteristics, a flexible direct valve body average electromagnetic transient model is constructed, and a model structure of the flexible direct valve body average electromagnetic transient model is determined;

[0011] Based on the model structure, key parameters of the flexible straight valve body average electromagnetic transient model are adjusted.

[0012] Optional, flexible straight valve body average electromagnetic transient model model structure, including:

[0013] Equivalent circuit of the flexible DC converter bridge arm and calculation model of the flexible DC average sub-module.

[0014] Optionally, an input signal of the flexible DC converter bridge arm equivalent circuit is the bridge arm output voltage Vs1 of the charging branch and the bridge arm output voltage Vs2 of the discharging branch, and an output signal is the bridge arm current value i arm ;

[0015] Another input signal of the flexible DC converter bridge arm equivalent circuit is the bridge arm unlocking signal Unlock, the number of conducting submodules N in , submodule voltage output mode VcMode and bridge arm current i arm , the other output signal is the bridge arm output voltage Vs1 and Vs2 of the charge and discharge branch.

[0016] Optionally, the equivalent circuit of the flexible DC converter bridge arm includes: two left and right parallel branches;

[0017] The left branch is a charging branch, which is composed of a diode D1, a controlled voltage source 1 and a resistor R1 connected in series.

[0018] The cathode of the diode D1 is connected to the anode of the controlled voltage source 1, and the cathode of the controlled voltage source 1 is connected to the resistor R1.

[0019] The diode D1 allows the bridge arm current i arm The charging current i p Flowing through the left bridge arm, preventing i arm The discharge current i n Flows through the left bridge arm;

[0020] The right branch is the discharge branch, which is composed of a diode D2, a controlled voltage source 2 and a resistor R2 connected in series.

[0021] The anode of the diode D2 is connected to the anode of the controlled voltage source 2, and the cathode of the controlled voltage source 2 is connected to the resistor R2.

[0022] The positive electrode of the diode D1 is connected to the negative electrode of the diode D2 to form the positive electrode of the flexible DC converter bridge arm, and the resistor R1 is connected to the resistor R2 to form the negative electrode of the flexible DC converter bridge arm;

[0023] The diode D2 blocks the bridge arm current i arm The charging current i p Flowing through the right bridge arm, allowing i arm The discharge current i n Flows through the right bridge arm.

[0024] Optionally, the soft average submodule calculates the input parameters of the model, including the following: simulation step size T s , submodule capacitance value C, submodule rated capacitance voltage value U smN , Number of bridge arm submodules N sm , the number of full bridge sub-modules N with normal bridge arms FBSM _ OK , Number of bridge arm fault submodules N Fault And the resistance value R in parallel with the submodule capacitor c .

[0025] Optionally, the flexible DC average submodule calculation model is used to calculate the output voltages Vs1 and Vs2 of the charging and discharging branch bridge arms. The calculation process includes:

[0026] Determine the submodule voltage output mode VcMode. If the submodule voltage output mode VcMode is 0, all submodule voltages V ceq (n) is set to 0p.u. If the submodule voltage output mode VcMode is 1, all submodule voltages V ceq (n) is set to 1p.u. If the submodule voltage output mode VcMode is 2, the bridge arm unlock signal Unlock is determined;

[0027] If the bridge arm unlock signal Unlock is 0, calculate the capacitor voltage of the full-bridge submodule and the half-bridge submodule according to the type of submodule;

[0028] The capacitor voltage calculation formula of the full-bridge submodule is as follows:

[0029]

[0030] V ceqFB (n) = i arm (n)T s / C+V ceqFB (n-1)

[0031] When calculating the capacitor voltage of the half-bridge submodule, the direction of the bridge arm current is judged to determine the charge and discharge state of the half-bridge submodule. arm When (n) is greater than or equal to 0, the half-bridge submodule is in the charging state, and the capacitor voltage calculation formula of the half-bridge submodule is as follows:

[0032] i ceq (n) = i arm (n)-V ceqHB (n-1) / R c

[0033] V ceqHB (n) = i arm (n)T s / C+V ceqHB (n-1)

[0034] When the bridge arm current i arm When (n) is less than 0, the half-bridge submodule is in a discharge state, and the capacitor voltage calculation formula of the half-bridge submodule is as follows:

[0035] V ceqHB (n) = V ceq (n-1)

[0036] According to the number of full-bridge sub-modules and half-bridge sub-modules and the capacitor voltage, the equivalent capacitor voltage of the bridge arm is calculated according to the principle of energy conservation. The calculation formula is as follows:

[0037] V ceq (n)=[V ceqFB (n) 2 N FBSM-OK +V ceqHB (n) 2 (N sm -N FBSM_OK -N Fault )] 0.5

[0038] If the bridge arm unlock signal Unlock is 1, the calculation formula of the bridge arm equivalent capacitor voltage is as follows:

[0039] i ceq (n) = i arm (n)-V ceq (n-1) / R c

[0040] V ceq (n) = i arm (n)T s N in (n) / (C(N Sm -N Fault )+V ceq (n-1)

[0041] The bridge arm equivalent capacitor voltage is limited to calculate the bridge arm output voltages Vs1 and Vs2 of the charge and discharge branches. The calculation formula is as follows:

[0042] V s1 (n) = N in (n)UnlockV ceq (n)+(N sm -N Fault )(1-Unlock)V ceq (n)

[0043] V s2 (n) = N in (n)UnlockV ceq (n)-N FBSM_OK (1-Unlock)V ceq (n)

[0044] The bridge arm equivalent capacitor voltage is limited. If the bridge arm equivalent capacitor voltage is less than zero, the bridge arm equivalent capacitor voltage is set to 0; otherwise, the bridge arm equivalent capacitor voltage is a calculated value.

[0045] Optionally, key parameters of the flexible straight valve body average electromagnetic transient model are adjusted, including:

[0046] The equivalent parameters of diodes D1 and D2 in the equivalent circuit of the flexible DC converter bridge arm are approximately adjusted by multiplying the actual parameters of a single diode by the number of submodules;

[0047] Resistors R1 and R2 are adjusted based on the converter losses at rated power.

[0048] Input parameters of the flexible DC average submodule calculation model are submodule capacitance value C, submodule rated capacitance voltage value U smN , Number of bridge arm submodules N sm , the number of full bridge sub-modules N with normal bridge armsFBSM_OK , Number of bridge arm fault submodules N Fault And the resistance value R in parallel with the submodule capacitor c , it is adjusted based on the engineering design data and actual operating conditions of the flexible DC converter;

[0049] Simulation step T s Adjust according to actual simulation requirements.

[0050] On the other hand, the present invention also proposes a system for adjusting key parameters of an average electromagnetic transient model of a flexible straight valve body, comprising:

[0051] an initialization unit, configured to obtain key parameter information of a flexible DC transmission system, and determine voltage fluctuation characteristics and charge and discharge process characteristics of submodules of the flexible DC transmission system based on the key parameter information;

[0052] a calculation unit, configured to construct an average electromagnetic transient model of a flexible direct current valve body based on the voltage fluctuation characteristics and the charge and discharge process characteristics, and determine a model structure of the average electromagnetic transient model of the flexible direct current valve body;

[0053] A tuning unit is used to tune key parameters of the average electromagnetic transient model of the flexible straight valve body based on the model structure.

[0054] Optional, flexible straight valve body average electromagnetic transient model model structure, including:

[0055] Equivalent circuit of the flexible DC converter bridge arm and calculation model of the flexible DC average sub-module.

[0056] Optionally, an input signal of the flexible DC converter bridge arm equivalent circuit is the bridge arm output voltage Vs1 of the charging branch and the bridge arm output voltage Vs2 of the discharging branch, and an output signal is the bridge arm current value i arm ;

[0057] Another input signal of the flexible DC converter bridge arm equivalent circuit is the bridge arm unlocking signal Unlock, the number of conducting submodules N in , submodule voltage output mode VcMode and bridge arm current i arm , the other output signal is the bridge arm output voltage Vs1 and Vs2 of the charge and discharge branch.

[0058] Optionally, the equivalent circuit of the flexible DC converter bridge arm includes: two left and right parallel branches;

[0059] The left branch is a charging branch, which is composed of a diode D1, a controlled voltage source 1 and a resistor R1 connected in series.

[0060] The cathode of the diode D1 is connected to the anode of the controlled voltage source 1, and the cathode of the controlled voltage source 1 is connected to the resistor R1.

[0061] The diode D1 allows the bridge arm current i arm The charging current i p Flowing through the left bridge arm, preventing i arm The discharge current i n Flows through the left bridge arm;

[0062] The right branch is the discharge branch, which is composed of a diode D2, a controlled voltage source 2 and a resistor R2 connected in series.

[0063] The anode of the diode D2 is connected to the anode of the controlled voltage source 2, and the cathode of the controlled voltage source 2 is connected to the resistor R2.

[0064] The positive electrode of the diode D1 is connected to the negative electrode of the diode D2 to form the positive electrode of the flexible DC converter bridge arm, and the resistor R1 is connected to the resistor R2 to form the negative electrode of the flexible DC converter bridge arm;

[0065] The diode D2 blocks the bridge arm current i arm The charging current i p Flowing through the right bridge arm, allowing i arm The discharge current i n Flows through the right bridge arm.

[0066] Optionally, the soft average submodule calculates the input parameters of the model, including the following: simulation step size T s , submodule capacitance value C, submodule rated capacitance voltage value U smN , Number of bridge arm submodules N sm , the number of full bridge sub-modules N with normal bridge arms FBSM_OK , Number of bridge arm fault submodules N Fault And the resistance value R in parallel with the submodule capacitor c .

[0067] Optionally, the flexible DC average submodule calculation model is used to calculate the output voltages Vs1 and Vs2 of the charging and discharging branch bridge arms. The calculation process includes:

[0068] Determine the submodule voltage output mode VcMode. If the submodule voltage output mode VcMode is 0, all submodule voltages V ceq (n) is set to 0p.u. If the submodule voltage output mode VcMode is 1, all submodule voltages V ceq (n) is set to 1p.u. If the submodule voltage output mode VcMode is 2, the bridge arm unlock signal Unlock is determined;

[0069] If the bridge arm unlock signal Unlock is 0, calculate the capacitor voltage of the full-bridge submodule and the half-bridge submodule according to the type of submodule;

[0070] The capacitor voltage calculation formula of the full-bridge submodule is as follows:

[0071]

[0072] V ceqFB (n) = i arm (n)T s / C+V ceqFB (n-1)

[0073] When calculating the capacitor voltage of the half-bridge submodule, the direction of the bridge arm current is judged to determine the charge and discharge state of the half-bridge submodule. arm When (n) is greater than or equal to 0, the half-bridge submodule is in the charging state, and the capacitor voltage calculation formula of the half-bridge submodule is as follows:

[0074] i ceq (n) = i arm (n)-V ceqHB (n-1) / R c

[0075] V ceqHB (n) = i arm (n)T s / C+V ceqHB (n-1)

[0076] When the bridge arm current i arm When (n) is less than 0, the half-bridge submodule is in a discharge state, and the capacitor voltage calculation formula of the half-bridge submodule is as follows:

[0077] V ceqHB (n) = V ceq (n-1)

[0078] According to the number of full-bridge sub-modules and half-bridge sub-modules and the capacitor voltage, the equivalent capacitor voltage of the bridge arm is calculated according to the principle of energy conservation. The calculation formula is as follows:

[0079] V ceq (n)=[V ceqFB (n) 2 N FBSM-OK +V ceqHB (n) 2 (N sm -N FBSM_OK -N Fault )] 0.5

[0080] If the bridge arm unlock signal Unlock is 1, the calculation formula of the bridge arm equivalent capacitor voltage is as follows:

[0081] i ceq (n) = i arm (n)-V ceq (n-1) / R c

[0082] V ceq (n) = i arm (n)T s N in (n) / (C(N Sm -N Fault )+V ceq (n-1)

[0083] The bridge arm equivalent capacitor voltage is limited to calculate the bridge arm output voltages Vs1 and Vs2 of the charge and discharge branches. The calculation formula is as follows:

[0084] V s1 (n) = N in (n)UnlockV ceq (n)+(N sm -N Fault )(1-Unlock)V ceq (n)

[0085] V s2 (n) = N in (n)UnlockV ceq (n)-N FBSM_OK (1-Unlock)V ceq (n)

[0086] The bridge arm equivalent capacitor voltage is limited. If the bridge arm equivalent capacitor voltage is less than zero, the bridge arm equivalent capacitor voltage is set to 0; otherwise, the bridge arm equivalent capacitor voltage is a calculated value.

[0087] Optionally, key parameters of the flexible straight valve body average electromagnetic transient model are adjusted, including:

[0088] The equivalent parameters of diodes D1 and D2 in the equivalent circuit of the flexible DC converter bridge arm are approximately adjusted by multiplying the actual parameters of a single diode by the number of submodules;

[0089] Resistors R1 and R2 are adjusted based on the converter losses at rated power.

[0090] Input parameters of the flexible DC average submodule calculation model are submodule capacitance value C, submodule rated capacitance voltage value U smN , Number of bridge arm submodules N sm , the number of full bridge sub-modules N with normal bridge armsFBSM_OK , Number of bridge arm fault submodules N Fault And the resistance value R in parallel with the submodule capacitor c , it is adjusted based on the engineering design data and actual operating conditions of the flexible DC converter;

[0091] Simulation step T s Adjust according to actual simulation requirements.

[0092] In yet another aspect, the present invention further provides a computing device comprising: one or more processors;

[0093] a processor for executing one or more programs;

[0094] When the one or more programs are executed by the one or more processors, the above-described method is implemented.

[0095] In another aspect, the present invention further provides a computer-readable storage medium having a computer program stored thereon, wherein when the computer program is executed, the method described above is implemented.

[0096] Compared with the prior art, the present invention has the following beneficial effects:

[0097] This invention proposes a method for adjusting the key parameters of a flexible DC valve average electromagnetic transient model, comprising: obtaining key parameter information of a flexible DC transmission system; determining the voltage fluctuation characteristics and charge-discharge process characteristics of the flexible DC transmission system submodules based on this key parameter information; constructing a flexible DC valve average electromagnetic transient model based on this voltage fluctuation characteristics and charge-discharge process characteristics, and determining the model structure of this flexible DC valve average electromagnetic transient model; and adjusting the key parameters of this flexible DC valve average electromagnetic transient model based on this model structure. This invention has the capability to simulate the entire process, including charging and unlocking. BRIEF DESCRIPTION OF THE DRAWINGS

[0098] Figure 1 is a flow chart of the method of the present invention;

[0099] Figure 2 This is a structural diagram of an electromagnetic transient model of a flexible straight valve body average value model considering the charging process in an embodiment of the method of the present invention;

[0100] Figure 3 This is an equivalent circuit diagram of a bridge arm of a flexible DC converter with charging function according to an embodiment of the method of the present invention;

[0101] Figure 4 This is a flow chart for calculating the bridge arm output voltages Vs1 and Vs2 using an embodiment of the method of the present invention;

[0102] Figure 5This is the simulation waveform of the entire process from charging to unlocking of the flexible DC converter valve using the flexible DC average submodule calculation model in the method embodiment of the present invention (from top to bottom, the DC voltage and the per-unit average voltage of the submodules of the six bridge arms of the converter valve);

[0103] Figure 6 The bridge arm current and submodule average voltage waveforms of the average value model (circles) and detailed switch device model (triangles) at a rated power of 3000MW according to the present invention;

[0104] Figure 7 It is a structural diagram of the system of the present invention. DETAILED DESCRIPTION

[0105] Exemplary embodiments of the present invention will now be described with reference to the accompanying drawings. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein. These embodiments are provided to provide a thorough and complete disclosure of the present invention and to fully convey the scope of the present invention to those skilled in the art. The terminology used in the exemplary embodiments shown in the accompanying drawings is not intended to limit the present invention. In the accompanying drawings, identical elements are denoted by the same reference numerals.

[0106] Unless otherwise specified, the terms used herein (including technical terms) have the meanings commonly understood by those skilled in the art. In addition, it is understood that terms defined in commonly used dictionaries should be understood to have the same meanings as those in the context of the relevant fields, and should not be understood as idealized or overly formal meanings.

[0107] Example 1:

[0108] The present invention proposes a method for adjusting key parameters of the average electromagnetic transient model of a flexible straight valve body, such as Figure 1 Shown, including:

[0109] Step 1: Acquire key parameter information of a flexible direct current transmission system, and determine voltage fluctuation characteristics and charge and discharge process characteristics of submodules of the flexible direct current transmission system based on the key parameter information;

[0110] Step 2: Based on the voltage fluctuation characteristics and the charge and discharge process characteristics, a flexible direct current valve average electromagnetic transient model is constructed, and a model structure of the flexible direct current valve average electromagnetic transient model is determined;

[0111] Step 3: Based on the model structure, key parameters of the flexible straight valve body average electromagnetic transient model are adjusted.

[0112] The model structure of the average electromagnetic transient model of the flexible straight valve body includes:

[0113] Equivalent circuit of the flexible DC converter bridge arm and calculation model of the flexible DC average sub-module.

[0114] Among them, one input signal of the bridge arm equivalent circuit of the flexible DC converter is the bridge arm output voltage Vs1 of the charging branch and the bridge arm output voltage Vs2 of the discharging branch, and one output signal is the bridge arm current value i arm ;

[0115] Another input signal of the flexible DC converter bridge arm equivalent circuit is the bridge arm unlocking signal Unlock, the number of conducting submodules N in , submodule voltage output mode VcMode and bridge arm current i arm , the other output signal is the bridge arm output voltage Vs1 and Vs2 of the charge and discharge branch.

[0116] The equivalent circuit of the bridge arm of the flexible DC converter includes: two parallel branches connected left and right;

[0117] The left branch is a charging branch, which is composed of a diode D1, a controlled voltage source 1 and a resistor R1 connected in series.

[0118] The cathode of the diode D1 is connected to the anode of the controlled voltage source 1, and the cathode of the controlled voltage source 1 is connected to the resistor R1.

[0119] The diode D1 allows the bridge arm current i arm The charging current i p Flowing through the left bridge arm, preventing i arm The discharge current i n Flows through the left bridge arm;

[0120] The right branch is the discharge branch, which is composed of a diode D2, a controlled voltage source 2 and a resistor R2 connected in series.

[0121] The anode of the diode D2 is connected to the anode of the controlled voltage source 2, and the cathode of the controlled voltage source 2 is connected to the resistor R2.

[0122] The positive electrode of the diode D1 is connected to the negative electrode of the diode D2 to form the positive electrode of the flexible DC converter bridge arm, and the resistor R1 is connected to the resistor R2 to form the negative electrode of the flexible DC converter bridge arm;

[0123] The diode D2 blocks the bridge arm current i arm The charging current i p Flowing through the right bridge arm, allowing i arm The discharge current i n Flows through the right bridge arm.

[0124] Among them, the input parameters of the flexible direct average submodule calculation model include the following: simulation step length Ts , submodule capacitance value C, submodule rated capacitance voltage value U smN , Number of bridge arm submodules N sm , the number of full bridge sub-modules N with normal bridge arms FBSM _ OK , Number of bridge arm fault submodules N Fault And the resistance value R in parallel with the submodule capacitor c .

[0125] The flexible DC average submodule calculation model is used to calculate the output voltages Vs1 and Vs2 of the charging and discharging branch bridge arms. The calculation process includes:

[0126] Determine the submodule voltage output mode VcMode. If the submodule voltage output mode VcMode is 0, all submodule voltages V ceq (n) is set to 0p.u. If the submodule voltage output mode VcMode is 1, all submodule voltages V ceq (n) is set to 1p.u. If the submodule voltage output mode VcMode is 2, the bridge arm unlock signal Unlock is determined;

[0127] If the bridge arm unlock signal Unlock is 0, calculate the capacitor voltage of the full-bridge submodule and the half-bridge submodule according to the type of submodule;

[0128] The capacitor voltage calculation formula of the full-bridge submodule is as follows:

[0129]

[0130] V ceqFB (n) = i arm (n)T s / C+V ceqFB (n-1)

[0131] When calculating the capacitor voltage of the half-bridge submodule, the direction of the bridge arm current is judged to determine the charge and discharge state of the half-bridge submodule. arm When (n) is greater than or equal to 0, the half-bridge submodule is in the charging state, and the capacitor voltage calculation formula of the half-bridge submodule is as follows:

[0132] i ceq (n) = i arm (n)-V ceqHB (n-1) / R c

[0133] V ceqHB (n) = i arm (n)T s / C+V ceqHB (n-1)

[0134] When the bridge arm current i arm When (n) is less than 0, the half-bridge submodule is in a discharge state, and the capacitor voltage calculation formula of the half-bridge submodule is as follows:

[0135] V ceqHB (n) = V ceq (n-1)

[0136] According to the number of full-bridge sub-modules and half-bridge sub-modules and the capacitor voltage, the equivalent capacitor voltage of the bridge arm is calculated according to the principle of energy conservation. The calculation formula is as follows:

[0137] V ceq (n)=[V ceqFB (n) 2 N FBSM-OK +V ceqHB (n) 2 (N sm -N FBSM_OK -N Fault )] 0.5

[0138] If the bridge arm unlock signal Unlock is 1, the calculation formula of the bridge arm equivalent capacitor voltage is as follows:

[0139] i ceq (n) = i arm (n)-V ceq (n-1) / R c

[0140] V ceq (n) = i arm (n)T s N in (n) / (C(N Sm -N Fault )+V ceq (n-1)

[0141] The bridge arm equivalent capacitor voltage is limited to calculate the bridge arm output voltages Vs1 and Vs2 of the charge and discharge branches. The calculation formula is as follows:

[0142] V s1 (n) = N in (n)UnlockV ceq (n)+(N sm -N Fault )(1-Unlock)V ceq (n)

[0143] V s2 (n) = N in (n)UnlockV ceq (n)-N FBSM_OK(1-Unlock)V ceq (n)

[0144] The bridge arm equivalent capacitor voltage is limited. If the bridge arm equivalent capacitor voltage is less than zero, the bridge arm equivalent capacitor voltage is set to 0; otherwise, the bridge arm equivalent capacitor voltage is a calculated value.

[0145] The key parameters of the average electromagnetic transient model of the flexible straight valve body are adjusted, including:

[0146] The equivalent parameters of diodes D1 and D2 in the equivalent circuit of the flexible DC converter bridge arm are approximately adjusted by multiplying the actual parameters of a single diode by the number of submodules;

[0147] Resistors R1 and R2 are adjusted based on the converter losses at rated power.

[0148] Input parameters of the flexible DC average submodule calculation model are submodule capacitance value C, submodule rated capacitance voltage value U smN , Number of bridge arm submodules N sm , the number of full bridge sub-modules N with normal bridge arms FBSM_OK , Number of bridge arm fault submodules N Fault And the resistance value R in parallel with the submodule capacitor c , it is adjusted based on the engineering design data and actual operating conditions of the flexible DC converter;

[0149] Simulation step T s Adjust according to actual simulation requirements.

[0150] The present invention will be further described below in conjunction with embodiments:

[0151] The present invention considers the electromagnetic transient model structure of the flexible straight valve body average value model during the charging process, such as Figure 2 As shown, it includes two parts: the flexible DC converter bridge arm equivalent circuit and the flexible DC average submodule calculation model. The input signal of the flexible DC converter bridge arm equivalent circuit is the bridge arm output voltage Vs1 of the charging branch and the bridge arm output voltage Vs2 of the discharging branch. The output signal is the bridge arm current value i arm The input signals of the equivalent circuit of the bridge arm of the flexible DC converter are the bridge arm unlocking signal Unlock and the number of conducting submodules N. in , submodule voltage output mode VcMode and bridge arm current i arm , the output signal is the bridge arm output voltage Vs1 and Vs2 of the charge and discharge branch.

[0152] The equivalent circuit of the flexible DC converter bridge arm is as follows: Figure 3 As shown in FIG, the flexible DC bridge arm equivalent circuit is composed of two left and right branches connected in parallel.

[0153] The left branch is the charging branch, which is composed of a diode D1, a controlled voltage source 1 and a resistor R1 connected in series. The cathode of the diode D1 is connected to the anode of the controlled voltage source 1, and the cathode of the controlled voltage source 1 is connected to the resistor R1. The diode D1 allows the bridge arm current i arm The charging current i p Flowing through the left bridge arm, preventing i arm The discharge current i n Flows through the left bridge arm. Controlled voltage source 1 represents the sum of the bridge arm submodule output voltages during charging. Resistor R1 represents the total bridge arm loss during charging.

[0154] The right branch is the discharge branch, which is composed of a diode D2, a controlled voltage source 2, and a resistor R2 connected in series. The anode of the diode D2 is connected to the anode of the controlled voltage source 2, and the cathode of the controlled voltage source 2 is connected to the resistor R2. The anode of the diode D1 is connected to the cathode of the diode D2 to form the anode of the flexible DC converter bridge arm, and the resistor R1 is connected to the resistor R2 to form the cathode of the flexible DC converter bridge arm. The diode D2 blocks the bridge arm current i arm The charging current i p Flowing through the right bridge arm, allowing i arm The discharge current i n Flows through the right bridge arm. Controlled voltage source 2 represents the sum of the output voltages of the bridge arm submodules during discharge. Resistor R2 represents the total loss of the bridge arm during discharge.

[0155] Calculation model of the flexible direct average submodule:

[0156] Input parameters of the calculation model of the flexible direct average submodule: simulation step length T s , submodule capacitance value C, submodule rated capacitance voltage value U smN , Number of bridge arm submodules N sm , the number of full bridge sub-modules N with normal bridge arms FBSM_OK , Number of bridge arm fault submodules N Fault , Submodule capacitor parallel resistance value R c .

[0157] The calculation process of the charging and discharging branch bridge arm output voltage Vs1 and Vs2 output by the flexible DC average submodule calculation model is as follows: Figure 4 As shown:

[0158] First, determine the submodule voltage output mode VcMode. If the submodule voltage output mode VcMode is 0, all submodule voltages V ceq (n) is set to 0p.u; if the submodule voltage output mode VcMode is 1, all submodule voltages V ceq (n) is set to 1p.u; if the submodule voltage output mode VcMode is 2, the bridge arm unlock signal Unlock is further determined.

[0159] If the bridge arm unlocking signal Unlock is 0, it is considered to be in a locked or uncontrolled charging state. According to the type of sub-module, the capacitor voltage of the full-bridge sub-module and the half-bridge sub-module are calculated respectively.

[0160] The capacitor voltage calculation formula of the full-bridge submodule is:

[0161] i ceq (n) = i arm (n)-V ceqFB (n-1) / R c

[0162] V ceqFB (n) = i arm (n)T s / C+V ceqFB (n-1)

[0163] The capacitance voltage calculation of the half-bridge submodule requires judging the direction of the bridge arm current to determine the charge and discharge state of the half-bridge submodule. arm When (n) is greater than or equal to 0, the half-bridge submodule is in the charging state, and the capacitor voltage calculation formula of the half-bridge submodule is:

[0164] i ceq (n) = i arm (n)-V ceqHB (n-1) / R c

[0165] V ceqHB (n) = i arm (n)T s / C+V ceqHB (n-1)

[0166] Bridge arm current i arm When (n) is less than 0, the half-bridge submodule is in the discharge state, and the capacitor voltage calculation formula of the half-bridge submodule is:

[0167] V ceqHB (n) = V ceq (n-1) (9)

[0168] According to the number and capacitor voltage of the full-bridge sub-module and half-bridge sub-module, the equivalent capacitor voltage of the bridge arm is further obtained according to the principle of energy conservation:

[0169] V ceq (n)=[V ceqFB (n) 2 N FBSM _ OK +V ceqHB (n) 2 (N sm -N FBSM_OK-N Fault )] 0.5

[0170] If the bridge arm unlock signal Unlock is 1, it is considered to be in the unlocked or controllable charging state, and the bridge arm equivalent capacitor voltage is calculated according to the following formula:

[0171] i ceq (n) = i arm (n)-V ceq (n-1) / R c

[0172] V ceq (n) = i arm (n)T s N in (n) / (C(N Sm -N Fault )+V ceq (n-1)

[0173] To ensure that the bridge arm equivalent capacitor voltage is non-negative, the bridge arm equivalent capacitor voltage needs to be limited. If the bridge arm equivalent capacitor voltage is less than zero, the bridge arm equivalent capacitor voltage is set to 0; otherwise, the bridge arm equivalent capacitor voltage is the calculated value.

[0174] Finally, the bridge arm output voltages Vs1 and Vs2 of the charge and discharge branches are obtained:

[0175] V s1 (n) = N in (n)UnlockV ceq (n)+(N sm -N Fault )(1-Unlock)V ceq (n)

[0176] V s2 (n) = N in (n)UnlockV ceq (n)-N FBSM_OK (1-Unlock)V ceq (n)

[0177] 4) Key parameter setting method of electromagnetic transient model of flexible straight valve body average value model

[0178] The equivalent parameters of diodes D1 and D2 in the equivalent circuit of the flexible DC converter bridge arm are approximately adjusted by multiplying the actual parameters of a single diode by the number of sub-modules; resistors R1 and R2 are adjusted according to the losses of the converter at rated power.

[0179] Input parameters of the flexible DC average submodule calculation model are submodule capacitance value C, submodule rated capacitance voltage value U smN , Number of bridge arm submodules Nsm , the number of full bridge sub-modules N with normal bridge arms FBSM_OK , Number of bridge arm fault submodules N Fault , Submodule capacitor parallel resistance value R c , according to the engineering design and actual operating conditions of the flexible DC converter; the simulation step length T s Adjust according to simulation requirements.

[0180] The proposed electromagnetic transient modeling method for a flexible straight valve body average value model is capable of simulating the entire charging and unlocking process. The proposed method involves a single bridge arm circuit consisting of six electrical nodes, equivalent to two submodules based on detailed switching devices, significantly improving computational efficiency. Under various operating conditions, the proposed modeling method achieved an average simulation error of less than 5% compared to a valve body model based on detailed switching devices.

[0181] The electromagnetic transient modeling method of the flexible DC valve body average value model and the detailed switching device model proposed in the present invention were respectively adopted. Based on the typical primary circuit of the Zhangbei flexible DC project, a four-terminal flexible DC power grid model was built to verify the effectiveness of the technical solution.

[0182] The input parameters of the flexible DC average submodule calculation model are submodule capacitance value C = 15mF, submodule rated capacitance voltage value U smN =1893.94V, number of bridge arm submodules N sm = 264, the number of full bridge submodules N with normal bridge arms FBSM_OK =0, number of bridge arm fault submodules N Fault =0, submodule capacitor parallel resistance value R c =4000W, simulation step size T s =50ms. The equivalent parameters of diodes D1 and D2 in the equivalent circuit of the flexible DC converter bridge arm are calculated by multiplying the actual parameters of a single diode by the number of submodules N. sm =264 is approximately set; resistors R1 and R2 are both 1.5W.

[0183] In the flexible DC grid simulation model using the flexible DC average submodule calculation model, the simulation waveforms of the entire process from uncontrolled charging, controlled charging to converter valve unlocking are as follows: Figure 5 As shown in the figure, after the AC grid-side switch is closed at time 1, the converter valve begins uncontrolled charging, and the average voltage and DC voltage of each bridge arm submodule begin to rise. When the average voltage of each bridge arm submodule reaches 0.7pu, controlled charging begins, and the average voltage of each bridge arm submodule increases by approximately 1.01pu, and the DC voltage increases to approximately 375kV. At time 12, the converter valve is unlocked, the DC voltage is controlled to the rated value of 500kV, and the average capacitor voltage of the bridge arm submodule stabilizes at approximately 0.99pu.

[0184] The above simulation results verify the correctness of the charging function of the proposed modeling method.

[0185] The bridge arm current and submodule average voltage of the flexible DC converter valve body average value model and detailed switch device model under 1.0pu (3000MW) working condition, such as Figure 6 As shown in the figure, the active power and DC voltage waveforms of the MMC average value model and the detailed switching device model show high consistency in the bridge arm current and submodule average voltage of the two models, with very low high-frequency components. Therefore, if the operating characteristics of the MMC are examined from the perspective of the entire bridge arm, the average value model and the detailed switching device model are interchangeable under steady-state conditions.

[0186] Example 2:

[0187] The present invention also proposes a key parameter setting system 200 for a flexible straight valve average electromagnetic transient model, such as Figure 7 Shown, including:

[0188] The initialization unit 201 is configured to obtain key parameter information of a flexible DC transmission system and determine voltage fluctuation characteristics and charge and discharge process characteristics of submodules of the flexible DC transmission system based on the key parameter information;

[0189] The calculation unit 202 is configured to construct an average electromagnetic transient model of the flexible direct current valve body based on the voltage fluctuation characteristics and the charge and discharge process characteristics, and determine a model structure of the average electromagnetic transient model of the flexible direct current valve body;

[0190] The tuning unit 203 is configured to tune key parameters of the flexible straight valve body average electromagnetic transient model based on the model structure.

[0191] The model structure of the average electromagnetic transient model of the flexible straight valve body includes:

[0192] Equivalent circuit of the flexible DC converter bridge arm and calculation model of the flexible DC average sub-module.

[0193] Optionally, an input signal of the flexible DC converter bridge arm equivalent circuit is the bridge arm output voltage Vs1 of the charging branch and the bridge arm output voltage Vs2 of the discharging branch, and an output signal is the bridge arm current value i arm ;

[0194] Another input signal of the flexible DC converter bridge arm equivalent circuit is the bridge arm unlocking signal Unlock, the number of conducting submodules N in , submodule voltage output mode VcMode and bridge arm current i arm , the other output signal is the bridge arm output voltage Vs1 and Vs2 of the charge and discharge branch.

[0195] The equivalent circuit of the bridge arm of the flexible DC converter includes: two parallel branches connected left and right;

[0196] The left branch is a charging branch, which is composed of a diode D1, a controlled voltage source 1 and a resistor R1 connected in series.

[0197] The cathode of the diode D1 is connected to the anode of the controlled voltage source 1, and the cathode of the controlled voltage source 1 is connected to the resistor R1.

[0198] The diode D1 allows the bridge arm current i arm The charging current i p Flowing through the left bridge arm, preventing i arm The discharge current i n Flows through the left bridge arm;

[0199] The right branch is the discharge branch, which is composed of a diode D2, a controlled voltage source 2 and a resistor R2 connected in series.

[0200] The anode of the diode D2 is connected to the anode of the controlled voltage source 2, and the cathode of the controlled voltage source 2 is connected to the resistor R2.

[0201] The positive electrode of the diode D1 is connected to the negative electrode of the diode D2 to form the positive electrode of the flexible DC converter bridge arm, and the resistor R1 is connected to the resistor R2 to form the negative electrode of the flexible DC converter bridge arm;

[0202] The diode D2 blocks the bridge arm current i arm The charging current i p Flowing through the right bridge arm, allowing i arm The discharge current i n Flows through the right bridge arm.

[0203] Among them, the input parameters of the flexible direct average submodule calculation model include the following: simulation step length T s , submodule capacitance value C, submodule rated capacitance voltage value U smN , Number of bridge arm submodules N sm , the number of full bridge sub-modules N with normal bridge arms FBSM _ OK , Number of bridge arm fault submodules N Fault And the resistance value R in parallel with the submodule capacitor c .

[0204] The flexible DC average submodule calculation model is used to calculate the output voltages Vs1 and Vs2 of the charging and discharging branch bridge arms. The calculation process includes:

[0205] Determine the submodule voltage output mode VcMode. If the submodule voltage output mode VcMode is 0, all submodule voltages Vceq (n) is set to 0p.u. If the submodule voltage output mode VcMode is 1, all submodule voltages V ceq (n) is set to 1p.u. If the submodule voltage output mode VcMode is 2, the bridge arm unlock signal Unlock is determined;

[0206] If the bridge arm unlock signal Unlock is 0, calculate the capacitor voltage of the full-bridge submodule and the half-bridge submodule according to the type of submodule;

[0207] The capacitor voltage calculation formula of the full-bridge submodule is as follows:

[0208]

[0209] V ceqFB (n) = i arm (n)T s / C+V ceqFB (n-1)

[0210] When calculating the capacitor voltage of the half-bridge submodule, the direction of the bridge arm current is judged to determine the charge and discharge state of the half-bridge submodule. arm When (n) is greater than or equal to 0, the half-bridge submodule is in the charging state, and the capacitor voltage calculation formula of the half-bridge submodule is as follows:

[0211] i ceq (n) = i arm (n)-V ceqHB (n-1) / R c

[0212] V ceqHB (n) = i arm (n)T s / C+V ceqHB (n-1)

[0213] When the bridge arm current i arm When (n) is less than 0, the half-bridge submodule is in a discharge state, and the capacitor voltage calculation formula of the half-bridge submodule is as follows:

[0214] V ceqHB (n) = V ceq (n-1)

[0215] According to the number of full-bridge sub-modules and half-bridge sub-modules and the capacitor voltage, the equivalent capacitor voltage of the bridge arm is calculated according to the principle of energy conservation. The calculation formula is as follows:

[0216] V ceq (n)=[V ceqFB (n) 2 N FBSM_OK +VceqHB (n) 2 (N sm -N FBSM_OK -N Fault )] 0.5

[0217] If the bridge arm unlock signal Unlock is 1, the calculation formula of the bridge arm equivalent capacitor voltage is as follows:

[0218] i ceq (n) = i arm (n)-V ceq (n-1) / R c

[0219] V ceq (n) = i arm (n)T s N in (n) / (C(N Sm -N Fault )+V ceq (n-1)

[0220] The bridge arm equivalent capacitor voltage is limited to calculate the bridge arm output voltages Vs1 and Vs2 of the charge and discharge branches. The calculation formula is as follows:

[0221] V s1 (n) = N in (n)UnlockV ceq (n)+(N sm -N Fault )(1-Unlock)V ceq (n)

[0222] V s2 (n) = N in (n)UnlockV ceq (n)-N FBSM_OK (1-Unlock)V ceq (n)

[0223] The bridge arm equivalent capacitor voltage is limited. If the bridge arm equivalent capacitor voltage is less than zero, the bridge arm equivalent capacitor voltage is set to 0; otherwise, the bridge arm equivalent capacitor voltage is a calculated value.

[0224] The key parameters of the average electromagnetic transient model of the flexible straight valve body are adjusted, including:

[0225] The equivalent parameters of diodes D1 and D2 in the equivalent circuit of the flexible DC converter bridge arm are approximately adjusted by multiplying the actual parameters of a single diode by the number of submodules;

[0226] Resistors R1 and R2 are adjusted based on the converter losses at rated power.

[0227] Input parameters of the flexible DC average submodule calculation model are submodule capacitance value C, submodule rated capacitance voltage value U smN , Number of bridge arm submodules N sm , the number of full bridge sub-modules N with normal bridge arms FBSM_OK , Number of bridge arm fault submodules N Fault And the resistance value R in parallel with the submodule capacitor c , it is adjusted based on the engineering design data and actual operating conditions of the flexible DC converter;

[0228] Simulation step T s Adjust according to actual simulation requirements.

[0229] The present invention has the ability to simulate the entire process including charging and unlocking.

[0230] Example 3:

[0231] Based on the same inventive concept, the present invention also provides a computer device, which includes a processor and a memory, wherein the memory is used to store a computer program, the computer program includes program instructions, and the processor is used to execute the program instructions stored in the computer storage medium. The processor may be a central processing unit (CPU), or may be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc. It is the computing core and control core of the terminal, which is suitable for implementing one or more instructions, specifically suitable for loading and executing one or more instructions in the computer storage medium to implement the corresponding method flow or corresponding function, so as to implement the steps of the method in the above embodiment.

[0232] Example 4:

[0233] Based on the same inventive concept, the present invention also provides a storage medium, specifically a computer-readable storage medium (Memory), which is a memory device in a computer device for storing programs and data. It can be understood that the computer-readable storage medium here can include both built-in storage media in the computer device and, of course, extended storage media supported by the computer device. The computer-readable storage medium provides a storage space that stores the operating system of the terminal. In addition, one or more instructions suitable for being loaded and executed by the processor are also stored in the storage space. These instructions can be one or more computer programs (including program codes). It should be noted that the computer-readable storage medium here can be a high-speed RAM memory or a non-volatile memory, such as at least one disk memory. The processor can load and execute one or more instructions stored in the computer-readable storage medium to implement the steps of the method in the above embodiment.

[0234] It will be understood by those skilled in the art that the embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code. The solutions in the embodiments of the present invention may be implemented in various computer languages, for example, the object-oriented programming language Java and the interpreted scripting language JavaScript.

[0235] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowcharts and / or block diagrams. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0236] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0237] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 The steps for the function specified in one or more boxes.

[0238] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0239] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A method for adjusting key parameters of an average electromagnetic transient model of a flexible straight valve body, characterized in that: The method comprises: Acquiring key parameter information of a flexible direct current transmission system, and determining voltage fluctuation characteristics and charging and discharging process characteristics of submodules of the flexible direct current transmission system based on the key parameter information; Based on the voltage fluctuation characteristics and the charge and discharge process characteristics, a flexible direct valve body average electromagnetic transient model is constructed, and a model structure of the flexible direct valve body average electromagnetic transient model is determined; Based on the model structure, key parameters of the average electromagnetic transient model of the flexible straight valve body are adjusted; The model structure of the flexible straight valve body average electromagnetic transient model includes: Flexible DC converter bridge arm equivalent circuit and flexible DC average submodule calculation model; The input parameters of the flexible average submodule calculation model include the following: simulation step length T s , submodule capacitance value C, submodule rated capacitance voltage value U smN , Number of bridge arm submodules N sm , the number of full bridge sub-modules N with normal bridge arms FBSM_OK , Number of bridge arm fault submodules N Fault And the resistance value R in parallel with the submodule capacitor c ; The flexible DC average submodule calculation model is used to calculate the output voltages Vs1 and Vs2 of the charging and discharging branch bridge arms. The calculation process includes: Determine the submodule voltage output mode VcMode. If the submodule voltage output mode VcMode is 0, all submodule voltages V ceq (n) is set to 0p.u. If the submodule voltage output mode VcMode is 1, all submodule voltages V ceq (n) is set to 1p.u. If the submodule voltage output mode VcMode is 2, the bridge arm unlock signal Unlock is determined; If the bridge arm unlock signal Unlock is 0, calculate the capacitor voltage of the full-bridge submodule and the half-bridge submodule according to the type of submodule; The capacitor voltage calculation formula of the full-bridge submodule is as follows: V ceqFB (n)=i arm (n)T s / C+V ceqFB (n-1) Among them, V ceqFB (n) is the full-bridge submodule voltage in the current calculation cycle, V ceqFB (n-1) is the full-bridge submodule voltage of the previous calculation cycle; When calculating the capacitor voltage of the half-bridge submodule, the direction of the bridge arm current is judged to determine the charge and discharge state of the half-bridge submodule. arm When (n) is greater than or equal to 0, the half-bridge submodule is in the charging state, and the capacitor voltage calculation formula of the half-bridge submodule is as follows: i ceq (n)=i arm (n)-V ceqHB (n-1) / R c V ceqHB (n)=i arm (n)T s / C+V ceqHB (n-1) Among them, V ceqHB (n) is the voltage of the half-bridge submodule in the current calculation cycle, V ceqHB (n-1) is the half-bridge submodule voltage of the previous calculation cycle; When the bridge arm current i arm When (n) is less than 0, the half-bridge submodule is in a discharge state, and the capacitor voltage calculation formula of the half-bridge submodule is as follows: V ceqHB (n)=V ceqHB (n-1) According to the number of full-bridge sub-modules and half-bridge sub-modules and the capacitor voltage, the equivalent capacitor voltage of the bridge arm is calculated according to the principle of energy conservation. The calculation formula is as follows: V ceq (n)=[V ceqFB (n) 2 N FBSM _ OK +V ceqHB (n) 2 (N sm -N FBSM_OK -N Fault )] 0.5 If the bridge arm unlock signal Unlock is 1, the calculation formula of the bridge arm equivalent capacitor voltage is as follows: i ceq (n)=i arm (n)-V ceq (n-1) / R c V ceq (n)=i arm (n)T s N in (n) / (C(N Sm -N Fault ))+V ceq (n-1) The bridge arm equivalent capacitor voltage is limited to calculate the bridge arm output voltages Vs1 and Vs2 of the charge and discharge branches. The calculation formula is as follows: V s1 (n)=N in (n)UnlockV ceq (n)+(N sm -N Fault )(1-Unlock)V ceq (n) V s2 (n)=N in (n)UnlockV ceq (n)-N FBSM_OK (1-Unlock)V ceq (n) The bridge arm equivalent capacitor voltage is limited. If the bridge arm equivalent capacitor voltage is less than zero, the bridge arm equivalent capacitor voltage is set to 0; otherwise, the bridge arm equivalent capacitor voltage is a calculated value; Among them, N in (n) is the number of conducting submodules.

2. The method according to claim 1, characterized in that The input signal of the bridge arm equivalent circuit of the flexible DC converter is the bridge arm output voltage Vs1 of the charging branch and the bridge arm output voltage Vs2 of the discharging branch, and the output signal is the bridge arm current value i arm ; Another input signal of the flexible DC converter bridge arm equivalent circuit is the bridge arm unlocking signal Unlock, the number of conducting submodules N in , submodule voltage output mode VcMode and bridge arm current i arm , the other output signal is the bridge arm output voltage Vs1 and Vs2 of the charge and discharge branch.

3. The method according to claim 1, characterized in that The flexible DC converter bridge arm equivalent circuit includes: two left and right parallel branches; The left branch is a charging branch, which is composed of a diode D1, a controlled voltage source 1 and a resistor R1 connected in series. The cathode of the diode D1 is connected to the anode of the controlled voltage source 1, and the cathode of the controlled voltage source 1 is connected to the resistor R1. The diode D1 allows the bridge arm current i arm The charging current i p Flowing through the left bridge arm, preventing i arm The discharge current i n Flows through the left bridge arm; The right branch is the discharge branch, which is composed of a diode D2, a controlled voltage source 2 and a resistor R2 connected in series. The anode of the diode D2 is connected to the anode of the controlled voltage source 2, and the cathode of the controlled voltage source 2 is connected to the resistor R2. The positive electrode of the diode D1 is connected to the negative electrode of the diode D2 to form the positive electrode of the flexible DC converter bridge arm, and the resistor R1 is connected to the resistor R2 to form the negative electrode of the flexible DC converter bridge arm; The diode D2 blocks the bridge arm current i arm The charging current i p Flowing through the right bridge arm, allowing i arm The discharge current i n Flows through the right bridge arm.

4. The method according to claim 1, wherein The key parameters of the average electromagnetic transient model of the flexible straight valve body are adjusted, including: The equivalent parameters of diodes D1 and D2 in the equivalent circuit of the flexible DC converter bridge arm are approximately adjusted by multiplying the actual parameters of a single diode by the number of submodules; Resistors R1 and R2 are adjusted based on the converter losses at rated power. Input parameters of the flexible DC average submodule calculation model are submodule capacitance value C, submodule rated capacitance voltage value U smN , Number of bridge arm submodules N sm , the number of full bridge sub-modules N with normal bridge arms FBSM_OK , Number of bridge arm fault submodules N Fault And the resistance value R in parallel with the submodule capacitor c , it is adjusted based on the engineering design data and actual operating conditions of the flexible DC converter; Simulation step T s Adjust according to actual simulation requirements.

5. A key parameter setting system for the average electromagnetic transient model of a flexible straight valve body, characterized by: The system comprises: an initialization unit, configured to obtain key parameter information of a flexible DC transmission system, and determine voltage fluctuation characteristics and charge and discharge process characteristics of submodules of the flexible DC transmission system based on the key parameter information; a calculation unit, configured to construct an average electromagnetic transient model of a flexible direct current valve body based on the voltage fluctuation characteristics and the charge and discharge process characteristics, and determine a model structure of the average electromagnetic transient model of the flexible direct current valve body; A tuning unit, configured to tune key parameters of the average electromagnetic transient model of the flexible straight valve body based on the model structure; The model structure of the flexible straight valve body average electromagnetic transient model includes: Flexible DC converter bridge arm equivalent circuit and flexible DC average submodule calculation model; The input parameters of the flexible average submodule calculation model include the following: simulation step length T s , submodule capacitance value C, submodule rated capacitance voltage value U smN , Number of bridge arm submodules N sm , the number of full bridge sub-modules N with normal bridge arms FBSM_OK , Number of bridge arm fault submodules N Fault And the resistance value R in parallel with the submodule capacitor c ; The flexible DC average submodule calculation model is used to calculate the output voltages Vs1 and Vs2 of the charging and discharging branch bridge arms. The calculation process includes: Determine the submodule voltage output mode VcMode. If the submodule voltage output mode VcMode is 0, all submodule voltages V ceq (n) is set to 0p.u. If the submodule voltage output mode VcMode is 1, all submodule voltages V ceq (n) is set to 1p.u. If the submodule voltage output mode VcMode is 2, the bridge arm unlock signal Unlock is determined; If the bridge arm unlock signal Unlock is 0, calculate the capacitor voltage of the full-bridge submodule and the half-bridge submodule according to the type of submodule; The capacitor voltage calculation formula of the full-bridge submodule is as follows: V ceqFB (n)=i arm (n)T s / C+V ceqFB (n-1) Among them, V ceqFB (n) is the full-bridge submodule voltage in the current calculation cycle, V ceqFB (n-1) is the full-bridge submodule voltage of the previous calculation cycle; When calculating the capacitor voltage of the half-bridge submodule, the direction of the bridge arm current is judged to determine the charge and discharge state of the half-bridge submodule. arm When (n) is greater than or equal to 0, the half-bridge submodule is in the charging state, and the capacitor voltage calculation formula of the half-bridge submodule is as follows: i ceq (n)=i arm (n)-V ceqHB (n-1) / R c V ceqHB (n)=i arm (n)T s / C+V ceqHB (n-1) Among them, V ceqHB (n) is the voltage of the half-bridge submodule in the current calculation cycle, V ceqHB (n-1) is the half-bridge submodule voltage of the previous calculation cycle; When the bridge arm current i arm When (n) is less than 0, the half-bridge submodule is in a discharge state, and the capacitor voltage calculation formula of the half-bridge submodule is as follows: V ceqHB (n)=V ceqHB (n-1) According to the number of full-bridge sub-modules and half-bridge sub-modules and the capacitor voltage, the equivalent capacitor voltage of the bridge arm is calculated according to the principle of energy conservation. The calculation formula is as follows: V ceq (n)=[V ceqFB (n) 2 N FBSM _ OK +V ceqHB (n) 2 (N sm -N FBSM_OK -N Fault )] 0.5 If the bridge arm unlock signal Unlock is 1, the calculation formula of the bridge arm equivalent capacitor voltage is as follows: i ceq (n)=i arm (n)-V ceq (n-1) / R c V ceq (n)=i arm (n)T s N in (n) / (C(N Sm -N Fault ))+V ceq (n-1) The bridge arm equivalent capacitor voltage is limited to calculate the bridge arm output voltages Vs1 and Vs2 of the charge and discharge branches. The calculation formula is as follows: V s1 (n)=N in (n)UnlockV ceq (n)+(N sm -N Fault )(1-Unlock)V ceq (n) V s2 (n)=N in (n)UnlockV ceq (n)-N FBSM_OK (1-Unlock)V ceq (n) The bridge arm equivalent capacitor voltage is limited. If the bridge arm equivalent capacitor voltage is less than zero, the bridge arm equivalent capacitor voltage is set to 0; otherwise, the bridge arm equivalent capacitor voltage is a calculated value; Among them, N in (n) is the number of conducting submodules.

6. The system according to claim 5, characterized in that The input signal of the bridge arm equivalent circuit of the flexible DC converter is the bridge arm output voltage Vs1 of the charging branch and the bridge arm output voltage Vs2 of the discharging branch, and the output signal is the bridge arm current value i arm ; Another input signal of the flexible DC converter bridge arm equivalent circuit is the bridge arm unlocking signal Unlock, the number of conducting submodules N in , submodule voltage output mode VcMode and bridge arm current i arm , the other output signal is the bridge arm output voltage Vs1 and Vs2 of the charge and discharge branch.

7. The system according to claim 5, characterized in that The flexible DC converter bridge arm equivalent circuit includes: two left and right parallel branches; The left branch is a charging branch, which is composed of a diode D1, a controlled voltage source 1 and a resistor R1 connected in series. The cathode of the diode D1 is connected to the anode of the controlled voltage source 1, and the cathode of the controlled voltage source 1 is connected to the resistor R1. The diode D1 allows the bridge arm current i arm The charging current i p Flowing through the left bridge arm, preventing i arm The discharge current i n Flows through the left bridge arm; The right branch is the discharge branch, which is composed of a diode D2, a controlled voltage source 2 and a resistor R2 connected in series. The anode of the diode D2 is connected to the anode of the controlled voltage source 2, and the cathode of the controlled voltage source 2 is connected to the resistor R2. The positive electrode of the diode D1 is connected to the negative electrode of the diode D2 to form the positive electrode of the flexible DC converter bridge arm, and the resistor R1 is connected to the resistor R2 to form the negative electrode of the flexible DC converter bridge arm; The diode D2 blocks the bridge arm current i arm The charging current i p Flowing through the right bridge arm, allowing i arm The discharge current i n Flows through the right bridge arm.

8. The system according to claim 5, wherein: The key parameters of the average electromagnetic transient model of the flexible straight valve body are adjusted, including: The equivalent parameters of diodes D1 and D2 in the equivalent circuit of the flexible DC converter bridge arm are approximately adjusted by multiplying the actual parameters of a single diode by the number of submodules; Resistors R1 and R2 are adjusted based on the converter losses at rated power. Input parameters of the flexible DC average submodule calculation model are submodule capacitance value C, submodule rated capacitance voltage value U smN , Number of bridge arm submodules N sm , the number of full bridge sub-modules N with normal bridge arms FBSM_OK , Number of bridge arm fault submodules N Fault And the resistance value R in parallel with the submodule capacitor c , it is adjusted based on the engineering design data and actual operating conditions of the flexible DC converter; Simulation step T s Adjust according to actual simulation requirements.

9. A computer device, characterized in that: include: one or more processors; a processor for executing one or more programs; When the one or more programs are executed by the one or more processors, the method according to any one of claims 1 to 4 is implemented.

10. A computer-readable storage medium, characterized in that A computer program is stored thereon, and when the computer program is executed, the method according to any one of claims 1 to 4 is implemented.

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