New energy grid-connected detection platform power grid impedance simulation control method

Abstract

The invention relates to the technical field of power grid impedance simulation control, and discloses a new energy grid-connected detection platform power grid impedance simulation control method which is based on a new energy grid-connected detection platform. Comprising the steps of output voltage and current sampling, phase voltage calculation, coordinate transformation, voltage regulation, modulation wave calculation, static coordinate system conversion, voltage calculation under simulation power grid impedance, SVPWM modulation and the like. According to the method, through accurate calculation and adjustment of each step, high-precision grid-connected performance evaluation can be realized, and reliable operation of new energy equipment under different conditions is ensured; performance testing can be carried out on different types of new energy equipment, by optimizing voltage regulation and SVPWM modulation, improvement of electric energy quality, reduction of harmonic waves and voltage fluctuation and guarantee of stability and high efficiency of a power system are facilitated, power grid impedance is simulated in a wide frequency domain, and engineering implementation is easy.

Description

Technical Field

[0001] The present invention relates to the technical field of power grid impedance simulation control, and in particular to a power grid impedance simulation control method for a new energy grid-connected detection platform. Background Art

[0002] At present, the new power system with new energy as the main body is gradually approaching. The continuous influx of high-proportion new energy power and the large-scale access of power electronic equipment will bring huge challenges to the safe and stable operation of the system. The power system has put forward increasingly stringent requirements on the operation ability of grid-connected new energy and power electronic equipment under external power grid faults. In order to study and test the operation ability of new energy and power electronic equipment under various power grid faults, special equipment is needed to accurately reproduce various states and fault conditions of the power grid, that is, the new energy grid-connected detection platform.

[0003] Since new energy power generation systems, mainly photovoltaic and wind power, are mostly distributed in remote places such as deserts and islands, they need to be connected to the grid through long-distance transmission and distribution lines. At this time, the system line impedance will not only change the impedance characteristics of the power grid, making the power grid present weak grid characteristics, but also affect the working performance of the power electronic grid-connected device, causing system stability problems. Therefore, in order to more realistically simulate the working conditions of the actual power grid and detect the weak grid adaptability of the power electronic grid-connected device, the new energy grid-connected detection platform should have the function of grid impedance simulation. Considering that the power grid contains high-frequency harmonics, only simulating the grid impedance characteristics at the fundamental frequency can no longer reflect the actual power grid situation. To this end, scholars have done some research on the grid impedance simulation control of the new energy grid-connected detection platform. For example, the Chinese invention patent application disclosure specification (CN116819210A) published on September 29, 2023, entitled "A control method, control device and power grid simulator for a power grid simulator", discloses a power grid impedance simulation control method, which uses an improved voltage and current dual closed-loop control strategy to control the power grid simulator, and obtains a direct-axis optimized voltage instruction by superimposing a direct-axis virtual impedance voltage divider on the direct-axis setting voltage instruction, and obtains a quadrature-axis optimized voltage instruction by superimposing a quadrature-axis virtual impedance voltage divider on the quadrature-axis setting voltage instruction, thereby simulating the power grid impedance. For example, the Chinese invention patent application disclosure specification (CN118068125A) published on May 24, 2024, entitled "Power grid simulator control method with transmission line impedance wide-frequency domain simulation function", discloses a wide-frequency domain power grid impedance simulation control method, which uses a distributed parameter circuit model to process the transmission line, and realizes a wide-frequency domain, high-precision, dynamic and real-time simulation of the power grid impedance through a multi-order linearization approximation method combined with a voltage and current closed-loop feedback control loop.

[0004] The Chinese invention patent application disclosure specification (CN116819210A) published on September 29, 2023, entitled "A control method, control device and power grid simulator for a power grid simulator", only simulates the power grid impedance characteristics at the fundamental frequency, but the actual power grid contains high-frequency harmonics, and the power grid impedance simulation at the fundamental frequency cannot reflect the actual power grid characteristics. The Chinese invention patent application disclosure specification (CN118068125A) published on May 24, 2024, entitled "Power grid simulator control method with wide-frequency domain simulation function of transmission line impedance", although this method simulates the power grid impedance in the wide-frequency domain, it is too complex and difficult to implement in engineering.

[0005] In summary, there is an urgent need for a grid impedance simulation control method for a new energy grid-connected detection platform that can simulate the grid impedance in a wide frequency domain. Summary of the invention

[0006] In order to solve the above problems, the present invention proposes a grid impedance simulation control method for a new energy grid-connected detection platform.

[0007] The technical solution adopted by the present invention is:

[0008] A method for simulating and controlling the impedance of a power grid of a new energy grid-connected detection platform, the method being based on the new energy grid-connected detection platform; the new energy grid-connected detection platform comprising a DC / AC inverter unit, a DC power supply connected to the DC side of the DC / AC inverter unit, a filter circuit connected to the AC side of the DC / AC inverter unit, a transformer connected to the filter circuit, and a device under test connected to the transformer;

[0009] The grid impedance simulation control method of the new energy grid-connected detection platform is based on the new energy grid-connected detection platform. By simulating and controlling the grid impedance, the grid-connected performance of various new energy power electronic equipment is studied and tested.

[0010] Furthermore, the grid impedance simulation control method of the new energy grid connection detection platform includes the following steps:

[0011] Step 1, output voltage and current sampling:

[0012] Sample the actual value of the three-phase output line voltage of the new energy grid-connected detection platform and record it as U ab , U bc , U ca ; Sample the actual value of the three-phase output line current of the new energy grid-connected detection platform and record it as I a ,I b ,I c ;

[0013] Step 2, calculate the phase voltage:

[0014] According to the actual value U of the three-phase output line voltage sampled in step 1 ab , U bc , U ca , the three-phase output phase voltage U is calculated a , U b , U c ;

[0015] Step 3, coordinate transformation:

[0016] Through synchronous rotating coordinate transformation, the three-phase output phase voltage U obtained in step 2 is a , U b , U c Converted into the d-axis component U of the three-phase output voltage in the rotating coordinate system d And the q-axis component U of the three-phase grid voltage q ;

[0017] Step 4, voltage regulation:

[0018] According to the system three-phase output voltage d-axis component reference value U dref , System three-phase output voltage q-axis component reference value U qref , and the three-phase output voltage d-axis component U obtained in step 3 d And the q-axis component U of the three-phase grid voltage q , respectively through the d-axis voltage regulator and the q-axis voltage regulator, the d-axis voltage regulator output U is calculated cnt_d and the q-axis voltage regulator output U cnt_q ;

[0019] Step 5, calculate the modulation wave:

[0020] According to the system three-phase output voltage d-axis component reference value U dref , System three-phase output voltage q-axis component reference value U qref , and the d-axis voltage regulator output U obtained in step 4 cnt_d and the q-axis voltage regulator output U cnt_q , the d-axis component U of the system three-phase output voltage modulation wave is calculated od The q-axis component U of the system three-phase output voltage modulation wave oq ;

[0021] Step 6, stationary coordinate system conversion:

[0022] According to the system three-phase output voltage modulation wave d-axis component U obtained in step 5 od The q-axis component U of the system three-phase output voltage modulation wave oq , through synchronous rotating coordinate transformation to the system three-phase output voltage modulation wave u in the stationary coordinate system oa 、u ob 、uoc ;

[0023] Step 7, calculate the voltage under the simulated grid impedance:

[0024] According to the system three-phase output voltage modulation wave u in the stationary coordinate system obtained in step 6 oa 、u ob 、u oc , the actual value of the three-phase output line current sampled in step 1 I a ,I b ,I c , the three-phase output voltage modulation wave e of the system after simulating the grid impedance in the stationary coordinate system is calculated a 、e b 、e c ;

[0025] Step 8, SVPWM modulation:

[0026] After simulating the grid impedance in the stationary coordinate system obtained in step 7, the three-phase output voltage modulation wave e a 、e b 、e c Send it to the SVPWM modulation module for modulation and wave generation.

[0027] Further, in step 2, the three-phase output phase voltage U a , U b , U c The calculation formula is:

[0028]

[0029] Where U a , U b , U c is the three-phase output phase voltage; U ab , U bc , U ca To sample the actual value of the three-phase output line voltage of the new energy grid-connected detection platform.

[0030] Furthermore, in step 3, the calculation formula for coordinate transformation is:

[0031]

[0032] Where U d is the d-axis component of the three-phase output voltage in the rotating coordinate system; U q is the q-axis component of the three-phase grid voltage in the rotating coordinate system; U a , U b , U c is the three-phase output phase voltage; θ is the starting impedance angle of the system.

[0033] Further, in step 4, the d-axis voltage regulator outputs U cnt_d and the q-axis voltage regulator output U cnt_q The calculation formula is:

[0034]

[0035] Where U cnt_d is the output of the d-axis voltage regulator; U cnt_q is the output of the q-axis voltage regulator; K up is the voltage regulator proportional coefficient; K ui is the voltage regulator integral coefficient; z Represents variables in the discrete time domain and is used to describe the dynamic behavior of the system; T s is the control period; U dref is the reference value of the d-axis component of the system three-phase output voltage; U d is the d-axis component of the three-phase output voltage in the rotating coordinate system; U qref is the reference value of the q-axis component of the system three-phase output voltage; U q is the q-axis component of the three-phase grid voltage in the rotating coordinate system.

[0036] Further, in step 5, the system three-phase output voltage modulation wave d-axis component U od The q-axis component U of the system three-phase output voltage modulation wave oq The calculation formula is:

[0037]

[0038] Where U od is the d-axis component of the system three-phase output voltage modulation wave; U oq is the q-axis component of the system three-phase output voltage modulation wave; U dref is the reference value of the d-axis component of the system three-phase output voltage; U qref is the reference value of the q-axis component of the system three-phase output voltage; U cnt_d is the output of the d-axis voltage regulator; U cnt_q is the q-axis voltage regulator output.

[0039] Furthermore, in step 6, the calculation formula for the stationary coordinate system conversion is:

[0040]

[0041] In the formula, u oa 、u ob 、u oc is the three-phase output voltage modulation wave of the system in the stationary coordinate system; U od is the d-axis component of the system three-phase output voltage modulation wave; U oqis the q-axis component of the system's three-phase output voltage modulation wave; θ is the system's starting impedance angle.

[0042] Further, in step 7, after simulating the grid impedance in the stationary coordinate system, the system three-phase output voltage modulation wave e a 、e b 、e c The calculation formula is:

[0043]

[0044] In the formula, e a 、e b 、e c is the three-phase output voltage modulation wave of the system after simulating the grid impedance in the stationary coordinate system; u oa 、u ob 、u oc is the three-phase output voltage modulation wave of the system in the stationary coordinate system; Lg is the equivalent inductance of the grid impedance; I a ,I b ,I c It is to sample the actual value of the three-phase output line current of the new energy grid-connected detection platform; Ts is the control period; z To represent variables in the discrete time domain, it is used to describe the dynamic behavior of the system.

[0045] Compared with the existing technology, the grid impedance simulation control method of the new energy grid-connected detection platform has the following beneficial effects:

[0046] Reliability and accuracy: The grid impedance simulation control method of the new energy grid-connected detection platform can achieve high-precision grid-connected performance evaluation through precise calculation and adjustment of each step, ensuring the reliable operation of new energy equipment under different conditions.

[0047] Versatility: The grid impedance simulation control method of the new energy grid-connected detection platform can perform performance tests on different types of new energy equipment, effectively adapt to a variety of application scenarios, and enhance the wide applicability of the test.

[0048] Improve power quality: By optimizing voltage regulation and SVPWM modulation, it helps to improve power quality, reduce harmonics and voltage fluctuations, and ensure the stability and efficiency of the power system.

[0049] Promoting the development of new energy: By improving the grid-connected performance of new energy equipment, it helps to improve the utilization efficiency of renewable energy, support the realization of sustainable development goals, and improve the optimization of the overall energy structure.

[0050] In summary, the grid impedance simulation control method of the new energy grid-connected detection platform can simulate the grid impedance in a wide frequency domain, and the engineering implementation is simple. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0052] in:

[0053] Figure 1 It is a schematic diagram of the composition of the new energy grid-connected detection platform of the present invention;

[0054] Figure 2 This is a control block diagram of a new energy grid-connected detection platform of the present invention;

[0055] Figure 3 The present invention is a flow chart of the grid impedance simulation control method of the new energy grid-connected detection platform. DETAILED DESCRIPTION

[0056] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0057] The prior art only simulates the grid impedance characteristics at the fundamental frequency, but the actual grid contains high-frequency harmonics, and the grid impedance simulation at the fundamental frequency cannot reflect the actual grid characteristics; at the same time, although the grid impedance is simulated in a wide frequency domain, it is too complicated and difficult to implement in engineering. Therefore, this embodiment provides a grid impedance simulation control method for a new energy grid-connected detection platform.

[0058] The grid impedance simulation control method of the new energy grid-connected detection platform is based on the new energy grid-connected detection platform; Figure 1 As shown, the new energy grid-connected detection platform includes a DC / AC inverter unit, a DC power supply connected to the DC side of the DC / AC inverter unit, a filter circuit connected to the AC side of the DC / AC inverter unit, a transformer connected to the filter circuit, and a device under test connected to the transformer; the device under test is a new energy and power electronic device whose grid-connected performance needs to be studied and tested. The grid impedance simulation control method of the new energy grid-connected detection platform is based on the new energy grid-connected detection platform, and the grid-connected performance of various new energy power electronic devices is studied and tested by simulating and controlling the grid impedance.

[0059] like Figure 2 and Figure 3As shown, the grid impedance simulation control method of the new energy grid-connected detection platform specifically includes the following steps:

[0060] Step 1, output voltage and current sampling:

[0061] Sample the actual value of the three-phase output line voltage of the new energy grid-connected detection platform and record it as U ab , U bc , U ca ; Sample the actual value of the three-phase output line current of the new energy grid-connected detection platform and record it as I a ,I b ,I c By accurately sampling the three-phase voltage and current, a basic data basis can be provided for subsequent analysis, ensuring real-time monitoring of the system and reliability of data.

[0062] Step 2, calculate the phase voltage:

[0063] According to the actual value U of the three-phase output line voltage sampled in step 1 ab , U bc , U ca , the three-phase output phase voltage U is calculated a , U b , U c ;

[0064] Three-phase output phase voltage U a , U b , U c The calculation formula is:

[0065]

[0066] Where U a , U b , U c is the three-phase output phase voltage; U ab , U bc , U ca To sample the actual value of the three-phase output line voltage of the new energy grid-connected detection platform.

[0067] Calculating the phase voltage helps convert the line voltage into the phase voltage, so that subsequent analysis and control can be based on more intuitive phasor data, thereby improving the accuracy of control.

[0068] Step 3, coordinate transformation:

[0069] Through synchronous rotating coordinate transformation, the three-phase output phase voltage U obtained in step 2 is a , U b , U c Converted into the d-axis component U of the three-phase output voltage in the rotating coordinate system d And the q-axis component U of the three-phase grid voltageq .

[0070] The calculation formula for coordinate transformation is:

[0071]

[0072] Where U d is the d-axis component of the three-phase output voltage in the rotating coordinate system; U q is the q-axis component of the three-phase grid voltage in the rotating coordinate system; U a , U b , U c is the three-phase output phase voltage; θ is the starting impedance angle of the system.

[0073] The phase voltage is converted into a synchronous rotating coordinate system (dq coordinate system), so that the control variables of power and current can be separated during the control process, which improves the effectiveness and response speed of the control algorithm.

[0074] Step 4, voltage regulation:

[0075] According to the system three-phase output voltage d-axis component reference value U dref , System three-phase output voltage q-axis component reference value U qref , and the three-phase output voltage d-axis component U obtained in step 3 d And the q-axis component U of the three-phase grid voltage q , respectively through the d-axis voltage regulator and the q-axis voltage regulator, the d-axis voltage regulator output U is calculated cnt_d and the q-axis voltage regulator output U cnt_q .

[0076] D-axis voltage regulator output U cnt_d and the q-axis voltage regulator output U cnt_q The calculation formula is:

[0077]

[0078] Where U cnt_d is the output of the d-axis voltage regulator; U cnt_q is the output of the q-axis voltage regulator; K up is the voltage regulator proportional coefficient; K ui is the voltage regulator integral coefficient; z represents the variable in the discrete time domain, which is used to describe the dynamic behavior of the system; T s is the control period; U dref is the reference value of the d-axis component of the system three-phase output voltage; U d is the d-axis component of the three-phase output voltage in the rotating coordinate system; U qref is the reference value of the q-axis component of the system three-phase output voltage; U qis the q-axis component of the three-phase grid voltage in the rotating coordinate system.

[0079] By adjusting the voltage of the d-axis and q-axis, the output voltage of the grid-connected equipment can be adjusted in real time to optimize the power quality and ensure the stability of the grid-connected equipment under different load conditions.

[0080] Step 5, calculate the modulation wave:

[0081] According to the system three-phase output voltage d-axis component reference value U dref , System three-phase output voltage q-axis component reference value U qref , and the d-axis voltage regulator output U obtained in step 4 cnt_d and the q-axis voltage regulator output U cnt_q , the d-axis component U of the system three-phase output voltage modulation wave is calculated od The q-axis component U of the system three-phase output voltage modulation wave oq .

[0082] The d-axis component U of the system three-phase output voltage modulation wave od The q-axis component U of the system three-phase output voltage modulation wave oq The calculation formula is:

[0083]

[0084] Where U od is the d-axis component of the system three-phase output voltage modulation wave; U oq is the q-axis component of the system three-phase output voltage modulation wave; U dref is the reference value of the d-axis component of the system three-phase output voltage; U qref is the reference value of the q-axis component of the system three-phase output voltage; U cnt_d is the output of the d-axis voltage regulator; U cnt_q is the q-axis voltage regulator output.

[0085] The generated modulation wave provides the necessary reference signal for subsequent voltage control, ensuring that the power electronic equipment can operate in an efficient manner and meet grid-connected requirements.

[0086] Step 6, stationary coordinate system conversion:

[0087] According to the system three-phase output voltage modulation wave d-axis component U obtained in step 5 od The q-axis component U of the system three-phase output voltage modulation wave oq , through synchronous rotating coordinate transformation to the system three-phase output voltage modulation wave u in the stationary coordinate system oa 、u ob 、u oc .

[0088] The calculation formula for the stationary coordinate system transformation is:

[0089]

[0090] In the formula, u oa 、u ob 、u oc is the three-phase output voltage modulation wave of the system in the stationary coordinate system; U od is the d-axis component of the system three-phase output voltage modulation wave; U oq is the q-axis component of the system's three-phase output voltage modulation wave; θ is the system's starting impedance angle.

[0091] Converting the modulated wave back to the stationary coordinate system makes the generated voltage waveform conform to the actual output current, ensuring the actual adaptability and stability of the equipment to the power grid.

[0092] Step 7, calculate the voltage under the simulated grid impedance:

[0093] According to the system three-phase output voltage modulation wave u in the stationary coordinate system obtained in step 6 oa 、u ob 、u oc , the actual value of the three-phase output line current sampled in step 1 I a ,I b ,I c , the three-phase output voltage modulation wave e of the system after simulating the grid impedance in the stationary coordinate system is calculated a 、e b 、e c .

[0094] The three-phase output voltage modulation wave of the system after simulating the grid impedance in the stationary coordinate system a 、e b 、e c The calculation formula is:

[0095]

[0096] In the formula, e a 、e b 、e c is the three-phase output voltage modulation wave of the system after simulating the grid impedance in the stationary coordinate system; u oa 、u ob 、u oc is the three-phase output voltage modulation wave of the system in the stationary coordinate system; L g is the equivalent inductance of the grid impedance; I a ,I b ,I c To sample the actual value of the three-phase output line current of the new energy grid-connected detection platform; T sis the control period; z is a variable in the discrete time domain, which is used to describe the dynamic behavior of the system.

[0097] In the simulation of grid impedance, considering the influence of current and inductance can more realistically reflect the grid-connected conditions and provide a basis that conforms to the actual situation for the grid-connected performance analysis.

[0098] Step 8, SVPWM modulation:

[0099] After simulating the grid impedance in the stationary coordinate system obtained in step 7, the three-phase output voltage modulation wave e a 、e b 、e c The voltage is sent to the SVPWM modulation module for modulation and wave generation. The SVPWM modulation technology can effectively reduce voltage distortion and improve the quality of output voltage, thereby improving the grid-connected compatibility of new energy equipment and reducing energy loss.

[0100] In summary, the grid impedance simulation control method of the new energy grid-connected detection platform can achieve high-precision grid-connected performance evaluation through precise calculation and adjustment of each step, ensuring the reliable operation of new energy equipment under different conditions; it can perform performance tests on different types of new energy equipment, effectively adapt to a variety of application scenarios, and enhance the wide applicability of the test; by optimizing voltage regulation and SVPWM modulation, it helps to improve power quality, reduce harmonics and voltage fluctuations, and ensure the stability and efficiency of the power system; it can simulate grid impedance in a wide frequency domain, and the engineering implementation is simple.

[0101] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the same elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

Claims

1. A grid impedance simulation control method for a new energy grid-connected detection platform, characterized in that: The grid impedance simulation control method of the new energy grid-connected detection platform is based on the new energy grid-connected detection platform; The new energy grid-connected detection platform includes a DC / AC inverter unit, a DC power supply connected to the DC side of the DC / AC inverter unit, a filter circuit connected to the AC side of the DC / AC inverter unit, a transformer connected to the filter circuit, and a device under test connected to the transformer; The grid impedance simulation control method of the new energy grid-connected detection platform is based on the new energy grid-connected detection platform. By simulating and controlling the grid impedance, the grid-connected performance of various new energy power electronic equipment is studied and tested.

2. The grid impedance simulation control method of the new energy grid connection detection platform according to claim 1 is characterized in that: The grid impedance simulation control method of the new energy grid-connected detection platform includes the following steps: Step 1, output voltage and current sampling: Sample the actual value of the three-phase output line voltage of the new energy grid-connected detection platform and record it as U ab , U bc , U ca ; Sample the actual value of the three-phase output line current of the new energy grid-connected detection platform and record it as I a ,I b ,I c ; Step 2, calculate the phase voltage: According to the actual value U of the three-phase output line voltage sampled in step 1 ab , U bc , U ca , the three-phase output phase voltage U is calculated a , U b , U c ; Step 3, coordinate transformation: Through synchronous rotating coordinate transformation, the three-phase output phase voltage U obtained in step 2 is a , U b , U c Converted into the d-axis component U of the three-phase output voltage in the rotating coordinate system d And the q-axis component U of the three-phase grid voltage q ; Step 4, voltage regulation: According to the system three-phase output voltage d-axis component reference value U dref , System three-phase output voltage q-axis component reference value U qref , and the three-phase output voltage d-axis component U obtained in step 3 d And the q-axis component U of the three-phase grid voltage q , respectively through the d-axis voltage regulator and the q-axis voltage regulator, the d-axis voltage regulator output U is calculated cnt_d and the q-axis voltage regulator output U cnt_q ; Step 5, calculate the modulation wave: According to the system three-phase output voltage d-axis component reference value U dref , System three-phase output voltage q-axis component reference value U qref , and the d-axis voltage regulator output U obtained in step 4 cnt_d and the q-axis voltage regulator output U cnt_q , the d-axis component U of the system three-phase output voltage modulation wave is calculated od The q-axis component U of the system three-phase output voltage modulation wave oq ; Step 6, stationary coordinate system conversion: According to the system three-phase output voltage modulation wave d-axis component U obtained in step 5 od The q-axis component U of the system three-phase output voltage modulation wave oq , through synchronous rotating coordinate transformation to the system three-phase output voltage modulation wave u in the stationary coordinate system oa 、u ob 、u oc ; Step 7, calculate the voltage under the simulated grid impedance: According to the system three-phase output voltage modulation wave u in the stationary coordinate system obtained in step 6 oa 、u ob 、u oc , the actual value of the three-phase output line current sampled in step 1 I a ,I b ,I c , the three-phase output voltage modulation wave e of the system after simulating the grid impedance in the stationary coordinate system is calculated a 、e b 、e c ; Step 8, SVPWM modulation: After simulating the grid impedance in the stationary coordinate system obtained in step 7, the three-phase output voltage modulation wave e a 、e b 、e c Send it to the SVPWM modulation module for modulation and wave generation.

3. The grid impedance simulation control method of the new energy grid connection detection platform according to claim 2 is characterized by: In step 2, the three-phase output phase voltage U a , U b , U c The calculation formula is: Where U a , U b , U c is the three-phase output phase voltage; U ab , U bc , U ca To sample the actual value of the three-phase output line voltage of the new energy grid-connected detection platform.

4. The grid impedance simulation control method of the new energy grid connection detection platform according to claim 2 is characterized by: In step 3, the coordinate transformation calculation formula is: Where U d is the d-axis component of the three-phase output voltage in the rotating coordinate system; U q is the q-axis component of the three-phase grid voltage in the rotating coordinate system; U a , U b , U c is the three-phase output phase voltage; θ is the starting impedance angle of the system.

5. The grid impedance simulation control method of the new energy grid connection detection platform according to claim 2 is characterized in that: In step 4, the d-axis voltage regulator outputs U cnt_d and the q-axis voltage regulator output U cnt_q The calculation formula is: Where U cnt_d is the output of the d-axis voltage regulator; U cnt_q is the output of the q-axis voltage regulator; K up is the voltage regulator proportional coefficient; K ui is the voltage regulator integral coefficient; z represents a variable in the discrete time domain, which is used to describe the dynamic behavior of the system; T s is the control period; U dref is the reference value of the d-axis component of the system three-phase output voltage; U d is the d-axis component of the three-phase output voltage in the rotating coordinate system; U qref is the reference value of the q-axis component of the system three-phase output voltage; U q is the q-axis component of the three-phase grid voltage in the rotating coordinate system.

6. The grid impedance simulation control method of the new energy grid connection detection platform according to claim 2 is characterized by: In step 5, the system three-phase output voltage modulation wave d-axis component U od The q-axis component U of the system three-phase output voltage modulation wave oq The calculation formula is: Where U od is the d-axis component of the system three-phase output voltage modulation wave; U oq is the q-axis component of the system three-phase output voltage modulation wave; U dref is the reference value of the d-axis component of the system three-phase output voltage; U qref is the reference value of the q-axis component of the system three-phase output voltage; U cnt_d is the output of the d-axis voltage regulator; U cnt_q is the q-axis voltage regulator output.

7. The grid impedance simulation control method of the new energy grid connection detection platform according to claim 2 is characterized by: In step 6, the calculation formula for the stationary coordinate system transformation is: In the formula, u oa 、u ob 、u oc is the three-phase output voltage modulation wave of the system in the stationary coordinate system; U od is the d-axis component of the system three-phase output voltage modulation wave; U oq is the q-axis component of the system's three-phase output voltage modulation wave; θ is the system's starting impedance angle.

8. The grid impedance simulation control method of the new energy grid connection detection platform according to claim 2 is characterized by: In step 7, after simulating the grid impedance in the stationary coordinate system, the system three-phase output voltage modulation wave e a 、e b 、e c The calculation formula is: In the formula, e a 、e b 、e c is the three-phase output voltage modulation wave of the system after simulating the grid impedance in the stationary coordinate system; u oa 、u ob 、u oc is the three-phase output voltage modulation wave of the system in the stationary coordinate system; L g is the equivalent inductance of the grid impedance; I a ,I b ,I c To sample the actual value of the three-phase output line current of the new energy grid-connected detection platform; T s is the control period; z is a variable in the discrete time domain, which is used to describe the dynamic behavior of the system.

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