Control method and apparatus for inverter simulation model

Abstract

Disclosed in the present application are a control method and apparatus for an inverter simulation model. The method comprises: acquiring a simulation equivalent model of a power distribution network; acquiring an output voltage measurement value, an active power measurement value, a reactive power measurement value and a grid-connected bus voltage measurement value of the power distribution network, and acquiring a voltage measurement value, a frequency measurement value, an inductive current measurement value, a grid-connected side voltage measurement value and a grid-connected side current measurement value of an inverter; determining an output voltage of the power distribution network; if the output voltage is less than or equal to a first voltage threshold value, implementing a droop characteristic-based V / F control strategy for a power loop controller; and if the output voltage is greater than a second voltage threshold value and less than or equal to a third voltage threshold value, implementing a droop characteristic-based P / Q control strategy for the power loop controller. The present invention can reduce the workload of inverter modeling and the amount of calculation of simulation processes, thereby improving the efficiency of evaluating corresponding control methods for inverter simulation models.

Description

A control method and device for an inverter simulation model Technical Field

[0001] This invention relates to the field of simulation technology, and in particular to a control method and apparatus for an inverter simulation model. Background Technology

[0002] In the modeling of photovoltaic inverters, the main focus is on the research of inverter control strategies. Existing inverter simulation models consider the types of parameters involved in the control, but these models have high dimensionality and the input parameters are difficult to determine. Furthermore, the computational load of such models is enormous, which is unfavorable for large-scale power system simulation and engineering applications, and cannot meet the accuracy requirements of engineering calculations. Therefore, existing inverter simulation model control methods suffer from low evaluation efficiency.

[0003] Therefore, there is an urgent need for a control strategy for inverter simulation models to solve the problem of low evaluation efficiency in the corresponding control methods of inverter simulation models. Summary of the Invention

[0004] This invention provides a control method and apparatus for an inverter simulation model to solve the problem of low evaluation efficiency in the control methods corresponding to inverter simulation models.

[0005] To address the above problems, one embodiment of the present invention provides a control method for an inverter simulation model, comprising:

[0006] Obtain a simulation equivalent model of the power distribution network; wherein the simulation equivalent model includes: a photovoltaic array, an inverter, and a power loop controller; the photovoltaic array is in the maximum power output state;

[0007] The system collects the output voltage measurement value, active power measurement value, reactive power measurement value, and grid-connected bus voltage measurement value of the distribution network, as well as the voltage measurement value, frequency measurement value, inductor current measurement value, grid-connected side voltage measurement value, and grid-connected side current measurement value of the inverter.

[0008] Determine the output voltage of the power distribution network;

[0009] If the output voltage is less than or equal to the first voltage threshold, then based on the output voltage measurement, the active power measurement, the reactive power measurement, the voltage measurement, the frequency measurement, and the inductor current measurement, the power loop controller implements a V / F control strategy based on droop characteristics.

[0010] If the output voltage is greater than the second voltage threshold and less than or equal to the third voltage threshold, then based on the measured value of the grid-connected bus voltage, the measured value of the grid-connected side voltage, and the measured value of the grid-connected side current, a P / Q control strategy based on droop characteristics is implemented on the power loop controller; wherein, the second voltage threshold is greater than the first voltage threshold, and the third voltage threshold is greater than the second voltage threshold.

[0011] As an improvement to the above scheme, the simulation equivalent model further includes: an electricity terminal; the inverter includes: a Boost circuit, an inverter circuit, and a filter circuit; wherein, the input of the Boost circuit is connected to the output of the photovoltaic array; the output of the Boost circuit is connected to the input of the inverter circuit; the output of the inverter circuit is connected to the input of the filter circuit, and the output of the filter circuit is connected to the electricity terminal; the inverter circuit is connected to the power loop controller.

[0012] As an improvement to the above scheme, the photovoltaic array is in a maximum power output state, including:

[0013] The photovoltaic array is subjected to maximum power point tracking based on the Boost circuit; wherein the Boost circuit calculates the maximum power point of the photovoltaic array according to the perturbation-observation method.

[0014] As an improvement to the above scheme, the inductor current measurement value includes: the d-axis current measurement value of the filter inductor flowing through the filter inductor in a rotating current coordinate system and the q-axis current measurement value of the filter inductor flowing through the filter inductor in a rotating current coordinate system; the output voltage measurement value includes: the d-axis output voltage measurement value and the q-axis output voltage measurement value; the implementation of a V / F control strategy based on droop characteristics for the power loop controller based on the output voltage measurement value, the active power measurement value, the reactive power measurement value, the voltage measurement value, the frequency measurement value, and the inductor current measurement value includes:

[0015] The output voltage measurement value, the active power measurement value, the reactive power measurement value, the voltage measurement value, the frequency measurement value, the d-axis current measurement value of the filter inductor under the current rotating coordinate system, and the q-axis current measurement value of the filter inductor under the current rotating coordinate system are substituted into the preset inner and outer loop control equations to calculate the PWM modulation signal; wherein, the PWM modulation signal includes: grid-connected active power adjustment value, grid-connected reactive power adjustment value, d-axis current adjustment value of the filter inductor under the current rotating coordinate system, and q-axis current adjustment value of the filter inductor under the current rotating coordinate system; the inner and outer loop control equations satisfy the following conditions:

[0016] In the formula, U ref f refThese are the preset voltage and frequency reference values ​​for the inverter, respectively; U and f are the measured voltage and frequency values ​​for the inverter, respectively; P ref Q ref These represent the grid-connected active power adjustment value and grid-connected reactive power adjustment value of the distribution network, respectively; P0 and Q0 represent the grid-connected active power measurement value and grid-connected reactive power measurement value of the distribution network, respectively; i Ld_ref i Lq_ref These represent the adjustment values ​​for the d-axis current flowing through the filter inductor in a rotating current coordinate system and the q-axis current flowing through the filter inductor in a rotating current coordinate system, respectively; i Ld i Lq These are the measured values ​​of the d-axis current flowing through the filter inductor in a rotating current coordinate system and the q-axis current flowing through the filter inductor in a rotating current coordinate system, respectively; e d e q These are the d-axis and q-axis measurements of the output voltage of the distribution network, respectively; k P_i and k i_i These are the proportional and integral coefficients of the PI controller, respectively; k P_f and k i_f These are the proportional and integral coefficients of the inverter output frequency deviation, respectively; k P_U and k i_U These are the proportional and integral coefficients of the inverter output voltage deviation, respectively; k P_d and k i_d These are the proportional and integral coefficients of the grid-connected active power deviation (d-axis component), respectively; k P_q and k i_q These are the proportional and integral coefficients of the grid-connected reactive power deviation (q-axis component), respectively; ω is the angular frequency, ω=2πf, f is the frequency; k P_u and ki _u represents the proportional and integral coefficients of the inner current loop; s is the complex frequency variable in the Laplace transform.

[0017] The power loop controller outputs according to the PWM modulation signal.

[0018] As an improvement to the above scheme, the implementation of a P / Q control strategy based on droop characteristics for the power loop controller based on the grid-connected bus voltage, the measured grid-connected side voltage, and the measured grid-connected side current includes:

[0019] The grid-connected bus voltage, the measured grid-connected side voltage, and the measured grid-connected side current are substituted into a preset control equation to calculate the control signal; the control equation satisfies the following condition:

[0020] In the formula, V d V qThese are the d-axis and q-axis components of the grid-connected voltage measurement, respectively, i d i q The d-axis and q-axis components of the grid-connected voltage measurement; ω n U is the rated angular frequency. n U is the grid-connected bus voltage; m and n are the droop power coefficients; u od_ref u od To synthesize the d-axis components of the three-phase reference voltage and the measured grid-connected voltage; u oq_ref u oq This is to synthesize the q-axis components of the three-phase reference voltage and the measured grid-connected voltage; C is the filter capacitance value;

[0021] The power loop controller outputs according to the control signal.

[0022] Accordingly, one embodiment of the present invention also provides a control device for an inverter simulation model, including: a data acquisition module, a data collection module, a data judgment module, a first control module, and a second control module.

[0023] The data acquisition module is used to acquire a simulation equivalent model of the power distribution network; wherein, the simulation equivalent model includes: a photovoltaic array, an inverter, and a power loop controller; the photovoltaic array is in a maximum power output state;

[0024] The data acquisition module is used to acquire the output voltage measurement value, active power measurement value, reactive power measurement value and grid-connected bus voltage measurement value of the distribution network, as well as the voltage measurement value, frequency measurement value, inductor current measurement value, grid-connected side voltage measurement value and grid-connected side current measurement value of the inverter;

[0025] The data judgment module is used to judge the output voltage of the power distribution network;

[0026] The first control module is configured to, if the output voltage is less than or equal to a first voltage threshold, implement a V / F control strategy based on droop characteristics on the power loop controller based on the output voltage measurement value, the active power measurement value, the reactive power measurement value, the voltage measurement value, the frequency measurement value, and the inductor current measurement value;

[0027] The second control module is configured to implement a P / Q control strategy based on droop characteristics on the power loop controller if the output voltage is greater than a second voltage threshold and less than or equal to a third voltage threshold; wherein the second voltage threshold is greater than a first voltage threshold and the third voltage threshold is greater than the second voltage threshold.

[0028] As an improvement to the above scheme, the simulation equivalent model further includes: an electricity terminal; the inverter includes: a Boost circuit, an inverter circuit, and a filter circuit; wherein, the input of the Boost circuit is connected to the output of the photovoltaic array; the output of the Boost circuit is connected to the input of the inverter circuit; the output of the inverter circuit is connected to the input of the filter circuit, and the output of the filter circuit is connected to the electricity terminal; the inverter circuit is connected to the power loop controller.

[0029] As an improvement to the above scheme, the photovoltaic array is in a maximum power output state, including:

[0030] The photovoltaic array is subjected to maximum power point tracking based on the Boost circuit; wherein the Boost circuit calculates the maximum power point of the photovoltaic array according to the perturbation-observation method.

[0031] As an improvement to the above scheme, the inductor current measurement value includes: the d-axis current measurement value of the filter inductor flowing through the filter inductor in a rotating current coordinate system and the q-axis current measurement value of the filter inductor flowing through the filter inductor in a rotating current coordinate system; the output voltage measurement value includes: the d-axis output voltage measurement value and the q-axis output voltage measurement value; the implementation of a V / F control strategy based on droop characteristics for the power loop controller based on the output voltage measurement value, the active power measurement value, the reactive power measurement value, the voltage measurement value, the frequency measurement value, and the inductor current measurement value includes:

[0032] The output voltage measurement value, the active power measurement value, the reactive power measurement value, the voltage measurement value, the frequency measurement value, the d-axis current measurement value of the filter inductor under the current rotating coordinate system, and the q-axis current measurement value of the filter inductor under the current rotating coordinate system are substituted into the preset inner and outer loop control equations to calculate the PWM modulation signal; wherein, the PWM modulation signal includes: grid-connected active power adjustment value, grid-connected reactive power adjustment value, d-axis current adjustment value of the filter inductor under the current rotating coordinate system, and q-axis current adjustment value of the filter inductor under the current rotating coordinate system; the inner and outer loop control equations satisfy the following conditions:

[0033] In the formula, U ref f ref These are the preset voltage and frequency reference values ​​for the inverter, respectively; U and f are the measured voltage and frequency values ​​for the inverter, respectively; P ref Q ref These represent the grid-connected active power adjustment value and grid-connected reactive power adjustment value of the distribution network, respectively; P0 and Q0 represent the grid-connected active power measurement value and grid-connected reactive power measurement value of the distribution network, respectively; i Ld _ refi Lq _ ref These represent the adjustment values ​​for the d-axis current flowing through the filter inductor in a rotating current coordinate system and the q-axis current flowing through the filter inductor in a rotating current coordinate system, respectively; i Ld i Lq These are the measured values ​​of the d-axis current flowing through the filter inductor in a rotating current coordinate system and the q-axis current flowing through the filter inductor in a rotating current coordinate system, respectively; e d e q These are the d-axis and q-axis measurements of the output voltage of the distribution network, respectively; k P_i and k i_i These are the proportional and integral coefficients of the PI controller, respectively; k P_f and k i_f These are the proportional and integral coefficients of the inverter output frequency deviation, respectively; k P_U and k i_U These are the proportional and integral coefficients of the inverter output voltage deviation, respectively; k P_d and k i_d These are the proportional and integral coefficients of the grid-connected active power deviation (d-axis component), respectively; k P_q and k i_q These are the proportional and integral coefficients of the grid-connected reactive power deviation (q-axis component), respectively; ω is the angular frequency, ω=2πf, f is the frequency; k P_u and ki _u represents the proportional and integral coefficients of the inner current loop; s is the complex frequency variable in the Laplace transform.

[0034] The power loop controller outputs according to the PWM modulation signal.

[0035] As an improvement to the above scheme, the implementation of a P / Q control strategy based on droop characteristics for the power loop controller based on the grid-connected bus voltage, the measured grid-connected side voltage, and the measured grid-connected side current includes:

[0036] The grid-connected bus voltage, the measured grid-connected side voltage, and the measured grid-connected side current are substituted into a preset control equation to calculate the control signal; the control equation satisfies the following condition:

[0037] In the formula, V d V q These are the d-axis and q-axis components of the grid-connected voltage measurement, respectively, i d i q The d-axis and q-axis components of the grid-connected voltage measurement; ω n U is the rated angular frequency. n U is the grid-connected bus voltage; m and n are the droop power coefficients; u od_refu od To synthesize the d-axis components of the three-phase reference voltage and the measured grid-connected voltage; u oq_ref u oq This is to synthesize the q-axis components of the three-phase reference voltage and the measured grid-connected voltage; C is the filter capacitance value;

[0038] The power loop controller outputs according to the control signal.

[0039] As can be seen from the above, the present invention has the following beneficial effects:

[0040] This invention provides a control method for an inverter simulation model, which obtains a simulation equivalent model of a distribution network; collects the output voltage, active power, reactive power, and grid-connected bus voltage measurements of the distribution network, as well as the voltage, frequency, inductor current, grid-connected side voltage, and grid-connected side current measurements of the inverter; determines the output voltage of the distribution network; if the output voltage is less than or equal to a first voltage threshold, a V / F control strategy based on droop characteristics is implemented on the power loop controller; if the output voltage is greater than a second voltage threshold and less than or equal to a third voltage threshold, a P / Q control strategy based on droop characteristics is implemented on the power loop controller; wherein the second voltage threshold is greater than the first voltage threshold, and the third voltage threshold is greater than the second voltage threshold. By analyzing different distribution network output voltages and selecting corresponding V / F or P / Q control strategies, this invention reduces the workload of inverter modeling and the computational burden of the simulation process, facilitating large-scale power system simulation and engineering applications, and thereby improving the evaluation efficiency of the control method corresponding to the inverter simulation model. Attached Figure Description

[0041] Figure 1 is a flowchart illustrating the control method of an inverter simulation model provided in an embodiment of the present invention;

[0042] Figure 2 is a schematic diagram of the control device of an inverter simulation model provided in an embodiment of the present invention;

[0043] Figure 3 is a schematic diagram of a terminal device structure provided in an embodiment of the present invention;

[0044] Figure 4 is a diagram of a two-stage single-phase photovoltaic grid-connected topology provided in an embodiment of the present invention;

[0045] Figure 5 is a diagram of a two-stage three-phase photovoltaic grid-connected topology provided in an embodiment of the present invention. Detailed Implementation

[0046] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0047] Example 1

[0048] Referring to Figure 1, which is a flowchart illustrating a control method for an inverter simulation model according to an embodiment of the present invention, this embodiment includes steps 101 to 105, and the specific steps are as follows:

[0049] Step 101: Obtain the simulation equivalent model of the power distribution network; wherein, the simulation equivalent model includes: photovoltaic array, inverter and power loop controller; the photovoltaic array is in the maximum power output state.

[0050] In this embodiment, the simulation equivalent model further includes: an electricity terminal; the inverter includes: a Boost circuit, an inverter circuit, and a filter circuit; wherein, the input of the Boost circuit is connected to the output of the photovoltaic array; the output of the Boost circuit is connected to the input of the inverter circuit; the output of the inverter circuit is connected to the input of the filter circuit, and the output of the filter circuit is connected to the electricity terminal; the inverter circuit is connected to the power loop controller.

[0051] In one specific embodiment, the inverter is a two-stage photovoltaic inverter, consisting of a boost circuit, an inverter circuit, and a filter circuit. Depending on different grid connection requirements, it is divided into single-phase (as shown in Figure 4) and three-phase grid-connected (as shown in Figure 5). The boost circuit enables maximum power point tracking (MPPT) of the photovoltaic system; the inverter circuit converts DC to AC; the filter circuit reduces harmonic components in the inverter output; in the bridge inverter circuit, a controller and a sinusoidal pulse width modulation module provide drive signals to the switching elements, controlling their on and off states to achieve grid connection conditions for the inverter.

[0052] The simulation equivalent model is a node equivalent model, which equates the detailed model to PV, PV(Q), and PQ nodes. This model is suitable for large-scale distribution network simulation and assesses the impact of photovoltaic (PV) access on the distribution network. The explanations for PV, PV(Q), and PQ nodes are as follows: For PV systems connected at 220V and 380V, the control strategy is droop V / F control, and these nodes can be considered PV nodes. The active power reference value is the rated output of the PV system, and the voltage reference value is the connected voltage level. When the reactive power of a PV node exceeds its limit, the PV node will transform into a PQ node, at which point the reactive power reference value is the upper or lower limit of reactive power output. For PV power plants connected at 10kV, the control strategy is droop PQ control, and these nodes are considered PQ nodes. The active and reactive power reference values ​​are set according to the feeder load.

[0053] In this embodiment, the photovoltaic array is in a maximum power output state, including:

[0054] The photovoltaic array is subjected to maximum power point tracking based on the Boost circuit; wherein the Boost circuit calculates the maximum power point of the photovoltaic array according to the perturbation-observation method.

[0055] In one specific embodiment, a small perturbation is first applied to the voltage of the photovoltaic array. Based on the power change, it can be determined whether the current operating point is to the left or right of the maximum power point. By continuously adjusting, the maximum power point is reached. In common designs, to maintain a balance, the perturbation step size is usually adjusted in the range of 0.1V to 1V. However, in some high-efficiency, high-power photovoltaic systems, larger step sizes may be used, and the optimal value needs to be determined through experiments and optimization.

[0056] Photovoltaic output is volatile. As can be seen from the output characteristics, there is only one maximum power point on the curve of its output power versus voltage. The operating point needs to be adjusted in real time to keep it working near the maximum power point.

[0057] Step 102: Collect the output voltage measurement value, active power measurement value, reactive power measurement value and grid-connected bus voltage measurement value of the distribution network, and collect the voltage measurement value, frequency measurement value, inductor current measurement value, grid-connected side voltage measurement value and grid-connected side current measurement value of the inverter.

[0058] Step 103: Determine the output voltage of the power distribution network.

[0059] Step 104: If the output voltage is less than or equal to the first voltage threshold, then based on the output voltage measurement, the active power measurement, the reactive power measurement, the voltage measurement, the frequency measurement, and the inductor current measurement, implement a V / F control strategy based on droop characteristics for the power loop controller.

[0060] In this embodiment, the inductor current measurement values ​​include: the d-axis current measurement value of the filter inductor flowing through the current in a rotating coordinate system and the q-axis current measurement value of the filter inductor flowing through the current in a rotating coordinate system; the output voltage measurement values ​​include: the d-axis output voltage measurement value and the q-axis output voltage measurement value; the implementation of a V / F control strategy based on droop characteristics for the power loop controller based on the output voltage measurement values, the active power measurement values, the reactive power measurement values, the voltage measurement values, the frequency measurement values, and the inductor current measurement values ​​includes:

[0061] The output voltage measurement value, the active power measurement value, the reactive power measurement value, the voltage measurement value, the frequency measurement value, the d-axis current measurement value of the filter inductor under the current rotating coordinate system, and the q-axis current measurement value of the filter inductor under the current rotating coordinate system are substituted into the preset inner and outer loop control equations to calculate the PWM modulation signal; wherein, the PWM modulation signal includes: grid-connected active power adjustment value, grid-connected reactive power adjustment value, d-axis current adjustment value of the filter inductor under the current rotating coordinate system, and q-axis current adjustment value of the filter inductor under the current rotating coordinate system; the inner and outer loop control equations satisfy the following conditions:

[0062] In the formula, U ref f ref These are the preset voltage and frequency reference values ​​for the inverter, respectively; U and f are the measured voltage and frequency values ​​for the inverter, respectively; P ref Q ref These represent the grid-connected active power adjustment value and grid-connected reactive power adjustment value of the distribution network, respectively; P0 and Q0 represent the grid-connected active power measurement value and grid-connected reactive power measurement value of the distribution network, respectively; i Ld_ref i Lq_ref These represent the adjustment values ​​for the d-axis current flowing through the filter inductor in a rotating current coordinate system and the q-axis current flowing through the filter inductor in a rotating current coordinate system, respectively; i Ld i Lq These are the measured values ​​of the d-axis current flowing through the filter inductor in a rotating current coordinate system and the q-axis current flowing through the filter inductor in a rotating current coordinate system, respectively; e d e q These are the d-axis and q-axis measurements of the output voltage of the distribution network, respectively; k P_i and k i_i These are the proportional and integral coefficients of the PI controller, respectively; k P_f and k i_f These are the proportional and integral coefficients of the inverter output frequency deviation, respectively; k P_U and k i_UThese are the proportional and integral coefficients of the inverter output voltage deviation, respectively; k P_d and k i_d These are the proportional and integral coefficients of the grid-connected active power deviation (d-axis component), respectively; k P_q and k i_q These are the proportional and integral coefficients of the grid-connected reactive power deviation (q-axis component), respectively; ω is the angular frequency, ω=2πf, f is the frequency; k P_u and ki _u represents the proportional and integral coefficients of the inner current loop; s is the complex frequency variable in the Laplace transform.

[0063] The power loop controller outputs according to the PWM modulation signal.

[0064] In one specific embodiment, a phase-locked loop (PLL) plus dual closed-loop control method is used. The actual voltage amplitude and frequency are obtained through the PLL, and the outer loop controls the grid-connected voltage and frequency by setting reference values. The inner loop is a current loop used to output the PWM modulation signal. The purpose of adopting a V / F control strategy based on droop characteristics is to ensure that the output voltage amplitude and frequency remain constant regardless of changes in photovoltaic output. This control strategy not only has a certain load power following characteristic but also ensures the stability of the low-voltage distribution network operation.

[0065] In one specific embodiment, the first voltage threshold can be 400V, and the distribution network is a low-voltage distribution network, mainly responsible for transmitting electrical energy from the substation to end users, providing power supply for industrial and residential use. The power supply range of the low-voltage distribution network is relatively small, often directly supplying the user's consumer equipment 1.

[0066] Step 105: If the output voltage is greater than the second voltage threshold and less than or equal to the third voltage threshold, then based on the measured value of the grid-connected bus voltage, the measured value of the grid-connected side voltage, and the measured value of the grid-connected side current, implement a P / Q control strategy based on droop characteristics for the power loop controller; wherein, the second voltage threshold is greater than the first voltage threshold, and the third voltage threshold is greater than the second voltage threshold.

[0067] In this embodiment, the implementation of a P / Q control strategy based on droop characteristics for the power loop controller based on the grid-connected bus voltage, the measured grid-connected side voltage, and the measured grid-connected side current includes:

[0068] The grid-connected bus voltage, the measured grid-connected side voltage, and the measured grid-connected side current are substituted into a preset control equation to calculate the control signal; the control equation satisfies the following condition:

[0069] In the formula, V d Vq These are the d-axis and q-axis components of the grid-connected voltage measurement, respectively, i d i q The d-axis and q-axis components of the grid-connected voltage measurement; ω n U is the rated angular frequency. n U is the grid-connected bus voltage; m and n are the droop power coefficients; u od_ref u od To synthesize the d-axis components of the three-phase reference voltage and the measured grid-connected voltage; u oq_ref u oq This is to synthesize the q-axis components of the three-phase reference voltage and the measured grid-connected voltage; C is the filter capacitance value;

[0070] The power loop controller outputs according to the control signal.

[0071] In a specific embodiment, in order to ensure the stability of the distribution network, the photovoltaic system needs to output active and reactive power according to the actual load demand. At this time, the output frequency and voltage amplitude of the photovoltaic system are determined by the distribution network, and a PQ control strategy based on droop characteristics is adopted for distributed photovoltaic systems.

[0072] In one specific embodiment, the second voltage threshold can be 1kV or 35kV. In this case, the distribution network is a medium-voltage distribution network, which mainly undertakes the task of stepping down the voltage of the power transmitted from the high-voltage distribution network through transformers and then distributing it to various end users through distribution cabinets. The coverage area of ​​the medium-voltage distribution network is wider than that of the low-voltage distribution network, and it can supply residential areas, commercial areas, industrial areas and other areas.

[0073] In one specific embodiment, the measuring devices in the power loop controller first acquire the grid-connected voltage and grid-connected current measurements of the inverter. The measured values ​​are converted into d-axis and q-axis components in a two-phase rotating coordinate system through Park transformation. The inverter output power is then calculated using the above formula. The output power is substituted into the droop control equation to obtain the reference voltage amplitude and angular frequency signal, thereby enabling the synthesis of a three-phase reference voltage.

[0074] Referring to Figure 2, which is a schematic diagram of the structure of a control device for an inverter simulation model provided in an embodiment of the present invention, the device includes: a data acquisition module 201, a data collection module 202, a data judgment module 203, a first control module 204, and a second control module 205.

[0075] The data acquisition module is used to acquire a simulation equivalent model of the power distribution network; wherein, the simulation equivalent model includes: a photovoltaic array, an inverter, and a power loop controller; the photovoltaic array is in a maximum power output state;

[0076] The data acquisition module is used to acquire the output voltage measurement value, active power measurement value, reactive power measurement value and grid-connected bus voltage measurement value of the distribution network, as well as the voltage measurement value, frequency measurement value, inductor current measurement value, grid-connected side voltage measurement value and grid-connected side current measurement value of the inverter;

[0077] The data judgment module is used to judge the output voltage of the power distribution network;

[0078] The first control module is configured to, if the output voltage is less than or equal to a first voltage threshold, implement a V / F control strategy based on droop characteristics on the power loop controller based on the output voltage measurement value, the active power measurement value, the reactive power measurement value, the voltage measurement value, the frequency measurement value, and the inductor current measurement value;

[0079] The second control module is configured to implement a P / Q control strategy based on droop characteristics on the power loop controller if the output voltage is greater than a second voltage threshold and less than or equal to a third voltage threshold; wherein the second voltage threshold is greater than a first voltage threshold and the third voltage threshold is greater than the second voltage threshold.

[0080] As an improvement to the above scheme, the simulation equivalent model further includes: an electricity terminal; the inverter includes: a Boost circuit, an inverter circuit, and a filter circuit; wherein, the input of the Boost circuit is connected to the output of the photovoltaic array; the output of the Boost circuit is connected to the input of the inverter circuit; the output of the inverter circuit is connected to the input of the filter circuit, and the output of the filter circuit is connected to the electricity terminal; the inverter circuit is connected to the power loop controller.

[0081] As an improvement to the above scheme, the photovoltaic array is in a maximum power output state, including:

[0082] The photovoltaic array is subjected to maximum power point tracking based on the Boost circuit; wherein the Boost circuit calculates the maximum power point of the photovoltaic array according to the perturbation-observation method.

[0083] As an improvement to the above scheme, the inductor current measurement value includes: the d-axis current measurement value of the filter inductor flowing through the filter inductor in a rotating current coordinate system and the q-axis current measurement value of the filter inductor flowing through the filter inductor in a rotating current coordinate system; the output voltage measurement value includes: the d-axis output voltage measurement value and the q-axis output voltage measurement value; the implementation of a V / F control strategy based on droop characteristics for the power loop controller based on the output voltage measurement value, the active power measurement value, the reactive power measurement value, the voltage measurement value, the frequency measurement value, and the inductor current measurement value includes:

[0084] The output voltage measurement value, the active power measurement value, the reactive power measurement value, the voltage measurement value, the frequency measurement value, the d-axis current measurement value of the filter inductor under the current rotating coordinate system, and the q-axis current measurement value of the filter inductor under the current rotating coordinate system are substituted into the preset inner and outer loop control equations to calculate the PWM modulation signal; wherein, the PWM modulation signal includes: grid-connected active power adjustment value, grid-connected reactive power adjustment value, d-axis current adjustment value of the filter inductor under the current rotating coordinate system, and q-axis current adjustment value of the filter inductor under the current rotating coordinate system; the inner and outer loop control equations satisfy the following conditions:

[0085] In the formula, U ref f ref These are the preset voltage and frequency reference values ​​for the inverter, respectively; U and f are the measured voltage and frequency values ​​for the inverter, respectively; P ref Q ref These represent the grid-connected active power adjustment value and grid-connected reactive power adjustment value of the distribution network, respectively; P0 and Q0 represent the grid-connected active power measurement value and grid-connected reactive power measurement value of the distribution network, respectively; i Ld_ref i Lq_ref These represent the adjustment values ​​for the d-axis current flowing through the filter inductor in a rotating current coordinate system and the q-axis current flowing through the filter inductor in a rotating current coordinate system, respectively; i Ld i Lq These are the measured values ​​of the d-axis current flowing through the filter inductor in a rotating current coordinate system and the q-axis current flowing through the filter inductor in a rotating current coordinate system, respectively; e d e q These are the d-axis and q-axis measurements of the output voltage of the distribution network, respectively; k P_i and k i_i These are the proportional and integral coefficients of the PI controller, respectively; k P_f and k i_f These are the proportional and integral coefficients of the inverter output frequency deviation, respectively; k P_U and k i_U These are the proportional and integral coefficients of the inverter output voltage deviation, respectively; k P_dand k i_d These are the proportional and integral coefficients of the grid-connected active power deviation (d-axis component), respectively; k P_q and k i_q These are the proportional and integral coefficients of the grid-connected reactive power deviation (q-axis component), respectively; ω is the angular frequency, ω=2πf, f is the frequency; k P_u and ki _u represents the proportional and integral coefficients of the inner current loop; s is the complex frequency variable in the Laplace transform.

[0086] The power loop controller outputs according to the PWM modulation signal.

[0087] As an improvement to the above scheme, the implementation of a P / Q control strategy based on droop characteristics for the power loop controller based on the grid-connected bus voltage, the measured grid-connected side voltage, and the measured grid-connected side current includes:

[0088] The grid-connected bus voltage, the measured grid-connected side voltage, and the measured grid-connected side current are substituted into a preset control equation to calculate the control signal; the control equation satisfies the following condition:

[0089] In the formula, V d V q These are the d-axis and q-axis components of the grid-connected voltage measurement, respectively, i d i q The d-axis and q-axis components of the grid-connected voltage measurement; ω n U is the rated angular frequency. n U is the grid-connected bus voltage; m and n are the droop power coefficients; u od_ref u od To synthesize the d-axis components of the three-phase reference voltage and the measured grid-connected voltage; u oq_ref u oq This is to synthesize the q-axis components of the three-phase reference voltage and the measured grid-connected voltage; C is the filter capacitance value;

[0090] The power loop controller outputs according to the control signal.

[0091] This embodiment obtains a simulation equivalent model of the distribution network; collects the output voltage, active power, reactive power, and grid-connected bus voltage measurements of the distribution network, as well as the voltage, frequency, inductor current, grid-connected side voltage, and grid-connected side current measurements of the inverter; determines the output voltage of the distribution network; if the output voltage is less than or equal to a first voltage threshold, a V / F control strategy based on droop characteristics is implemented on the power loop controller; if the output voltage is greater than a second voltage threshold and less than or equal to a third voltage threshold, a P / Q control strategy based on droop characteristics is implemented on the power loop controller; wherein the second voltage threshold is greater than the first voltage threshold, and the third voltage threshold is greater than the second voltage threshold. This invention, by analyzing different distribution network output voltages and selecting corresponding V / F or P / Q control strategies, reduces the workload of inverter modeling and the computational burden of the simulation process, facilitating large-scale power system simulation and engineering applications, and thereby improving the evaluation efficiency of the control methods corresponding to the inverter simulation model.

[0092] Example 2

[0093] Referring to Figure 3, Figure 3 is a schematic diagram of the terminal device structure provided in an embodiment of the present invention.

[0094] One terminal device in this embodiment includes a processor 301, a memory 302, and a computer program stored in the memory 302 and executable on the processor 301. When the processor 301 executes the computer program, it implements the steps of the control methods for the various inverter simulation models described above in the embodiments, such as all the steps of the control method for the inverter simulation model shown in FIG1. ​​Alternatively, when the processor executes the computer program, it implements the functions of each module in the various device embodiments described above, such as all modules of the control device for the inverter simulation model shown in FIG2.

[0095] In addition, embodiments of the present invention also provide a computer-readable storage medium, the computer-readable storage medium including a stored computer program, wherein, when the computer program is executed, it controls the device where the computer-readable storage medium is located to execute the control method of the inverter simulation model as described in any of the above embodiments.

[0096] Those skilled in the art will understand that the schematic diagram is merely an example of a terminal device and does not constitute a limitation on the terminal device. It may include more or fewer components than shown in the diagram, or combine certain components, or different components. For example, the terminal device may also include input / output devices, network access devices, buses, etc.

[0097] The processor 301 may be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor. The processor 301 is the control center of the terminal device, connecting various parts of the terminal device through various interfaces and lines.

[0098] The memory 302 can be used to store the computer programs and / or modules. The processor 301 implements various functions of the terminal device by running or executing the computer programs and / or modules stored in the memory and calling the data stored in the memory 302. The memory 302 may mainly include a program storage area and a data storage area. The program storage area may store the operating system, at least one application program required for a function (such as sound playback function, image playback function, etc.), etc.; the data storage area may store data created according to the use of the mobile phone (such as audio data, phonebook, etc.). In addition, the memory may include high-speed random access memory, and may also include non-volatile memory, such as hard disk, memory, plug-in hard disk, smart media card (SMC), secure digital (SD) card, flash card, at least one disk storage device, flash memory device, or other volatile solid-state storage device.

[0099] Wherein, if the modules / units integrated in the terminal device are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the methods of the above embodiments of the present invention can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying the computer program code, recording media, USB flash drives, portable hard drives, magnetic disks, optical disks, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc.

[0100] It should be noted that the device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Furthermore, in the accompanying drawings of the device embodiments provided by this invention, the connection relationships between modules indicate that they have communication connections, which can be specifically implemented as one or more communication buses or signal lines. Those skilled in the art can understand and implement this without any creative effort.

[0101] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A control method of an inverter simulation model, characterized by, The method comprises: acquiring a simulation equivalent model of a power distribution network; wherein the simulation equivalent model comprises a photovoltaic array, an inverter, and a power loop controller; the photovoltaic array is in a maximum power output state; collecting output voltage measurement values, active power measurement values, reactive power measurement values, and grid-connected bus voltage measurement values of the power distribution network, and collecting voltage measurement values, frequency measurement values, inductance current measurement values, grid-connected side voltage measurement values, and grid-connected side current measurement values of the inverter; judging an output voltage of the power distribution network; if the output voltage is less than or equal to a first voltage threshold, implementing a V / F control strategy based on the droop characteristics on the power loop controller based on the output voltage measurement values, the active power measurement values, the reactive power measurement values, the voltage measurement values, the frequency measurement values, and the inductance current measurement values; if the output voltage is greater than a second voltage threshold and less than or equal to a third voltage threshold, implementing a P / Q control strategy based on the droop characteristics on the power loop controller based on the grid-connected bus voltage measurement values, the grid-connected side voltage measurement values, and the grid-connected side current measurement values; wherein the second voltage threshold is greater than the first voltage threshold, and the third voltage threshold is greater than the second voltage threshold.

2. The control method of the inverter emulation model according to claim 1, characterized by, The simulation equivalent model further comprises a power consumption terminal; the inverter comprises a Boost circuit, an inverter circuit, and a filter circuit; wherein the input of the Boost circuit is connected with the output of the photovoltaic array; the output of the Boost circuit is connected with the input of the inverter circuit; the output of the inverter circuit is connected with the input of the filter circuit, and the output of the filter circuit is connected with the power consumption terminal; the inverter circuit is connected with the power loop controller.

3. The control method of the inverter emulation model according to claim 2, characterized by, The photovoltaic array is in a maximum power output state, which comprises: performing maximum power point tracking on the photovoltaic array based on the Boost circuit; wherein the Boost circuit performs maximum power point calculation on the photovoltaic array according to the perturb and observe method.

4. The control method of the inverter emulation model according to claim 3, characterized by, The inductance current measurement values comprise d-axis current measurement values and q-axis current measurement values of the filter inductance under current rotating coordinates; the output voltage measurement values comprise d-axis measurement values and q-axis measurement values of the output voltage; and the implementation of the V / F control strategy based on the droop characteristics on the power loop controller based on the output voltage measurement values, the active power measurement values, the reactive power measurement values, the voltage measurement values, the frequency measurement values, and the inductance current measurement values comprises: The output voltage measurement, the active power measurement, the reactive power measurement, the voltage measurement, the frequency measurement, the current measurement flowing through the filter inductance in the d-axis in the current rotating coordinate, and the current measurement flowing through the filter inductance in the q-axis in the current rotating coordinate are substituted into preset inner-outer loop control equations to calculate a pwm modulation signal; wherein the pwm modulation signal comprises a grid-connected active power adjustment value, a grid-connected reactive power adjustment value, a current adjustment value flowing through the filter inductance in the d-axis in the current rotating coordinate, and a current adjustment value flowing through the filter inductance in the q-axis in the current rotating coordinate; and the inner-outer loop control equations satisfy the following conditions: wherein U ref and f ref are the preset voltage reference value and frequency reference value of the inverter, respectively; U, f are the measured voltage value and frequency value of the inverter, respectively; P ref and Q ref are the grid-connected active power adjustment value and grid-connected reactive power adjustment value of the distribution network, respectively, P0, Q0 are the measured grid-connected active power value and grid-connected reactive power value of the distribution network, respectively; i Ld_ref and i Lq_ref are the d-axis current adjustment value and q-axis current adjustment value flowing through the filter inductor in the current rotating coordinate, respectively; i Ld and i Lq are the measured d-axis current value and q-axis current value flowing through the filter inductor in the current rotating coordinate, respectively; e d and e q are the measured d-axis output voltage value and q-axis output voltage value of the distribution network, respectively; k P_i and k i_i are the proportional and integral coefficients of the PI regulator, respectively; k P_f and k i_f are the proportional and integral coefficients of the inverter output frequency deviation, respectively; k P_U and k i_U are the proportional and integral coefficients of the inverter output voltage deviation, respectively; k P_d and k i_d are the proportional and integral coefficients of the grid-connected active power deviation (d-axis component), respectively; k P_q and k i_q are the proportional and integral coefficients of the grid-connected reactive power deviation (q-axis component), respectively; ω is the angular frequency, ω = 2πf, f is the frequency; k P_u and ki _u are the proportional and integral coefficients of the current inner loop, respectively; s is the complex frequency variable in Laplace transform. controlling the power loop controller to output according to the pwm modulation signal.

5. The control method of the inverter emulation model according to claim 4, characterized by, The implementation of the P / Q control strategy based on the droop characteristics on the power loop controller based on the grid-connected bus voltage, the grid-connected side voltage measurement values, and the grid-connected side current measurement values comprises: The grid-connected bus voltage, the grid-connected side voltage measurement value and the grid-connected side current measurement value are substituted into a preset control equation to calculate a control signal; the control equation satisfies the following conditions: where V d , V q are the d, q-axis components of the grid-side voltage measurement, respectively, i d , i q are the d, q-axis components of the grid-side voltage measurement; ω n is the angular frequency reference value; Unis the grid bus voltage; m, n are the droop power coefficients; u od_ref , u od is the d-axis component of the synthesized three-phase reference voltage and the measured grid voltage; u oq_ref , u oq is the q-axis component of the synthesized three-phase reference voltage and the measured grid voltage; C is the filter capacitance value; controlling the power loop controller to output according to the control signal.

6. A control device of an inverter simulation model, characterized by comprising: The method comprises: a data acquisition module, a data collection module, a data judgment module, a first control module, and a second control module. The data acquisition module is configured to acquire a simulation equivalent model of the power distribution network, wherein the simulation equivalent model comprises a photovoltaic array, an inverter, and a power loop controller; and the photovoltaic array is in a maximum power output state. The data acquisition module is configured to acquire an output voltage measurement value, an active power measurement value, a reactive power measurement value, and a grid-connected bus voltage measurement value of the power distribution network, and acquire a voltage measurement value, a frequency measurement value, an inductor current measurement value, a grid-connected side voltage measurement value, and a grid-connected side current measurement value of the inverter. The data judgment module is configured to judge an output voltage of the power distribution network. The first control module is configured to, if the output voltage is less than or equal to a first voltage threshold, implement a V / F control strategy based on a droop characteristic on the power loop controller based on the output voltage measurement value, the active power measurement value, the reactive power measurement value, the voltage measurement value, the frequency measurement value, and the inductor current measurement value. The second control module is configured to, if the output voltage is greater than a second voltage threshold and less than or equal to a third voltage threshold, implement a P / Q control strategy based on a droop characteristic on the power loop controller based on the grid-connected bus voltage measurement value, the grid-connected side voltage measurement value, and the grid-connected side current measurement value; wherein the second voltage threshold is greater than the first voltage threshold, and the third voltage threshold is greater than the second voltage threshold.

7. The control device of the inverter emulation model according to claim 6, wherein The simulation equivalent model further comprises a power consumption terminal; the inverter comprises a Boost circuit, an inverter circuit, and a filter circuit; wherein an input of the Boost circuit is connected with an output of the photovoltaic array; an output of the Boost circuit is connected with an input of the inverter circuit; an output of the inverter circuit is connected with an input of the filter circuit, and an output of the filter circuit is connected with the power consumption terminal; the inverter circuit is connected with the power loop controller.

8. The control device of the inverter emulation model according to claim 7, characterized by, The photovoltaic array in the maximum power output state comprises: The Boost circuit performs maximum power point tracking on the photovoltaic array; wherein the Boost circuit performs maximum power point calculation on the photovoltaic array according to a perturb and observe method.

9. The control device of the inverter emulation model according to claim 8, characterized by, The inductor current measurement value comprises a d-axis inductor current measurement value and a q-axis inductor current measurement value in a current rotating coordinate; the output voltage measurement value comprises a d-axis output voltage measurement value and a q-axis output voltage measurement value; and the implementation of the V / F control strategy based on the droop characteristic on the power loop controller based on the output voltage measurement value, the active power measurement value, the reactive power measurement value, the voltage measurement value, the frequency measurement value, and the inductor current measurement value comprises: The output voltage measurement, the active power measurement, the reactive power measurement, the voltage measurement, the frequency measurement, the current measurement flowing through the filter inductance in the d-axis in the current rotating coordinate, and the current measurement flowing through the filter inductance in the q-axis in the current rotating coordinate are substituted into preset inner-outer loop control equations to calculate a pwm modulation signal; wherein the pwm modulation signal comprises a grid-connected active power adjustment value, a grid-connected reactive power adjustment value, a current adjustment value flowing through the filter inductance in the d-axis in the current rotating coordinate, and a current adjustment value flowing through the filter inductance in the q-axis in the current rotating coordinate; and the inner-outer loop control equations satisfy the following conditions: wherein U ref and f ref are the preset voltage reference value and frequency reference value of the inverter, respectively; U, f are the measured voltage value and frequency value of the inverter, respectively; P ref and Q ref are the grid-connected active power adjustment value and grid-connected reactive power adjustment value of the distribution network, respectively, P0, Q0 are the measured grid-connected active power value and grid-connected reactive power value of the distribution network, respectively; i Ld_ref and i Lq_ref are the current adjustment value flowing through the filter inductor in the d-axis and the current adjustment value flowing through the filter inductor in the q-axis in the current rotating coordinate, respectively; i Ld and i Lq are the measured current value flowing through the filter inductor in the d-axis and the measured current value flowing through the filter inductor in the q-axis in the current rotating coordinate, respectively; e d and e q are the measured output voltage value in the d-axis and the measured output voltage value in the q-axis of the distribution network, respectively; k P_i and k i_i are the proportional and integral coefficients of the PI regulator, respectively; k P_f and k i_f are the proportional and integral coefficients of the inverter output frequency deviation, respectively; k P_U and k i_U are the proportional and integral coefficients of the inverter output voltage deviation, respectively; k P_d and k i_d are the proportional and integral coefficients of the grid-connected active power deviation (d-axis component), respectively; k P_q and k i_q are the proportional and integral coefficients of the grid-connected reactive power deviation (q-axis component), respectively; ω is the angular frequency, ω = 2πf, f is the frequency; k P_u and ki _u are the proportional and integral coefficients of the current inner loop, respectively; s is the complex frequency variable in Laplace transform. controlling the power loop controller to output according to the pwm modulation signal.

10. The control device of the inverter emulation model according to claim 9, characterized by, The implementation of the P / Q control strategy based on the droop characteristic on the power loop controller based on the grid-connected bus voltage measurement value, the grid-connected side voltage measurement value, and the grid-connected side current measurement value comprises: The grid-connected bus voltage, the grid-connected side voltage measurement value and the grid-connected side current measurement value are substituted into a preset control equation to calculate a control signal; the control equation satisfies the following conditions: where V d , V q are the d, q-axis components of the grid-side voltage measurement, respectively, i d , i q are the d, q-axis components of the grid-side voltage measurement; ω n is the angular frequency reference value; U n is the grid bus voltage; m, n are the droop power coefficients; u od_ref , u od is the d-axis component of the synthesized three-phase reference voltage and the measured grid voltage; u oq_ref , u oq is the q-axis component of the synthesized three-phase reference voltage and the measured grid voltage; C is the filter capacitance value; controlling the power loop controller to output according to the control signal.

Images