Virtual inertia control method and device of microgrid, electronic equipment and storage medium

Abstract

The application provides a virtual inertia control method and device of a micro-grid, electronic equipment and a storage medium. Through the relationship between the energy released by the DC bus capacitor and the energy required by the virtual inertia response, the maximum virtual inertia algorithm is used to accurately determine the maximum virtual inertia that can be provided by the micro-grid, thereby effectively avoiding the instability of the micro-grid caused by improper setting of the virtual inertia. In addition, by comparing the relationship between the initial input virtual inertia and the maximum virtual inertia, the virtual inertia setting value is flexibly adjusted to be always not greater than the maximum virtual inertia, ensuring that the micro-grid operates within its carrying capacity, thereby improving the stability and safety of the micro-grid and ensuring the stable and efficient operation of the micro-grid.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of micro-grid control, and particularly relates to a virtual inertia control method and device for a micro-grid, an electronic device and a storage medium. BACKGROUND

[0002] At present, a micro-grid system composed of distributed energy generation, dynamic load and energy storage units is rapidly developing and gradually becomes an important part of a modern power system. However, the intermittency and volatility of new energy generation, the change of load power and the charge-discharge fluctuation of the energy storage system, and various disturbances easily cause serious frequency fluctuation, which significantly affects the frequency of the micro-grid. Meanwhile, the low inertia problem caused by a large number of power electronic converters further reduces the anti-interference ability of the system, thereby causing the micro-grid to be difficult to operate stably.

[0003] However, in the micro-grid, the virtual inertia directly affects the stability of the micro-grid. Therefore, how to control the virtual inertia to ensure that the micro-grid can maintain stable operation becomes a problem to be solved at present. SUMMARY

[0004] Therefore, the purpose of the present application is to provide a virtual inertia control method and device for a micro-grid, an electronic device and a storage medium to solve the above technical problems.

[0005] To achieve the above purpose, the first aspect of the present application provides a virtual inertia control method for a micro-grid, comprising:

[0006] determining the release energy of a direct current bus capacitor of the micro-grid, and determining the energy required by a virtual inertia response of the micro-grid;

[0007] processing the release energy of the direct current bus capacitor and the energy required by the virtual inertia response through a maximum virtual inertia algorithm according to the release energy of the direct current bus capacitor and the energy required by the virtual inertia response, to determine the maximum virtual inertia that can be provided by the micro-grid;

[0008] receiving an initial input virtual inertia of the micro-grid, and comparing the initial input virtual inertia with the maximum virtual inertia to obtain a comparison result;

[0009] in response to the comparison result being that the initial input virtual inertia is less than or equal to the maximum virtual inertia, controlling the micro-grid to operate according to the initial input virtual inertia; or

[0010] in response to the comparison result being that the initial input virtual inertia is greater than the maximum virtual inertia, adjusting the initial input virtual inertia of the micro-grid to be within the maximum virtual inertia to obtain an adjusted virtual inertia, and controlling the micro-grid to operate according to the adjusted virtual inertia.

[0011] Based on the same inventive concept, a second aspect of the present application provides a virtual inertia control device of a microgrid, comprising:

[0012] an energy determination module configured to determine a released energy of a DC bus capacitor of the microgrid, and determine an energy required for a virtual inertia response of the microgrid;

[0013] a virtual inertia determination module configured to determine a maximum virtual inertia of the microgrid by a maximum virtual inertia algorithm according to the released energy of the DC bus capacitor and the energy required for the virtual inertia response;

[0014] a comparison module configured to receive an initial input virtual inertia of the microgrid, and compare the initial input virtual inertia with the maximum virtual inertia to obtain a comparison result;

[0015] a first operation module configured to, in response to the comparison result being that the initial input virtual inertia is less than or equal to the maximum virtual inertia, control the microgrid to operate according to the initial input virtual inertia; or,

[0016] a second operation module configured to, in response to the comparison result being that the initial input virtual inertia is greater than the maximum virtual inertia, adjust the initial input virtual inertia of the microgrid to be within the maximum virtual inertia to obtain an adjusted virtual inertia, and control the microgrid to operate according to the adjusted virtual inertia.

[0017] Based on the same inventive concept, a third aspect of the present application provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executed by the processor, wherein the processor implements the method of the first aspect when executing the computer program.

[0018] Based on the same inventive concept, a fourth aspect of the present application provides a non-transitory computer readable storage medium, which stores computer instructions for causing a computer to execute the method of the first aspect.

[0019] From the above, it can be seen that the micro-grid virtual inertia control method, device, electronic equipment and storage medium provided by the application, through the relationship between the energy released by the DC bus capacitor and the energy required by the virtual inertia response, accurately determines the maximum virtual inertia that the micro-grid can provide by using the maximum virtual inertia algorithm, thereby effectively avoiding the instability of the micro-grid caused by improper setting of the virtual inertia. In addition, by comparing the relationship between the initial input virtual inertia and the maximum virtual inertia, the virtual inertia setting value is flexibly adjusted to be always less than or equal to the maximum virtual inertia, ensuring that the micro-grid operates within its carrying capacity, thereby improving the stability and safety of the micro-grid and ensuring the stable and efficient operation of the micro-grid. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the application or related art, the drawings needed to be used in the embodiments or related art description will be briefly introduced. Obviously, the drawings in the following description are only embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0021] Figure 1 The structure schematic diagram of the cascaded DC / DC converter and the DC / AC converter of the embodiment of the application;

[0022] Figure 2 The VSM control strategy block diagram of the DC-AC converter of the embodiment of the application;

[0023] Figure 3 The three-phase abc static coordinate system and the two-phase dq synchronous rotating coordinate system schematic diagram of the embodiment of the application;

[0024] Figure 4 The adjusted active power-frequency loop schematic diagram of the embodiment of the application;

[0025] Figure 5 The DC / DC converter and the double closed-loop control strategy schematic diagram of the embodiment of the application;

[0026] Figure 6 The dynamics curve schematic diagram of the rotor angle frequency of the virtual synchronous generator of the embodiment of the application;

[0027] Figure 7-1 The adjustment time curve schematic diagram of the embodiment of the application along with the increase of the virtual inertia J;

[0028] Figure 7-2 The frequency overcharge size curve schematic diagram of the embodiment of the application along with the increase of the virtual inertia J;

[0029] Figure 8A relationship curve between virtual inertia J and frequency deviation of the embodiment of the present application;

[0030] Figure 9 A step response curve of VSM active power when different under-damping ζ is applied of the embodiment of the present application;

[0031] Figure 10 A DC bus voltage variation curve when load power is increased of the embodiment of the present application;

[0032] Figure 11 A flow chart of the virtual inertia control method of the micro-grid of the embodiment of the present application;

[0033] Figure 12 A DC / DC converter cascaded DC / AC converter system simulation model of the embodiment of the present application;

[0034] Figure 13-1 A DC bus voltage V dc waveform (A group) schematic diagram;

[0035] Figure 13-2 A DC / AC converter output voltage u abc and current i abc (A group) schematic diagram;

[0036] Figure 14-1 A DC bus voltage V dc waveform (B group) schematic diagram;

[0037] Figure 14-2 A DC / AC converter output voltage u abc and current i abc (B group) schematic diagram;

[0038] Figure 15 A structure block diagram of the virtual inertia control device of the micro-grid of the embodiment of the present application;

[0039] Figure 16 A schematic diagram of the electronic device of the embodiment of the present application. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below in combination with specific embodiments and with reference to the drawings.

[0041] It should be noted that, unless otherwise defined, technical terms or scientific terms used in the embodiments of the present application shall have the common meaning understood by one of ordinary skill in the art to which the present application pertains. The terms "first", "second", and similar terms used in the embodiments of the present application do not denote any order, quantity, or importance, but are merely used to distinguish different components. The terms "include", "contain", and similar terms mean that the elements or objects before the terms encompass the elements or objects listed after the terms and their equivalents, and do not exclude other elements or objects. The terms "connect" or "connected" and similar terms do not mean physical or mechanical connection, but can include electrical connection, whether direct or indirect. The terms "upper", "lower", "left", "right", and the like are merely used to indicate relative positional relationships, and when the absolute positions of the described objects are changed, the relative positional relationships can also be changed accordingly.

[0042] It can be understood that, before using the technical solutions of the embodiments of the present application, the types of personal information involved, the use range, the use scenario, and the like are informed to the user in a proper manner, and the authorization of the user is obtained.

[0043] For example, in response to receiving the active request of the user, prompt information is sent to the user to explicitly prompt the user that the operation requested to be performed will require obtaining and using personal information of the user. Thus, the user can voluntarily choose whether to provide personal information to the software or hardware, such as an electronic device, an application program, a server, or a storage medium, that performs the operation of the technical solutions of the present application according to the prompt information.

[0044] As an optional but non-limiting implementation manner, in response to accepting the active request of the user, the manner of sending prompt information to the user may, for example, be a pop-up window manner, and the prompt information may, for example, be presented in the form of text in the pop-up window. In addition, the pop-up window may, for example, carry a selection control for the user to select "agree" or "disagree" to provide personal information to the electronic device.

[0045] It can be understood that the above notification and obtaining of user authorization process is only illustrative, and does not limit the implementation manners of the present application, and other manners meeting relevant laws and regulations can also be applied to the implementation manners of the present application.

[0046] Currently, microgrid systems composed of distributed new energy generation, dynamic load and energy storage units are rapidly developing and gradually becoming an important part of modern power systems. However, the intermittency and volatility of new energy generation, the change of load power and the charge-discharge fluctuation of energy storage system, various disturbances can easily cause serious frequency fluctuations, which has a significant impact on the frequency of microgrid. At the same time, the low inertia problem caused by a large number of power electronic converters further reduces the anti-interference ability of the system, thereby causing the microgrid to be difficult to operate stably. In serious cases, the instability of the microgrid may even cause the entire power system to collapse, so it is urgent to improve the inertia of the microgrid to achieve stable operation.

[0047] However, in the microgrid, the virtual inertia directly affects the stability of the microgrid. Increasing the inertia of the microgrid can use the virtual synchronous machine (VSM) strategy introduced for the converter to increase the virtual inertia of the system. This method is based on the electromagnetic equation and rotor motion equation of the synchronous motor, and considers the active power, electromagnetic torque, mechanical torque, virtual inertia and virtual damping coefficient in the control loop, and the reactive power and droop coefficient in the reactive power ring. However, when a disturbance occurs, the virtual inertia is too small to provide sufficient frequency support, and a large virtual inertia is often needed to maintain stable operation of the system. However, the maximum virtual inertia of the virtual synchronous machine strategy is not only determined by the control parameters, but is closely related to the main circuit parameters of the actual converter. When the load or power changes, the VSM control strategy wants to achieve power balance but cannot do so immediately and needs a certain adjustment time. For example, when the switching frequency of the converter is 20 kHz, the response time of the virtual synchronous machine strategy is about 0.1 seconds, which means that within 0 to 0.1 seconds, the unbalanced energy is mainly absorbed or released by the DC bus capacitor. Therefore, the capacity of the DC bus capacitor plays a decisive role in virtual inertia control, and the maximum virtual inertia provided by the virtual synchronous machine is strictly limited by the capacity of the DC bus capacitor.

[0048] The present application finds that with the development of virtual synchronous machine (VSM) technology, the introduction of virtual inertia enables microgrids with a large number of power electronic converters to have anti-interference ability, however, small virtual inertia J cannot provide sufficient frequency support, and a large inertia is often needed. However, the virtual inertia that the inverter can provide is not infinite, but is strictly limited by the circuit parameters, and since the response of the VSM cannot be completed instantaneously, a certain adjustment time is needed, and during this period, the unbalanced energy required by the system is mainly absorbed or released by the DC bus capacitor, therefore, the capacity of the capacitor determines the maximum virtual inertia that the converter can provide to a large extent.

[0049] Based on the DC bus capacitor capacity, converter regulation speed and power step conditions, the maximum virtual inertia formula that the converter applying virtual synchronous machine algorithm can provide is derived, and it is proposed that the maximum value of virtual inertia is strictly constrained by the capacitor capacity, and is also related to the rated DC bus voltage, rated angular frequency, minimum DC bus voltage and minimum angular frequency. On the other hand, the virtual damping coefficient is divided into a pure damping part and a flexible adjustment part participating in primary frequency modulation. Finally, simulation verification is carried out, which proves the correctness of the proposed maximum inertia constraint condition of the virtual synchronous machine based on the DC bus capacitor capacity, and provides a reliable theoretical basis for the inertia evaluation of the microgrid system.

[0050] As shown in Figure 1 , a direct current-direct current (DC / DC) converter cascaded direct current-alternating current (DC / AC) converter (i.e. inverter) system is given, the energy storage unit is connected to the DC / DC converter, the DC bus voltage is controlled to 700V, and the DC / AC converter applies virtual synchronous machine control to provide virtual inertia.

[0051] I. Control strategy

[0052] 1. Virtual synchronous machine control (VSM)

[0053] Virtual synchronous machine control is a control method that introduces the rotor motion equation and stator equation of a virtual synchronous generator into the control algorithm, so that the inverter has an inertia response. Therefore, the VSM technology can increase the inertia of the inverter.

[0054] The virtual rotor rotation equation of the virtual synchronous generator (in the case of 1 pole pair of the virtual virtual synchronous generator) is represented as:

[0055]

[0056] In the above formula, θ is the virtual operating angle, ω is the angular frequency, ω n is the synchronous mechanical angular frequency, P m and P e are the mechanical power and electromagnetic power of the virtual synchronous machine, J is the virtual rotational inertia, and D p is the virtual damping coefficient of the active-power-frequency relationship block diagram.

[0057] The droop characteristic between the active power and the frequency of the virtual synchronous machine is represented as:

[0058] P m = P ref + K m (ω n - ω)

[0059] In the above formula, P ref is the active power reference value of the VSM, Km It is the active-frequency droop coefficient.

[0060] Similarly, the droop characteristic between the reactive power and voltage of a virtual synchronous generator is expressed as:

[0061] Q m =Q ref +D q (U n -U)

[0062] In the above formula, Q m It is reactive power, Q ref It is the reactive power reference value, U n It is the rated voltage, D q It is the virtual damping coefficient of the reactive power-voltage control loop.

[0063] reactive power Q e and mechanical reactive power Q m The relation is:

[0064] E = E0 + K Q (Q m -Q e )

[0065] In the above formula, E is the voltage after reactive power regulation of the VSM, and K Q E0 is the proportional factor for reactive voltage control, and E0 is a fixed voltage value.

[0066] VSM-controlled three-phase DC-AC converter, such as Figure 2 As shown, the fully controlled switches of the converter are Q1 to Q6, and C f and L f These are the filter capacitor and the filter inductor, respectively, V dc This is the DC bus voltage. a v b and v c This represents the three-phase voltage of the DC-AC converter, v. oa v ob and v oc Indicates three-phase AC voltage, i fa i fb and i fc Represents alternating current, E is the grid voltage of VSM, E0 is the given reference voltage, P m and P e These are the mechanical active power and electromagnetic power of the virtual synchronizer, J is the virtual moment of inertia, and ω is the angular frequency. n It is the synchronous mechanical angular frequency, θ is the virtual working angle, and P ref This is the active power reference value for the VSM, K. mIt is the active frequency droop factor, D p Q is the virtual damping coefficient of the active frequency control loop. m It is mechanical reactive power, Q ref This is the reactive power reference value, Q. e It is the reactive power of the virtual synchronous machine, U n It is the rated voltage, D q and K Q These are the virtual damping coefficient and the proportional factor for reactive power voltage control, respectively. o and l f These are the voltage and current of the VSM, used for coordinate transformation.

[0067] The VSM control strategy includes dual closed-loop control of voltage and current, and derives the grid voltage E using the reactive power-voltage relationship, and derives the virtual angle e using the active power-frequency relationship. For example... Figure 2 As shown, firstly, an abc (three-phase stationary natural coordinate system) - dq (synchronous rotating coordinate system) transformation is used, based on the voltage v o and current l f The active power P was calculated. e and reactive power Q e In the active power loop, according to the above formula: P m =P ref +K m (ω n -ω) indicates that, from the reference active power P ref Subtract K from the middle m and angular frequency change (ω-ω n The product of ) yields the mechanical active power P. m Similar to the primary frequency regulation of a virtual synchronous generator, and then P m and electromagnetic power P e The difference between them divided by the synchronization angular frequency ω n Therefore, 1 / J S Substituting DP into the above formula: The angular frequency ω can be obtained, and integrating ω yields the virtual operating angle θ. On the other hand, in the reactive power loop, according to the above formula: Q m =Q ref +D q (U n -U), reference reactive power Q ref and virtual damping coefficient D q Multiplying by the difference in voltage change yields the reactive power Q. m According to the above formula: E=E0+K Q (Q m -Q e ), Q m With reactive power Qe The difference is substituted into the proportional factor K Q and the fixed voltage E0, the network voltage E is calculated, and E and θ are jointly input to the three-phase voltage calculation part of the voltage and current dual-loop control, and the output is subjected to dq-abc transformation, and finally the pulse width modulation (PWM) signal is obtained.

[0068] Abc-dq and dq-abc transformation are commonly used in alternating current systems, and the alternating quantity in the abc static coordinate system can be converted into the direct quantity in the dq synchronous rotating coordinate system, and the two coordinate systems are as shown in Figure 3 , θ represents the included angle between the a axis of the static reference coordinate system and the d axis of the rotating reference coordinate system, and the rotating frequency of the dq coordinate system is the synchronous angular frequency ω n .

[0069] The conversion matrix of the abc-dq transformation is:

[0070]

[0071] In the above formula, F abc is the voltage and current in the abc coordinate system, F dq is the voltage and current in the dq synchronous rotating coordinate system, the included angle θ between the a axis of the static reference system and the d axis of the rotating reference coordinate system, and the angle is related to the integral of the synchronous angular frequency ω n of the dq coordinate system.

[0072] As shown in Figure 2 , in the active frequency loop, the virtual damping coefficient D p is divided into D p1 and D p2 , D p1 is the classical damping coefficient, and D p2 participates in power regulation, so that Figure 2 the active frequency loop has changed, as shown in Figure 4 .

[0073] In Figure 4 , K m and D p2 simulate the primary frequency modulation process of the synchronous machine, when P e is less than P ref , P ref is subtracted by (Km+D p2 *ω n ); when P e is greater than P ref , P ref is added by (Km+Dp2*ω n), which reduces the difference between the reference power and the electromagnetic power, and at the same time reduces the frequency deviation. Therefore, only D p1 plays a damping role, D p2 can be flexibly adjusted to participate in the frequency modulation process, and the virtual damping coefficient D p has a large adjustment range. In addition, the DC / DC converter and the double closed-loop control strategy are shown in Figure 5 .

[0074] 2. Principle of DC / DC converter

[0075] The structure of the DC / DC converter is shown in Figure 4 , which adopts a double closed-loop circuit with voltage outer loop control and current inner loop control to maintain the DC bus voltage constant, that is, to ensure that the voltage across the capacitor C dc is constant.

[0076] II. Maximum virtual inertia constraint condition

[0077] When facing load or power fluctuations, a small virtual inertia J cannot provide sufficient frequency support, which may lead to instability or even collapse of the entire system. Therefore, a larger virtual inertia is usually designed in the design of VSM. However, the maximum virtual inertia provided by VSM is not determined by the control parameters arbitrarily, and in fact, its value is determined by the actual parameters of the main circuit of the converter. When the power of the load or power supply changes, the VSM control strategy tries to respond immediately and return to the new stable state as soon as possible, but this response process takes a certain amount of time. For example, when the switching frequency of the converter is 20 kHz, the response time of VSM is about 0.1 seconds. Within 0 to 0.1 seconds, the unbalanced energy is mainly absorbed or released by the DC bus capacitor, that is, the DC bus capacitor capacity plays a decisive role in the response of the virtual inertia. That is, the maximum virtual inertia provided by VSM is strictly constrained by the DC bus capacitor capacity.

[0078] 1. Virtual inertia design process based on VSM

[0079] Ignoring losses, the rotor kinetic energy E k of the virtual synchronous generator in stable operation is represented as

[0080]

[0081] In the above formula, P E is the electromagnetic power, P T is the mechanical power input by the rotor shaft, ω n is the synchronous angular frequency, and J is the rotational inertia of the generator. If the angular frequency of the virtual synchronous generator changes from ω0 to ω1, the change in kinetic energy of the virtual synchronous generator is:

[0082]

[0083] The ratio of kinetic energy to the rated capacity of the virtual synchronous generator is defined as the inertia time constant, which is closely related to the inertia, and the inertia time constant H s is:

[0084]

[0085] According to the above formula and the above formula The kinetic energy E k can be expressed as:

[0086] E k = H s S N

[0087] The formula shows that the inertia time constant H s is proportional to the kinetic energy E k . The dynamic curve of the angular frequency ω of the virtual synchronous generator is shown in Figure 6 When the virtual inertia and damping coefficient are constant, the angular frequency change process can be divided into four stages. From t1 to t2, the virtual rotor angular frequency ω is greater than the synchronous angular frequency ω n , and gradually increases, and the angular frequency change rate dω / dt is always positive. In this process, in order to minimize the maximum frequency deviation Δω, a larger virtual inertia J is better than a constant virtual inertia J. From t2 to t3, the virtual rotor angular frequency ω is also greater than the synchronous angular frequency ω n , but gradually decreases, and the angular frequency dω / dt change rate is always negative. In this process, the angular frequency ω needs to return to ω n as soon as possible, so a smaller virtual inertia J is needed. Similarly, from t3 to t4, ω is less than ω n , and gradually decreases, and dω / dt is always negative. In order to minimize the maximum frequency deviation Δω, a larger virtual inertia J is needed. From t4 to t5, ω is also less than ω n , but gradually increases, and dω / dt is always positive, and ω needs to return to ω n as soon as possible, so a smaller J is needed. The relationship between the maximum frequency deviation Δω, the frequency change rate dω / dt, the virtual rotor angular frequency ω and the virtual inertia J of the virtual synchronous generator is shown in Table 1.

[0088] Table 1 Relationship table between frequency change, frequency change rate, virtual rotor speed and virtual inertia J of virtual synchronous generator

[0089]

[0090] According to Table 1, compared with constant virtual inertia J, taking variable virtual inertia J can significantly reduce the maximum frequency deviation Δω and the change of frequency dω / dt.

[0091] Based on the VSM control block diagram in Figure 2 , the transfer function between electromagnetic power P e and mechanical power P m is obtained:

[0092]

[0093] In the above formula, K = 3*V o V pcc / X s , V o and V pcc are VSM reference voltage and common coupling voltage point respectively, and X s is gate impedance. Based on the above formula, the dynamic response of electromagnetic power and mechanical power can be obtained. In engineering applications, because the response speed of over-damped system is very slow, it is usually designed as an under-damped system, and based on the VSM control block diagram shown in Figure 2 , the transfer function between mechanical power P m and frequency change Δω is derived as:

[0094]

[0095] According to the above formula, when a disturbance occurs, with the increase of virtual inertia, the frequency adjustment time and frequency overshoot characteristics are as shown in Figure 7-1 and Figure 7-2 .

[0096] According to Figure 7-1 , Figure 7-2 and Table 1, it can be found that with the increase of virtual inertia, the maximum frequency deviation and the initial change rate of frequency are relatively small, but the frequency adjustment time is longer. As shown in Figure 8 , when J increases, the frequency deviation becomes smaller. J min can be calculated according to the maximum frequency deviation and frequency change rate allowed by the system.

[0097] Next, how to design virtual damping coefficient D p1 is studied. The step response of VSM active power with different ζ is as shown in Figure 9 . When ζ = 1, the step response of VSM active power is curve (3), and the absorbed energy is the area enclosed by curve (3) and P m . When the system is slightly under-damped (ζ = 0.707), the absorbed energy is the area between curve (2) and P m . From Figure 9It can be seen that the energy absorbed by the under-damped system is less than that absorbed by the critically damped system. However, a smaller damping coefficient is extremely prone to power oscillation, and therefore, ζ = 0.707 is applied.

[0098] According to the above formula: The second-order transfer function shown above is derived as ζ = D pI / 2Jω n , and after moving the term, the virtual damping coefficient is:

[0099] D P1 = 2Jζω n

[0100] 2. Maximum virtual inertia based on energy transient process

[0101] As Figure 1 shown, when the power of the three-phase load suddenly increases, the VSM control of the DC / AC converter cannot complete the response within 0-0.1s, and the DC bus capacitor C dc immediately releases energy to respond to the power change. After a period of time, the bus voltage decreases, the duty cycle of the DC / DC converter gradually increases, and the output power gradually increases. When the converter output power is large enough, on the one hand, it meets the power demand of the load, and on the other hand, it charges the C dc and eventually realizes the stability of the DC bus voltage. Under the condition that the three-phase load suddenly increases by the same power, different C dc will bring different changes in the DC bus voltage, as Figure 10 shown.

[0102] In Figure 10 , the capacitance of curve 1 is smaller than that of curve 2, U dcmin1 and U dcmin2 represent the minimum voltage of the DC bus under the condition of two different capacitances, and t1 and t2 represent the time when the minimum voltage is reached. From Figure 10 it can be seen that when the bus capacitor C dc is large, the DC bus voltage decreases slowly, and the minimum bus voltage is high.

[0103] According to Figure 10 , the energy released by the capacitor C dc during the sudden increase in load power is represented as:

[0104]

[0105] On the other hand, the energy required by the virtual inertia response is:

[0106]

[0107] In the above formula, Δω = ωn - ω1, ω n is the rated angular frequency, and ω1is the minimum angular frequency. In the worst case, all the energy of the load surge is provided by the capacitor C dc , according to the above-mentioned capacitor C dc The expression of the energy released during the sudden increase of the load power and the expression of the energy required by the virtual inertia response can be derived to the maximum virtual inertia:

[0108]

[0109] According to the above formula, the maximum virtual inertia that the DC / AC converter VSM control can provide is determined by the DC bus capacitor C dc , and is also related to the rated DC bus voltage U dcref , the rated angular frequency ω n , the minimum voltage U dcmin and the minimum angular frequency ω1. Let the load power change be ΔP, and ΔP is proportional to ΔE, and the relationship is:

[0110]

[0111] In the above formula, K is a scaling factor, T r is the response time of the DC / AC converter VSM control. It is obvious that the power change ΔP is closely related to the capacitor C dc and the bus voltage change. Therefore, when planning a microgrid, how to determine the DC bus capacitor capacity is crucial to the stable operation of the system, and the maximum load power change and the allowed DC bus voltage change need to be considered. For evaluating the maximum load power fluctuation that the existing microgrid can provide, the bus capacitor C dc , the maximum voltage change and the converter control parameters need to be considered.

[0112] The embodiment of the application provides a virtual inertia control method of a microgrid. By the relationship between the energy released by the DC bus capacitor and the energy required by the virtual inertia response, the maximum virtual inertia algorithm is used to accurately determine the maximum virtual inertia that the microgrid can provide, so that the instability of the microgrid caused by improper setting of the virtual inertia is effectively avoided. In addition, by comparing the relationship between the initial input virtual inertia and the maximum virtual inertia, the virtual inertia setting value is flexibly adjusted to be always not greater than the maximum virtual inertia, so that the microgrid is ensured to operate within the range of the carrying capacity, and the stability and safety of the microgrid are improved, and the stable and efficient operation of the microgrid is ensured.

[0113] As shown in Figure 11 , the method of the embodiment comprises:

[0114] Step 1101, determine the release energy of the DC bus capacitor of the microgrid, and determine the energy required for the virtual inertia response of the microgrid.

[0115] In this step, the DC bus capacitor is an important energy storage element that can provide or absorb energy when the grid fluctuates to maintain the stability of the grid.

[0116] When the grid needs additional energy to respond to certain events (such as load mutations), the DC bus capacitor can release its stored energy to meet this demand. The amount of energy released or absorbed depends on the size of the voltage change and the capacity of the capacitor.

[0117] Virtual inertia is a concept in microgrids that simulates the inertia of traditional power grids, helping to slow down the speed of frequency changes in the grid, thereby providing more time for other devices in the grid to respond and adjust.

[0118] When the grid frequency changes, the virtual inertia system needs to consume a certain amount of energy to provide the necessary inertia support to maintain the stability of the grid.

[0119] Virtual inertia response refers to the simulation of the response characteristics of traditional rotating machines in power systems through advanced control techniques to provide the dynamic behavior required by the grid. In microgrids, virtual inertia response technology can improve the stability and inertia support capacity of the system.

[0120] The energy required for the virtual inertia response of the microgrid can be determined through simulation analysis or experimental testing. This usually involves modeling the dynamic characteristics of the system, optimizing the control strategy, and evaluating the performance of energy storage devices.

[0121] Determining the release energy of the DC bus capacitor of the microgrid and the energy required for the virtual inertia response requires considering multiple factors and overall system performance requirements. When designing a microgrid, these factors need to be considered comprehensively to ensure the stability and reliability of the system.

[0122] Step 1102, according to the release energy of the DC bus capacitor and the energy required for the virtual inertia response, process through the maximum virtual inertia algorithm to determine the maximum virtual inertia that the microgrid can provide.

[0123] In this step, in the microgrid, through the maximum virtual inertia algorithm, the maximum virtual inertia that the microgrid can provide can be determined according to the releaseable energy of the DC bus capacitor and the energy required for the virtual inertia response.

[0124] This algorithm takes into account various factors such as the energy storage state of the capacitor, the frequency change rate of the grid, and the energy demand of the virtual inertia system, to ensure that the effect of virtual inertia is maximized without affecting the stability of the grid.

[0125] By running the maximum virtual inertia algorithm, the maximum virtual inertia value that the micro-grid can allow to provide under the given conditions can be determined, which directly affects the stability and response speed of the power grid, thereby effectively avoiding the instability of the micro-grid caused by improper virtual inertia setting, and ensuring the stability and reliability of the micro-grid during operation.

[0126] Step 1103, receiving the initial input virtual inertia of the micro-grid, and comparing the initial input virtual inertia with the maximum virtual inertia to obtain a comparison result.

[0127] In this step, by comparing the initial input virtual inertia with the maximum virtual inertia, a comparison result is obtained, and the virtual inertia setting is flexibly adjusted based on the comparison result to ensure that the micro-grid operates within its carrying capacity, thereby improving the stability and safety of the micro-grid and ensuring the stable and efficient operation of the micro-grid.

[0128] Step 1104, in response to the comparison result that the initial input virtual inertia is less than or equal to the maximum virtual inertia, controlling the micro-grid to operate according to the initial input virtual inertia. Or,

[0129] In this step, when the comparison result is that the initial input virtual inertia is less than or equal to the maximum virtual inertia, it means that the set virtual inertia is within the range of the maximum virtual inertia that the micro-grid can allow to provide, and the micro-grid can be controlled to operate according to the initial input virtual inertia, which can ensure the stability and safety of the micro-grid.

[0130] Step 1105, in response to the comparison result that the initial input virtual inertia is greater than the maximum virtual inertia, adjusting the initial input virtual inertia of the micro-grid to be within the maximum virtual inertia to obtain an adjusted virtual inertia, and controlling the micro-grid to operate according to the adjusted virtual inertia.

[0131] In this step, when the comparison result is that the initial input virtual inertia is greater than the maximum virtual inertia, it means that the set virtual inertia is not properly set and is not within the range of the maximum virtual inertia that the micro-grid can allow to provide, which will cause instability of the micro-grid. Therefore, the virtual inertia setting is flexibly adjusted, the initial input virtual inertia of the micro-grid is adjusted to be within the maximum virtual inertia to obtain an adjusted virtual inertia, and the micro-grid is controlled to operate according to the adjusted virtual inertia, which ensures that the micro-grid operates within its carrying capacity, thereby improving the stability and safety of the micro-grid and ensuring the stable and efficient operation of the micro-grid.

[0132] By the above scheme, the maximum virtual inertia that the microgrid can provide is accurately determined by the relationship between the energy released by the DC bus capacitor and the energy required by the virtual inertia response, thereby effectively avoiding the instability of the microgrid caused by improper setting of the virtual inertia. In addition, by comparing the relationship between the initial input virtual inertia and the maximum virtual inertia, the virtual inertia setting value is flexibly adjusted to be always not greater than the maximum virtual inertia, ensuring that the microgrid operates within its carrying capacity, thereby improving the stability and safety of the microgrid and ensuring the stable and efficient operation of the microgrid.

[0133] In some embodiments, in step 1101, the determination of the released energy of the DC bus capacitor of the microgrid comprises:

[0134] Step A1, obtaining the DC bus capacitor of the microgrid, the rated voltage of the DC bus of the microgrid, and the minimum voltage of the DC bus of the microgrid.

[0135] Step A2, square processing the rated voltage of the DC bus to obtain a rated voltage processing result, and square processing the minimum voltage of the DC bus to obtain a minimum voltage processing result.

[0136] Step A3, multiplying the preset first constant parameter, the DC bus capacitor and the rated voltage processing result to obtain a first product processing result.

[0137] Step A4, multiplying the preset first constant parameter, the minimum voltage processing result and the minimum voltage processing result to obtain a second product processing result.

[0138] Step A5, difference processing the first product processing result and the second product processing result to obtain the released energy of the DC bus capacitor of the microgrid.

[0139] In the above scheme, the DC bus capacitor is the capacitor capacity on the DC bus in the microgrid, usually in Farad (F) units. It is used to smooth the voltage fluctuation on the DC bus.

[0140] The rated voltage of the DC bus is the design voltage value of the DC bus under normal operation, which is the basis for stable operation of the system.

[0141] The minimum voltage of the DC bus is the minimum voltage value that the DC bus may reach under certain conditions (such as load change, fault, etc.).

[0142] Square processing the rated voltage to obtain the rated voltage processing result. This is because the energy released by the capacitor is proportional to the square of the voltage.

[0143] The lowest voltage is also squared to obtain the lowest voltage processing result. This is also because the energy stored in the capacitor is proportional to the square of the voltage.

[0144] The first product processing result represents the total energy of the capacitor at the rated voltage, and the second product processing result represents the total energy at the lowest voltage.

[0145] Based on the difference between the two, the release energy of the DC bus capacitor is obtained. This difference represents the energy released by the capacitor from the rated voltage to the lowest voltage.

[0146] The DC bus capacitor C dc The energy released during the sudden increase in load power can be represented as follows:

[0147]

[0148] where ΔE represents the release energy of the DC bus capacitor, C dc represents the DC bus capacitor of the microgrid, U dcref represents the rated voltage of the DC bus of the microgrid, U dcmin represents the lowest voltage of the DC bus of the microgrid, and the first constant parameter is

[0149] By comprehensively considering the DC bus capacitor of the microgrid, the rated voltage of the DC bus of the microgrid, and the lowest voltage of the DC bus of the microgrid, the release energy of the DC bus capacitor of the microgrid determined is more accurate.

[0150] In some embodiments, in step 1101, the energy required for determining the virtual inertia response of the microgrid includes:

[0151] Step B1, obtaining the rated angular frequency of the virtual synchronous generator of the microgrid, and determining the angular frequency variation of the virtual synchronous generator of the microgrid;

[0152] Step B2, multiplying the preset second constant parameter and the rated angular frequency of the virtual synchronous generator to obtain the rated angular frequency processing result;

[0153] Step B3, performing difference processing on the rated angular frequency processing result and the angular frequency variation of the virtual synchronous generator to obtain the difference processing result;

[0154] Step B4, multiplying the preset virtual inertia parameter, the preset third constant parameter, and the difference processing result to obtain the energy required for the virtual inertia response of the microgrid.

[0155] In the above scheme, the rated angular frequency is the angular frequency of the virtual synchronous generator under rated operating conditions, usually in units of radians per second (rad / s). This value usually corresponds to the standard frequency of the power grid, for example, in a 50 Hz power grid, the rated angular frequency is 2π×50 rad / s.

[0156] The angular frequency variation refers to the difference between the actual angular frequency of the virtual synchronous generator and the rated angular frequency due to load changes, disturbances, or control strategies, etc. This variation reflects one aspect of the dynamic behavior of the system.

[0157] The energy required for the virtual inertia response can be expressed as follows:

[0158]

[0159] In the above formula, ΔE k represents the energy required for the virtual inertia response, △ω represents the angular frequency variation of the virtual synchronous generator of the microgrid, Δω = ω n -ω1, ω n is the rated angular frequency, ω1 is the minimum angular frequency, J represents the preset virtual inertia parameter, the second constant parameter is 2, and the third constant parameter is

[0160] By comprehensively considering the angular frequency variation of the virtual synchronous generator of the microgrid, the preset virtual inertia parameter, and the rated angular frequency, the energy required for the determined virtual inertia response can be more accurate, thereby helping to improve the stability and reliability of the microgrid.

[0161] In some embodiments, in step B1, the angular frequency variation of the virtual synchronous generator of the microgrid is determined by:

[0162] Step C1, obtaining the minimum angular frequency of the virtual synchronous generator of the microgrid.

[0163] Step C2, performing difference processing on the rated angular frequency of the virtual synchronous generator and the minimum angular frequency of the virtual synchronous generator to obtain the angular frequency variation of the virtual synchronous generator.

[0164] In the above scheme, the rated angular frequency is subtracted from the minimum angular frequency, and the difference obtained is the angular frequency variation of the virtual synchronous generator. This variation represents the possible fluctuation range of the generator angular frequency under normal operating conditions, which is crucial for evaluating the performance of the generator, the stability of the microgrid, and designing an appropriate control system.

[0165] The size of the angular frequency variation can reflect the ability of the generator to adapt to load changes, maintain voltage and frequency stability, and the ability of the microgrid to maintain operational continuity in the face of disturbances.

[0166] may be expressed as follows:

[0167] Δω = ω n - ω1

[0168] wherein, Δω represents the change of the angular frequency of the virtual synchronous generator of the microgrid, ω n is the rated angular frequency, and ω1 is the minimum angular frequency.

[0169] The change of the angular frequency of the virtual synchronous generator of the microgrid can be quickly determined through the rated angular frequency and the minimum angular frequency.

[0170] In some embodiments, step 1102 comprises:

[0171] Step D1, constructing an energy constraint function based on the energy required by the virtual inertia response and the released energy of the DC bus capacitor through the following formula:

[0172] ΔE k ≤ ΔE

[0173] wherein, ΔE k represents the energy required by the virtual inertia response, and ΔE represents the released energy of the DC bus capacitor, J represents a preset virtual inertia parameter, ω n represents the rated angular frequency of the virtual synchronous generator of the microgrid, ω1 represents the minimum angular frequency of the virtual synchronous generator of the microgrid, and Δω represents the change of the angular frequency of the virtual synchronous generator of the microgrid, C dc represents the DC bus capacitor of the microgrid, U dcref represents the rated voltage of the DC bus of the microgrid, U dcmin represents the minimum voltage of the DC bus of the microgrid.

[0174] Step D2, processing the energy constraint function with respect to the preset virtual inertia parameter through a virtual inertia parameter solving algorithm to obtain the maximum virtual inertia of the microgrid.

[0175] In the above scheme, the DC bus capacitor C dc of the microgrid releases energy during the sudden increase of the load power, which is expressed as:

[0176]

[0177] On the other hand, the energy required by the virtual inertia response is:

[0178]

[0179] Based on the expressions of the two, let ΔE k ≤ ΔE to construct an energy constraint function.

[0180] After the energy constraint function is constructed, the function is processed by a virtual inertia parameter solving algorithm to find a solution that maximizes the virtual inertia parameter under the condition of meeting the energy constraint, and the maximum virtual inertia value of the micro-grid (i.e., the maximum virtual inertia of the micro-grid) is output. This value is the maximum virtual inertia that can be achieved under the premise of ensuring system stability and energy balance, which helps to improve the frequency response capability and overall stability of the micro-grid.

[0181] In some embodiments, step D2 comprises:

[0182] Step E1, constructing a maximum virtual inertia constraint function about the preset virtual inertia parameter based on the energy constraint function by the following formula:

[0183]

[0184] wherein J represents the preset virtual inertia parameter, C dc represents the DC bus capacitor of the micro-grid, U dcref represents the rated voltage of the DC bus of the micro-grid, U dcmin represents the minimum voltage of the DC bus of the micro-grid, and Δω represents the angular frequency change of the virtual synchronous generator of the micro-grid, ω n represents the rated angular frequency of the virtual synchronous generator of the micro-grid.

[0185] Step E2, determining the maximum value of the preset virtual inertia parameter based on the maximum virtual inertia constraint function, and taking the maximum value of the preset virtual inertia parameter as the maximum virtual inertia of the micro-grid.

[0186] In the above scheme, the DC bus capacitor C dc The energy released during the sudden increase in load power is represented as:

[0187]

[0188] On the other hand, the energy required for the virtual inertia response is:

[0189]

[0190] Based on the expressions of both, let ΔE k ≤ ΔE to construct an energy constraint function, and after moving the term, the maximum virtual inertia constraint function about the preset virtual inertia parameter can be derived:

[0191]

[0192] According to the maximum virtual inertia constraint function, the maximum value of the preset virtual inertia parameter can be quickly determined, and the maximum value of the preset virtual inertia parameter is taken as the maximum virtual inertia of the micro-grid.

[0193] In some embodiments, in step 1101, the determination of the release energy of the DC bus capacitor of the micro-grid includes:

[0194] Step F1, obtaining the response time of the virtual synchronous generator control of the micro-grid and the load power variation of the micro-grid.

[0195] Step F2, multiplying the preset scaling coefficient parameter, the response time of the virtual synchronous generator control and the load power variation of the micro-grid to obtain the release energy of the DC bus capacitor of the micro-grid.

[0196] In the above scheme, the response time of the virtual synchronous generator control refers to the time interval from the system detecting the load change or disturbance to the virtual synchronous generator control starting to respond. This time interval is usually very short, in milliseconds or seconds, to ensure that the system can respond quickly and remain stable.

[0197] The load power variation of the micro-grid refers to the variation of the load demand in the micro-grid, which may be caused by the switching of the load, the change of the load characteristics or the fluctuation of the output power of the distributed power supply. This variation is crucial for the stable operation of the micro-grid, as it directly affects the power balance of the system and the stability of the bus voltage.

[0198] The scaling coefficient parameter is a preset parameter for adjusting the scale of the calculation result.

[0199] The multiplication of the above three parameters can be represented as follows:

[0200]

[0201] In the above formula, △E represents the release energy of the DC bus capacitor, K is the scaling coefficient parameter, T r is the response time of the DC / AC converter vSM control. It is obvious that the power variation ΔP is closely related to the capacitor C dc and the bus voltage variation. Therefore, when planning the micro-grid, how to determine the DC bus capacitor capacity is crucial for the stable operation of the system, and the maximum load power variation and the allowed DC bus voltage variation need to be considered. For evaluating the maximum load power fluctuation that the existing micro-grid can provide, the bus capacitor C dc , the maximum voltage variation and the converter control parameter need to be considered.

[0202] By considering the response time of the virtual synchronous generator control, the load power variation and the preset scaling coefficient parameter, the energy required to be released by the system when the load changes can be accurately evaluated. Further, it can ensure that the micro-grid has sufficient energy reserve to maintain the stability of the bus voltage when the load changes, which helps to improve the reliability and stability of the micro-grid and reduce the risk of system failure.

[0203] In some embodiments, to verify the maximum virtual inertia constraint function of the DC / AC converter VSM control shown in the following formula of the application:

[0204]

[0205] Based on Figure 1 , the simulation model of the DC / DC converter cascaded DC / AC converter as shown in Figure 12 is built by using mathematical software (Matlab) software. The simulation model is composed of a DC power supply, a DC bus voltage stabilizing capacitor, a DC / DC converter, a DC / AC converter, a three-phase filter inductor and a three-phase filter capacitor. The DC / DC converter adopts a voltage and current double closed loop control strategy, and the DC / AC converter adopts a virtual synchronous machine control strategy. The specific simulation parameters are shown in Table 2. To verify the maximum inertia constraint condition of the DC / AC converter using the virtual synchronous machine control strategy, A and B two groups of simulation experiments are respectively carried out under the condition of different VSM virtual inertia J.

[0206] Table 2 Simulation system parameters and load power step parameters of A and B two groups of experiments

[0207] Parameter Value AC bus voltage V s ]]> 311V Direct current bus voltage v dc ]]> 700V DC / DC converter DC side voltage stabilizing capacitor C dc ]]> 4000 μF Voltage loop proportional control parameter k of dc / dc converter vp ]] 0.8 DC / dc converter current loop proportional control parameter k ip ]]> 0.9 Voltage loop integral control parameter k of dc / dc converter vi ]] 26 Integral control parameter k of current loop of dc / dc converter ii ]] 22 AC side filter capacitor C s ]]> 10 μF AC side filter inductance L s ]]> 1 mH VSM proportional control parameter k in active voltage loop dvp ]] 1.03 Integral control parameter k in VSM active voltage loop dvi ]] 184.46 VSM active current loop proportional control parameter k dip ]]> 5 Integral control parameter k in VSM active current loop dii ]] 100 initial load power P1 50 kW step back load power P2 80 kW Step time 3s [Group A VSM virtual inductance J A ]]> 1 B group VSM virtual inductance J B ]]> 50

[0208] The virtual inertia in group A is 1, which satisfies the maximum virtual inertia constraint function of the application, while the virtual inertia in group B is 50, which does not satisfy the maximum virtual inertia constraint function of the application. Under the same disturbance condition, when the load power suddenly increases by 30kW at 3s, the simulation results of A group and B group are shown in Figure 13-1 、 Figure 13-2 、 Figure 14-1 and Figure 14-2 .

[0209] As shown in Figure 12 , when using the parameters of group A, due to the load power step at 3s, the voltage of the DC bus first decreases and returns to steady state after 0.2 seconds, at the same time, the AC voltage slightly decreases and then quickly recovers to steady state. After a short adjustment, the three-phase current increases by about 0.5 times. Figure 13-1 and Figure 13-2 indicate that when the virtual inertia satisfies the maximum constraint, the system can recover to stability during the disturbance.

[0210] AsFigure 14-1 and Figure 14-2 As shown in FIG. 9, when the B group parameters are used, the DC bus voltage, AC voltage and current will fluctuate sharply when the load power jumps at 3s, and the system cannot operate stably. As shown in FIG. 10, Figure 13-1 、 Figure 13-2 、 Figure 14-1 and Figure 14-2 It can be seen that when the virtual inertia J exceeds the maximum constraint condition, the system cannot operate normally, therefore, limiting the maximum virtual inertia of the DC / AC converter VSM control can ensure that the system responds to power changes quickly and stably.

[0211] Through simulation experiments, it is proved that the maximum virtual inertia constraint function of the virtual synchronous machine based on the DC capacitor capacity provided in the application can provide an important theoretical basis for setting the virtual synchronous machine control parameters in the DC / AC converter system, which is conducive to the stable operation of the system.

[0212] It should be noted that the method of the embodiments of the application can be executed by a single device, such as a computer or a server, etc. The method of the embodiments can also be applied to a distributed scenario, and be completed by multiple devices cooperating with each other. In this distributed scenario, one of the multiple devices can only execute one or more steps in the method of the embodiments of the application, and the multiple devices can interact with each other to complete the method.

[0213] It should be noted that some embodiments of the application have been described above. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims can be performed in a different order and still achieve desirable results. Additionally, the processes depicted in the figures do not necessarily require the particular order shown, or sequential order, to achieve the desired results. In certain implementations, multitasking and parallel processing can be advantageous.

[0214] Based on the same inventive concept, the application also provides a virtual inertia control device of a microgrid corresponding to any of the above-mentioned method embodiments.

[0215] Referring to Figure 15 , the virtual inertia control device of the microgrid comprises:

[0216] The energy determination module 1501 is configured to determine the released energy of the DC bus capacitor of the microgrid, and determine the energy required by the virtual inertia of the microgrid in response;

[0217] The virtual inertia determination module 1502 is configured to determine the maximum virtual inertia that can be provided by the micro-grid by processing the maximum virtual inertia algorithm according to the release energy of the DC bus capacitor and the energy required by the virtual inertia response;

[0218] The comparison module 1503 is configured to receive the initial input virtual inertia of the micro-grid, and compare the initial input virtual inertia with the maximum virtual inertia to obtain a comparison result;

[0219] The first operation module 1504 is configured to control the micro-grid to operate according to the initial input virtual inertia in response to the comparison result being that the initial input virtual inertia is less than or equal to the maximum virtual inertia; or,

[0220] The second operation module 1505 is configured to adjust the initial input virtual inertia of the micro-grid to be within the maximum virtual inertia to obtain an adjusted virtual inertia, and control the micro-grid to operate according to the adjusted virtual inertia in response to the comparison result being that the initial input virtual inertia is greater than the maximum virtual inertia.

[0221] In some embodiments, the energy determination module 1501 is specifically configured to:

[0222] Obtain the DC bus capacitor of the micro-grid, the rated voltage of the DC bus of the micro-grid, and the minimum voltage of the DC bus of the micro-grid;

[0223] Square process the rated voltage of the DC bus to obtain a rated voltage processing result, and square process the minimum voltage of the DC bus to obtain a minimum voltage processing result;

[0224] Multiply process a preset first constant parameter, the DC bus capacitor and the rated voltage processing result to obtain a first multiplication processing result;

[0225] Multiply process a preset first constant parameter, the minimum voltage processing result and the minimum voltage processing result to obtain a second multiplication processing result;

[0226] Difference process the first multiplication processing result and the second multiplication processing result to obtain the release energy of the DC bus capacitor of the micro-grid.

[0227] In some embodiments, the energy determination module 1502 includes:

[0228] The change amount determination unit is configured to obtain the rated angular frequency of the virtual synchronous generator of the micro-grid, and determine the angular frequency change amount of the virtual synchronous generator of the micro-grid;

[0229] a product processing unit configured to perform product processing on the preset second constant parameter and the rated angular frequency of the virtual synchronous generator to obtain a rated angular frequency processing result;

[0230] a difference processing unit configured to perform difference processing on the rated angular frequency processing result and an angular frequency variation of the virtual synchronous generator to obtain a difference processing result;

[0231] an energy determination unit configured to perform product processing on a preset virtual inertia parameter, a preset third constant parameter and the difference processing result to obtain energy required for a virtual inertia response of the microgrid.

[0232] In some embodiments, the variation determination unit is specifically configured to:

[0233] obtain a minimum angular frequency of the virtual synchronous generator of the microgrid;

[0234] perform difference processing on the rated angular frequency of the virtual synchronous generator and the minimum angular frequency of the virtual synchronous generator to obtain the angular frequency variation of the virtual synchronous generator.

[0235] In some embodiments, the virtual inertia determination module 1502 comprises:

[0236] a construction unit configured to construct an energy constraint function based on the energy required for the virtual inertia response and the release energy of the DC bus capacitor through the following formula:

[0237] △E k ≤△E

[0238] wherein ΔE k represents the energy required for the virtual inertia response, ΔE represents the release energy of the DC bus capacitor, J represents the preset virtual inertia parameter, ω n represents the rated angular frequency of the virtual synchronous generator of the microgrid, ω1 represents the minimum angular frequency of the virtual synchronous generator of the microgrid, and △ω represents the angular frequency variation of the virtual synchronous generator of the microgrid, C dc represents the DC bus capacitor of the microgrid, U dcref represents the rated voltage of the DC bus of the microgrid, U dcmin represents the minimum voltage of the DC bus of the microgrid;

[0239] a virtual inertia determination unit configured to process the energy constraint function with respect to the preset virtual inertia parameter through a virtual inertia parameter solving algorithm to obtain the maximum virtual inertia of the microgrid.

[0240] In some embodiments, the virtual inertia determination unit is specifically configured to:

[0241] The maximum virtual inertia constraint function about the preset virtual inertia parameter is constructed based on the energy constraint function by the following formula:

[0242]

[0243] wherein J represents the preset virtual inertia parameter, C dc represents the DC bus capacitor of the microgrid, U dcref represents the rated voltage of the DC bus of the microgrid, U dcmin represents the minimum voltage of the DC bus of the microgrid, Δω represents the angular frequency variation of the virtual synchronous generator of the microgrid, ω n represents the rated angular frequency of the virtual synchronous generator of the microgrid.

[0244] The maximum value of the preset virtual inertia parameter is determined based on the maximum virtual inertia constraint function, and the maximum value of the preset virtual inertia parameter is taken as the maximum virtual inertia of the microgrid.

[0245] In some embodiments, the energy determination module 1501 is specifically configured to:

[0246] obtain the response time of the virtual synchronous generator control of the microgrid and the load power variation of the microgrid;

[0247] The release energy of the DC bus capacitor of the microgrid is obtained by multiplying the preset scaling coefficient parameter, the response time of the virtual synchronous generator control and the load power variation of the microgrid.

[0248] For the convenience of description, the above device is described as various modules respectively described in function. Of course, in the implementation of the present application, the functions of each module can be implemented in the same or multiple software and / or hardware.

[0249] The device of the above embodiments is used to implement the corresponding virtual inertia control method of the microgrid in any of the above embodiments, and has the beneficial effects of the corresponding method embodiments, which are not described here.

[0250] Based on the same inventive concept, corresponding to the method of any of the above embodiments, the present application also provides an electronic device, which comprises a memory, a processor and a computer program stored in the memory and executable on the processor, and the processor implements the virtual inertia control method of the microgrid according to any of the above embodiments when executing the program.

[0251] Figure 16A more specific electronic device hardware structure schematic diagram provided by the embodiment is shown. The device can include a processor 1601, a memory 1602, an input / output interface 1603, a communication interface 1604, and a bus 1605. The processor 1601, the memory 1602, the input / output interface 1603, and the communication interface 1604 are connected to each other through the bus 1605 for internal communication.

[0252] The processor 1601 can be implemented by a general-purpose CPU (Central Processing Unit), a microprocessor, an ASIC (Application Specific Integrated Circuit), or one or more integrated circuits, etc., for executing related programs to implement the technical solutions provided by the embodiments of the present specification.

[0253] The memory 1602 can be implemented by a ROM (Read Only Memory), a RAM (Random Access Memory), a static storage device, a dynamic storage device, etc. The memory 1602 can store an operating system and other application programs. When the technical solutions provided by the embodiments of the present specification are implemented by software or firmware, the related program codes are stored in the memory 1602 and are called and executed by the processor 1601.

[0254] The input / output interface 1603 is used to connect input / output modules to realize information input and output. The input / output modules can be configured as components in the device (not shown in the figure) or externally connected to the device to provide corresponding functions. The input device can include a keyboard, a mouse, a touch screen, a microphone, various sensors, etc., and the output device can include a display, a speaker, a vibrator, an indicator light, etc.

[0255] The communication interface 1604 is used to connect a communication module (not shown in the figure) to realize the communication interaction between the device and other devices. The communication module can realize communication through a wired manner (such as USB, network cable, etc.) or through a wireless manner (such as mobile network, WIFI, Bluetooth, etc.).

[0256] The bus 1605 includes a channel for transmitting information between various components (such as the processor 1601, the memory 1602, the input / output interface 1603, and the communication interface 1604) of the device.

[0257] It should be noted that although the above device only shows the processor 1601, the memory 1602, the input / output interface 1603, the communication interface 1604 and the bus 1605, but in the specific implementation process, the device can also include other components necessary for normal operation. In addition, those skilled in the art can understand that the above device can also only contain the components necessary to implement the embodiments of the present application, and does not have to contain all the components shown in the figure.

[0258] The electronic device of the above embodiment is used to implement the virtual inertia control method of the corresponding micro-grid in any of the preceding embodiments, and has the beneficial effects of the corresponding method embodiments, which are not described here.

[0259] Based on the same inventive concept, corresponding to the method of any of the above embodiments, the present application also provides a non-transitory computer readable storage medium storing computer instructions for causing the computer to perform the virtual inertia control method of the micro-grid as described in any of the above embodiments.

[0260] The computer readable medium of the present embodiment includes permanent and non-permanent, removable and non-removable media, which can be realized by any method or technology to store information. The information can be computer readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical storage, magnetic cassette, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information accessible by a computing device.

[0261] The computer instructions stored in the storage medium of the above embodiment are used to cause the computer to perform the virtual inertia control method of the micro-grid as described in any of the above embodiments, and have the beneficial effects of the corresponding method embodiments, which are not described here.

[0262] Those skilled in the art should understand that the discussion of any of the above embodiments is only exemplary and is not intended to limit the scope of the present application to these examples; under the idea of the present application, the above embodiments or technical features in different embodiments can also be combined, the steps can be implemented in any order, and there are many other changes of different aspects of the embodiments of the present application as described above. In order to be brief, they are not provided in detail.

[0263] Additionally, to simplify the description and discussion, and so as not to obscure the embodiments of the application being presented, the well-known functions or constructions of integrated circuit (IC) chips and other components can or can not be shown in the figures and will be omitted as not to unnecessarily obscure the embodiments of the application being presented. Moreover, the devices can be shown in block diagram form in order to avoid obscuring the embodiments of the application, and this also acknowledges the fact that the details in regards to the implementation of such block devices are highly dependent on the platform upon which the embodiments of the application are being implemented (i.e., these details should be well within the purview of one of ordinary skill in the art). Where specific details are set forth in order to describe an illustrative embodiment of the application, it will be apparent to one of ordinary skill in the art that the embodiments of the application can be practiced without, or with variation of, these specific details. Thus, the description is to be considered as illustrative and not restrictive, and the scope of the application should be determined not with reference to the above description, but should be given to the appended claims.

[0264] While the application has been described in connection with specific embodiments thereof, many alternatives, modifications and variations will be apparent to those skilled in the art in light of the foregoing description. For example, other memory architectures (e.g., dynamic RAM (DRAM)) can use the embodiments discussed.

[0265] Embodiments of the application are intended to cover all such alternatives, modifications and variations as falling within the scope of the application. Accordingly, any omission, modification, equivalent replacement, improvement, etc. made within the spirit and principle of the embodiments of the application should be included in the scope of protection of the application.

Claims

1. A virtual inertia control method for a microgrid, characterized in that, include: Determine the released energy of the DC bus capacitor of the microgrid and the energy required for the virtual inertial response of the microgrid. Based on the released energy of the DC bus capacitor and the energy required for the virtual inertia response, the maximum virtual inertia that the microgrid can provide is determined by processing the data through the maximum virtual inertia algorithm. The initial input virtual inertia of the microgrid is received, and the initial input virtual inertia is compared with the maximum virtual inertia to obtain the comparison result; In response to the comparison result indicating that the initial input virtual inertia is less than or equal to the maximum virtual inertia, the microgrid is controlled to operate according to the initial input virtual inertia; or... In response to the comparison result that the initial input virtual inertia is greater than the maximum virtual inertia, the initial input virtual inertia of the microgrid is adjusted to be within the maximum virtual inertia to obtain the adjusted virtual inertia, and the microgrid is controlled to operate according to the adjusted virtual inertia. The process of determining the maximum virtual inertia that the microgrid can provide through the maximum virtual inertia algorithm includes: Based on the energy constraint function, the maximum virtual inertia constraint function with respect to the preset virtual inertia parameters is constructed using the following formula: ； in, This represents the preset virtual inertia parameter. This represents the DC bus capacitance of the microgrid. This indicates the rated voltage of the DC bus of the microgrid. This indicates the minimum voltage of the DC bus in the microgrid. This represents the change in angular frequency of the virtual synchronous generator in the microgrid. This represents the rated angular frequency of the virtual synchronous generator in the microgrid; The maximum value of the preset virtual inertia parameter is determined based on the maximum virtual inertia constraint function, and the maximum value of the preset virtual inertia parameter is taken as the maximum virtual inertia of the microgrid.

2. The method according to claim 1, characterized in that, The determination of the released energy of the DC bus capacitor of the microgrid includes: Obtain the DC bus capacitance of the microgrid, the rated voltage of the DC bus of the microgrid, and the minimum voltage of the DC bus of the microgrid; The rated voltage of the DC bus is squared to obtain the rated voltage result, and the minimum voltage of the DC bus is squared to obtain the minimum voltage result. The preset first constant parameter, the DC bus capacitance, and the rated voltage processing result are multiplied to obtain the first product processing result; The preset first constant parameter, the minimum voltage processing result, and the minimum voltage processing result are multiplied to obtain the second product processing result; The energy released by the DC bus capacitor of the microgrid is obtained by performing a difference operation based on the first product processing result and the second product processing result.

3. The method according to claim 1, characterized in that, The energy required to determine the virtual inertial response of the microgrid includes: Obtain the rated angular frequency of the virtual synchronous generator in the microgrid, and determine the angular frequency variation of the virtual synchronous generator in the microgrid. The rated angular frequency is obtained by multiplying the preset second constant parameter with the rated angular frequency of the virtual synchronous generator. The difference between the rated angular frequency processing result and the angular frequency change of the virtual synchronous generator is calculated to obtain the difference processing result; The energy required for the virtual inertia response of the microgrid is obtained by multiplying the preset virtual inertia parameters, the preset third constant parameters, and the difference processing results.

4. The method according to claim 3, characterized in that, The determination of the angular frequency change of the virtual synchronous generator in the microgrid includes: Obtain the lowest angular frequency of the virtual synchronous generator in the microgrid; The difference between the rated angular frequency and the lowest angular frequency of the virtual synchronous generator is calculated to obtain the change in angular frequency of the virtual synchronous generator.

5. The method according to claim 1, characterized in that, The process of determining the maximum virtual inertia of the microgrid by processing the released energy of the DC bus capacitor and the energy required for the virtual inertia response using a maximum virtual inertia algorithm includes: Based on the energy required for the virtual inertia response and the released energy of the DC bus capacitor, the energy constraint function is constructed using the following formula: in, This represents the energy required for the virtual inertia response. This represents the energy released by the DC bus capacitor. , This represents the preset virtual inertia parameter. This represents the rated angular frequency of the virtual synchronous generator in the microgrid. This represents the lowest angular frequency of the virtual synchronous generator in the microgrid. This represents the change in angular frequency of the virtual synchronous generator in the microgrid. , This represents the DC bus capacitance of the microgrid. This indicates the rated voltage of the DC bus of the microgrid. This indicates the minimum voltage of the DC bus in the microgrid. The energy constraint function is processed with respect to the preset virtual inertia parameters by a virtual inertia parameter solving algorithm to obtain the maximum virtual inertia of the microgrid.

6. The method according to claim 1, characterized in that, The determination of the released energy of the DC bus capacitor of the microgrid also includes: The response time of the virtual synchronous generator synchronous machine control in the microgrid, as well as the load power change of the microgrid, are obtained. The energy released by the DC bus capacitor of the microgrid is obtained by multiplying the preset scaling factor parameters, the response time of the virtual synchronous generator control, and the load power change of the microgrid.

7. A virtual inertia control device for a microgrid, characterized in that, include: The energy determination module is configured to determine the released energy of the DC bus capacitor of the microgrid and the energy required for the virtual inertial response of the microgrid. The virtual inertia determination module is configured to determine the maximum virtual inertia of the microgrid by processing the energy released by the DC bus capacitor and the energy required for the virtual inertia response through a maximum virtual inertia algorithm. The comparison module is configured to receive the initial input virtual inertia of the microgrid and compare the initial input virtual inertia with the maximum virtual inertia to obtain a comparison result; The first operating module is configured to control the microgrid to operate according to the initial input virtual inertia in response to the comparison result that the initial input virtual inertia is less than or equal to the maximum virtual inertia; or, The second operating module is configured to, in response to the comparison result that the initial input virtual inertia is greater than the maximum virtual inertia, adjust the initial input virtual inertia of the microgrid to within the maximum virtual inertia, obtain the adjusted virtual inertia, and control the microgrid to operate according to the adjusted virtual inertia; The virtual inertia determination module is specifically configured as follows: Based on the energy constraint function, the maximum virtual inertia constraint function with respect to the preset virtual inertia parameters is constructed using the following formula: ； in, This represents the preset virtual inertia parameter. This represents the DC bus capacitance of the microgrid. This indicates the rated voltage of the DC bus of the microgrid. This indicates the minimum voltage of the DC bus in the microgrid. This represents the change in angular frequency of the virtual synchronous generator in the microgrid. This represents the rated angular frequency of the virtual synchronous generator in the microgrid; The maximum value of the preset virtual inertia parameter is determined based on the maximum virtual inertia constraint function, and the maximum value of the preset virtual inertia parameter is taken as the maximum virtual inertia of the microgrid.

8. 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 program, it implements the method as described in any one of claims 1 to 6.

9. A non-transitory computer-readable storage medium storing computer instructions, characterized in that, The computer instructions are used to cause the computer to perform the method according to any one of claims 1 to 6.

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