New energy flexible direct delivery system network construction control method based on matching control

Abstract

The invention belongs to the technical field of matching control, and discloses a matching-control-based network construction control method for a new energy flexible direct current transmission system, and the method comprises the following steps: constructing a grid-connected system of a new energy field through a flexible direct current transmission system, and the grid-connected system comprises a new energy plant and a flexible direct current transmission system; establishing a VdcIq control strategy of the DC side voltage of the new energy side converter; establishing a Vf control strategy of the alternating current side voltage of the REVSC converter; establishing a matching-based control strategy of the DC side voltage of the GSVSC converter and the active power input at the converter grid-connected point; all control strategies act together to realize stable output of the grid-connected system. According to the matching control-based network construction control method for the new energy through the flexible direct-current delivery system, a phase-locked loop does not need to extract a phase, the angular velocity and the phase are obtained by matching the direct-current voltage with the angular velocity of the rotor of the synchronous machine and simulating the synchronous machine, the problems of oscillation and the like in a hybrid power grid in which the synchronous machine and an inverter coexist are solved, and the stability is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of matching control, and in particular to a matching control-based new energy flexible direct current transmission system networking control method. Background Art

[0002] With the development of renewable energy, the traditional grid mode has changed. Renewable energy is usually connected to the AC grid through an inverter. The power system has gradually formed a hybrid grid where inverters and synchronous machine interfaces coexist, especially in some microgrids. But this situation may cause many problems, mostly caused by the response time difference between the synchronous machine and the inverter. Traditional droop control is widely used in inverters, but it cannot provide inertia, which will lead to a faster response time of the inverter. In order to improve the low inertia state, many new control strategies have been proposed in academia. Among them, matching control performs better in hybrid grids.

[0003] Matching control is a new type of grid-building control method. Compared with traditional droop control and VSM control, it is more stable in a hybrid grid where synchronous machines and inverters coexist. Unlike traditional droop control, matching control does not require a phase-locked loop to extract the phase. It simulates the synchronous machine by matching the synchronous machine rotor angular velocity with a DC voltage to obtain the angular velocity and phase.

[0004] However, when new energy is connected to a weak power grid via a flexible direct current transmission system, unstable situations such as oscillations may occur, and it is necessary to build a new grid-connected control method that can provide voltage and frequency support. Summary of the invention

[0005] The purpose of the present invention is to provide a method for controlling the networking of a new energy flexible direct current transmission system based on matching control. The method does not require a phase-locked loop to extract the phase. The angular velocity and phase of the synchronous machine are obtained by simulating the synchronous machine by matching the angular velocity of the synchronous machine rotor with a DC voltage. The method overcomes oscillation problems in a hybrid power grid where synchronous machines and inverters coexist, and has stability.

[0006] To achieve the above object, the present invention provides a method for controlling a new energy network through a flexible direct current transmission system based on matching control, comprising the following steps:

[0007] Build a grid-connected system for new energy fields via a flexible DC transmission system, including a new energy plant and a flexible DC transmission system; the new energy field consists of a photovoltaic array; the flexible DC transmission system consists of a new energy field-side converter REVSC, a grid-side converter GSVSC and a DC line;

[0008] The terminal voltage of the new energy field is 690V, which is fed into the 35kV line through the new energy step-up transformer, and then connected to the flexible DC transmission system through the 35 / 110kV transformer;

[0009] Target reference value V of DC side voltage of new energy side converter dc1ref , through the VdcIq control strategy, the DC side voltage is stabilized;

[0010] The target reference value v of the voltage in the dq coordinate system of the AC side of the REVSC converter Ld2ref 、v Lq2ref , through the Vf control strategy, the three-phase AC voltage at the connection point between the renewable energy and the flexible DC transmission system is stabilized;

[0011] The target reference value V of the DC side voltage of the GSVSC converter dcref and the target reference value P of the active power input at the grid connection point of the converter PCCref ,Through the matching based control strategy, the DC voltage of the DC transmission line is stabilized, and the AC side of the GSVSC is connected to the AC grid through the line impedance.

[0012] Preferably, the new energy side converter obtains the target reference value V of the input converter DC side voltage dc1ref , the dq axis current parameters are obtained through the outer loop voltage PID controller, and then the dq axis voltage data is obtained through the inner loop current PID controller, which is converted into PWM wave as the AC side control signal of the new energy side converter; all control strategies work together to meet the power flow demand so as to achieve the control of the DC side voltage of the new energy side converter following the input reference value.

[0013] Preferably, the target reference value V of the DC side voltage of the new energy side converter is dc1ref , through the VdcIq control strategy, the DC side voltage is stabilized. The specific process is as follows:

[0014] Set the target reference value V of the DC side voltage of the converter dc1ref , collect the actual voltage value V on the DC side of the converter dc1 The difference between the two is obtained by the regulator PI1 d1ref ;

[0015] Extract ω1 through the phase-locked loop according to the voltage at the connection point between the new energy source and REVSC;

[0016] Collect the dq axis current i at the connection point between the new energy source and REVSC d1 、i q1 , and the dq axis voltage u d1 、u q1 ,i d1ref with i d1 The difference is added through the regulator PI2 and u d1 Subtract ωLi q1 Get v d1ref ;i q1refwith i q1 The difference is added through the regulator PI3 and u q1 Subtract ωLi d1 Get v q1ref ;

[0017] v d1ref With v q1ref Convert to v in abc coordinate system adc1ref ; Then it is converted into a PWM1 wave signal and input into the control signal of the new energy grid-connected inverter.

[0018] Preferably, the REVSC converter obtains a target reference value v of the voltage in the dq coordinate system of the AC side of the REVSC converter input Ld2ref 、v Lq2ref , the dq-axis inductor current parameters are obtained through the outer loop voltage PID controller, and then the dq-axis inductor voltage data is obtained through the inner loop current PID controller, which is converted into PWM wave as the DC side control signal of the REVSC converter; all control strategies work together to meet the power flow demand to achieve the conversion of the AC side voltage and frequency of the REVSC converter following the input data.

[0019] Preferably, the target reference value v of the voltage in the dq coordinate system of the AC side of the REVSC converter is Ld2ref 、v Lq2ref , through the Vf control strategy, the three-phase AC voltage at the connection point between the new energy and the flexible DC transmission system is stabilized. The specific process is as follows:

[0020] Obtain ω2 according to the grid-connected standard frequency;

[0021] Set the target reference value v of the voltage in the dq coordinate system of the AC side of the REVSC converter Ld2ref 、v Lq2ref , collect the actual voltage value v in the dq coordinate system of the AC side of the REVSC converter Ld2 、v Lq2 , the difference between the reference value and the actual value is respectively passed through the regulator PI6 and the regulator PI7 to obtain the deviation value;

[0022] Collect the actual current value i in the dq coordinate system of the AC side of the REVSC converter d2 、i q2 , based on the dq axis deviation values ​​obtained in the previous step, add i d2 、i q2 , minus ω2Cv Ld2 ω2Cv Lq2 Get i Ld2ref 、i Lq2ref ;

[0023] Collect the dq axis current i on the inductor side of the REVSC converterLd2 、i Lq2 , and the dq axis voltage v Ld2 、v Lq2 ,i Ld2ref 、i Lq2ref with i Ld2 、i Lq2 The difference is added to the regulator PI4 and the regulator PI5. Ld2 、v Lq2 Subtract ω2L i Ld2 ,ω2L i Lq2 Get v d2ref 、v q2ref ;

[0024] v d2ref 、v q2ref Convert to v in abc coordinate system adc2ref ; Then converted into PWM2 wave signal and input into the control signal of REVSC converter.

[0025] Preferably, the GSVSC converter obtains a target reference value V of the DC side voltage of the input GSVSC converter dcref and the target reference value P of the active power input at the grid connection point of the converter PCCref , through droop control and PID controller to PCCref Processing obtains the DC current control parameters of the system front end, and V dcref Process and obtain the PWM wave control signal of the GSVSC converter; all control strategies work together to meet the power demand of the power flow to achieve controllable DC voltage, AC voltage amplitude and AC side grid-connected frequency on both sides of the GSVSC converter.

[0026] Preferably, the target reference value V of the DC side voltage of the GSVSC converter is dcref and the target reference value P of the active power input at the grid connection point of the converter PCCref , through the matching control strategy, the DC voltage of the DC transmission line is stabilized. The AC side of the GSVSC is connected to the AC grid through the line impedance. The specific process is as follows:

[0027] Set the target reference value V of the DC side voltage of the converter dcref , collect the actual voltage value V on the DC side of the converter dc ;

[0028] Set the target reference value f of the AC grid frequency ref According to the domestic frequency standard, let f ref =50Hz, and the target reference value ω of the simulated synchronous motor rotor angular velocity is obtained. ref , we can get the V matching the inner loop dc-ωThe coefficient η is:

[0029]

[0030] Collect the three-phase voltage V at the inverter grid connection point C , three-phase current i abc ;

[0031] Calculate the active power P input at the inverter grid connection point based on the three-phase voltage and three-phase current PCC And the three-phase voltage effective value at the inverter grid connection point||V C ||;

[0032] According to the line voltage amplitude V of the AC power grid CL , calculate the target reference value of the effective value of the phase voltage at the grid-connected point of the converter || V C || ref , calculate ||V C || ref and ||V obtained in step S404 C The difference between ||Δ||V C ||, Δ||V C ||Input control module PI9 to obtain the amplitude deviation compensation Δμ of the modulation signal, as shown below:

[0033]

[0034] Among them, K P_μ is the proportional control parameter; K I_μ is the integral control parameter; s is the complex variable in Laplace transform;

[0035] According to the line voltage amplitude V of the AC power grid CL , calculate the target reference value of the effective value of the line voltage || V CL || ref , set the amplitude of the modulation signal μ ref , as shown below:

[0036]

[0037] Δμ plus μ obtained in step S406 ref Get the modulation signal amplitude μ;

[0038] Set the target reference value of the active power input at the inverter grid connection point to P PCCref , calculate P PCCref and P obtained in step S404 PCC The difference between the two is multiplied by the active droop coefficient K to obtain the DC voltage amplitude deviation compensation ΔV dc , ΔV dc Add Vdcref Subtract V dc Input control module PI8 to obtain the DC current amplitude deviation compensation ΔI s , as shown below:

[0039]

[0040] Among them, K P_Is is the proportional control parameter; K I_Is is the integral control parameter; s is the complex variable in Laplace transform;

[0041] P PCCref Divide by V dcref Get the target reference value I of DC current sref , I sref Add ΔI s Get the DC current I s ;

[0042] V dc Multiply by η to get the simulated synchronous motor rotor angular velocity ω; integrate the angular velocity ω to get the phase θ;

[0043] The modulated wave signal can be obtained from the phase θ and the modulation signal amplitude μ, as shown below:

[0044]

[0045] Preferably, the control device includes control strategies for three converters: the new energy side, REVSC, and GSVSC; wherein the control strategy for each converter includes the following modules:

[0046] Input module: obtain the input reference value of the controlled parameter;

[0047] Measurement unit: The measurement unit is used to measure and sample the key parameters of voltage, current and frequency in real time;

[0048] Control module: converts input data and measurement data into control signals of the converter through control strategies;

[0049] Modulation module: converts the control signal into a modulation wave through PWM technology to directly control the converter;

[0050] Output module: connects the converter output data to the grid.

[0051] Preferably, a computer device comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor implements the method according to any one of claims 1 to 4 when executing the computer program.

[0052] Preferably, a computer-readable storage medium stores a computer program thereon, wherein the computer program implements the method according to any one of claims 1 to 4 when executed by a processor.

[0053] Therefore, the present invention adopts the above-mentioned new energy network control method based on matching control through flexible direct current transmission system, which does not require a phase-locked loop to extract the phase. By using DC voltage to match the angular velocity of the synchronous machine rotor to simulate the synchronous machine to obtain the angular velocity and phase, it overcomes oscillation and other problems in a hybrid power grid where synchronous machines and inverters coexist, and has stability.

[0054] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 It is a structural schematic diagram of the new energy grid-connected system via VSC-HVQC of the present invention;

[0056] Figure 2 It is a structural topology and control strategy diagram of the circuit of the new energy through flexible direct current transmission system of the present invention;

[0057] Figure 3 is the actual power change at the grid connection point when the power reference value changes in the embodiment of the present invention;

[0058] Figure 4 It is the change of DC voltage at the flexible DC channel when the power reference value changes in the embodiment of the present invention. DETAILED DESCRIPTION

[0059] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0060] The present invention provides a method for controlling a network of a new energy source through a flexible direct current transmission system based on matching control, comprising the following steps:

[0061] S1. Build a grid-connected system for the new energy field through a flexible DC transmission system.

[0062] The grid-connected system of the new energy field through the flexible direct current transmission system includes the new energy plant and the flexible direct current transmission system (VSC-HVDC). Figure 1 As shown in the figure, the new energy field is mainly composed of photovoltaic arrays, with a port voltage of 690V, which is connected to the 35kV line through the new energy step-up transformer and then connected to the VSC-HVDC system through the 35 / 110kV transformer. The new energy side is simplified, and the simplified circuit uses a current source parallel capacitor structure to simulate the power sent by the new energy field. The target reference value of the DC side voltage of the new energy side converter is V dc1ref , through the VdcIq control strategy, the DC side voltage is stabilized. The specific implementation steps are as follows:

[0063] The new energy side converter obtains the target reference value V of the DC side voltage of the input converter dc1ref , the dq axis current parameters are obtained through the outer loop voltage PID controller, and then the dq axis voltage data is obtained through the inner loop current PID controller, which is converted into PWM wave as the AC side control signal of the new energy side converter; all control strategies work together to meet the power flow demand so as to achieve the control of the DC side voltage of the new energy side converter following the input reference value.

[0064] The VSC-HVDC system consists of a renewable energy side VSC (REVSC), a grid side VSC (GSVSC) and a DC line. The target reference value v of the voltage on the AC side of the REVSC converter in the dq coordinate system is Ld2ref 、v Lq2ref , through the Vf control strategy, the three-phase AC voltage at the connection point between the new energy and the flexible DC transmission system is stabilized. The specific implementation steps are as follows:

[0065] The REVSC converter obtains the target reference value v of the voltage in the dq coordinate system of the AC side of the REVSC converter input Ld2ref 、v Lq2ref , the dq-axis inductor current parameters are obtained through the outer loop voltage PID controller, and then the dq-axis inductor voltage data is obtained through the inner loop current PID controller, which is converted into PWM wave as the DC side control signal of the REVSC converter; all control strategies work together to meet the power flow demand to achieve the conversion of the AC side voltage and frequency of the REVSC converter following the input data.

[0066] The target reference value V of the DC side voltage of the GSVSC converter dcref and the target reference value P of the active power input at the grid connection point of the converter PCCref , through the matching control strategy, the DC voltage of the DC transmission line is stabilized, and the AC side of the GSVSC is connected to the AC grid through the line impedance. The specific implementation steps are as follows:

[0067] The GSVSC converter obtains the target reference value V of the DC side voltage of the input GSVSC converter dcref and the target reference value P of the active power input at the grid connection point of the converter PCCref , through droop control and PID controller to PCCref Processing obtains the DC current control parameters of the system front end, and V dcrefProcess and obtain the PWM wave control signal of the GSVSC converter; all control strategies work together to meet the power demand of the power flow to achieve controllable DC voltage, AC voltage amplitude and AC side grid-connected frequency on both sides of the GSVSC converter.

[0068] S2. Establish a control strategy for the new energy side converter using VdcIq.

[0069] like Figure 2 As shown, the converter on the new energy side uses the VdcIq control strategy. The specific process is as follows:

[0070] S21, set the target reference value V of the DC side voltage of the converter dc1ref , collect the actual voltage value V on the DC side of the converter dc1 The difference between the two is obtained by the regulator PI1 d1ref ;

[0071] S22, extracting ω1 through a phase-locked loop according to the voltage at the connection point between the new energy source and REVSC;

[0072] S23, collect the dq axis current i at the connection point between the new energy source and REVSC d1 、i q1 , and the dq axis voltage u d1 、u q1 ,i d1ref with i d1 The difference is added through the regulator PI2 and u d1 Subtract ωLi q1 Get v d1ref ;i q1ref with i q1 The difference is added through the regulator PI3 and u q1 Subtract ωLi d1 Get v q1ref ;

[0073] S24, v d1ref With v q1ref Convert to v in abc coordinate system adc1ref ; Then it is converted into a PWM1 wave signal and input into the control signal of the new energy grid-connected inverter.

[0074] S3. Establish the control strategy of REVSC using Vf.

[0075] like Figure 2 As shown, REVSC uses the Vf control strategy, and the specific process is as follows:

[0076] S31, obtaining ω2 according to the grid-connected standard frequency;

[0077] S32, set the target reference value v of the voltage in the dq coordinate system on the AC side of the REVSC converterLd2ref 、v Lq2ref , collect the actual voltage value v in the dq coordinate system of the AC side of the REVSC converter Ld2 、v Lq2 , the difference between the reference value and the actual value is respectively passed through the regulator PI6 and the regulator PI7 to obtain the deviation value;

[0078] S33, collect the actual current value i in the dq coordinate system of the AC side of the REVSC converter d2 、i q2 , based on the dq axis deviation values ​​obtained in the previous step, add i d2 、i q2 , minus ω2Cv Ld2 ω2Cv Lq2 Get i Ld2ref 、i Lq2ref ;

[0079] S34, collect the dq axis current i on the inductor side of the REVSC converter Ld2 、i Lq2 , and the dq axis voltage v Ld2 、v Lq2 ,i Ld2ref 、i Lq2ref with i Ld2 、i Lq2 The difference is added to the regulator PI4 and the regulator PI5. Ld2 、v Lq2 Subtract ω2L i Ld2 ,ω2L i Lq2 Get v d2ref 、v q2ref ;

[0080] S35, v d2ref 、v q2ref Convert to v in abc coordinate system adc2ref ; Then converted into PWM2 wave signal and input into the control signal of REVSC converter.

[0081] S4. Establish a strategy for GSVSC to use matching control.

[0082] like Figure 2 As shown, GSVSC uses a matching control strategy, and the specific process is as follows:

[0083] S401, setting the target reference value V of the DC side voltage of the converter dcref , collect the actual voltage value V on the DC side of the converter dc ;

[0084] S402, setting the target reference value f of the AC power grid frequency refAccording to the domestic frequency standard, let f ref =50Hz, and the target reference value ω of the simulated synchronous motor rotor angular velocity is obtained. ref , we can get the V matching the inner loop dc-ω The coefficient η is:

[0085]

[0086] S403, collect the three-phase voltage V at the grid connection point of the converter C , three-phase current i abc ;

[0087] S404: Calculate the active power P input at the grid connection point of the converter according to the three-phase voltage and three-phase current acquired in step S403. PCC And the three-phase voltage effective value at the inverter grid connection point||V C ||;

[0088] S405, according to the line voltage amplitude V of the AC power grid CL , calculate the target reference value of the effective value of the phase voltage at the grid-connected point of the converter || V C || ref , calculate ||V C || ref and ||V obtained in step S404 C The difference between ||Δ||V C ||, Δ||V C ||Input control module PI9 to obtain the amplitude deviation compensation Δμ of the modulation signal, as shown below:

[0089]

[0090] Among them, K P_μ is the proportional control parameter; K I_μ is the integral control parameter; s is the complex variable in Laplace transform;

[0091] S406, according to the line voltage amplitude V of the AC power grid CL , calculate the target reference value of the effective value of the line voltage || V CL || ref , set the amplitude of the modulation signal μ ref , as shown below:

[0092]

[0093] S407, Δμ obtained in step S405 plus μ obtained in step S406 ref Get the modulation signal amplitude μ;

[0094] S408, setting the target reference value of the active power input at the inverter grid connection point to P PCCref , calculate P PCCref and P obtained in step S404 PCC The difference between the two is multiplied by the active droop coefficient K to obtain the DC voltage amplitude deviation compensation ΔV dc , ΔV dc Add V dcref Subtract V dc Input control module PI8 to obtain the DC current amplitude deviation compensation ΔI s , as shown below:

[0095]

[0096] Among them, K P_Is is the proportional control parameter; K I_Is is the integral control parameter; s is the complex variable in Laplace transform;

[0097] S409: P set in step S408 PCCref Divided by the V set in step S401 dcref Get the target reference value I of DC current sref , I sref Add the ΔI obtained in step S408 s Get the DC current I s ;

[0098] S410: V collected in step S401 dc Multiplying by η obtained in step S402 obtains the simulated synchronous motor rotor angular velocity ω; integrating the angular velocity ω obtains the phase θ;

[0099] S411, the modulated wave signal can be obtained from the phase θ and the modulation signal amplitude μ, as shown below:

[0100]

[0101] In addition, when the grid frequency is normally 50Hz, the frequency fluctuation cannot exceed ±0.2Hz, which can achieve V dc V dcref Due to the existence of the η coefficient, the converter has the frequency support capability and can track f ref ; At this time P PCC It can also achieve P PCCref Tracking; AC side three-phase voltage effective value || V C ||Can also track||V C || ref When the grid frequency fluctuates and changes to f, V dc Track f in proportion to the η coefficient, and PPCC The active frequency droop characteristic is shown as follows:

[0102]

[0103] V dcref -V dc -K(P PCC -P PCCref )=0;

[0104]

[0105] According to the above method, the present invention also proposes a network control device for a new energy flexible direct current transmission system based on matching control, which includes control strategies for three converters: a new energy side, a REVSC, and a GSVSC; wherein the control strategy of each converter includes the following modules:

[0106] Input module: obtain the input reference value of the controlled parameter;

[0107] Measurement unit: The measurement unit is used to measure and sample the key parameters of voltage, current and frequency in real time;

[0108] Control module: converts input data and measurement data into control signals of the converter through control strategies;

[0109] Modulation module: converts the control signal into a modulation wave through PWM technology to directly control the converter;

[0110] Output module: connects the converter output data to the grid.

[0111] A computer device comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor implements the control method proposed in the present invention when executing the computer program.

[0112] A computer-readable storage medium stores a computer program, which implements the control method proposed in the present invention when executed by a processor.

[0113] Example

[0114] After building the relevant model in Matlab, simulation verification was carried out. The relevant parameters of the double-terminal flexible DC system are shown in Table 1, and the control parameters of the three converters are shown in Table 2, Table 3 and Table 4;

[0115] Table 1 Related parameters of double-ended flexible direct current system

[0116]

[0117] Table 2 Control parameter settings for the new energy side

[0118]

[0119] Table 3 Vf control parameter settings of REVSC

[0120]

[0121] Table 4 GSVSC matching control parameter settings

[0122] Parameter name Value Parameter name Value <![CDATA[DC voltage reference value V dcref > 200kV <![CDATA[The effective value of the three-phase voltage at the grid connection point ||V C ||]]> 220kV / √3 / √2 <![CDATA[Grid connection point power reference value P PCCref > 100MW <![CDATA[Modulation signal amplitude μ ref > 1.1 Grid connection point line voltage amplitude 220kV <![CDATA[DC current reference value I sref > 500A <![CDATA[V for matching the inner control loop dc-ω Coefficient η]]> 0.00157 Active power droop coefficient K 0.00004 <![CDATA[K P_μ ]]> 0.00001 <![CDATA[K P_Vdc1ref ]]> 3 <![CDATA[K I_μ ]]> 0.001 <![CDATA[K I_Vdc1ref ]]> 10

[0123] When the grid frequency is stable at 50Hz, set P PCCref From 124MW to 100MW in the 6th second, the simulation results are as follows:

[0124] like Figure 3 As shown in Figure 2, the AC side output power of GSVSC can keep up with the reference value; Figure 4 As shown, the GSVSC DC voltage tracks the reference value and can recover stability as quickly as possible after the power reference value changes.

[0125] Therefore, the present invention adopts the above-mentioned new energy network control method based on matching control through flexible direct current transmission system, which does not require a phase-locked loop to extract the phase. By using DC voltage to match the angular velocity of the synchronous machine rotor to simulate the synchronous machine to obtain the angular velocity and phase, it overcomes oscillation and other problems in a hybrid power grid where synchronous machines and inverters coexist, and has stability.

[0126] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for controlling a network of a new energy source through a flexible direct current transmission system based on matching control, characterized in that: The following steps are involved: Build a grid-connected system for new energy fields via a flexible DC transmission system, including a new energy plant and a flexible DC transmission system; the new energy field consists of a photovoltaic array; the flexible DC transmission system consists of a new energy field-side converter REVSC, a grid-side converter GSVSC and a DC line; The terminal voltage of the new energy field is 690V, which is fed into the 35kV line through the new energy step-up transformer, and then connected to the flexible DC transmission system through the 35 / 110kV transformer; Target reference value V of DC side voltage of new energy side converter dc1ref , through the VdcIq control strategy, the DC side voltage is stabilized; The target reference value v of the voltage in the dq coordinate system of the AC side of the REVSC converter Ld2ref 、v Lq2ref , through the Vf control strategy, the three-phase AC voltage at the connection point between the renewable energy and the flexible DC transmission system is stabilized; The target reference value V of the DC side voltage of the GSVSC converter dcref and the target reference value P of the active power input at the grid connection point of the converter PCCref ,Through the matching based control strategy, the DC voltage of the DC transmission line is stabilized, and the AC side of the GSVSC is connected to the AC grid through the line impedance.

2. According to the matching control-based method of claim 1, the method is characterized in that: The new energy side converter obtains the target reference value V of the DC side voltage of the input converter dc1ref , the dq axis current parameters are obtained through the outer loop voltage PID controller, and then the dq axis voltage data is obtained through the inner loop current PID controller, which is converted into PWM wave as the AC side control signal of the new energy side converter; all control strategies work together to meet the power flow demand so as to achieve the control of the DC side voltage of the new energy side converter following the input reference value.

3. According to the matching control-based method of claim 2, the method is characterized in that: Target reference value V of DC side voltage of new energy side converter dc1ref , through the VdcIq control strategy, the DC side voltage is stabilized. The specific process is as follows: Set the target reference value V of the DC side voltage of the converter dc1ref , collect the actual voltage value V on the DC side of the converter dc1 The difference between the two is obtained by the regulator PI1 d1ref ; Extract ω1 through the phase-locked loop according to the voltage at the connection point between the new energy source and REVSC; Collect the dq axis current i at the connection point between the new energy source and REVSC d1 、i q1 , and the dq axis voltage u d1 、u q1 ,i d1ref with i d1 The difference is added through the regulator PI2 and u d1 Subtract ωLi q1 Get v d1ref ;i q1ref with i q1 The difference is added through the regulator PI3 and u q1 Subtract ωLi d1 Get v q1ref ; v d1ref With v q1ref Convert to v in abc coordinate system adc1ref ; Then it is converted into a PWM1 wave signal and input into the control signal of the new energy grid-connected inverter.

4. According to the matching control-based method of claim 1, the method is characterized in that: The REVSC converter obtains the target reference value v of the voltage in the dq coordinate system of the AC side of the REVSC converter input Ld2ref 、v Lq2ref , the dq-axis inductor current parameters are obtained through the outer loop voltage PID controller, and then the dq-axis inductor voltage data is obtained through the inner loop current PID controller, which is converted into PWM wave as the DC side control signal of the REVSC converter; all control strategies work together to meet the power flow demand to achieve the conversion of the AC side voltage and frequency of the REVSC converter following the input data.

5. According to the matching control-based method of claim 4, the method is characterized in that: The target reference value v of the voltage in the dq coordinate system of the AC side of the REVSC converter Ld2ref 、v Lq2ref , through the Vf control strategy, the three-phase AC voltage at the connection point between the new energy and the flexible DC transmission system is stabilized. The specific process is as follows: Obtain ω2 according to the grid-connected standard frequency; Set the target reference value v of the voltage in the dq coordinate system of the AC side of the REVSC converter Ld2ref 、v Lq2ref , collect the actual voltage value v in the dq coordinate system of the AC side of the REVSC converter Ld2 、v Lq2 , the difference between the reference value and the actual value is respectively passed through the regulator PI6 and the regulator PI7 to obtain the deviation value; Collect the actual current value i in the dq coordinate system of the AC side of the REVSC converter d2 、i q2 , based on the dq axis deviation values ​​obtained in the previous step, add i d2 、i q2 , minus ω2Cv Ld2 ω2Cv Lq2 Get i Ld2ref 、i Lq2ref ; Collect the dq axis current i on the inductor side of the REVSC converter Ld2 、i Lq2 , and the dq axis voltage v Ld2 、v Lq2 ,i Ld2ref 、i Lq2ref with i Ld2 、i Lq2 The difference is added to the regulator PI4 and the regulator PI5. Ld2 、v Lq2 Subtract ω2L i Ld2 ,ω2L i Lq2 Get v d2ref 、v q2ref ; v d2ref 、v q2ref Convert to v in abc coordinate system adc2ref ; Then converted into PWM2 wave signal and input into the control signal of REVSC converter.

6. According to the matching control-based method of claim 1, the method is characterized in that: The GSVSC converter obtains the target reference value V of the DC side voltage of the input GSVSC converter dcref and the target reference value P of the active power input at the grid connection point of the converter PCCref , through droop control and PID controller to PCCref Processing obtains the DC current control parameters of the system front end, and V dcref Process and obtain the PWM wave control signal of the GSVSC converter; all control strategies work together to meet the power demand of the power flow to achieve controllable DC voltage, AC voltage amplitude and AC side grid-connected frequency on both sides of the GSVSC converter.

7. According to claim 6, a method for controlling the network construction of a new energy flexible direct current transmission system based on matching control, characterized in that: The target reference value V of the DC side voltage of the GSVSC converter dcref and the target reference value P of the active power input at the grid connection point of the converter PCCref , through the matching control strategy, the DC voltage of the DC transmission line is stabilized. The AC side of the GSVSC is connected to the AC grid through the line impedance. The specific process is as follows: Set the target reference value V of the DC side voltage of the converter dcref , collect the actual voltage value V on the DC side of the converter dc ; Set the target reference value f of the AC grid frequency ref According to the domestic frequency standard, let f ref =50Hz, and the target reference value ω of the simulated synchronous motor rotor angular velocity is obtained. ref , we can get the V matching the inner loop dc-ω The coefficient η is: Collect the three-phase voltage V at the inverter grid connection point C , three-phase current i abc ; Calculate the active power P input at the inverter grid connection point based on the three-phase voltage and three-phase current PCC And the three-phase voltage effective value at the inverter grid connection point||V C ||; According to the line voltage amplitude V of the AC power grid CL , calculate the target reference value of the effective value of the phase voltage at the grid-connected point of the converter || V C || ref , calculate ||V C || ref With ||V C The difference between ||Δ||V C ||, Δ||V C ||Input control module PI9 to obtain the amplitude deviation compensation Δμ of the modulation signal, as shown below: Among them, K P_μ is the proportional control parameter; K I_μ is the integral control parameter; s is the complex variable in Laplace transform; According to the line voltage amplitude V of the AC power grid CL , calculate the target reference value of the effective value of the line voltage || V CL || ref , set the amplitude of the modulation signal μ ref , as shown below: Δμ plus μ ref Get the modulation signal amplitude μ; Set the target reference value of the active power input at the inverter grid connection point to P PCCref , calculate P PCCref With P PCC The difference between the two is multiplied by the active droop coefficient K to obtain the DC voltage amplitude deviation compensation ΔV dc , ΔV dc Add V dcref Subtract V dc Input control module PI8 to obtain the DC current amplitude deviation compensation ΔI s , as shown below: Among them, K P_Is is the proportional control parameter; K I_Is is the integral control parameter; s is the complex variable in Laplace transform; P PCCref Divide by V dcref Get the target reference value I of DC current sref , I sref Add ΔI s Get the DC current I s ; V dc Multiply by η to get the simulated synchronous motor rotor angular velocity ω; integrate the angular velocity ω to get the phase θ; The modulated wave signal can be obtained from the phase θ and the modulation signal amplitude μ, as shown below:

8. A network control device for a new energy flexible direct current transmission system based on matching control according to the method of any one of claims 1 to 7, characterized in that: The control device includes control strategies for three converters: the new energy side, REVSC, and GSVSC; wherein the control strategy for each converter includes the following modules: Input module: obtain the input reference value of the controlled parameter; Measurement unit: The measurement unit is used to measure and sample the key parameters of voltage, current and frequency in real time; Control module: converts input data and measurement data into control signals of the converter through control strategies; Modulation module: converts the control signal into a modulation wave through PWM technology to directly control the converter; Output module: connects the converter output data to the grid.

9. A computer device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the method according to any one of claims 1 to 4 is implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method according to any one of claims 1 to 4 is implemented.

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