Control Method, Device, Equipment and Medium Based on Networking Proportion and Network Composition Proportion

Abstract

The present invention provides a control method, device, equipment and medium based on the grid-following ratio and grid-forming ratio, which relates to the technical field of power systems. The method includes: obtaining the system capacity and device capacity of the power system; wherein, the system capacity refers to the sum of the rated capacities of various hub substations in the power system, and the device capacity refers to the installed capacity of the equipment integrating the grid-following function and grid-forming function within a preset range in the power system; determining the short-circuit ratio according to the system capacity and device capacity; determining the grid-following ratio and grid-forming ratio according to the short-circuit ratio; obtaining the three-phase voltage, three-phase current, DC-side voltage and DC-side reference voltage of the power system; and performing pulse-width control according to the three-phase voltage, three-phase current, DC-side voltage, DC-side reference voltage, grid-following ratio and grid-forming ratio. The technical solution of the present invention controls and adjusts the pulse width of the power system comprehensively by determining the grid-following ratio and grid-forming ratio and based on the grid-following ratio and grid-forming ratio.

Description

Technical Field

[0001] The present invention relates to the technical field of power systems, and particularly to a control method, device, equipment and medium based on the grid-following ratio and grid-forming ratio. Background Art

[0002] In recent years, with the access of a high proportion of power electronic inverters and a high proportion of new energy sources in the new power system, the inertia and damping characteristics of the power grid have shown a downward trend, affecting the transient synchronous stability of the power system.

[0003] In the prior art, the current Static Var Generator (SVG) is commonly used for new energy grid connection to improve the voltage stability of the power system. The current SVG mostly adopts a grid-following control strategy and can provide stable voltage support for the power system under a strong power grid with a large short-circuit ratio. For a weak power grid with a small short-circuit ratio, the grid-forming SVG has more obvious advantages. The grid-forming control adopts a power synchronization method, which can avoid the interference of voltage and current harmonics under a weak grid. However, there is power fluctuation when multiple machines are connected in parallel, and there is a risk of low-frequency oscillation when operating under a strong grid. In summary, the grid-following inverter has better stability under a strong power grid with a large short-circuit ratio, and the grid-forming inverter has better stability under a weak power grid with a small short-circuit ratio. However, using only grid-following or grid-forming control for the power system requires preconditions, resulting in poor grid stability of the power system.

[0004] Therefore, there is an urgent need for a control method based on the grid-following ratio and grid-forming ratio to adapt to the power system and improve the grid stability of the power system. Summary of the Invention

[0005] The present invention provides a control method, device, equipment and medium based on the grid-following ratio and grid-forming ratio to solve the defect that using only grid-following or grid-forming control for the power system requires preconditions, resulting in poor grid stability of the power system, and to achieve determining the grid-following ratio and grid-forming ratio and comprehensively adjusting the pulse width of the power system based on the grid-following ratio and grid-forming ratio to improve the grid stability of the power system.

[0006] The present invention provides a control method based on the grid-following ratio and grid-forming ratio, including the following steps.

[0007] Obtain the system capacity and device capacity of the power system; where the system capacity refers to the sum of the rated capacities of various hub substations in the power system, and the device capacity refers to the installed capacity of the equipment integrating the grid-following function and grid-forming function within a preset range of the power system.

[0008] Determine the short-circuit ratio according to the system capacity and device capacity.

[0009] Determine the grid connection ratio and grid formation ratio according to the short - circuit ratio.

[0010] Obtain the three - phase voltage, three - phase current, DC - side voltage, and DC - side reference voltage of the power system.

[0011] Conduct pulse - width control according to the three - phase voltage, three - phase current, DC - side voltage, DC - side reference voltage, grid connection ratio, and grid formation ratio.

[0012] According to a control method based on the grid connection ratio and grid formation ratio provided by the present invention, determine the short - circuit ratio according to the system capacity and device capacity, including: determining the short - circuit ratio according to the ratio of the system capacity to the device capacity.

[0013] According to a control method based on the grid connection ratio and grid formation ratio provided by the present invention, determine the grid connection ratio and grid formation ratio according to the short - circuit ratio, including: determining the corresponding relationship between the grid short - circuit ratio, the target grid formation ratio, and the target grid connection ratio; based on the corresponding relationship, obtain the grid connection ratio and grid formation ratio corresponding to the short - circuit ratio.

[0014] According to a control method based on the grid connection ratio and grid formation ratio provided by the present invention, determine the corresponding relationship between the grid short - circuit ratio, the target grid formation ratio, and the target grid connection ratio, including: under a specific grid short - circuit ratio, simulate the initial grid connection ratio and the initial grid formation ratio of the grid short - circuit ratio, and obtain the initial grid connection ratio, the initial grid formation ratio, the critical clearing angle corresponding to the substation in the power system, and the power amplitude value; wherein, both the initial grid connection ratio and the initial grid formation ratio are at least one kind; fit the initial grid connection ratio, the initial grid formation ratio, the critical clearing angle, and the power amplitude value to obtain the target relational expression; determine the cost function according to the target relational expression; solve the cost function to obtain the target grid connection ratio and the target grid formation ratio corresponding to the grid short - circuit ratio, and determine the corresponding relationship based on the grid short - circuit ratio, the target grid connection ratio, and the target grid formation ratio.

[0015] According to a control method based on the grid connection ratio and grid formation ratio provided by the present invention, determine the cost function according to the target relational expression, including: determining the first weight corresponding to the critical clearing angle and the second weight determined by the power amplitude value according to the target relational expression; determining the cost function according to the first weight and the second weight.

[0016] According to a control method based on the grid connection ratio and grid formation ratio provided by the present invention, conduct pulse - width control according to the three - phase voltage, three - phase current, DC - side voltage, DC - side reference voltage, grid connection ratio, and grid formation ratio, including: determining the internal potential phase angle and the internal potential amplitude according to the three - phase voltage, three - phase current, DC - side voltage, DC - side reference voltage, grid connection ratio, and grid formation ratio; determining the three - phase modulation voltage according to the internal potential phase angle and the internal potential amplitude; conducting pulse - width control according to the three - phase modulation voltage.

[0017] A control method based on the grid - following ratio and grid - forming ratio provided by the present invention determines the internal potential phase angle and internal potential amplitude according to three - phase voltage, three - phase current, DC - side voltage, DC - side reference voltage, grid - following ratio, and grid - forming ratio, including: determining two - phase voltage and two - phase current according to three - phase voltage and three - phase current; where the two - phase voltage includes a first voltage and a second voltage; determining the grid - following angular frequency according to the first voltage and the grid - following ratio; determining the actual reactive power value and the actual active power value according to the first voltage, the second voltage, and the two - phase current; determining the internal potential amplitude according to the actual reactive power value; determining the grid - forming angular frequency according to the DC - side voltage, the DC - side reference voltage, the actual active power value, and the grid - forming ratio; and determining the internal potential phase angle according to the grid - following angular frequency, the grid - forming angular frequency, and the angular frequency reference value.

[0018] The present invention also provides a control device based on the grid - following ratio and grid - forming ratio, including the following modules.

[0019] The first acquisition module is used to acquire the system capacity and device capacity of the power system; where the system capacity refers to the sum of the rated capacities of various hub substations in the power system, and the device capacity refers to the installed capacity of equipment integrating grid - following function and grid - forming function within a preset range of the power system.

[0020] The first determination module is used to determine the short - circuit ratio according to the system capacity and device capacity.

[0021] The second determination module is used to determine the grid - following ratio and grid - forming ratio according to the short - circuit ratio.

[0022] The second acquisition module is used to acquire the three - phase voltage, three - phase current, DC - side voltage, and DC - side reference voltage of the power system.

[0023] The pulse - width control module is used to perform pulse - width control according to the three - phase voltage, three - phase current, DC - side voltage, DC - side reference voltage, grid - following ratio, and grid - forming ratio.

[0024] The present invention also provides an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the computer program, it implements any one of the above - mentioned control methods based on the grid - following ratio and grid - forming ratio.

[0025] The present invention also provides a non - transient computer - readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, it implements any one of the above - mentioned control methods based on the grid - following ratio and grid - forming ratio.

[0026] The present invention also provides a computer program product, including a computer program. When the computer program is executed by a processor, it implements any one of the above - mentioned control methods based on the grid - following ratio and grid - forming ratio.

[0027] A control method, device, equipment and medium based on the grid - following ratio and grid - forming ratio provided by the present invention obtain the system capacity and device capacity of the power system; wherein, the system capacity refers to the sum of the rated capacities of various hub substations in the power system, and the device capacity refers to the installed capacity of the equipment integrating the grid - following function and grid - forming function within a preset range in the power system; determine the short - circuit ratio according to the system capacity and device capacity; determine the grid - following ratio and grid - forming ratio according to the short - circuit ratio; obtain the three - phase voltage, three - phase current, DC - side voltage and DC - side reference voltage of the power system; and perform pulse - width control according to the three - phase voltage, three - phase current, DC - side voltage, DC - side reference voltage, grid - following ratio and grid - forming ratio. The technical solution of the present invention determines the grid - following ratio and grid - forming ratio, and comprehensively adjusts the pulse width of the power system based on the grid - following ratio and grid - forming ratio, thereby improving the grid stability of the power system of the power grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0029] Figure 1 It is a schematic flowchart of the control method based on the grid - following ratio and grid - forming ratio provided by the present invention.

[0030] Figure 2 It is one of the schematic diagrams of the simulation setting of the grid short - circuit ratio provided by the present invention.

[0031] Figure 3 It is another schematic diagram of the simulation setting of the grid short - circuit ratio provided by the present invention.

[0032] Figure 4 It is a schematic diagram of the selection of the grid - following ratio and grid - forming ratio provided by the present invention.

[0033] Figure 5a It is a schematic diagram of the power system structure provided by the present invention.

[0034] Figure 5b It is a schematic diagram of pulse - width modulation provided by the present invention.

[0035] Figure 6 It is a schematic diagram of the structure of the control device based on the grid - following ratio and grid - forming ratio provided by the present invention.

[0036] Figure 7 It is a schematic diagram of the structure of the electronic device provided by the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0037] To make the objectives, technical solutions, and advantages of the present invention clearer, the following will clearly and completely describe the technical solutions in the present invention in conjunction with the accompanying drawings in the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

[0038] The following will describe Figures 1-6 the control method provided by the present invention based on the grid-following ratio and grid-forming ratio. The control method provided by the present invention based on the grid-following ratio and grid-forming ratio is applicable to adjusting the stability of the power grid system. The execution subject of this method can be an electronic device or a control device based on the grid-following ratio and grid-forming ratio set in the electronic device. The control device based on the grid-following ratio and grid-forming ratio can be implemented through software, hardware, or a combination of both. Figure 1 is a schematic flow chart of the control method provided by the present invention based on the grid-following ratio and grid-forming ratio. As Figure 1 shown, the method includes the following steps 101, 102, 103, 104, and 105.

[0039] Step 101: Obtain the system capacity and device capacity of the power system.

[0040] In this step, the system capacity refers to the sum of the rated capacities of various hub substations in the power system, and the device capacity refers to the installed capacity of the equipment integrating the grid-following function and grid-forming function within a preset range of the power system.

[0041] Specifically, the power system includes a regional strength identification system, which includes three layers of devices: a master station, a sub-station, and an execution station. The regional strength identification system is configured at sites such as thermal / hydro / synchronous condensers, new energy power stations, and switch stations in the power system. The master station is generally set in the hub substation of the regional power grid of the power system. The sub-station obtains the rated capacities of various hub substations in the power system, and the sub-station also obtains the installed capacity of the equipment integrating the grid-following function and grid-forming function within a preset range of the power system. The master station receives the installed capacity obtained by the sub-station and the rated capacities of various hub substations in the power system, and the master station sums up the sum of the rated capacities of various hub substations in the power system obtained by the sub-station to obtain the system capacity.

[0042] Step 102: Determine the short-circuit ratio according to the system capacity and device capacity.

[0043] In a specific embodiment, determining the short-circuit ratio according to the system capacity and device capacity includes: determining the short-circuit ratio according to the ratio of the system capacity to the device capacity; where the short-circuit ratio , Indicates the system capacity, Indicates the device capacity.

[0044] Specifically, after the master station obtains the system capacity and the installed capacity, the short-circuit ratio is determined according to the ratio of the system capacity to the device capacity. The short-circuit ratio , Indicates the system capacity, Indicates the device capacity.

[0045] Step 103: Determine the grid-following ratio and the grid-forming ratio according to the short-circuit ratio.

[0046] Specifically, after the master station obtains the short-circuit ratio, it sends the short-circuit ratio to the execution station, and then the execution station sends the short-circuit ratio to the grid-forming and grid-following coordination control system of the power system. Further, the grid-forming and grid-following coordination control system calculates the grid-following ratio and the grid-forming ratio of the grid-following type and the grid-forming type through an optimization method based on the short-circuit ratio with the transient synchronous stability optimization target.

[0047] In this step, there are mainly two indicators for evaluating the transient synchronous stability: the critical clearing angle after a large disturbance and the amplitude of the power oscillation after a small disturbance. First is the critical clearing angle. For a synchronous generator, the greater the damping coefficient, the greater the damping torque, the greater the decelerating area of the power angle, the smaller the accelerating area, the greater the critical clearing angle, and the better the transient stability. Similarly, for the SVG with the integration of the grid-following and grid-forming phase angles, the improvement of the transient stability can also be achieved by increasing the proportion of the grid-forming part Kp (assuming that the sum of the proportions of the grid-following and grid-forming parts is 1, then the proportion of the grid-following part is 1 - Kp) and increasing the damping coefficient. Second is the amplitude of the power oscillation after a small disturbance. Under a strong grid with a large short-circuit ratio SCR, the devices applying the grid-forming strategy will become unstable after being subjected to a small disturbance. Figure 2 Is one of the schematic diagrams of the simulation setting of the grid short-circuit ratio provided by the present invention. As Figure 2 shown, the short-circuit ratio SCR of the simulation setting of the grid is 30, and a small disturbance occurs at 0.2 s. Figure 2 The ordinate of (a) represents the output voltage (KV), and the abscissa represents the time (S). When a small disturbance occurs at 0.2 s, the output voltage of the device applying the grid-forming strategy remains unchanged. Figure 2 The ordinate of (b) represents the output current (A), and the abscissa represents the time (S). When a small disturbance occurs at 0.2 s, the output current of the device applying the grid-forming strategy oscillates. Figure 2 The ordinate of (c) represents the output active power (p.u.), and the abscissa represents the time (S). When a small disturbance occurs at 0.2 s, the power of the device applying the grid-forming strategy oscillates. Therefore, it is determined that under a weak grid with a small short-circuit ratio, the devices applying the grid-following strategy will become unstable after being subjected to a small disturbance. Figure 3 Is the second schematic diagram of the simulation setting of the grid short-circuit ratio provided by the present invention. As Figure 3As shown, the simulation sets the short-circuit ratio SCR of the power grid to 1, and a small disturbance occurs at 1.2 s. Figure 3 The ordinate of (a) represents the output voltage (KV), and the abscissa represents the time (S). When a small disturbance occurs at 0.2 s, the output voltage of the device adopting the grid-forming strategy oscillates. Figure 3 The ordinate of (b) represents the output current (A), and the abscissa represents the time (S). When a small disturbance occurs at 0.2 s, the output current of the device adopting the grid-forming strategy oscillates. Figure 3 The ordinate of (c) represents the output active power (p.u.), and the abscissa represents the time (S). When a small disturbance occurs at 0.2 s, the power of the device adopting the grid-forming strategy oscillates. Therefore, it is necessary to adjust the grid-forming and grid-following ratios according to the short-circuit ratio.

[0048] In order to obtain the optimal target grid-following ratio and target grid-forming ratio under a certain specific power grid short-circuit ratio, three steps need to be completed: The first is to establish the target relationships between the critical clearing angle, the amplitude of the power oscillation after being subjected to a small disturbance, and the grid-following and grid-forming ratios under a certain specific power grid short-circuit ratio. The second is to balance the first weight of the critical clearing angle and the second weight of the amplitude of the power oscillation after being subjected to a small disturbance, and establish a cost function. The third is to optimize the solution of the cost function to obtain the target grid-following ratio and target grid-forming ratio.

[0049] In a specific embodiment, determining the grid-following ratio and grid-forming ratio according to the short-circuit ratio includes: determining the corresponding relationship between the power grid short-circuit ratio, the target grid-forming ratio, and the target grid-following ratio; based on the corresponding relationship, obtaining the grid-following ratio and grid-forming ratio corresponding to the short-circuit ratio.

[0050] In a specific embodiment, determining the corresponding relationship between the power grid short-circuit ratio, the target grid-forming ratio, and the target grid-following ratio includes: under a specific power grid short-circuit ratio, simulating the initial grid-following ratio and initial grid-forming ratio of the power grid short-circuit ratio, and obtaining the initial grid-following ratio and initial grid-forming ratio, the critical clearing angle corresponding to the substation in the power system, and the power amplitude value; wherein, both the initial grid-following ratio and the initial grid-forming ratio are at least one; fitting the initial grid-following ratio and initial grid-forming ratio, the critical clearing angle, and the power amplitude value to obtain the target relationship; determining the cost function according to the target relationship; solving the cost function to obtain the target grid-following ratio and target grid-forming ratio corresponding to the power grid short-circuit ratio, and determining the corresponding relationship based on the power grid short-circuit ratio, the target grid-following ratio, and the target grid-forming ratio.

[0051] In a specific embodiment, determining the cost function according to the target relationship includes: determining the first weight corresponding to the critical clearing angle according to the target relationship and the second weight determined by the power amplitude value; determining the cost function according to the first weight and the second weight.

[0052] Specifically, at a specific grid short-circuit ratio, at least one initial grid-following ratio and initial grid-forming ratio obtained are simulated to obtain the initial grid-following ratio, initial grid-forming ratio, the critical clearing angle and power amplitude value corresponding to the substation in the power system. The least squares method is used to fit the initial grid-following ratio, initial grid-forming ratio, critical clearing angle and power amplitude value, and an objective relationship between the initial grid-following ratio, initial grid-forming ratio, critical clearing angle and power amplitude value after being subjected to small disturbances is established. Then, the entropy weight method is used to obtain the first weight corresponding to the critical clearing angle and the second weight determined by the power amplitude value, and the first weight and the second weight are linearly weighted to establish a cost function. Thus, the cost function is solved to obtain the optimal target grid-following ratio and target grid-forming ratio at a specific short-circuit ratio, and the corresponding relationship is determined based on the grid short-circuit ratio, target grid-following ratio and target grid-forming ratio.

[0053] Exemplarily, let the grid-forming ratio be kp, and its n values be kp1, ……, kpn respectively. Let the critical clearing angles at n grid-forming ratios be δ1, ……, δn respectively; the power amplitude values be A1, ……, An respectively. A data sample X is constructed through the critical clearing angle and the power amplitude value, and the data sample X is as shown in formula (1).

[0054] (1)

[0055] First, the least squares method is used to obtain the objective relationship between the grid-forming ratio, critical clearing angle and oscillation amplitude. The objective relationship is as shown in formula (2).

[0056] (2)

[0057] Second, the entropy weight method is used to obtain the first weight corresponding to the critical clearing angle and the second weight determined by the power amplitude value. Specifically, first, data standardization is performed, and each index data is standardized to eliminate the influence of different dimensions and magnitudes on the evaluation result. Determine the positive index critical clearing angle For the positive index critical clearing angle The original data can be standardized and calculated through the following formula (3).

[0058] (3)

[0059] Determine the negative index power oscillation amplitude after being subjected to small disturbances For the negative index power oscillation amplitude after being subjected to small disturbances The original data can be standardized and calculated through the following formula (4).

[0060] (4)

[0061] Finally, the standardized data samples are obtained. , the data samples are as shown in formula (5).

[0062] (5)

[0063] Thirdly, further calculate the first numerical ratio corresponding to the critical clearing angle and the second numerical ratio determined by the power amplitude value . The calculation of the first numerical ratio is as shown in formula (6), and the calculation of the second numerical ratio is as shown in formula (7).

[0064] (6)

[0065] (7)

[0066] Furthermore, in calculating the first numerical ratio and the second numerical ratio, according to the definition of information entropy in information theory, the first information entropy corresponding to the first numerical ratio and the second information entropy corresponding to the second numerical ratio are obtained respectively. The calculation of the first information entropy is as shown in formula (8), and the calculation of the second information entropy is as shown in formula (9).

[0067] (8)

[0068] (9)

[0069] where n represents the number of data.

[0070] Fourthly, according to the first information entropy corresponding to the first numerical ratio and the second information entropy corresponding to the second numerical ratio , the first weight and the second weight are calculated. The calculation of the first weight is as shown in formula (10), and the calculation of the second weight is as shown in formula (11).

[0071] (10)

[0072] (11)

[0073] Finally, according to the first weight and the second weight Perform fitting to establish the cost function L. The calculation formula of the cost function L is shown in formula (12).

[0074] (12)

[0075] Further solve for the maximum value of the cost function L to obtain the optimal target grid - following ratio and target grid - forming ratio corresponding to the grid short - circuit ratio. The target grid - following ratio and target grid - forming ratio include the grid - forming ratio Kp and the grid - following ratio of 1 - Kp. Figure 4 is a schematic diagram for selecting the grid - following ratio and grid - forming ratio provided by the present invention. As Figure 4 shown, the abscissa represents the short - circuit ratio SCR, and the ordinate represents the grid - following ratio and grid - forming ratio. When the short - circuit ratio is large, increase the grid - following ratio and decrease the grid - forming ratio; when the short - circuit ratio is small, increase the grid - forming ratio and decrease the grid - following ratio.

[0076] In a specific embodiment, the grid - forming and grid - following coordinated control system of the power system includes a host and slave machines, and a real - time control local area network (LAN) for networking; the host is responsible for communicating with the regional intensity identification system and configuring algorithms to determine the grid - forming and grid - following operation ratios of this station; to improve the reliability of the power system, the host and slave machines can be configured in a primary - standby redundant mode; the real - time control LAN can be configured in a dual - network redundant mode to improve the reliability of the networking communication link; the slave machines communicate with the grid - forming device controller through the Generic Object Oriented Substation Event (GOOSE) network, execute the grid - forming and grid - following operation strategies, and adjust and control the simulation parameters in real time.

[0077] Step 104: Obtain the three - phase voltage, three - phase current, DC - side voltage, and DC - side reference voltage of the power system.

[0078] In this step, the three - phase voltage includes the three - phase first voltage U a , the three - phase second voltage U b , and the three - phase third voltage U c . The three - phase current includes the three - phase first current I a , the three - phase second current I b , and the three - phase third current I c . The DC - side voltage refers to the voltage value on the DC side of the power system. The DC - side reference voltage is a preset voltage value, which is not limited in this embodiment.

[0079] Specifically, after determining the grid - following ratio and grid - forming ratio, further obtain the three - phase voltage, three - phase current, DC - side voltage, and DC - side reference voltage of the power system.

[0080] Step 105: Perform pulse width control based on three-phase voltage, three-phase current, DC-side voltage, DC-side reference voltage, grid-following ratio, and grid-forming ratio.

[0081] In a specific embodiment, the grid-following ratio and the grid-forming ratio include the grid-following ratio and the grid-forming ratio; performing pulse width control based on three-phase voltage, three-phase current, DC-side voltage, DC-side reference voltage, grid-following ratio, and grid-forming ratio includes: determining the internal potential phase angle and the internal potential amplitude according to the three-phase voltage, three-phase current, DC-side voltage, DC-side reference voltage, grid-following ratio, and grid-forming ratio; determining the three-phase modulation voltage according to the internal potential phase angle and the internal potential amplitude; and performing pulse width control according to the three-phase modulation voltage.

[0082] In a specific embodiment, determining the internal potential phase angle and the internal potential amplitude according to the three-phase voltage, three-phase current, DC-side voltage, DC-side reference voltage, grid-following ratio, and grid-forming ratio includes: determining two-phase voltage and two-phase current according to the three-phase voltage and the three-phase current; wherein the two-phase voltage includes a first voltage and a second voltage; determining the grid-following angular frequency according to the first voltage and the grid-following ratio; determining the actual reactive power value and the actual active power value according to the first voltage, the second voltage, and the two-phase current; determining the internal potential amplitude according to the actual reactive power value; determining the grid-forming angular frequency according to the DC-side voltage, the DC-side reference voltage, the actual active power value, and the grid-forming ratio; and determining the internal potential phase angle according to the grid-following angular frequency, the grid-forming angular frequency, and the angular frequency reference value.

[0083] Specifically, Figure 5a is the schematic diagram of the power system structure provided by the present invention, Figure 5b is the schematic diagram of pulse width modulation provided by the present invention. As Figure 5a shown, the device capacity is obtained by fusing the grid-forming function and the grid-following function devices, the short-circuit ratio is determined by the system for identifying the difference intensity of the power system, and then the grid-following ratio and the grid-forming ratio are determined according to the grid-forming and grid-following coordinated control system. Further, pulse width control is performed according to the grid-following strategy and the grid-forming strategy as Figure 5b shown. In the specific modulation process, first, the three-phase voltage and the three-phase current are obtained. Based on the grid-following strategy, the three-phase voltage and the three-phase current are converted into two-phase voltage and two-phase current. The converted two-phase current includes two-phase first current I d and two-phase second current I q , and the converted two-phase voltage includes two-phase first voltage U d and two-phase second voltage U q . Then, according to the two-phase first current I d , the two-phase second current I q , the two-phase first voltage U d and the two-phase second voltage U qPerform power calculation to obtain the actual reactive power value Q and the actual active power value P. The actual reactive power value Q = U d I d +U q I q , and the actual active power value P = U d I d -U q I q . Then, input the second voltage U q into the P (Proportional) I (Integral) control algorithm to calculate the initial angular frequency, and multiply the initial angular frequency voltage by the grid-following ratio to obtain the grid-following angular frequency . Meanwhile, obtain the DC-side voltage V dc , the DC-side reference voltage V dcref , and through , substitute the DC-side voltage V dc , the DC-side reference voltage V dcref into respectively to obtain the squared value of V dc and the squared value of V dcref . By calculating the difference between the squared value of V dcref and the squared value of V dc , obtain the DC-side voltage difference, and input the DC-side voltage difference into the PI algorithm to obtain the actual reference value of active power P ref . Calculate the difference between the actual reference value of active power P ref and the actual value of active power P, and multiply them with 1 / J S (J represents the inertia time constant, and S is for integration) and K DW (K DW represents the grid-forming damping coefficient) respectively, and then accumulate the product results to obtain the angular frequency adjustment amount . Finally, multiply the angular frequency adjustment amount by the grid-forming ratio Kp to obtain the grid-forming angular frequency . Obtain the angular frequency reference value . By summing the angular frequency reference value , the grid-following angular frequency and the grid-forming angular frequency , obtain the angular frequency sum value, and then perform 1 / S integral calculation on the angular frequency sum value to finally obtain the internal potential phase angle θ. Meanwhile, obtain the actual reference value of reactive power Q ref . Calculate the reactive power difference by the difference between the actual reference value of reactive power Q ref and the actual value of reactive power Q, and further calculate the product of the reactive power difference and ( represents the reactive power integration coefficient) to obtain the actual amplitude of the internal potential. Through the actual amplitude of the internal potential and the internal potential reference value E0 The sum is obtained to get the amplitude E of the internal potential, and the amplitude E of the internal potential and the phase angle θ of the internal potential are converted from two-phase to three-phase, so as to obtain the converted three-phase modulation voltage. The three-phase modulation voltage includes three-phase first modulation voltages , three-phase second modulation voltages and three-phase third modulation voltages . Finally, pulse width control (PWM) modulation is performed according to the three-phase modulation voltage. Specifically, the filter inductor, filter capacitor, effective value of the grid voltage, equivalent inductor on the grid side, etc. can be adjusted, which is not limited in this embodiment.

[0084] The advantage of such a setting is that by fusing the grid-following ratio and grid-forming ratio, the parallel connection of grid-following control and grid-forming control is realized, and finally pulse width control modulation is performed through the first weight and the second weight in parallel to improve the grid stability of the power system of the grid.

[0085] A control method, device, equipment and medium based on the grid-following ratio and grid-forming ratio provided by the present invention obtain the system capacity and device capacity of the power system; wherein, the system capacity refers to the sum of the rated capacities of various hub substations in the power system, and the device capacity refers to the installed capacity of the equipment integrating the grid-following function and grid-forming function within a preset range of the power system; determine the short-circuit ratio according to the system capacity and device capacity; determine the grid-following ratio and grid-forming ratio according to the short-circuit ratio; obtain the three-phase voltage, three-phase current, DC-side voltage and DC-side reference voltage of the power system; perform pulse width control according to the three-phase voltage, three-phase current, DC-side voltage, DC-side reference voltage, grid-following ratio and grid-forming ratio. On the basis of the above embodiments, the technical solution of the present invention determines the grid-following ratio and grid-forming ratio, and comprehensively adjusts the pulse width of the power system based on the grid-following ratio and grid-forming ratio, so as to improve the grid stability of the power system of the grid.

[0086] The control device based on the grid-following ratio and grid-forming ratio provided by the present invention is described below. The control device based on the grid-following ratio and grid-forming ratio described below can be correspondingly referred to the control method based on the grid-following ratio and grid-forming ratio described above.

[0087] Figure 6 is a schematic structural diagram of the control device based on the grid-following ratio and grid-forming ratio provided by the present invention. Referring to Figure 6 as shown, the control device 600 based on the grid-following ratio and grid-forming ratio includes: a first acquisition module 601, a first determination module 602, a second determination module 603, a second acquisition module 604 and a width control module 605.

[0088] The first acquisition module 601 is configured to acquire the system capacity and the device capacity of the power system; wherein, the system capacity refers to the sum of the rated capacities of various hub substations in the power system, and the device capacity refers to the installed capacity of the equipment integrating grid-connected functions and grid-forming functions within a preset range of the power system.

[0089] The first determination module 602 is configured to determine the short-circuit ratio according to the system capacity and the device capacity.

[0090] The second determination module 603 is configured to determine the grid-connected ratio and the grid-forming ratio according to the short-circuit ratio.

[0091] The second acquisition module 604 is configured to acquire the three-phase voltage, three-phase current, DC-side voltage, and DC-side reference voltage of the power system.

[0092] The pulse width control module 605 is configured to perform pulse width control according to the three-phase voltage, three-phase current, DC-side voltage, DC-side reference voltage, grid-connected ratio, and grid-forming ratio.

[0093] In an exemplary embodiment, the first determination module 602 is specifically configured to: determine the short-circuit ratio according to the ratio of the system capacity to the device capacity.

[0094] In an exemplary embodiment, the second determination module 603 is specifically configured to: determine the correspondence between the grid short-circuit ratio and the target grid-forming ratio and the target grid-connected ratio; based on the correspondence, obtain the grid-connected ratio and the grid-forming ratio corresponding to the short-circuit ratio.

[0095] In an exemplary embodiment, for the second determination module 603 to determine the correspondence between the grid short-circuit ratio and the target grid-forming ratio and the target grid-connected ratio, it is specifically configured to: at a specific grid short-circuit ratio, simulate the initial grid-connected ratio and the initial grid-forming ratio, and obtain the initial grid-connected ratio, the initial grid-forming ratio, the critical clearing angle corresponding to the substation in the power system, and the power amplitude value; wherein, both the initial grid-connected ratio and the initial grid-forming ratio are at least one; fit the initial grid-connected ratio, the initial grid-forming ratio, the critical clearing angle, and the power amplitude value to obtain the target relational expression; determine the cost function according to the target relational expression; solve the cost function to obtain the target grid-connected ratio and the target grid-forming ratio corresponding to the grid short-circuit ratio, and determine the correspondence based on the grid short-circuit ratio, the target grid-connected ratio, and the target grid-forming ratio.

[0096] In an exemplary embodiment, for the second determination module 603 to determine the cost function according to the target relational expression, it is specifically configured to: determine the first weight corresponding to the critical clearing angle and the second weight determined by the power amplitude value according to the target relational expression; determine the cost function according to the first weight and the second weight.

[0097] In an exemplary embodiment, the width control module 605 is specifically configured to: determine the internal potential phase angle and the internal potential amplitude according to the three-phase voltage, the three-phase current, the DC-side voltage, the DC-side reference voltage, the grid connection ratio, and the grid forming ratio; determine the three-phase modulation voltage according to the internal potential phase angle and the internal potential amplitude; and perform pulse width control according to the three-phase modulation voltage.

[0098] In an exemplary embodiment, the width control module 605 determines the internal potential phase angle and the internal potential amplitude according to the three-phase voltage, the three-phase current, the DC-side voltage, the DC-side reference voltage, the grid connection ratio, and the grid forming ratio, and is specifically configured to: determine the two-phase voltage and the two-phase current according to the three-phase voltage and the three-phase current; where the two-phase voltage includes a first voltage and a second voltage; determine the grid connection angular frequency according to the first voltage and the grid connection ratio; determine the actual reactive power value and the actual active power value according to the first voltage, the second voltage, and the two-phase current; determine the internal potential amplitude according to the actual reactive power value; determine the grid forming angular frequency according to the DC-side voltage, the DC-side reference voltage, the actual active power value, and the grid forming ratio; and determine the internal potential phase angle according to the grid connection angular frequency, the grid forming angular frequency, and the angular frequency reference value.

[0099] The device in this embodiment can be used to execute the method in any one of the method embodiments of the control method based on the grid connection ratio and the grid forming ratio. The specific implementation process and technical effects are similar to those in the method embodiments of the control method based on the grid connection ratio and the grid forming ratio. For details, reference can be made to the detailed introduction in the method embodiments of the control method based on the grid connection ratio and the grid forming ratio, which will not be elaborated here.

[0100] Figure 7 is a schematic structural diagram of an electronic device provided by the present invention. As Figure 7 shown, the electronic device may include: a processor 710, a communication interface 720, a memory 730, and a communication bus 740. Among them, the processor 710, the communication interface 720, and the memory 730 complete communication with each other through the communication bus 740. The processor 710 can call the logical instructions in the memory 730 to execute the control method based on the grid connection ratio and the grid forming ratio. The method includes: obtaining the system capacity and the device capacity of the power system; where the system capacity refers to the sum of the rated capacities of various hub substations in the power system, and the device capacity refers to the installed capacity of the equipment integrating the grid connection function and the grid forming function within a preset range of the power system; determining the short-circuit ratio according to the system capacity and the device capacity; determining the grid connection ratio and the grid forming ratio according to the short-circuit ratio; obtaining the three-phase voltage, the three-phase current, the DC-side voltage, and the DC-side reference voltage of the power system; and performing pulse width control according to the three-phase voltage, the three-phase current, the DC-side voltage, the DC-side reference voltage, the grid connection ratio, and the grid forming ratio.

[0101] In addition, when the logical instructions in the above-mentioned memory 730 are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or a part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods in various embodiments of the present invention. The aforementioned storage medium includes: various media such as USB flash drives, mobile hard disks, read-only memories (ROM, Read-Only Memory), random access memories (RAM, Random Access Memory), magnetic disks, or optical discs that can store program codes.

[0102] On the other hand, the present invention also provides a computer program product. The computer program product includes a computer program that can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer can execute the control method based on the grid-connection ratio and grid-forming ratio provided by the above-mentioned various methods. The method includes: obtaining the system capacity and device capacity of the power system; where the system capacity refers to the sum of the rated capacities of various hub substations in the power system, and the device capacity refers to the installed capacity of the equipment integrating the grid-connection function and grid-forming function within a preset range of the power system; determining the short-circuit ratio according to the system capacity and device capacity; determining the grid-connection ratio and grid-forming ratio according to the short-circuit ratio; obtaining the three-phase voltage, three-phase current, DC-side voltage, and DC-side reference voltage of the power system; and performing pulse-width control according to the three-phase voltage, three-phase current, DC-side voltage, DC-side reference voltage, grid-connection ratio, and grid-forming ratio.

[0103] On another aspect, the present invention also provides a non-transitory computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, it implements the control method based on the grid-connection ratio and grid-forming ratio provided by the above-mentioned various methods. The method includes: obtaining the system capacity and device capacity of the power system; where the system capacity refers to the sum of the rated capacities of various hub substations in the power system, and the device capacity refers to the installed capacity of the equipment integrating the grid-connection function and grid-forming function within a preset range of the power system; determining the short-circuit ratio according to the system capacity and device capacity; determining the grid-connection ratio and grid-forming ratio according to the short-circuit ratio; obtaining the three-phase voltage, three-phase current, DC-side voltage, and DC-side reference voltage of the power system; and performing pulse-width control according to the three-phase voltage, three-phase current, DC-side voltage, DC-side reference voltage, grid-connection ratio, and grid-forming ratio.

[0104] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art can understand and implement it without creative efforts.

[0105] Through the description of the above embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on such an understanding, the essence of the above technical solution, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0106] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments or equivalently replace some of the technical features. These modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A control method based on network following ratio and network building ratio, characterized in that: include: Obtain the system capacity and device capacity of the power system; wherein the system capacity refers to the sum of the rated capacities of various hub substations in the power system, and the device capacity refers to the installed capacity of the integrated network-following function and network-building function equipment of the power system within a preset range; Determining a short circuit ratio according to the system capacity and the device capacity; Determine the grid-following ratio and the grid-forming ratio according to the short-circuit ratio; wherein, the determining the grid-following ratio and the grid-forming ratio according to the short-circuit ratio includes: determining the correspondence between the short-circuit ratio of the power grid and the target grid-forming ratio and the target grid-following ratio; based on the correspondence, obtain the grid-following ratio and the grid-forming ratio corresponding to the short-circuit ratio; the determining the correspondence between the short-circuit ratio of the power grid and the target grid-forming ratio and the target grid-following ratio includes: under the specific short-circuit ratio of the power grid, simulate the initial grid-following ratio and the initial grid-forming ratio of the short-circuit ratio of the power grid, obtain the initial grid-following ratio, the initial The initial grid-following ratio, the limit cut-off angle and the power amplitude value corresponding to the substation in the power system; wherein the initial grid-following ratio and the initial grid-following ratio are at least one; the initial grid-following ratio and the initial grid-following ratio, the limit cut-off angle and the power amplitude value are fitted to obtain a target relationship; a cost function is determined according to the target relationship; the cost function is solved to obtain the target grid-following ratio and the target grid-following ratio corresponding to the grid short-circuit ratio, and the corresponding relationship is determined based on the grid short-circuit ratio, the target grid-following ratio and the target grid-following ratio; Obtaining the three-phase voltage, three-phase current, DC side voltage and DC side reference voltage of the power system; Pulse width control is performed according to the three-phase voltage, the three-phase current, the DC side voltage, the DC side reference voltage, the grid-following ratio and the grid-forming ratio.

2. The control method based on the network following ratio and the network building ratio according to claim 1 is characterized in that: Determining the short-circuit ratio according to the system capacity and the device capacity includes: The short circuit ratio is determined according to a ratio of the system capacity to the device capacity.

3. The control method based on the network following ratio and the network building ratio according to claim 1 is characterized in that: The step of determining a cost function according to the target relational expression comprises: Determine, according to the target relationship, a first weight corresponding to the limit resection angle and a second weight determined by the power amplitude value; A cost function is determined according to the first weight and the second weight.

4. The control method based on the network following ratio and the network building ratio according to any one of claims 1 to 3, characterized in that: The pulse width control is performed according to the three-phase voltage, the three-phase current, the DC side voltage, the DC side reference voltage, the grid-following ratio and the grid-forming ratio, including: Determine the internal potential phase angle and the internal potential amplitude according to the three-phase voltage, the three-phase current, the DC side voltage, the DC side reference voltage, the grid-following ratio and the grid-forming ratio; Determining a three-phase modulation voltage according to the internal potential phase angle and the internal potential amplitude; Pulse width control is performed according to the three-phase modulation voltage.

5. The control method based on the network following ratio and the network building ratio according to claim 4 is characterized in that: The determining of the internal potential phase angle and the internal potential amplitude according to the three-phase voltage, the three-phase current, the DC side voltage, the DC side reference voltage, the grid-following ratio and the grid-forming ratio comprises: Determine a two-phase voltage and a two-phase current according to the three-phase voltage and the three-phase current; wherein the two-phase voltage includes a first voltage and a second voltage; Determining a grid-following angular frequency according to the first voltage and the grid-following ratio; Determine a reactive power actual value and an active power actual value according to the first voltage, the second voltage and the two-phase current; Determining the internal potential amplitude according to the reactive power actual value; Determining a network angular frequency according to the DC side voltage, the DC side reference voltage, the actual value of active power and the network ratio; The internal potential phase angle is determined according to the grid-following angular frequency, the grid-building angular frequency and an angular frequency reference value.

6. A control device based on the network following ratio and network building ratio, characterized in that: include: The first acquisition module is used to acquire the system capacity and device capacity of the power system; wherein the system capacity refers to the sum of the rated capacities of various hub substations in the power system, and the device capacity refers to the installed capacity of the integrated network-following function and network-building function equipment of the power system within a preset range; A first determination module, configured to determine a short circuit ratio according to the system capacity and the device capacity; The second determination module is used to determine the grid-following ratio and the grid-forming ratio according to the short-circuit ratio; wherein, the determination of the grid-following ratio and the grid-forming ratio according to the short-circuit ratio includes: determining the correspondence between the short-circuit ratio of the power grid and the target grid-forming ratio and the target grid-following ratio; based on the correspondence, obtaining the grid-following ratio and the grid-forming ratio corresponding to the short-circuit ratio; the determination of the correspondence between the short-circuit ratio of the power grid and the target grid-forming ratio and the target grid-following ratio includes: under the specific short-circuit ratio of the power grid, simulating the initial grid-following ratio and the initial grid-forming ratio of the short-circuit ratio of the power grid to obtain the initial grid-following ratio For example, the initial grid-following ratio, the limit cut-off angle and the power amplitude value corresponding to the substation in the power system; wherein the initial grid-following ratio and the initial grid-following ratio are at least one; the initial grid-following ratio and the initial grid-following ratio, the limit cut-off angle and the power amplitude value are fitted to obtain a target relationship; a cost function is determined according to the target relationship; the cost function is solved to obtain the target grid-following ratio and the target grid-following ratio corresponding to the grid short-circuit ratio, and the corresponding relationship is determined based on the grid short-circuit ratio, the target grid-following ratio and the target grid-following ratio; A second acquisition module is used to acquire the three-phase voltage, three-phase current, DC side voltage and DC side reference voltage of the power system; A width control module is used to perform pulse width control according to the three-phase voltage, the three-phase current, the DC side voltage, the DC side reference voltage, the grid-following ratio and the grid-forming ratio.

7. An electronic device comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that: When the processor executes the computer program, the control method based on the network following ratio and the network building ratio as described in any one of claims 1 to 5 is implemented.

8. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the control method based on the network following ratio and the network building ratio as described in any one of claims 1 to 5 is implemented.

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