Virtual inertia control method and device of micro-grid, electronic equipment and storage medium

Abstract

The invention provides a virtual inertia control method and device for a micro-grid, electronic equipment and a storage medium, and the method comprises the steps: precisely determining the maximum virtual inertia which can be provided by the micro-grid through the relation between the energy released by a DC bus capacitor and the energy required by virtual inertia response, and employing a maximum virtual inertia algorithm; and therefore, the instability of the micro-grid caused by improper setting of the virtual inertia can be effectively avoided. Besides, the relation between the initial input virtual inertia and the maximum virtual inertia is compared, the virtual inertia setting value is flexibly adjusted to be not larger than the maximum virtual inertia all the time, it is ensured that the micro-grid operates within the range not exceeding the bearing capacity of the micro-grid, then the stability and safety of the micro-grid are improved, and stable and efficient operation of the micro-grid is ensured.

Description

Technical Field

[0001] The present application relates to the field of microgrid control technology, and in particular to a virtual inertia control method, device, electronic device and storage medium for a microgrid. Background Art

[0002] At present, the microgrid system composed of distributed energy generation, dynamic load and energy storage units is developing rapidly and gradually becoming an important part of the modern power system. However, the intermittent and volatile nature of renewable energy generation, the change of load power and the charging and discharging fluctuation of energy storage systems, various interferences can easily cause serious frequency fluctuations, which have a significant impact on the frequency of microgrids. At the same time, the low inertia problem caused by a large number of power electronic converters further reduces the system's anti-interference ability, making it difficult for microgrids to operate stably.

[0003] However, in microgrids, virtual inertia directly affects the stability of microgrids. Therefore, how to control virtual inertia to ensure that microgrids can maintain stable operation has become an urgent problem to be solved. Summary of the invention

[0004] In view of this, the purpose of the present application is to propose a virtual inertia control method, device, electronic device and storage medium for a microgrid to solve the above technical problems.

[0005] Based on the above purpose, the first aspect of the present application provides a virtual inertia control method for a microgrid, comprising:

[0006] Determine the released energy of the DC bus capacitor of the microgrid and determine the energy required for the virtual inertia response of the microgrid;

[0007] According to the released energy of the DC bus capacitor and the energy required for the virtual inertia response, a maximum virtual inertia algorithm is used to determine the maximum virtual inertia that can be provided by the microgrid;

[0008] Receiving an initial input virtual inertia of the microgrid, and comparing the initial input virtual inertia with the maximum virtual inertia to obtain a comparison result;

[0009] In response to the comparison result that the initial input virtual inertia is less than or equal to the maximum virtual inertia, controlling the microgrid to operate according to the initial input virtual inertia; or,

[0010] 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 an adjusted virtual inertia, and the microgrid is controlled to operate according to the adjusted virtual inertia.

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

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

[0013] A virtual inertia determination module is configured to determine 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 through a maximum virtual inertia algorithm;

[0014] A comparison module is 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 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

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

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

[0018] Based on the same inventive concept, the fourth aspect of the present application provides a non-transitory computer-readable storage medium, which stores computer instructions, and the computer instructions are used to enable a computer to execute the method described in the first aspect above.

[0019] From the above, it can be seen that the virtual inertia control method, device, electronic device and storage medium of the microgrid provided by the present application, through the relationship between the energy released by the DC bus capacitor and the energy required for the virtual inertia response, accurately determines the maximum virtual inertia that the microgrid can provide by using the maximum virtual inertia algorithm, thereby effectively avoiding the instability of the microgrid caused by improper virtual inertia setting. 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 no greater than the maximum virtual inertia, ensuring that the microgrid operates within the range that does not exceed its carrying capacity, thereby improving the stability and safety of the microgrid and ensuring the stable and efficient operation of the microgrid. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the present application or related technologies, the drawings required for use in the embodiments or related technical descriptions are briefly introduced below. Obviously, the drawings described below are only embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0021] Figure 1 A schematic diagram of the structure of a cascaded DC / DC converter and a DC / AC converter according to an embodiment of the present application;

[0022] Figure 2 A block diagram of a VSM control strategy for a DC-AC converter according to an embodiment of the present application;

[0023] Figure 3 A schematic diagram of a three-phase abc static coordinate system and a two-phase dq synchronous rotating coordinate system according to an embodiment of the present application;

[0024] Figure 4 This is a schematic diagram of an active power-frequency loop after adjustment according to an embodiment of the present application;

[0025] Figure 5 A schematic diagram of a DC / DC converter and a dual closed-loop control strategy according to an embodiment of the present application;

[0026] Figure 6 A schematic diagram of a dynamic curve of a virtual synchronous generator rotor angular frequency according to an embodiment of the present application;

[0027] Figure 7-1 It is a schematic diagram of the adjustment time variation curve as the virtual inertia J increases according to the embodiment of the present application;

[0028] Figure 7-2 It is a schematic diagram of a frequency overcharge magnitude variation curve as the virtual inertia J increases according to an embodiment of the present application;

[0029] Figure 8A schematic diagram of a curve showing the relationship between the virtual inertia J and the frequency deviation in an embodiment of the present application;

[0030] Fig. 9 It is a schematic diagram of a step response curve of the active power of the VSM when different underdamping ζ is applied in an embodiment of the present application;

[0031] Fig.10 A schematic diagram of a DC bus voltage variation curve with different capacitor capacities when the load power increases according to an embodiment of the present application;

[0032] Fig.11 A flowchart of a virtual inertia control method of a microgrid according to an embodiment of the present application;

[0033] Fig.12 A schematic diagram of a simulation model of a DC / DC converter cascaded DC / AC converter system according to an embodiment of the present application;

[0034] Figure 13-1 is the DC bus voltage V in the embodiment of the present application dc Schematic diagram of waveform (group A);

[0035] Figure 13-2 is the output voltage u of the DC / AC converter of the embodiment of the present application abc and current i abc (Panel A) Schematic diagram;

[0036] Figure 14-1 is the DC bus voltage V in the embodiment of the present application dc Schematic diagram of waveform (group B);

[0037] Figure 14-2 is the output voltage u of the DC / AC converter of the embodiment of the present application abc and current i abc (Panel B) Schematic diagram;

[0038] Fig.15 A structural block diagram of a virtual inertia control device of a microgrid according to an embodiment of the present application;

[0039] Fig.16 A schematic diagram of an electronic device according to an embodiment of the present application. DETAILED DESCRIPTION

[0040] In order to make the objectives, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0041] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the embodiments of the present application should be the usual meanings understood by people with ordinary skills in the field to which the present application belongs. The "first", "second" and similar words used in the embodiments of the present application do not represent any order, quantity or importance, but are only used to distinguish different components. "Including" or "comprising" and similar words mean that the elements or objects appearing in front of the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0042] It is understandable that before using the technical solutions of each embodiment of the present application, the type, scope of use, usage scenarios, etc. of the personal information involved will be informed to the user in an appropriate manner, and the user's authorization will be obtained.

[0043] For example, in response to receiving an active request from a user, a prompt message is sent to the user to clearly remind the user that the operation requested to be performed will require obtaining and using the user's personal information. Thus, the user can independently choose whether to provide personal information to the electronic device, application, server, storage medium or other software or hardware that performs the operation of the technical solution of the present application according to the prompt message.

[0044] As an optional but non-limiting implementation, in response to receiving the user's active request, the prompt information may be sent to the user in the form of a pop-up window, in which the prompt information may be presented in text form. In addition, the pop-up window may also carry a selection control for the user to choose "agree" or "disagree" to provide personal information to the electronic device.

[0045] It is understandable that the above notification and the process of obtaining user authorization are merely illustrative and do not constitute a limitation on the implementation method of this application. Other methods that meet relevant laws and regulations may also be applied to the implementation method of this application.

[0046] At present, the microgrid system composed of distributed renewable energy generation, dynamic loads and energy storage units is developing rapidly and gradually becoming an important part of the modern power system. However, the intermittent and volatile nature of renewable energy generation, the change of load power and the charging and discharging fluctuations of the energy storage system, various interferences can easily cause serious frequency fluctuations, which have a significant impact on the frequency of the microgrid. At the same time, the low inertia problem caused by a large number of power electronic converters further reduces the system's anti-interference ability, making it difficult for the microgrid to operate stably. In severe cases, the instability of the microgrid may even cause the collapse of the entire power system. Therefore, it is urgent to increase the inertia of the microgrid to achieve stable operation.

[0047] However, in microgrids, virtual inertia directly affects the stability of microgrids. Increasing the inertia of microgrids can be achieved by introducing a virtual synchronous machine (VSM) strategy for the converter to increase the virtual inertia of the system. This method is based on the electromagnetic equations and rotor motion equations of synchronous motors, and is proposed by considering the active power, electromagnetic torque, mechanical torque, virtual inertia and virtual damping coefficient in the control loop, and reactive power and droop coefficient in the reactive power loop. However, when disturbances occur, the virtual inertia is too small to provide sufficient frequency support, and a larger virtual inertia is often required to maintain the 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 supply power changes, the VSM control strategy wants to achieve power balance but cannot do so immediately, and requires a certain adjustment time. For example, when the switching frequency of the converter is 20kHz, the time it takes for the virtual synchronous machine strategy to complete the response 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 has enabled microgrids that use a large number of power electronic converters to have anti-interference capabilities. However, a small virtual inertia J cannot provide sufficient frequency support, and a larger inertia is often required. However, the virtual inertia that the inverter can provide is not infinite, but is strictly limited by circuit parameters. Since the response of the VSM cannot be completed instantly, a certain adjustment time is required. During this period of time, the unbalanced energy required by the system is mainly absorbed or released by the DC bus capacitor. Therefore, the capacitor capacity largely determines the maximum virtual inertia that the converter can provide.

[0049] Based on the DC bus capacitance, converter regulation speed and power step conditions, this application derives the maximum virtual inertia formula that can be provided by the converter using the virtual synchronous machine algorithm, and proposes that the maximum value of the virtual inertia is strictly constrained by the capacitance, 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 that participates in the primary frequency modulation. Finally, a simulation verification was carried out to prove the correctness of the proposed virtual synchronous machine maximum inertia constraint condition based on the DC bus capacitance, providing a reliable theoretical basis for the inertia evaluation of the microgrid system.

[0050] like Figure 1 As shown, a DC-DC (DC / DC) converter cascaded DC-AC (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 uses virtual synchronous machine control to provide virtual inertia.

[0051] 1. Control strategy

[0052] 1. Virtual Synchronous Machine Control (VSM)

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

[0054] The rotor rotation equation of the virtual virtual synchronous generator (when the number of pole pairs of the virtual virtual synchronous generator is 1) is expressed as:

[0055]

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

[0057] The droop characteristic between active power and frequency of the virtual synchronous machine is expressed 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 VSM, Km is the active power-frequency droop coefficient.

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

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

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

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

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

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

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

[0067] The VSM control strategy includes voltage and current dual closed-loop control, and the grid voltage E is derived by applying the reactive power-voltage relationship, and the virtual angle e is derived by applying the active power-frequency relationship. Figure 2 As shown, first, the abc (three-phase stationary natural coordinate system)-dq (synchronous rotating coordinate system) transformation is adopted, according to the voltage v o and current l f Calculate the active power P 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) we can know that from the reference active power P ref Subtract K from m and angular frequency change (ω-ω n ) to obtain the mechanical active power P m , similar to the primary frequency modulation of a virtual synchronous generator, and then P m and electromagnetic power P e The difference between the two divided by the synchronous angular frequency ω n , and then 1 / J S Substitute ΔP and Dp into the above formula: The angular frequency ω can be obtained, and the virtual working angle θ can be obtained by integrating ω. 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 Multiply the difference in voltage change to get reactive power Q m According to the above formula: E=E0+K Q (Q m -Q e ), Q m and reactive power Qe Subtract and substitute the proportional factor K Q and the fixed voltage E0, the network voltage E is calculated, and then E and θ are input together into the three-phase voltage calculation part of the voltage and current dual-loop control, and the output is transformed into dq-abc, and finally a pulse width modulation (PWM) signal is obtained.

[0068] Abc-dq and dq-abc transformations are commonly used in AC systems. The AC quantity in the abc static coordinate system can be converted into a DC quantity in the dq synchronous rotating coordinate system. The two coordinate systems are as follows: Figure 3 As shown, θ represents the angle between the a-axis of the stationary reference coordinate system and the d-axis of the rotating reference coordinate system, and the rotation frequency of the dq coordinate system is the synchronous angular frequency ω n .

[0069] The conversion matrix of 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 angle θ between the a-axis of the stationary reference system and the d-axis of the rotating reference coordinate system, and the synchronous angular frequency ω of the dq coordinate system n It is related to the points.

[0072] like Figure 2 As shown, in the active frequency loop, the virtual damping coefficient D p Divided into D p1 and D p2 Two parts, D p1 That is the classical damping coefficient, and D p2 Then it participates in power regulation, so, Figure 2 The active frequency loop has changed, such as Figure 4 shown.

[0073] exist Figure 4 In, K m and D p2 The synchronous machine frequency modulation process is simulated. e Less than P ref When using P ref Subtract (Km+D p2 *ω n ); when P e Greater than P ref When using P ref Plus (Km+Dp2*ω n), which reduces the difference between the reference power and the electromagnetic power and reduces the frequency deviation. Therefore, only D p1 Plays a damping role, D p2 It can flexibly adjust the virtual damping coefficient D p The adjustment range is very large. In addition, the DC / DC converter and the dual closed-loop control strategy are shown in the figure. Figure 5 shown.

[0074] 2. Principle of DC / DC converter

[0075] The DC / DC converter structure is as follows Figure 4 As shown, a dual closed loop circuit of voltage outer loop control and current inner loop control is used to maintain the DC bus voltage constant, that is, to ensure that the capacitor C dc The voltage across both ends is constant.

[0076] 2. Maximum virtual inertia constraints

[0077] When facing load or power fluctuations, the smaller virtual inertia J cannot provide sufficient frequency support, which will cause the entire system to face the risk of instability or even collapse. Therefore, a larger virtual inertia is usually designed in the design of VSM. However, the maximum virtual inertia that VSM can provide is not arbitrarily determined by the control parameters. 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 attempts to respond immediately and return to a 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 20kHz, the time for VSM to complete the response 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 virtual inertia response. In other words, 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 the loss, the rotor kinetic energy E of the virtual synchronous generator in stable operation is k Expressed as

[0080]

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

[0084]

[0085] According to the above formula And the above formula Kinetic Energy k It can be expressed as:

[0086] E k =H s S N

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

[0091] based on Figure 2 The VSM control block diagram in the figure shows the electromagnetic power P e and mechanical power P m The transfer function between:

[0092]

[0093] In the above formula, K = 3*V o V pcc / X s , V o and V pcc They are VSM reference voltage and common coupling voltage point, X s is the gate impedance. Based on the above formula, the dynamic response of electromagnetic power and mechanical power can be obtained. In engineering applications, since the overdamped system responds very slowly, it is usually designed as an underdamped system. Figure 2 The VSM control block diagram is shown, and the mechanical power P is derived m The transfer function between the frequency change Δω is:

[0094]

[0095] According to the above formula, when disturbance occurs, as the virtual inertia increases, the frequency adjustment time and frequency overshoot characteristics are as follows: Figure 7-1 and Figure 7-2 shown.

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

[0097] Next, we study how to design the virtual damping coefficient D p1 The step response of VSM active power when different ζ are applied is as follows: Fig. 9 When ζ = 1, the step response of the VSM active power is curve (3), and the absorbed energy is curve (3) and P m When the system is slightly underdamped (ζ = 0.707), the absorbed energy is curve (2) and P m The area between Fig. 9It can be seen that the energy absorbed by the underdamped system is less than that absorbed by the critically damped system. However, a small damping coefficient is very likely to produce power oscillations, so ζ = 0.707 is applied.

[0098] According to the above formula: The second-order transfer function shown in Figure 1 derives ζ = D pI / 2Jω n , after transposing the term, the virtual damping coefficient is:

[0099] D P1 =2Jζω n

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

[0101] like Figure 1 As shown in the figure, when the power of the three-phase load suddenly increases, the DC bus capacitor C dc The energy is released immediately 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 load power demand, and on the other hand, it is C dc The DC bus voltage increases and finally the DC bus voltage is stabilized. Under the condition that the three-phase load suddenly increases the same power, different C dc Will bring different DC bus voltage changes, such as Fig.10 shown.

[0102] exist Fig.10 In the figure, the capacitance of curve 1 is smaller than that of curve 2, U dcmin1 and U dcmin2 They represent the minimum voltage of the DC bus under two capacitance conditions, and t1 and t2 represent the time to reach the minimum voltage. Fig.10 It can be seen that when the bus capacitance C dc When it is larger, the DC bus voltage drops more slowly and the minimum bus voltage is higher.

[0103] according to Fig.10 , capacitor C dc The energy released during the sudden increase of load power is expressed as:

[0104]

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

[0106]

[0107] In the above formula, Δω=ωn -ω1,ω n is the rated angular frequency, and ω1 is the minimum angular frequency. In the worst case, all load surge energy is dissipated by capacitor C dc Provided that, according to the above capacitor C dc The expression of the energy released during the sudden increase of load power and the expression of the energy required for the virtual inertia response can be derived to obtain 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 Determined by the rated DC bus voltage U dcref , rated angular frequency ω n , minimum voltage U dcmin It is related to the minimum angular frequency ω1. Let the load power change be ΔP, ΔP is proportional to ΔE, and the relationship is:

[0110]

[0111] In the above formula, K is the scaling factor, T r is the response time of the DC / AC converter VSM control. Obviously, the power change ΔP is related to the capacitance C dc It is closely related to 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. It is necessary to consider the maximum load power change and the allowable DC bus voltage change. When evaluating the maximum load power fluctuation that an existing microgrid can provide, it is necessary to consider the bus capacitor C dc , maximum voltage variation and converter control parameters.

[0112] The embodiment of the present application provides a virtual inertia control method for a microgrid, which uses the relationship between the energy released by the DC bus capacitor and the energy required for the virtual inertia response, and uses the maximum virtual inertia algorithm to accurately determine the maximum virtual inertia that the microgrid can provide, thereby effectively avoiding the instability of the microgrid caused by improper virtual inertia setting. 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 no greater than the maximum virtual inertia, ensuring that the microgrid operates within the range that does not exceed its carrying capacity, thereby improving the stability and safety of the microgrid and ensuring the stable and efficient operation of the microgrid.

[0113] like Fig.11 As shown, the method of this embodiment includes:

[0114] Step 1101, determining the released energy of the DC bus capacitor of the microgrid, and determining 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, which can provide or absorb energy when the power grid fluctuates to maintain the stability of the power grid.

[0116] When the grid needs additional energy in response to some event (such as a sudden change in load), the DC bus capacitor can release its stored energy to provide 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. It helps slow down the speed of frequency changes when they occur in the grid, giving other devices in the grid more time 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 inertial support to maintain the stability of the grid.

[0119] Virtual inertia response refers to the use of advanced control technology to simulate the response characteristics of traditional rotating motors in power systems to provide the dynamic behavior required by the power grid. In microgrids, virtual inertia response technology can improve the stability and inertia support capabilities 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 the energy storage device.

[0121] Determining the release energy of the DC bus capacitor of the microgrid and the energy required for the virtual inertia response requires consideration of multiple factors and the overall performance requirements of the system. 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 released energy of the DC bus capacitor and the energy required for the virtual inertia response, a maximum virtual inertia algorithm is used to determine the maximum virtual inertia that can be provided by the microgrid.

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

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

[0125] By running the maximum virtual inertia algorithm, the maximum virtual inertia value that the microgrid can provide under given conditions can be determined. This maximum virtual inertia value directly affects the stability and response speed of the power grid, thereby effectively avoiding microgrid instability caused by improper virtual inertia setting, and thus ensuring that the microgrid can remain stable and reliable during operation.

[0126] Step 1103 , receiving the initial input virtual inertia of the microgrid, 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 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.

[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, control the microgrid to operate according to the initial input virtual inertia.

[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 maximum virtual inertia range that the microgrid can provide, and then the microgrid is controlled to operate according to the initial input virtual inertia, which can ensure the stability and safety of the microgrid.

[0130] Step 1105, 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 an adjusted virtual inertia, and the microgrid is controlled 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 virtual inertia is improperly set and is not within the maximum virtual inertia range that the microgrid can provide. This will cause instability in the operation of the microgrid. Therefore, the virtual inertia setting is flexibly adjusted, and the initial input virtual inertia of the microgrid is adjusted to within the maximum virtual inertia to obtain the adjusted virtual inertia, and the microgrid is controlled to operate according to the adjusted virtual inertia to ensure 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.

[0132] Through the above scheme, the maximum virtual inertia that the microgrid can provide is accurately determined by the maximum virtual inertia algorithm through the relationship between the energy released by the DC bus capacitor and the energy required for the virtual inertia response, thereby effectively avoiding the instability of the microgrid caused by improper virtual inertia setting. 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 no 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, determining the released energy of the DC bus capacitor of the microgrid includes:

[0134] Step A1, obtaining 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.

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

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

[0137] Step A4, performing product processing on a 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: performing difference processing based on 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 capacity of the capacitor on the DC bus in the microgrid, usually measured in Farad (F). It is used to smooth the voltage fluctuations on the DC bus.

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

[0141] The minimum voltage of the DC bus is the lowest voltage value that the DC bus may reach under specific conditions (such as load changes, faults, etc.).

[0142] The rated voltage is squared to obtain the rated voltage 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 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 minimum voltage.

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

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

[0147]

[0148] Where, ΔE represents the released energy of the DC bus capacitor, C dc Represents the DC bus capacitance of the microgrid, U dcref Indicates the rated voltage of the DC bus of the microgrid, U dcmin Represents the minimum voltage of the DC bus of the microgrid. The first constant parameter is

[0149] By comprehensively considering 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 release energy of the DC bus capacitance of the microgrid can be determined more accurately.

[0150] In some embodiments, in step 1101, determining the energy required for 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 change of the virtual synchronous generator of the microgrid;

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

[0153] Step B3, performing a difference processing on the rated angular frequency processing result and the angular frequency change of the virtual synchronous generator to obtain a 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 radians per second (rad / s). This value usually corresponds to the standard frequency of the power grid, for example, in a 50Hz power grid, the rated angular frequency is 2π×50rad / s.

[0156] The angular frequency variation refers to the difference between the actual angular frequency and the rated angular frequency of the virtual synchronous generator 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 change 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 change of the virtual synchronous generator of the microgrid, the preset virtual inertia parameters, and the rated angular frequency, the energy required for the determined virtual inertia response can be made more accurate, which helps to improve the stability and reliability of the microgrid.

[0161] In some embodiments, in step B1, determining the angular frequency change of the virtual synchronous generator of the microgrid includes:

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

[0163] Step C2, performing a 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 change of the virtual synchronous generator.

[0164] In the above scheme, the rated angular frequency is subtracted from the minimum angular frequency, and the difference 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 magnitude of the angular frequency change can reflect the generator's ability to adapt to load changes and maintain voltage and frequency stability, as well as the microgrid's ability to maintain operational continuity in the face of disturbances.

[0166] It can be expressed as follows:

[0167] Δω=ω n -ω1

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

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

[0170] In some embodiments, step 1102 includes:

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

[0172] ΔE k ≤ΔE

[0173] Where, ΔE k It represents the energy required for virtual inertia response, △E represents the released energy of 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, △ω represents the angular frequency change of the virtual synchronous generator of the microgrid, C dc Represents the DC bus capacitance of the microgrid, U dcref Indicates the rated voltage of the DC bus of the microgrid, U dcmin Indicates 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 by 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 of the microgrid dc The energy released during the sudden increase of load power is expressed as:

[0176]

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

[0178]

[0179] Based on the expressions of the two, let △E k ≤△E constructs the energy constraint function.

[0180] After constructing the energy constraint function, the function is processed by the virtual inertia parameter solving algorithm to find the solution that maximizes the virtual inertia parameter while satisfying the energy constraint. The maximum virtual inertia value of the microgrid (i.e., the maximum virtual inertia of the microgrid) is output. This value is the maximum virtual inertia that can be achieved while ensuring system stability and energy balance, which helps to improve the frequency response capability and overall stability of the microgrid.

[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 using the following formula:

[0183]

[0184] Among them, J represents the preset virtual inertia parameter, C dc Represents the DC bus capacitance of the microgrid, U dcref Indicates the rated voltage of the DC bus of the microgrid, U dcmin represents the minimum voltage of the DC bus of the microgrid, △ω represents the angular frequency change of the virtual synchronous generator of the microgrid, ω n Represents the rated angular frequency of the virtual synchronous generator of the microgrid.

[0185] Step E2: determining a maximum value of a 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 microgrid.

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

[0187]

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

[0189]

[0190] Based on the two expressions, let ΔE k ≤ΔE constructs the energy constraint function, and the maximum virtual inertia constraint function about the preset virtual inertia parameters can be derived by shifting the terms:

[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 used as the maximum virtual inertia of the microgrid.

[0193] In some embodiments, in step 1101, determining the released energy of the DC bus capacitor of the microgrid includes:

[0194] Step F1, obtaining the response time of the virtual synchronous generator control of the microgrid and the load power change of the microgrid.

[0195] Step F2, multiplying the preset scaling factor parameter, the response time of the virtual synchronous generator control and the load power change of the microgrid to obtain the released energy of the DC bus capacitor of the microgrid.

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

[0197] The load power variation of a microgrid refers to the variation of load demand in the microgrid, which may be caused by load switching, changes in load characteristics, or fluctuations in the output power of distributed power sources. This variation is crucial to the stable operation of the microgrid because it directly affects the power balance of the system and the stability of the bus voltage.

[0198] The scaling factor parameter is a preset parameter used to adjust the scale of the calculation results.

[0199] The above three parameters are multiplied and can be expressed as follows:

[0200]

[0201] In the above formula, △E represents the released energy of the DC bus capacitor, K is the scaling factor parameter, and T r is the response time of the DC / AC converter vSM control. Obviously, the power change ΔP is related to the capacitance C dc It is closely related to 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. It is necessary to consider the maximum load power change and the allowable DC bus voltage change. When evaluating the maximum load power fluctuation that an existing microgrid can provide, it is necessary to consider the bus capacitor C dc , maximum voltage variation and converter control parameters.

[0202] By considering the response time of the virtual synchronous generator control, the load power change and the preset scaling factor parameters, the energy required to be released by the system when the load changes can be accurately evaluated. This can ensure that the microgrid has sufficient energy reserves to maintain the stability of the bus voltage when the load changes, which helps to improve the reliability and stability of the microgrid and reduce the risk of system failure.

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

[0204]

[0205] based on Figure 1 , the applied mathematics software (Matlab) software built Fig.12 The simulation model of the DC / DC converter cascaded DC / AC converter shown in FIG. 1 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 dual 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. In order to verify the maximum inertia constraint condition of the DC / AC converter using the virtual synchronous machine control strategy, two groups of simulation experiments, A and B, were carried out under different VSM virtual inertia J conditions.

[0206] Table 2 Experimental simulation system parameters and load power step parameters for groups A and B

[0207] parameter Numeric <![CDATA[AC bus voltage V s > 311V <![CDATA[DC bus voltage v dc > 700V <![CDATA[DC / DC converter DC-side voltage stabilizing capacitor C dc > 4000μF <![CDATA[The voltage loop proportional control parameter k of the DC / DC converter vp > 0.8 <![CDATA[DC / DC converter current loop proportional control parameter k ip > 0.9 <![CDATA[The voltage loop integral control parameter k of the DC / DC converter vi > 26 <![CDATA[The current loop integral control parameter k of the DC / DC converter ii > 22 <![CDATA[AC side filter capacitor C s > 10μF <![CDATA[AC-side filtering inductor L s > 1mH <![CDATA[Proportional control parameter k in the VSM active voltage loop dvp > 1.03 <![CDATA[Integral control parameter k in the active voltage loop of VSM dvi > 184.46 <![CDATA[Proportional control parameter k in the VSM active current loop dip > 5 <![CDATA[Integral control parameter k in the VSM active current loop dii > 100 <![CDATA[Initial load power P1]]> 50kW <![CDATA[Load power P2 after step]]> 80kW Step time 3s <![CDATA[Group A VSM virtual inertia J A > 1 <![CDATA[VSM virtual inertia J of Group B B > 50

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

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

[0210] like Figure 14-1 and Figure 14-2 As shown in the figure, when the parameters of group B are used, when the load power jumps at 3s, the DC bus voltage, AC voltage and current will fluctuate sharply, and the system cannot operate stably. 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, the system cannot operate normally. Therefore, limiting the maximum virtual inertia of the DC / AC converter VSM control can ensure that the system responds quickly and stably to power changes.

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

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

[0213] It should be noted that the above describes some embodiments of the present application. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recorded in the claims can be performed in an order different from that in the above embodiments and still achieve the desired results. In addition, the processes depicted in the accompanying drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

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

[0215] refer to Fig.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 for the virtual inertia response of the microgrid;

[0217] The virtual inertia determination module 1502 is configured to determine the maximum virtual inertia that the microgrid can provide according to the released energy of the DC bus capacitor and the energy required for the virtual inertia response by processing through a maximum virtual inertia algorithm;

[0218] A comparison module 1503 is 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;

[0219] The first operation module 1504 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

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

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

[0222] Obtaining 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;

[0223] The rated voltage of the DC bus is squared to obtain a rated voltage processing result, and the minimum voltage of the DC bus is squared to obtain a minimum voltage processing result;

[0224] Performing product processing on a preset first constant parameter, the DC bus capacitance and the rated voltage processing result to obtain a first product processing result;

[0225] Performing product processing on a preset first constant parameter, the minimum voltage processing result, and the minimum voltage processing result to obtain a second product processing result;

[0226] A difference process is performed based on the first product processing result and the second product processing result to obtain the released energy of the DC bus capacitor of the microgrid.

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

[0228] a variation determination unit configured to obtain a rated angular frequency of a virtual synchronous generator of the microgrid and determine an angular frequency variation of the virtual synchronous generator of the microgrid;

[0229] a product processing unit configured to perform product processing using a 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 is configured to perform a difference processing on the rated angular frequency processing result and the angular frequency variation of the virtual synchronous generator to obtain a difference processing result;

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

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

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

[0234] The rated angular frequency of the virtual synchronous generator and the minimum angular frequency of the virtual synchronous generator are subjected to difference processing to obtain the angular frequency variation of the virtual synchronous generator.

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

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

[0237] △E k ≤△E

[0238] Among them, ΔE k represents the energy required for virtual inertia response, ΔE represents the released energy of 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, △ω represents the angular frequency change of the virtual synchronous generator of the microgrid, C dc Represents the DC bus capacitance of the microgrid, U dcref Indicates the rated voltage of the DC bus of the microgrid, U dcmin Indicates the minimum voltage of the DC bus of the microgrid;

[0239] The virtual inertia determination unit is 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 as follows:

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

[0242]

[0243] Among them, J represents the preset virtual inertia parameter, C dc Represents the DC bus capacitance of the microgrid, U dcref Indicates 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 change of the virtual synchronous generator of the microgrid, ω n represents the rated angular frequency of the virtual synchronous generator of the microgrid;

[0244] A maximum value of a 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 used 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 change of the microgrid;

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

[0248] For the convenience of description, the above device is described in terms of functions divided into various modules. Of course, when implementing 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 embodiment is used to implement the virtual inertia control method of the microgrid corresponding to any of the above embodiments, and has the beneficial effects of the corresponding method embodiment, which will not be repeated here.

[0250] Based on the same inventive concept, corresponding to any of the above-mentioned embodiments and methods, the present application also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the virtual inertia control method of the microgrid described in any of the above embodiments is implemented.

[0251] Fig.16A more specific schematic diagram of the hardware structure of an electronic device provided in this embodiment is shown, and the device may 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 in communication within the device through the bus 1605.

[0252] The processor 1601 can be implemented by a general-purpose CPU (Central Processing Unit), a microprocessor, an application-specific integrated circuit (ASIC), or one or more integrated circuits, and is used to execute relevant programs to implement the technical solutions provided in the embodiments of this specification.

[0253] The memory 1602 may be implemented in the form of ROM (Read Only Memory), RAM (Random Access Memory), static storage device, dynamic storage device, etc. The memory 1602 may store an operating system and other application programs. When the technical solutions provided in the embodiments of this specification are implemented by software or firmware, the relevant 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 the input / output module to realize information input and output. The input / output module can be configured in the device as a component (not shown in the figure), or it can be externally connected to the device to provide corresponding functions. The input device may include a keyboard, a mouse, a touch screen, a microphone, various sensors, etc., and the output device may 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) to realize communication interaction between the device and other devices. The communication module can realize communication through wired means (such as USB, network cable, etc.) or wireless means (such as mobile network, WIFI, Bluetooth, etc.).

[0256] The bus 1605 includes a path that transmits information between the various components of the device (eg, the processor 1601 , the memory 1602 , the input / output interface 1603 , and the communication interface 1604 ).

[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, in the specific implementation process, the device may also include other components necessary for normal operation. In addition, it can be understood by those skilled in the art that the above device may also only include the components necessary for implementing the embodiments of the present specification, and does not necessarily include 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 microgrid corresponding to any of the above embodiments, and has the beneficial effects of the corresponding method embodiment, which will not be repeated here.

[0259] Based on the same inventive concept, corresponding to any of the above-mentioned embodiment methods, the present application also provides a non-transitory computer-readable storage medium, wherein the non-transitory computer-readable storage medium stores computer instructions, and the computer instructions are used to enable the computer to execute the virtual inertia control method of the microgrid as described in any of the above embodiments.

[0260] The computer-readable medium of this embodiment includes permanent and non-permanent, removable and non-removable media, and information storage can be implemented by any method or technology. Information can be computer-readable instructions, data structures, modules of programs, 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 technology, read-only compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, magnetic tape magnetic disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device.

[0261] The computer instructions stored in the storage medium of the above embodiment are used to enable the computer to execute the virtual inertia control method of the microgrid as described in any of the above embodiments, and have the beneficial effects of the corresponding method embodiments, which will not be repeated here.

[0262] A person skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present application is limited to these examples. In line with the concept of the present application, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the embodiments of the present application as described above, which are not provided in detail for the sake of simplicity.

[0263] In addition, to simplify the description and discussion, and in order not to make the embodiments of the present application difficult to understand, the known power supply / ground connection with the integrated circuit (IC) chip and other components may or may not be shown in the provided drawings. In addition, the device can be shown in the form of a block diagram to avoid making the embodiments of the present application difficult to understand, and this also takes into account the fact that the details of the implementation of these block diagram devices are highly dependent on the platform to be implemented in the embodiments of the present application (that is, these details should be fully within the scope of understanding of those skilled in the art). In the case of elaborating specific details (e.g., circuits) to describe exemplary embodiments of the present application, it is obvious to those skilled in the art that the embodiments of the present application can be implemented without these specific details or when these specific details are changed. Therefore, these descriptions should be considered to be illustrative rather than restrictive.

[0264] Although the present application has been described in conjunction with specific embodiments of the present application, many replacements, modifications and variations of these embodiments will be apparent to those skilled in the art from the foregoing description. For example, other memory architectures (e.g., dynamic RAM (DRAM)) may use the embodiments discussed.

[0265] The embodiments of the present application are intended to cover all such substitutions, modifications and variations that fall within the broad scope of the present application. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present application should be included in the protection scope of the present 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 determine the energy required for the virtual inertia response of the microgrid; According to the released energy of the DC bus capacitor and the energy required for the virtual inertia response, a maximum virtual inertia algorithm is used to determine the maximum virtual inertia that can be provided by the microgrid; Receiving an initial input virtual inertia of the microgrid, and comparing the initial input virtual inertia with the maximum virtual inertia to obtain a comparison result; In response to the comparison result that the initial input virtual inertia is less than or equal to the maximum virtual inertia, controlling the microgrid 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 an adjusted virtual inertia, and the microgrid is controlled to operate according to the adjusted virtual inertia.

2. The method according to claim 1, characterized in that The step of determining the released energy of the DC bus capacitor of the microgrid comprises: Obtaining 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 a rated voltage processing result, and the minimum voltage of the DC bus is squared to obtain a minimum voltage processing result; Performing product processing on a preset first constant parameter, the DC bus capacitance and the rated voltage processing result to obtain a first product processing result; Performing product processing on a preset first constant parameter, the minimum voltage processing result, and the minimum voltage processing result to obtain a second product processing result; A difference process is performed based on the first product processing result and the second product processing result to obtain the released energy of the DC bus capacitor of the microgrid.

3. The method according to claim 1, characterized in that The energy required for determining the virtual inertia response of the microgrid includes: Obtaining a rated angular frequency of a virtual synchronous generator of the microgrid, and determining an angular frequency change of the virtual synchronous generator of the microgrid; Performing a product process using a preset second constant parameter and the rated angular frequency of the virtual synchronous generator to obtain a rated angular frequency processing result; Performing a difference processing on the rated angular frequency processing result and the angular frequency change amount of the virtual synchronous generator to obtain a difference processing result; The preset virtual inertia parameter, the preset third constant parameter and the difference processing result are multiplied to obtain the energy required for the virtual inertia response of the microgrid.

4. The method according to claim 3, characterized in that The step of determining the angular frequency change of the virtual synchronous generator of the microgrid comprises: Obtain the minimum angular frequency of the virtual synchronous generator of the microgrid; The rated angular frequency of the virtual synchronous generator and the minimum angular frequency of the virtual synchronous generator are subjected to difference processing to obtain the angular frequency variation of the virtual synchronous generator.

5. The method according to claim 1, characterized in that The method 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 through a maximum virtual inertia algorithm includes: An energy constraint function is constructed based on the energy required for the virtual inertia response and the released energy of the DC bus capacitor by the following formula: ΔE k ≤ΔE Where, ΔE k represents the energy required for virtual inertia response, ΔE represents the released energy of 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, Δω represents the angular frequency change of the virtual synchronous generator of the microgrid, C dc Represents the DC bus capacitance of the microgrid, U dcref Indicates the rated voltage of the DC bus of the microgrid, U dcmin Indicates the minimum voltage of the DC bus of the microgrid; The energy constraint function is processed with respect to the preset virtual inertia parameter by a virtual inertia parameter solving algorithm to obtain the maximum virtual inertia of the microgrid.

6. The method according to claim 5, characterized in that The step of processing the energy constraint function with respect to the preset virtual inertia parameter by using a virtual inertia parameter solving algorithm to obtain the maximum virtual inertia of the microgrid includes: Based on the energy constraint function, a maximum virtual inertia constraint function about the preset virtual inertia parameter is constructed by the following formula: Among them, J represents the preset virtual inertia parameter, C dc Represents the DC bus capacitance of the microgrid, U dcref Indicates 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 change of the virtual synchronous generator of the microgrid, ω n represents the rated angular frequency of the virtual synchronous generator of the microgrid; A maximum value of a 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 used as the maximum virtual inertia of the microgrid.

7. The method according to claim 1, characterized in that The step of determining the released energy of the DC bus capacitor of the microgrid further includes: Obtain the response time of the virtual synchronous generator synchronous machine control of the microgrid and the load power change of the microgrid; The released energy of the DC bus capacitor of the microgrid is obtained by multiplying the preset scaling factor parameter, the response time of the virtual synchronous generator control and the load power change of the microgrid.

8. A virtual inertia control device for a microgrid, characterized in that: include: An energy determination module is configured to determine the released energy of the DC bus capacitor of the microgrid and determine the energy required for the virtual inertia response of the microgrid; A virtual inertia determination module is configured to determine 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 through a maximum virtual inertia algorithm; A comparison module is 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; A first operation 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 operation module is configured to adjust the initial input virtual inertia of the microgrid to within the maximum virtual inertia in response to the comparison result that the initial input virtual inertia is greater than the maximum virtual inertia, obtain the adjusted virtual inertia, and control the microgrid to operate according to the adjusted virtual inertia.

9. 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, the method according to any one of claims 1 to 7 is implemented.

10. A non-transitory computer-readable storage medium storing computer instructions, characterized in that: The computer instructions are used to enable a computer to execute the method according to any one of claims 1 to 7.

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