Inertia support control method and device of power electronic converter, electronic equipment and storage medium

Abstract

The invention discloses an inertia support control method and device for a power electronic converter, electronic equipment and a storage medium, and belongs to the field of power electronic converters, and the method comprises the steps: obtaining the power grid frequency of a common coupling point of the power electronic converter in real time; when each power grid frequency is obtained, calculating a frequency deviation and a frequency change rate between the power grid frequency and a preset power grid rated frequency; when the frequency deviation and the frequency change rate both exceed corresponding preset response threshold values, a direct-current voltage reference value is calculated and generated according to the current frequency deviation and the current frequency change rate; and a control instruction is sent to a control terminal, so that after the control instruction is received, the direct-current side voltage of the power electronic converter is adjusted to the direct-current voltage reference value, and then energy stored in a direct-current side capacitor in the power electronic converter is released. Therefore, by implementing the method, the problem of inertia support response lag in the prior art can be solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power electronic converters, in particular to an inertia support control method and device of a power electronic converter, an electronic device and a storage medium. BACKGROUND

[0002] With the high proportion of renewable energy access in the power system, power electronic converters gradually replace traditional synchronous generators and become the main electric energy conversion and transmission device. However, unlike the natural inertia of synchronous generators, power electronic converters do not have physical inertia and need to achieve "virtual inertia" support through control strategies. When the power grid is disturbed, such as frequency mutation, power electronic converters with good inertia support capability can quickly release or absorb energy, effectively suppress frequency fluctuations and improve the stability and safety of the power system. Therefore, timely response to dynamic changes in grid frequency and energy injection is one of the key technologies in the current power electronic control field.

[0003] However, the existing inertia support control method still has obvious limitations in practical application. On the one hand, in the response mechanism, most control strategies treat the response to frequency deviation (frequency regulation) and the response to frequency change rate (inertia) as independent links, lack of collaborative judgment, resulting in low sensitivity to disturbance identification and response lag in the initial stage of power grid frequency mutation. On the other hand, in terms of energy utilization, the existing technology usually controls the DC voltage near a conventional rated value when using the DC side capacitor for support. The main purpose is to stabilize the basic operating point of the inverter, and the steady-state operating point of the DC voltage is not strategically optimized from the perspective of maximizing energy reserves. This conservative voltage control strategy results in very limited effective voltage margin (voltage difference) available for rapid adjustment in the DC side capacitor, thereby limiting the total amount of energy that can be released instantaneously during the transient process, greatly reducing the potential of inertia support. SUMMARY

[0004] The embodiments of the present application provide an inertia support control method and device of a power electronic converter, an electronic device and a storage medium, which can solve the inertia support response lag problem in the prior art.

[0005] An embodiment of the present application provides an inertia support control method of a power electronic converter, comprising:

[0006] The grid frequency of the power electronic converter common coupling point is acquired in real time; wherein the power electronic converter comprises a DC side capacitor; the DC side voltage of the power electronic converter is configured as an upper limit value in a preset adjustable operating range;

[0007] calculating a frequency deviation between the grid frequency and a preset grid rated frequency and a frequency change rate each time the grid frequency is acquired;

[0008] when both the frequency deviation and the frequency change rate exceed corresponding preset response thresholds, calculating a direct-current voltage reference value according to the current frequency deviation and the current frequency change rate;

[0009] sending a control instruction to a control terminal, so that the control instruction adjusts a direct-current side voltage of a power electronic converter to the direct-current voltage reference value after receiving the control instruction, thereby releasing energy stored in the direct-current side capacitor.

[0010] Further, the capacitance value of the direct-current side capacitor is determined by the following method, comprising:

[0011] acquiring performance boundary parameters of the power electronic converter and external operating condition parameters; wherein the performance boundary parameters comprise a rated capacity, a target voltage value at a direct-current side output steady-state voltage, a steady-state modulation ratio, and a maximum modulation ratio; the external operating condition parameters comprise a grid rated angular frequency, a minimum angular frequency allowed by the grid, and power that can be additionally provided by a previous stage device;

[0012] calculating an energy release standard value of the converter according to the steady-state modulation ratio and the maximum modulation ratio by the following formula:

[0013]

[0014] wherein m0 is the steady-state modulation ratio of the power electronic converter; η is a rated voltage margin coefficient; m max is the maximum modulation ratio of the power electronic converter;

[0015] calculating an energy release standard value of the equivalent synchronous generator according to the grid rated angular frequency and the minimum angular frequency allowed by the grid by the following formula:

[0016]

[0017] wherein ω min is the minimum angular frequency allowed by the grid; ω0 is the grid rated angular frequency;

[0018] calculating a capacitance value of the direct-current side capacitor according to the energy release standard value of the converter, the energy release standard value of the equivalent synchronous generator, the rated capacity, the target voltage value, and the power that can be additionally provided by the previous stage device by the following formula:

[0019]

[0020] wherein C dcC is a DC side capacitance value; S C P is a rated capacity of the power electronic converter; T j T is a preset equivalent inertia time constant; Δ G Δ is an equivalent synchronous generator releasable energy unit value; Δ is an energy additionally provided by a previous stage device during inertia support; t0 is a time when a power disturbance occurs; Δp in Δp is a power additionally provided by the previous stage device during inertia support; τ is a duration during which inertia support plays a dominant role; U dc0 U is a steady-state operating DC voltage; Δ C Δ is a converter releasable energy unit value.

[0021] Further, the upper limit value in the adjustable operating range is calculated by the following method:

[0022] The product of the target voltage value and a preset rated voltage margin coefficient is calculated to generate the upper limit value in the adjustable operating range of the DC side voltage of the power electronic converter.

[0023] Further, the DC voltage reference value is calculated by the following formula:

[0024] u dcref =(K1s+K2)(f pcc -f0)+u dcref0

[0025] In the formula, u dcref is a DC voltage reference value; K1 is an inverter inertia support coefficient; s is a Laplace operator, representing a differential operation on time; K2 is a frequency modulation coefficient; f0 is a rated frequency of the power grid; f pcc is a power grid frequency of a point of common coupling of the power electronic converter; u dcref0 is a DC voltage rated value.

[0026] On the basis of the above-mentioned method embodiment, the application correspondingly provides a device embodiment.

[0027] An embodiment of the application provides an inertia support control device of a power electronic converter, comprising: a point of common coupling frequency acquisition module, a frequency comparison module, a DC voltage reference value generation module and an inertia support module.

[0028] The point of common coupling frequency acquisition module is used for acquiring a power grid frequency of a point of common coupling of the power electronic converter in real time; wherein the power electronic converter comprises a DC side capacitor; a DC side voltage of the power electronic converter is configured as an upper limit value in a preset adjustable operating range;

[0029] The frequency comparison module is configured to calculate a frequency deviation and a frequency change rate between the power grid frequency and a preset power grid rated frequency each time the power grid frequency is acquired.

[0030] The DC voltage reference value generation module is configured to calculate and generate a DC voltage reference value according to the current frequency deviation and the current frequency change rate when both the frequency deviation and the frequency change rate exceed corresponding preset response thresholds.

[0031] The inertia support module is configured to send a control instruction to a control terminal, so that the control instruction adjusts a DC side voltage of the power electronic converter to the DC voltage reference value after receiving the control instruction, thereby releasing the energy stored in the DC side capacitor.

[0032] Further, the inertia support control device of the power electronic converter further comprises a DC side capacitor value determination module.

[0033] The DC side capacitor value determination module determines the capacitance value of the DC side capacitor by the following manner:

[0034] The performance boundary parameters of the power electronic converter and external operating condition parameters are acquired, wherein the performance boundary parameters include a rated capacity, a target voltage value at a DC side output steady-state voltage, a steady-state modulation ratio, and a maximum modulation ratio; and the external operating condition parameters include a power grid rated angular frequency, a minimum angular frequency allowed by the power grid, and power that can be additionally provided by a previous stage device;

[0035] According to the steady-state modulation ratio and the maximum modulation ratio, the energy releaseable by the converter is calculated by the following formula:

[0036]

[0037] In the formula, m0 is the steady-state modulation ratio of the power electronic converter; η is a rated voltage margin coefficient; m max is the maximum modulation ratio of the power electronic converter;

[0038] According to the power grid rated angular frequency and the minimum angular frequency allowed by the power grid, the energy releaseable by the equivalent synchronous generator is calculated by the following formula:

[0039]

[0040] In the formula, ω min is the minimum angular frequency allowed by the power grid; and ω0 is the power grid rated angular frequency;

[0041] According to the energy release index value of the converter, the energy release index value of the equivalent synchronous generator, the rated capacity, the target voltage value and the power additionally provided by the previous stage device, the capacitance value of the DC side capacitor is calculated by the following formula:

[0042]

[0043] In the formula, C dc is the DC side capacitance value; S C is the rated capacity of the power electronic converter; T j is the preset equivalent inertia time constant; Δ G is the energy release index value of the equivalent synchronous generator; is the energy additionally provided by the previous stage device during inertia support; t0 is the time when the power disturbance occurs; Δp in is the power additionally provided by the previous stage device during inertia support; τ is the duration during which inertia support plays a dominant role; U dc0 is the steady-state operating DC voltage; Δ C is the energy release index value of the converter.

[0044] Further, the inertia support control device of the power electronic converter further comprises a DC side voltage value determination module.

[0045] The DC side voltage value determination module calculates the upper limit value in the adjustable operating range by the following method:

[0046] The product of the target voltage value and a preset rated voltage margin coefficient is calculated to generate the upper limit value in the adjustable operating range of the DC side voltage of the power electronic converter.

[0047] Further, the inertia support control device of the power electronic converter, the DC voltage reference value generation module calculates the DC voltage reference value by the following formula:

[0048] u dcref =(K1s+K2)(f pcc -f0)+u dcref0

[0049] In the formula, u dcref is the DC voltage reference value; K1 is the inertia support coefficient of the inverter; s is the Laplace operator, representing the differential operation with respect to time; K2 is the frequency modulation coefficient; f0 is the rated frequency of the power grid; f pcc is the frequency of the power grid at the point of common coupling of the power electronic converter; u dcref0 is the DC voltage rated value.

[0050] On the basis of the above-mentioned method embodiment, the present application correspondingly provides an electronic device embodiment.

[0051] An embodiment of the present application provides an electronic device, comprising a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, and the processor implements the inertia support control method of the power electronic converter in any of the method embodiments when executing the computer program.

[0052] On the basis of the above-mentioned method embodiments, the present application correspondingly provides storage medium embodiments.

[0053] An embodiment of the present application provides a storage medium, which stores a computer program, wherein the device where the storage medium is located executes the inertia support control method of the power electronic converter in any of the method embodiments when the computer program runs.

[0054] Compared with the prior art, the present application has the following beneficial effects:

[0055] Embodiments of the present application provide an inertia support control method, device, electronic equipment and storage medium of a power electronic converter. The method acquires the grid frequency of the power electronic converter in real time; wherein the power electronic converter comprises a DC side capacitor; the DC side voltage of the power electronic converter is configured as an upper limit value in a preset adjustable operating range; when each of the grid frequency is acquired, the frequency deviation between the grid frequency and the preset grid rated frequency and the frequency change rate are calculated; when the frequency deviation and the frequency change rate both exceed the corresponding preset response threshold, the DC voltage reference value is calculated and generated according to the current frequency deviation and the current frequency change rate; the control instruction is sent to the control terminal, so that the control instruction adjusts the DC side voltage of the power electronic converter to the DC voltage reference value after receiving the control instruction, and then releases the energy stored in the DC side capacitor.

[0056] The present application enhances the recognition sensitivity of frequency disturbance by introducing the joint judgment mechanism of frequency deviation and frequency change rate, effectively solves the problem of response lag in the prior art; at the same time, the DC side voltage is configured as an adjustable upper limit operating value, so that the DC capacitor has a larger adjustable pressure difference in the release process, thereby improving the energy release amount during inertia support. BRIEF DESCRIPTION OF DRAWINGS

[0057] Figure 1 is a flowchart of an inertia support control method of a power electronic converter provided by an embodiment of the present application.

[0058] Figure 2 is a typical power electronic converter grid-connected system topology provided by an embodiment of the present application.

[0059] Figure 3 is a structural schematic diagram of an inertia support control device of a power electronic converter provided by an embodiment of the present application. DETAILED DESCRIPTION

[0060] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0061] As Figure 1 shown, to solve the inertia support response lag problem in the prior art, an embodiment of the present application provides an inertia support control method of a power electronic converter, at least including the following steps:

[0062] Step S1, acquiring the grid frequency of a power electronic converter common coupling point in real time; wherein the power electronic converter includes a DC side capacitor; the DC side voltage of the power electronic converter is configured as an upper limit value in a preset adjustable operating range;

[0063] Specifically, first, the current grid frequency is continuously and in real time acquired by a frequency measurement unit deployed at the power electronic converter common coupling point. The power electronic converter to which the method is applied contains a DC side capacitor as a core energy storage element in its internal structure, and in order to achieve efficient inertia support, the control strategy of the method has previously configured and stably maintained the DC side voltage of the converter at an upper limit value in a preset adjustable operating range.

[0064] The purpose of configuring the DC side voltage at the upper limit of the operating range is to maximize the physical energy storage potential of the DC side capacitor. According to the capacitor energy storage principle, a higher steady-state operating voltage means that more available energy is stored in the capacitor, which lays a foundation for releasing stronger support power when the grid frequency is disturbed subsequently. Through this pre-energy storage strategy, the total amount of energy that can be released by the converter in the transient process is effectively improved.

[0065] In a preferred embodiment, the capacitance value of the DC side capacitor is determined by the following method, including:

[0066] Acquiring performance boundary parameters and external operating condition parameters of the power electronic converter; wherein the performance boundary parameters include rated capacity, target voltage value at DC side output steady-state voltage, steady-state modulation ratio and maximum modulation ratio; the external operating condition parameters include grid rated angular frequency, minimum angular frequency allowed by the grid and power that can be additionally provided by a previous stage device;

[0067] According to the steady-state modulation ratio and the maximum modulation ratio, the energy release standard value of the converter is calculated by the following formula:

[0068]

[0069] In the formula, m0 is the steady-state modulation ratio of the power electronic converter; η is the rated voltage margin coefficient; m max is the maximum modulation ratio of the power electronic converter;

[0070] According to the grid rated angular frequency and the minimum angular frequency allowed by the grid, the energy release standard value of the equivalent synchronous generator is calculated by the following formula:

[0071]

[0072] In the formula, ω min is the minimum angular frequency allowed by the grid; ω0 is the grid rated angular frequency;

[0073] According to the energy release standard value of the converter, the energy release standard value of the equivalent synchronous generator, the rated capacity, the target voltage value and the power additionally provided by the previous stage device, the capacitance value of the generated DC side capacitor is calculated by the following formula:

[0074]

[0075] In the formula, C dc is the DC side capacitor value; S C is the rated capacity of the power electronic converter; T j is the preset equivalent inertia time constant; Δ G is the energy release standard value of the equivalent synchronous generator; is the energy additionally provided by the previous stage device during inertia support; t0 is the time when the power disturbance occurs; Δp in is the power additionally provided by the previous stage device during inertia support; τ is the duration during which inertia support plays a dominant role; U dc0 is the steady-state operation DC voltage; Δ C is the energy release standard value of the converter.

[0076] Specifically, in a preferred embodiment, the inertia support control method of the present application, in its design stage, first needs to obtain a series of basic parameters for quantitative design. These parameters can be divided into two categories, the first category is the performance boundary parameter describing the converter's own ability, which specifically includes the rated capacity of the power electronic converter, the target voltage value when it outputs a steady-state voltage on the DC side, and the steady-state modulation ratio and maximum modulation ratio set to ensure normal operation. The second category is the external operating condition parameter describing the operating environment of the converter, which specifically includes the rated angular frequency and the minimum angular frequency allowed by the grid standard, and the additional power that can be provided by the characteristics of the previous stage device.

[0077] After obtaining the above parameters, the method then solves the final required DC side capacitance value through a series of calculations. First, the method calculates the releasable energy unit value of the converter itself according to the obtained steady-state modulation ratio and maximum modulation ratio parameters through formula (1). At the same time, according to the grid frequency specification parameters obtained, the releasable energy unit value of the equivalent synchronous generator as the design reference is calculated through formula (2). Finally, these two calculated energy unit values, together with the rated capacity, target voltage value, and previous stage device power parameters, are substituted into formula (3) established based on the energy equivalence principle, to accurately calculate the DC side capacitance value that can meet the preset inertia support target.

[0078] Through the above quantitative design process, the present application can configure an optimal DC side capacitance for the power electronic converter, ensuring that it can provide the desired support strength when performing inertia support control.

[0079] It should be noted that the ultimate goal of the technical solution of the present application is to propose a quantitatively designed method of providing inertia support using the DC side capacitance of the power electronic converter. The entire derivation process starts with defining the control strategy, then establishing the physical model, and finally solving the design parameters of the core hardware through the energy equivalence principle. In the following, the power electronic converter grid-connected system topology as shown in Figure 2 will be introduced.

[0080] The typical power electronic converter grid-connected system topology is shown in Figure 2 The previous stage new energy or energy storage device is connected to the DC side of the converter, and after being inverted by the converter, it is connected to the point of common coupling (PCC) through the LC filter, and then connected to the power grid through the transmission line. In the figure, L g represents the line inductance; L f and C f represent the filter inductance and filter capacitance, respectively; C dc represents the DC side capacitance of the converter; P inActive power delivered to DC side from previous stage; P dc Output active power of DC capacitor; P out Active power delivered to converter from DC side.

[0081] Firstly, the present application proposes a core control law for realizing the coordinated control of inertia support and frequency modulation, as shown in formula (4). The introduction of this formula is to define a clear operation mode: that is, how to dynamically generate a DC voltage reference value according to the real-time monitored power grid frequency deviation and its rate of change.

[0082] u dcref = (K1s + K2) (f pcc -f0) + u dcref0 (4)

[0083] In the formula, u dcref is the DC voltage reference value; K1 is the inverter inertia support coefficient; s is the Laplace operator, representing the differential operation on time; K2 is the frequency modulation coefficient; f0 is the rated frequency of the power grid; f pcc is the power grid frequency at the point of common coupling of the power electronic converter; u dcref0 is the rated value of the DC voltage.

[0084] After defining the control law, the physical behavior of the system under the action of the control law needs to be analyzed. Formula (5) describes the power balance state of the system in the ideal steady state, that is, the input power is equal to the output power, and at this time the DC capacitor has no energy throughput.

[0085] p in = p out (5)

[0086] In the formula, p in is the active power delivered to the DC side from the previous stage; p out is the active power output to the grid side by the converter.

[0087] With the steady state as the benchmark, formula (6) further describes the power balance relationship of the system in the transient state based on the law of conservation of energy. When p out is not balanced with p in , the difference power p dc must be compensated by the DC capacitor. The introduction of this formula physically establishes that the DC capacitor is the core buffer link to cope with power imbalance.

[0088]

[0089] In the formula, p dc is the output active power of the DC capacitor; C dc is the capacitance value of the DC side capacitor of the converter; udc is the real-time voltage of the DC side; is the rate of change of the DC side voltage.

[0090] Then, formula (7) is introduced as a condition judgment to define the specific scenario in which the application works, i.e. only when the power of the previous stage device is insufficient to meet the transient demand, the DC capacitor needs to be started to compensate.

[0091] p out <P max (7)

[0092] In the formula, P max is the maximum active power that the previous stage device can provide.

[0093] After the control law and the physical model are determined, a safety boundary must be set for the operation of the controller. Formula (8) first conceptually proposes this requirement, i.e. the DC voltage reference value generated by formula (4) must be limited between a safe upper and lower limit.

[0094] U dcmin <u dcref <U dcmax (8)

[0095] In the formula, U dcmin is the lower limit of the allowable range of DC voltage; U dcmax is the upper limit of the allowable range of DC voltage.

[0096] In order to obtain the specific value of this range, first introduce the basic physical principle of the operation of the converter, i.e. formula (9).

[0097]

[0098] In the formula, U lm is the AC line voltage amplitude of the inverter output; m is the modulation ratio; U dc is the DC side voltage.

[0099] Based on the principle of formula (9), the lower limit of the voltage required to ensure the normal operation of the converter can be derived, and its calculation method is given in formula (10).

[0100]

[0101] In the formula, m0 is the preset steady-state modulation ratio; m max is the maximum modulation ratio; U dc0 is the preset steady-state DC voltage.

[0102] For the upper limit of the voltage, it can be determined according to formula (11):

[0103] Udcmax = ηU dc0 (11)

[0104] where η is the rated voltage margin coefficient, which can be taken as 1.1.

[0105] Based on the above, the final expression of the complete adjustable operating range of the DC voltage is obtained, as shown in equation (12).

[0106]

[0107] where u dc is the real-time variable of the DC voltage.

[0108] The core design stage starts from the quantification of the object of imitation (synchronous machine). Equation (13) calculates the proportion of the energy that can be released by the synchronous machine.

[0109]

[0110] where Δ G is the per-unit value of the energy that can be released by the synchronous generator; ω min is the minimum angular frequency allowed by the power grid; and ω0 is the rated angular frequency of the power grid.

[0111] Correspondingly, equation (14) calculates the proportion of the energy that can be released by the converter in this scheme.

[0112]

[0113] where m0 is the steady-state modulation ratio of the power electronic converter; η is the rated voltage margin coefficient; and m max is the maximum modulation ratio of the power electronic converter.

[0114] Equation (15) gives the total energy stored by the capacitor in the steady state.

[0115]

[0116] where E C is the total energy stored by the capacitor in the steady state; and C dc is the capacitance of the DC side capacitor of the converter.

[0117] In order to establish a unified energy analysis framework, the per-unit swing equation, i.e., equation (16), is introduced, and its integral gives the energy balance relationship, i.e., equation (17).

[0118]

[0119] where T C is the equivalent inertial time constant of the converter; and ω *The unit of the virtual angular frequency of the converter; The unit of the reference active power; The unit of the output active power of the converter.

[0120]

[0121] Where τ is the duration of the inertia support; t0 is the disturbance time; The unit of the output energy of the converter; The unit of the input energy of the prime mover of the converter; The unit of the released energy of the inertia;

[0122] Based on this framework, the total released energy of the synchronous machine and the converter are quantified in equations (18) and (19), respectively.

[0123]

[0124] Where T j is the inertia time constant of the synchronous generator; E G is the total kinetic energy of the synchronous generator; S G is the rated capacity of the synchronous generator;

[0125]

[0126] Where S C is the rated capacity of the converter; Δp in is the additional power provided by the previous stage device.

[0127] Finally, by equating the released energy of the two systems (i.e., the energy equivalence principle) and substituting the previous definitions, the final design formula (20) is obtained by algebraic solving, which gives the exact value of the required capacitor configuration.

[0128]

[0129] Where C dc is the DC side capacitor value; S C is the rated capacity of the power electronic converter; T j is the preset equivalent inertia time constant; Δ G is the equivalent energy that can be released by the synchronous generator; is the additional energy provided by the previous stage device during the inertia support; t0 is the time when the power disturbance occurs; Δp in is the additional power provided by the previous stage device during the inertia support; τ is the duration of the inertia support; U dc0 is the steady-state operating DC voltage; Δ C is the energy that can be released by the converter.

[0130] In a preferred embodiment, the upper limit value in the adjustable operating range is calculated by the following way:

[0131] The product of the target voltage value and the preset rated voltage margin coefficient is calculated to generate the upper limit value in the adjustable operating range of the DC side voltage of the power electronic converter. The rated voltage margin coefficient can be 1.1.

[0132] Step S2, when each of the grid frequencies is obtained, the frequency deviation between the grid frequency and the preset grid rated frequency and the frequency change rate are calculated;

[0133] Specifically, after the real-time grid frequency is obtained by the measurement unit, the real-time frequency value is continuously and dynamically compared with the preset grid rated frequency (for example, 50 Hz) in the system. Through the comparison, two key dynamic indicators can be calculated and generated: one is the frequency deviation reflecting the degree of deviation of the current frequency from the steady state, and the other is the frequency change rate reflecting the degree of disturbance intensity obtained by the differential operation of the continuous frequency measurement value. At the same time, the two indicators are obtained, so that the subsequent control decision can comprehensively consider the deviation amplitude and the change speed of the frequency, and provide complete input basis for realizing fast and accurate inertia support.

[0134] Step S3, when the frequency deviation and the frequency change rate both exceed the corresponding preset response threshold, the DC voltage reference value is calculated and generated according to the current frequency deviation and the current frequency change rate;

[0135] In a preferred embodiment, the DC voltage reference value is calculated and generated by the following formula:

[0136] u dcref =(K1s+K2)(f pcc -f0)+u dcref0 (21)

[0137] In the formula, u dcref is the DC voltage reference value; K1 is the inverter inertia support coefficient; s is the Laplace operator, representing the differential operation with respect to time; K2 is the frequency modulation coefficient; f0 is the grid rated frequency; f pcc is the grid frequency of the power electronic converter common coupling point; and u dcref0 is the DC voltage rated value.

[0138] Specifically, in one embodiment of the present application, the core of the control method lies in its response mechanism to grid frequency disturbance. When the system determines whether inertia support is needed, it sets a frequency deviation threshold and a frequency rate of change threshold. Only when the current values of the two indicators, i.e. the real-time calculated frequency deviation and frequency rate of change, simultaneously exceed the respective preset response thresholds, the control method is activated. Once activated, the method immediately takes the current frequency deviation value and frequency rate of change value as input, and calculates a dynamic DC voltage reference value for guiding voltage drop through a preset control law.

[0139] The above control law can be implemented by a proportional-differential controller as shown in formula (21). By this way of integrated and collaborative calculation of the two dynamic indicators, the generated DC voltage reference value can accurately reflect the severity and urgency of the disturbance, providing a reliable target for subsequent precise energy release control.

[0140] Step S4, sending a control instruction to the control terminal, so that after receiving the control instruction, the control terminal adjusts the DC side voltage of the power electronic converter to the DC voltage reference value, thereby releasing the energy stored in the DC side capacitor.

[0141] Specifically, in the control process of the present application, once the target DC voltage reference value is generated according to the real-time dynamic calculation of the grid frequency, the system will generate and send a clear control instruction to a control terminal based on this reference value. After receiving the control instruction, the control terminal will immediately analyze it and convert it into specific operation signals for the internal switching devices of the power electronic converter, such as adjusting the duty cycle of its pulse width modulation (PWM) signal.

[0142] Through accurate control of the switching devices, the converter actively adjusts and follows the actual voltage of its DC side to the newly generated target DC voltage reference value. It is this active and controllable voltage drop process that breaks the original energy balance, thereby forcing the DC side capacitor to release its pre-stored energy in the form of active power. Through this way of directly regulating voltage to release energy, the present application can achieve fast response and effective inertia support to grid frequency disturbance.

[0143] On the basis of the above-mentioned method embodiment, the present application correspondingly provides a device embodiment.

[0144] As shown in Figure 3 An embodiment of the present application provides an inertia support control device for a power electronic converter, comprising: a point of common coupling frequency acquisition module, a frequency comparison module, a DC voltage reference value generation module, and an inertia support module.

[0145] The common coupling point frequency acquisition module is configured to acquire the grid frequency of the common coupling point of the power electronic converter in real time; wherein the power electronic converter comprises a DC side capacitor; and the DC side voltage of the power electronic converter is configured as an upper limit value within a preset adjustable operating range.

[0146] The frequency comparison module is configured to calculate the frequency deviation and the frequency change rate between the grid frequency and a preset grid rated frequency each time the grid frequency is acquired.

[0147] The DC voltage reference value generation module is configured to calculate and generate a DC voltage reference value according to the current frequency deviation and the current frequency change rate when both the frequency deviation and the frequency change rate exceed corresponding preset response thresholds.

[0148] The inertia support module is configured to send a control instruction to a control terminal, so that the control instruction adjusts the DC side voltage of the power electronic converter to the DC voltage reference value after receiving the control instruction, thereby releasing the energy stored in the DC side capacitor.

[0149] In a preferred embodiment, the inertia support control device of the power electronic converter further comprises a DC side capacitor value determination module.

[0150] The DC side capacitor value determination module determines the capacitance value of the DC side capacitor by the following method:

[0151] The performance boundary parameters of the power electronic converter and the external operating condition parameters are acquired; wherein the performance boundary parameters comprise a rated capacity, a target voltage value at a DC side output steady-state voltage, a steady-state modulation ratio and a maximum modulation ratio; and the external operating condition parameters comprise a grid rated angular frequency, a minimum angular frequency allowed by the grid and a power that can be additionally provided by a previous stage device;

[0152] According to the steady-state modulation ratio and the maximum modulation ratio, the energy release standard value of the converter is calculated by the following formula:

[0153]

[0154] In the formula, m0 is the steady-state modulation ratio of the power electronic converter; η is a rated voltage margin coefficient; m max is the maximum modulation ratio of the power electronic converter;

[0155] According to the grid rated angular frequency and the minimum angular frequency allowed by the grid, the energy release standard value of the equivalent synchronous generator is calculated by the following formula:

[0156]

[0157] wherein ω min is the minimum angular frequency allowed by the power grid; ω0is the rated angular frequency of the power grid;

[0158] According to the energy release index value of the converter, the energy release index value of the equivalent synchronous generator, the rated capacity, the target voltage value, and the power additionally provided by the previous stage device, the capacitance value of the DC side capacitor is calculated by the following formula:

[0159]

[0160] wherein C dc is the capacitance value of the DC side capacitor; S C is the rated capacity of the power electronic converter; T j is the preset equivalent inertia time constant; Δ G is the energy release index value of the equivalent synchronous generator; is the energy additionally provided by the previous stage device during inertia support; t0is the time when the power disturbance occurs; Δp in is the power additionally provided by the previous stage device during inertia support; τ is the duration during which inertia support plays a dominant role; u dc0 is the DC voltage in steady state operation; Δ C is the energy release index value of the converter.

[0161] In a preferred embodiment, the inertia support control device of the power electronic converter further comprises a DC side voltage value determination module.

[0162] The DC side voltage value determination module calculates the upper limit value in the adjustable operating range by the following method:

[0163] The product of the target voltage value and a preset rated voltage margin coefficient is calculated to generate the upper limit value in the adjustable operating range of the DC side voltage of the power electronic converter.

[0164] In a preferred embodiment, the inertia support control device of the power electronic converter, the DC voltage reference value generation module calculates the DC voltage reference value by the following formula:

[0165] u dcref = (K1s + K2) (f pcc -f0) + u dcref0 (25)

[0166] wherein u dcref is the DC voltage reference value; K1is the inertia support coefficient of the inverter; s is the Laplace operator, representing the differential operation with respect to time; K2is the frequency modulation coefficient; f0is the rated frequency of the power grid; f pcca grid frequency for a common coupling point of the power electronic converter; u dcref0 a DC voltage rating.

[0167] It should be noted that the above-described embodiments of the device are corresponding to the above-mentioned embodiments of the present application, which can realize the inertia support control method of the power electronic converter according to any one of the above-mentioned embodiments of the present application. In addition, the above-mentioned embodiments of the device are only illustrative, wherein the modules described as separate components can or can not be physically separated, and the components displayed as modules can or can not be physical units, i.e., they can be located in one place or distributed on multiple network units. Part or all of the modules can be selected to achieve the purpose of the present embodiment according to actual needs. In addition, the connection relationship between the modules in the device embodiments provided by the present application indicates that there is a communication connection between them, which can be implemented as one or more communication buses or signal lines. Those skilled in the art can understand and implement it without creative labor.

[0168] On the basis of the above-mentioned method embodiments of the present application, an electronic device embodiment is provided.

[0169] An electronic device is provided in an embodiment of the present application, which comprises a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, the inertia support control method of the power electronic converter according to any one of the embodiments of the present application is realized, or when the processor executes the computer program, the functions of the modules in the above-mentioned device embodiments are realized.

[0170] For example, the computer program can be divided into one or more modules, which are stored in the memory and executed by the processor to complete the present application. The one or more modules can be a series of computer program instruction segments capable of completing a specific function, which are used to describe the execution process of the computer program in the terminal device.

[0171] The terminal device can be a desktop computer, a notebook computer, a palm computer, a cloud server, and other computing devices. The terminal device can include, but is not limited to, a processor and a memory.

[0172] The processor can be a central processing unit (CPU), and can also be other general-purpose processors, digital signal processors (DSP), application specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor and the like, which is a control center of the terminal device and connects all parts of the terminal device through various interfaces and lines.

[0173] The memory can be used to store the computer program and / or modules, and the processor realizes various functions of the terminal device by running or executing the computer program and / or modules stored in the memory and calling the data stored in the memory. The memory can mainly include a program storage area and a data storage area, wherein the program storage area can store an operating system, at least one application required by a function, etc.; and the data storage area can store data created according to the use of the mobile phone, etc. In addition, the memory can include a high-speed random access memory, and can also include a nonvolatile memory, for example, a hard disk, a memory, a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, at least one disk storage device, a flash memory device, or other volatile solid-state memory devices.

[0174] On the basis of the above-mentioned method embodiment, the application further provides a storage medium embodiment;

[0175] Another embodiment of the application provides a storage medium, which comprises a stored computer program, wherein when the computer program runs, the device where the storage medium is located performs the inertia support control method of any one of the power electronic converters mentioned above.

[0176] The storage medium is a computer readable storage medium, and the computer program includes computer program code in the form of source code, object code, an executable file, or some intermediate form, etc. The computer readable medium can include any entity or device capable of carrying the computer program code, a recording medium, a U disk, a mobile hard disk, a magnetic disk, an optical disk, a computer memory, a read-only memory (ROM), a random access memory (RAM), an electrical carrier signal, a telecommunication signal, a software distribution medium, etc.

[0177] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example" or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. Moreover, the specific features, structures, materials or characteristics described can be combined in any suitable manner in any one or more embodiments or examples. In addition, the person skilled in the art can combine and combine the different embodiments or examples described in the present specification and the features of the different embodiments or examples without contradiction.

[0178] The above is the preferred embodiment of the present application. It should be pointed out that for those skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, which are also considered within the scope of protection of the present application.

Claims

1. An inertia support control method of a power electronic converter, characterized by, The method comprises: real-time acquisition of a grid frequency at a common coupling point of a power electronic converter; wherein the power electronic converter comprises a DC side capacitor; a DC side voltage of the power electronic converter is configured as an upper limit value within a preset adjustable operating range; at each acquisition of the grid frequency, calculation of a frequency deviation and a frequency change rate between the grid frequency and a preset grid rated frequency; when both the frequency deviation and the frequency change rate exceed corresponding preset response thresholds, calculation of a DC voltage reference value according to the current frequency deviation and the current frequency change rate; sending of a control instruction to a control terminal, so that the control instruction adjusts the DC side voltage of the power electronic converter to the DC voltage reference value after receiving the control instruction, thereby releasing the energy stored in the DC side capacitor.

2. The inertia support control method of a power electronic converter according to claim 1, characterized by, The capacitance value of the DC side capacitor is determined by the following method: acquisition of performance boundary parameters and external operating condition parameters of the power electronic converter; wherein the performance boundary parameters comprise a rated capacity, a target voltage value at a DC side output steady-state voltage, a steady-state modulation ratio, and a maximum modulation ratio; the external operating condition parameters comprise a grid rated angular frequency, a minimum angular frequency allowed by the grid, and an additional power that can be provided by a previous stage device; calculation of an energy release standard value of the converter according to the steady-state modulation ratio and the maximum modulation ratio by the following formula: where m0 is the steady-state modulation ratio of the power electronic converter; η is the rated voltage margin coefficient; m max is the maximum modulation ratio of the power electronic converter; calculation of an energy release standard value of an equivalent synchronous generator according to the grid rated angular frequency and the minimum angular frequency allowed by the grid by the following formula: In the formula, ω min ω0 is the minimum permissible angular frequency of the power grid; ω0 is the rated angular frequency of the power grid. calculation of the capacitance value of the DC side capacitor according to the energy release standard value of the converter, the energy release standard value of the equivalent synchronous generator, the rated capacity, the target voltage value, and the additional power that can be provided by the previous stage device by the following formula: In the formula, C dc is the DC side capacitance value; S C is the rated capacity of the power electronic converter; T j is the preset equivalent inertia time constant; Δ G is the equivalent synchronous generator releasable energy unit value; is the energy additionally provided by the previous stage device during inertia support; t0 is the time when the power disturbance occurs; Δp in is the power additionally provided by the previous stage device during inertia support; τ is the duration during which inertia support plays a dominant role; U dc0 is the steady-state operating DC voltage; Δ C is the converter releasable energy unit value.

3. The inertia support control method of a power electronic converter according to claim 2, characterized by, the upper limit value within the adjustable operating range is calculated by the following method: calculation of the product of the target voltage value and a preset rated voltage margin coefficient to generate the upper limit value within the adjustable operating range of the DC side voltage of the power electronic converter.

4. The inertia support control method of a power electronic converter according to claim 3, characterized by, The DC voltage reference value is calculated by the following formula: u dcref = (K1s + K2)(f pcc -f0) + u dcref0 wherein u dcref is the DC voltage reference; K1 is the inverter inertia support coefficient; s is the Laplace operator, representing the differentiation operation with respect to time; K2 is the frequency modulation coefficient; f0 is the grid rated frequency; f pcc is the grid frequency at the point of common coupling of the power electronic converter; u dcref0 is the DC voltage rated value.

5. An inertia support control device of a power electronic converter, characterized by, The method comprises: a common coupling point frequency acquisition module, a frequency comparison module, a DC voltage reference value generation module, and an inertia support module; the common coupling point frequency acquisition module is configured to acquire a grid frequency at a common coupling point of a power electronic converter in real time; wherein the power electronic converter comprises a DC side capacitor; a DC side voltage of the power electronic converter is configured as an upper limit value within a preset adjustable operating range; the frequency comparison module is configured to calculate a frequency deviation and a frequency change rate between the grid frequency and a preset grid rated frequency at each acquisition of the grid frequency; the DC voltage reference value generation module is configured to calculate a DC voltage reference value according to the current frequency deviation and the current frequency change rate when both the frequency deviation and the frequency change rate exceed corresponding preset response thresholds; The inertia support module is configured to send a control instruction to a control terminal, so that the control instruction adjusts a direct current side voltage of the power electronic converter to the direct current voltage reference value after receiving the control instruction, and then releases the energy stored in the direct current side capacitor.

6. The inertia support control device of a power electronic converter according to claim 5, characterized by Further comprising: A direct current side capacitor value determination module; The direct current side capacitor value determination module determines the capacitance value of the direct current side capacitor by the following method: Obtain the performance boundary parameters of the power electronic converter and the external operating condition parameters; wherein, the performance boundary parameters include rated capacity, target voltage value when the direct current side output steady-state voltage, steady-state modulation ratio and maximum modulation ratio; the external operating condition parameters include grid rated angular frequency, minimum angular frequency allowed by the grid and power that can be additionally provided by the previous stage device; According to the steady-state modulation ratio and the maximum modulation ratio, the energy releaseable by the converter is calculated by the following formula: where m0 is the steady-state modulation ratio of the power electronic converter; η is the rated voltage margin coefficient; m max is the maximum modulation ratio of the power electronic converter; According to the grid rated angular frequency and the minimum angular frequency allowed by the grid, the energy releaseable by the equivalent synchronous generator is calculated by the following formula: In the formula, ω min ω0 is the minimum permissible angular frequency of the power grid; ω0 is the rated angular frequency of the power grid. According to the energy releaseable by the converter, the energy releaseable by the equivalent synchronous generator, the rated capacity, the target voltage value and the power that can be additionally provided by the previous stage device, the capacitance value of the direct current side capacitor is calculated by the following formula: In the formula, C dc is the DC side capacitance value; S C is the rated capacity of the power electronic converter; T j is the preset equivalent inertia time constant; Δ G is the equivalent synchronous generator releasable energy unit value; is the energy additionally provided by the previous stage device during inertia support; t0 is the time when the power disturbance occurs; Δp in is the power additionally provided by the previous stage device during inertia support; τ is the duration during which inertia support plays a dominant role; U dc0 is the steady-state operating DC voltage; Δ C is the releasable energy unit value of the converter.

7. An inertia support control device for a power electronic converter as claimed in claim 6, characterised in that, Further comprising: A direct current side voltage value determination module; The direct current side voltage value determination module calculates the upper limit value in the adjustable operating range by the following method: Calculate the product of the target voltage value and the preset rated voltage margin coefficient to generate the upper limit value in the adjustable operating range of the direct current side voltage of the power electronic converter.

8. The inertia support control device of a power electronic converter according to claim 7, characterized by, The direct current voltage reference value generation module calculates the direct current voltage reference value by the following formula: u dcref = (K1s + K2)(f pcc -f0) + u dcref0 wherein u dcref is the DC voltage reference; K1 is the inverter inertia support coefficient; s is the Laplace operator, representing the differentiation operation with respect to time; K2 is the frequency modulation coefficient; f0 is the grid rated frequency; f pcc is the grid frequency at the point of common coupling of the power electronic converter; u dcref0 is the DC voltage rated value.

9. An electronic device, comprising: The storage medium includes a stored computer program, wherein, when the computer program runs, the device where the storage medium is located executes the inertia support control method of the power electronic converter as claimed in any one of claims 1 to 4.

10. A storage medium, characterized by The storage medium includes a stored computer program, wherein, when the computer program runs, the device where the storage medium is located executes the inertia support control method of the power electronic converter as claimed in any one of claims 1 to 4.

Images