Power regulation method and device based on SVG and energy storage technology

Abstract

This invention discloses a power regulation method and apparatus based on SVG and energy storage technology. The method includes: multiple energy storage units connected to a cascaded H-bridge SVG power module circuit via a converter; obtaining a zero-sequence voltage reference value by performing inter-phase SOC equalization control based on the average state of charge (SOC) of all energy storage units, the average SOC of the three phases of the energy storage units, and the three-phase current values ​​of the converter; obtaining an additional voltage regulation amount by performing intra-arm SOC equalization control based on the SOC of each energy storage unit and the average value; and obtaining a reference voltage command after SOC adjustment based on the voltage value after zero-sequence voltage injection and the regulation amount. This command, after being modulated by carrier phase shift, generates a trigger pulse which is used to input to the converter to ensure that the AC system frequency remains within the target range. This invention can dynamically adjust active power based on system frequency fluctuations, building upon the reactive power compensation and harmonic suppression functions of SVG, achieving excellent dynamic performance.

Description

Technical Field

[0001] This invention relates to the fields of power transmission and distribution systems and new energy application technology, and in particular to a power regulation method and device based on SVG and energy storage technology. Background Technology

[0002] This section is intended to provide background or context for the embodiments of the invention set forth in the claims. The description herein is not an admission that it is prior art simply because it is included in this section.

[0003] In the current context of energy structure optimization and transformation, building a new power system with new energy sources as the mainstay is an important measure to deepen power system reform. This involves the deep integration of new energy sources into the power generation supply and the extensive re-electrification of distribution equipment. The power system's source, grid, and load equipment exhibit a high degree of power electronics, and the low inertia and weak damping characteristics of the system make frequency fluctuations more prominent. Although a high proportion of new energy power systems can efficiently replace fossil fuels and achieve sustainable utilization, the quality of its power supply is a major concern, especially the difficult-to-solve problem of frequency stability.

[0004] Currently, SVG can achieve dynamic reactive power compensation in the power grid. Its internal control system adopts a hierarchical control strategy, mainly divided into converter control and valve control. The converter control includes two control loops: outer loop control and inner loop control. The input to the outer loop controller is the reference value of the controlled object issued by the upper-level control and protection system, as well as the real-time measured values ​​of system current and voltage. It implements closed-loop regulation of the controlled object according to relevant strategies. The output of the outer loop controller is the current reference value of the inner loop controller. The inner loop controller adopts an instantaneous current control strategy to achieve precise and rapid control of the converter chain current. The output of the inner loop control is a set of voltage reference waves, which are introduced into the valve control section to generate modulation trigger pulses for the SVG power module.

[0005] The core control strategy of the SVG control system is as follows: Figure 1 As shown. Based on the basic control functions described above, a harmonic suppression function can be added. When the system contains significant harmonics, operators can manually activate the harmonic control function to eliminate harmonic components in the system. Considering the widespread use of SVG devices and the frequency fluctuation and voltage peak-shaving / valley-filling issues that need to be addressed in practical systems, it is crucial to combine the energy storage unit with the SVG power module and explore a suitable frequency regulation method for AC systems with this structure. Summary of the Invention

[0006] This invention provides a power regulation method based on SVG and energy storage technology. It offers a frequency regulation method for AC systems using a power module combination structure of energy storage units and SVG. This method achieves dynamic adjustment of active power based on system frequency fluctuations, building upon the reactive power compensation and harmonic suppression functions of the SVG. Multiple energy storage units are connected to the SVG power module circuit of a cascaded H-bridge reactive power compensation generator via a DC / DC converter. The energy storage units are used to support or compensate for power fluctuations in the AC system. The method includes:

[0007] Based on the average state of charge (SOC) of all energy storage units, the average SOC of the three phases of the energy storage units, and the three-phase current of the converter, SOC balancing control of the phase-to-phase energy storage units is performed to obtain the zero-sequence voltage reference value converted from the SOC of the energy storage units. The zero-sequence voltage reference value is injected into the three-phase reference voltage value output by the inner loop controller to obtain a three-phase reference voltage value containing phase-to-phase SOC balancing adjustment. The three-phase current value of the converter is obtained by detecting the AC system frequency at the access point of the cascaded H-bridge converter.

[0008] Based on the state of charge (SOC) of each energy storage unit and the average SOC of all energy storage units, SOC equalization control is performed on the energy storage units within the bridge arm to obtain the additional voltage adjustment amount for each energy storage unit within the phase. The additional voltage adjustment amount for each energy storage unit within the phase, together with the three-phase reference voltage value containing inter-phase SOC equalization control, obtains the reference voltage command for each module of the corresponding three phases after SOC adjustment of the energy storage unit. The trigger pulse of the three-phase cascaded H-bridge power module obtained by carrier phase shift modulation of the reference voltage command is used to input the cascaded H-bridge converter to ensure that the AC system frequency at the access point is kept within the target range.

[0009] This invention also provides a power regulation device based on SVG and energy storage technology, which provides a frequency regulation method for AC systems using a power module combination structure of energy storage units and SVG. This method achieves dynamic adjustment of active power based on system frequency fluctuations, building upon the reactive power compensation and harmonic suppression functions of the SVG. Multiple energy storage units are connected to the SVG power module circuit of a cascaded H-bridge reactive power compensation generator via a DC / DC converter. The energy storage units are used to support or compensate for power fluctuations in the AC system. The device includes:

[0010] The inter-phase SOC balancing control unit is used to perform inter-phase SOC balancing control of energy storage units based on the average state of charge of all energy storage units, the average state of charge of the three phases of the energy storage units, and the three-phase current value of the converter, to obtain the zero-sequence voltage reference value converted from the state of charge of the energy storage units; the zero-sequence voltage reference value is injected into the three-phase reference voltage value output by the inner loop controller to obtain the three-phase reference voltage value containing inter-phase SOC balancing adjustment; the three-phase current value of the converter is obtained by detecting the AC system frequency at the access point of the cascaded H-bridge converter;

[0011] The SOC equalization control unit within the bridge arm is used to perform SOC equalization control of the energy storage units within the bridge arm based on the state of charge of each energy storage unit and the average SOC of all energy storage units, thereby obtaining the additional voltage adjustment amount for each energy storage unit within the phase. The additional voltage adjustment amount for each energy storage unit within the phase, together with the three-phase reference voltage value containing inter-phase SOC equalization adjustment, obtains the reference voltage command for each module of the corresponding three phases after the SOC of the energy storage unit is adjusted. The trigger pulse of the three-phase cascaded H-bridge power module obtained by the reference voltage command being phase-shifted by the carrier is used to input the cascaded H-bridge converter to ensure that the AC system frequency at the access point is kept within the target range.

[0012] This invention also provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the above-described power regulation method based on SVG and energy storage technology.

[0013] This invention also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the aforementioned power regulation method based on SVG and energy storage technology.

[0014] This invention also provides a computer program product, which includes a computer program that, when executed by a processor, implements the aforementioned power regulation method based on SVG and energy storage technology.

[0015] In this embodiment of the invention, the power regulation scheme based on SVG and energy storage technology proceeds as follows: The AC system frequency at the access point of the cascaded H-bridge converter is detected to obtain the three-phase current value of the converter; multiple energy storage units are connected to the SVG power module loop of the cascaded H-bridge reactive power compensation generator via a DC / DC converter, and the energy storage units are used to support or compensate for power fluctuations in the AC system; based on the average state of charge (SOC) of all energy storage units, the average SOC of the three phases of the energy storage units, and the three-phase current value of the converter, inter-phase SOC balancing control is performed to obtain the zero-sequence voltage reference value converted from the SOC of the energy storage units; the zero-sequence voltage reference value is injected into the three-phase reference voltage value output by the inner loop controller to obtain a three-phase reference voltage value containing inter-phase SOC balancing adjustment; based on the SOC of each energy storage unit and the average SOC of all energy storage units... The average state of charge (SOC) of the energy storage units is used to perform SOC equalization control within the bridge arm, resulting in the additional voltage adjustment for each energy storage unit in the phase. Based on the three-phase reference voltage values ​​containing inter-phase SOC equalization control and the additional voltage adjustment for each energy storage unit in the phase, the reference voltage command for each module of the corresponding three phases after SOC adjustment of the energy storage units is obtained. The trigger pulses of the three-phase cascaded H-bridge power modules obtained by carrier phase shift modulation of the reference voltage command are used to input the cascaded H-bridge converter to ensure that the AC system frequency at the access point remains within the target range. This provides a frequency modulation method for AC systems in the combined structure of energy storage units and SVG power modules, realizing dynamic adjustment of active power based on system frequency fluctuations on the basis of SVG reactive power compensation and harmonic suppression functions, achieving good dynamic performance. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings:

[0017] Figure 1 This is a block diagram of the SVG core control structure in an embodiment of the present invention;

[0018] Figure 2 This is a schematic block diagram of a power regulator based on SVG and energy storage technology in an embodiment of the present invention;

[0019] Figure 3 This is a diagram of the main circuit of a single-phase series H-bridge in an embodiment of the present invention;

[0020] Figure 4 This is an equivalent circuit diagram of the new energy power generation system in an embodiment of the present invention;

[0021] Figure 5 This is a block diagram of the overall control system in an embodiment of the present invention;

[0022] Figure 6 This is a block diagram of the frequency control of a power regulator containing an energy storage unit in an embodiment of the present invention;

[0023] Figure 7 This is a schematic diagram of the connection structure between the energy storage unit and the H-bridge in an embodiment of the present invention;

[0024] Figure 8 This is a schematic diagram of the output power waveform of the power regulator in an embodiment of the present invention;

[0025] Figure 9 This is a schematic diagram of the capacitor voltage output waveforms of all cascaded modules of the power regulator in an embodiment of the present invention;

[0026] Figure 10 This is a schematic diagram of the system frequency waveform when the active power regulation function is not engaged in an embodiment of the present invention;

[0027] Figure 11 This is a schematic diagram of the system frequency waveform when the active power regulation function is activated in an embodiment of the present invention;

[0028] Figure 12 This is a schematic diagram of the output power waveform of the power regulator when the active power regulation function is activated in an embodiment of the present invention;

[0029] Figure 13 This is a flowchart illustrating the power regulation method based on SVG and energy storage technology in an embodiment of the present invention.

[0030] Figure 14 This is a schematic diagram of the power regulation device based on SVG and energy storage technology in an embodiment of the present invention. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. Here, the illustrative embodiments of the present invention and their descriptions are used to explain the present invention, but are not intended to limit the present invention.

[0032] This invention relates to the field of power transmission and distribution systems and new energy applications, and involves a power regulation scheme based on a reactive power compensation generator (SVG) and energy storage technology. When frequency fluctuations occur during the normal operation of an AC system, a scheme using cascaded energy storage units is adopted to achieve frequency support.

[0033] Figure 2 In the three-phase star-type H-bridge cascaded SVG circuit, each H-bridge power module is converted by a converter ( Figure 2 (DC / DC) and energy storage units ( Figure 2 The batteries are connected in parallel, with each phase consisting of N H-bridges connected in series, and connected via reactor L. s Connected to the power grid, i a i b i c These are the output currents of the three-phase H-bridge, i la i lb i lc These are the three-phase load currents, V ai V bi V ci These represent the capacitor voltages of each of the three-phase H-bridge power modules.

[0034] Without considering the energy storage unit, the operating principle of the above-mentioned SVG is analyzed, resulting in the main circuit structure of the single-phase H-bridge cascade shown below. Figure 3 As shown.

[0035] Therefore, the circuit differential equation is obtained as shown below:

[0036]

[0037] Performing the Park transformation on the above expression in the abc coordinate system, we obtain:

[0038]

[0039] Where P is the Park matrix, P -1 Let it be the inverse matrix. The above equation can be described on the dq axis as follows:

[0040]

[0041] In the upper-level algorithm module, this paper adopts a reactive power detection method based on instantaneous reactive power theory, in the p-axis of the dq synchronous rotating coordinate system. s and q s It can be expressed as:

[0042]

[0043] From the above formula, we can obtain:

[0044]

[0045] As shown in the above formula, by default, the d-axis follows the phase of the grid voltage, i.e., U q If the value is zero, then the reactive power can be dynamically adjusted by following the reactive current command value.

[0046] Based on the aforementioned SVG background technology, a battery is connected to the SVG power module as an energy storage unit. To simplify the impact of the battery model on the connected system, a mathematical model of an ideal controlled voltage source in series with a resistor is selected, such as... Figure 4 As shown.

[0047] The mathematical model expression for the battery is:

[0048]

[0049] E is the battery terminal voltage; E0 is the battery open-circuit voltage; K is the polarization voltage; Q is the battery capacity; A is the exponential band amplitude; B is the reciprocal of the exponential band time constant. The relationship between battery voltage and SOC can be simplified to an expression related to SOC (State of Charge).

[0050]

[0051] As can be seen from the above formula, the change of SOC can realize the control of the charging and discharging process of the energy storage battery cell.

[0052] The following is a detailed introduction to this power regulation scheme based on SVG and energy storage technology.

[0053] Figure 13 This is a flowchart illustrating a power regulation method based on SVG and energy storage technology in an embodiment of the present invention. Multiple energy storage units are connected to the SVG power module circuit of a cascaded H-bridge reactive power compensation generator via a DC / DC converter. The energy storage units are used to support or compensate for power fluctuations in the AC system. Figure 13 As shown, the method includes the following steps:

[0054] Step 101: Based on the average state of charge (SOC) of all energy storage units, the average SOC of the three phases of the energy storage units, and the three-phase current of the converter, perform SOC balancing control between phase-to-phase energy storage units to obtain the zero-sequence voltage reference value converted from the SOC of the energy storage units; the zero-sequence voltage reference value is injected into the three-phase reference voltage value output by the inner loop controller to obtain a three-phase reference voltage value containing inter-phase SOC balancing adjustment; the three-phase current value of the converter is obtained by detecting the AC system frequency at the access point of the cascaded H-bridge converter.

[0055] Step 102: Based on the state of charge (SOC) of each energy storage unit and the average SOC of all energy storage units, perform SOC equalization control of the energy storage units within the bridge arm to obtain the additional voltage adjustment amount for each energy storage unit within the phase; the additional voltage adjustment amount for each energy storage unit within the phase, together with the three-phase reference voltage value containing inter-phase SOC equalization adjustment, obtains the reference voltage command for each module of the corresponding three phases after the SOC adjustment of the energy storage unit; the trigger pulse of the three-phase cascaded H-bridge power module obtained by carrier phase shift modulation of the reference voltage command is used to input the cascaded H-bridge converter to ensure that the AC system frequency at the access point is kept within the target range.

[0056] The power regulation method based on SVG and energy storage technology provided in this embodiment of the invention operates as follows: The AC system frequency at the access point of the cascaded H-bridge converter is detected to obtain the three-phase current value of the converter; multiple energy storage units are connected to the SVG power module loop of the cascaded H-bridge reactive power compensation generator via a DC / DC converter, and the energy storage units are used to support or compensate for power fluctuations in the AC system; based on the average state of charge (SOC) of all energy storage units, the average SOC of the three phases of the energy storage units, and the three-phase current value of the converter, SOC balancing control of the inter-phase energy storage units is performed to obtain the zero-sequence voltage reference value converted from the SOC of the energy storage units; the zero-sequence voltage reference value is injected into the three-phase reference voltage value output by the inner loop controller to obtain a three-phase reference voltage value containing inter-phase SOC balancing adjustment; based on the SOC of each energy storage unit and all... The average state of charge (SOC) of the energy storage units is used to perform SOC equalization control of the energy storage units within the bridge arm, resulting in the additional voltage adjustment amount for each energy storage unit within a phase. Based on the three-phase reference voltage value containing inter-phase SOC equalization control and the additional voltage adjustment amount for each energy storage unit within a phase, the reference voltage command for each module of the corresponding three phases after SOC adjustment of the energy storage units is obtained. The trigger pulse of the three-phase cascaded H-bridge power modules obtained by carrier phase shift modulation of the reference voltage command is used to input the cascaded H-bridge converter to ensure that the AC system frequency at the access point is kept within the target range. This provides a frequency modulation method for AC systems in the combined structure of energy storage units and SVG power modules, realizing dynamic adjustment of active power according to system frequency fluctuations based on the reactive power compensation and harmonic suppression functions of the SVG, achieving good dynamic performance.

[0057] Specifically, in Figure 5 Middle,U s I s These represent the three-phase voltage and three-phase current of the AC system, respectively; f s For the frequency of the AC system; I svg The three-phase currents of the converter are represented by i. a i b i cIndicate; u d u q , These are the reference values ​​for active and reactive voltage and current output from the outer loop controller, respectively. The three-phase reference voltage output by the inner loop controller; These are the reference voltage commands for each of the three-phase modules; SOC xi Let x represent the state of charge of each energy storage unit, where x represents the three phases a, b, and c, and i represents the i-th energy storage unit among the 1 to N energy storage units in each phase; This represents the average state of charge (SOC) of all energy storage units. This represents the average state of charge of the three-phase energy storage unit. The zero-sequence voltage reference value is the result of the energy storage unit's state of charge; PMV_A, PWM_B, and PMV_C are the trigger pulses for the three-phase H-bridge power modules.

[0058] In practical implementation, the power regulation method based on SVG and energy storage technology provided in this embodiment of the invention can connect 3N (N≥2) energy storage units to the cascaded H-bridge structure SVG power module loop via a converter. Based on the dynamic reactive power compensation function of SVG, the active power of the system is dynamically adjusted through the energy storage units. This can be coordinated with the SOC equalization control of the energy storage units to achieve long-term stable operation of the system.

[0059] The following section provides a detailed introduction to this power regulation method based on SVG and energy storage technology.

[0060] The power regulation method based on SVG and energy storage technology provided in this embodiment is a power regulation method when the frequency of an AC system fluctuates. The core is to use an energy storage unit to support or compensate for the power fluctuation of the AC system. By detecting the AC system frequency at the access point of the cascaded H-bridge converter and tracking and adjusting it in real time according to the load status of the energy storage unit, the AC system frequency at the access point is ultimately kept within the target range.

[0061] The specific implementation shall be carried out in the following steps:

[0062] 1. System frequency control strategy

[0063] System frequency control is the main component of the outer loop control. Since the main circuit of this method is based on a cascaded H-bridge structure, it has basic functions such as reactive power regulation and harmonic suppression, which will not be elaborated further here. When considering the active power regulation effect of the energy storage unit, the active power regulation of the connected system can be achieved by detecting the frequency of the AC grid and using a dual-PI control method that considers the frequency dead zone. That is, in one embodiment, the above-mentioned power regulation method based on SVG and energy storage technology may further include: using a dual-PI control method that considers the frequency dead zone to regulate the active power of the connected AC system. Figure 5 The “outer loop control PI control” section shown below details the dual PI control method considering the frequency dead zone, as described in the following examples.

[0064] like Figure 6 As shown, f 1ref To account for the lower frequency limit target value of the frequency dead zone, f 2ref To account for the upper frequency limit target value of the frequency dead zone, the real-time frequency measurement value of the AC system is f. s Δf1 and Δf2 are f 1ref f 2ref with f s frequency deviation value, k p1 , k p2 , These are the proportional-integral (PI) parameters of the two PI controllers, P p_max_i P p_min_i These are the upper and lower limits of the integral element of the PI controller, P. 1_max P 1_min P 2_max P 2_min These are the upper and lower limit values ​​output by the two PI controllers, k. P / V This is the current output conversion coefficient of the regulator, which controls the output active current by adjusting the system frequency at the access point.

[0065] The above method can achieve bidirectional adjustment of the frequency of the AC system. If f is set... 1ref =49.97Hz, f 2ref =50.03Hz, P 1_min =0, P 2_max =0, according to the primary frequency modulation dead zone requirements of the connected system, when the real-time frequency measurement value of the AC system is lower than 49.97Hz (considering the lower limit target value of the frequency dead zone), I d1 The output is a positive value, I d2 The output is zero; when the real-time measured frequency of the AC system is higher than 50.03Hz (considering the upper limit target value of the frequency dead zone), I d1 The output is zero, I d2The output is negative. Compared with the frequency control method using a single PI structure, the dual PI control method that considers the frequency dead zone has better regulation performance.

[0066] 2. Energy storage unit SOC balancing

[0067] In the process of regulating the frequency of the AC power grid, it is mainly achieved through the charging and discharging of energy storage units. Therefore, ensuring the SOC balance of each energy storage unit during the charging and discharging process is very important. A zero-sequence voltage injection method is used to maintain the average SOC of the three-phase energy storage units, and an additional voltage regulation method is used to maintain the SOC balance of each energy storage unit within a phase.

[0068] like Figure 5 As shown, let SOC xi Let x represent the state of charge of each energy storage unit, which can be three phases: a, b, and c. Let i represent the i-th energy storage unit among 1 to N energy storage units in each phase. Then the following relationship exists:

[0069]

[0070]

[0071] With ΔSOC (abc) The difference between the average state of charge (SOC) of each phase energy storage unit and the average SOC of all energy storage units is given by the following formula:

[0072]

[0073] To maintain the SOC balance of the three-phase energy storage units, the three-phase difference needs to be kept within a certain range. Therefore, the SOC imbalance component of each phase energy storage unit can be constructed as a zero-sequence voltage component, expressed as:

[0074]

[0075] Where K0 is the proportionality constant, and ΔSOC is the three-phase unbalance component ΔSOC. x The square root of the sum of the squares of , For alternating current and three-phase unbalance component ΔSOC x The initial phase angle is obtained by transformation.

[0076] In one embodiment, based on the average state of charge (SOC) of all energy storage units, the average SOC of the three phases of the energy storage units, and the three-phase current of the converter, SOC balancing control of the phase-to-phase energy storage units is performed to obtain the zero-sequence voltage reference value transformed by the SOC of the energy storage units. This can include the following: The relationship yields the zero-sequence voltage reference value, which is more conducive to the dynamic adjustment of active power based on system frequency fluctuations.

[0077] The above construction formula can achieve the balance of SOC of each energy storage unit between phases. In order to ensure the balance of SOC of each energy storage unit within each phase, on the basis that the sum of the voltage regulation of each phase is zero, it is also necessary to construct an additional voltage regulation of each energy storage unit within the phase to ensure the balance of SOC within each phase (bridge arm).

[0078] With ΔSOC xi The difference between the state of charge of each energy storage unit and the average state of charge of all energy storage units is represented by the following formula:

[0079]

[0080] The expressions for the additional voltage components acting on each energy storage unit are as follows:

[0081]

[0082] Where K1 is a proportionality constant, ΔSOC xi From the above formula, we can see that δ can be 0 in the charging state and π in the discharging state.

[0083] In one embodiment, based on the state of charge (SBC) of each energy storage unit and the average SBC of all energy storage units, SBC equalization control is performed on the energy storage units within the bridge arm to obtain the additional voltage regulation amount for each energy storage unit within the phase. This can include the following: The relationship yields the additional voltage regulation of each energy storage unit within the phase (i.e., the additional voltage component acting on each energy storage unit), which is more conducive to the dynamic adjustment of active power according to the system frequency fluctuation.

[0084] 3. Voltage transformation between energy storage unit and H-bridge

[0085] Energy exchange between the energy storage unit and the cascaded H-bridge SVG is achieved via DC / DC converter, and its simplified structure is as follows: Figure 7 As shown. In one embodiment, the energy storage unit can be a new energy power generation system, capable of cooperating with the new energy power generation system to achieve primary frequency regulation.

[0086] Energy transfer during battery charging and discharging is achieved through a DC / DC converter, which enables bidirectional energy flow. Internally, it controls the Buck / Boost circuit to perform voltage conversion. Taking the battery terminal voltage boosting process as an example, the boost conversion principle is implemented using the following equation:

[0087]

[0088] Where X dcV is the capacitor terminal voltage, d is the duty cycle of the DC / DC converter, and V bat Let be the voltage across the battery terminals. The target voltage can be achieved by controlling the duty cycle of the boost circuit in the above formula, while simultaneously meeting the power transfer requirements.

[0089] The method was verified through simulation using an example. A three-phase cascaded H-bridge converter model connected to an energy storage unit was built in PSCAD / EMTDC software. This regulator device was connected in parallel in a 10kV AC system. Each phase contained 12 H-bridge power module units. Each H-bridge was connected to the energy storage unit via a DC / DC converter. The active power output of the power regulator was set to 3MW and the reactive power output to 4MVar. After the system stabilized, the active and reactive power were reversed, and the response during the power ride-through process was observed. Figure 8 and Figure 9 As shown.

[0090] from Figure 8 and Figure 9 It can be seen that the reactive power decreases and increases at 5.5s and 6.5s respectively, and the active power decreases and increases at 7s and 8s respectively. The output power of the regulator can follow the set target value well, and the capacitor voltage of the H-bridge cascade module basically remains around 800V during the power ride-through process.

[0091] To verify the frequency regulation capability of the power regulator, functional verification was performed in simulation software. The example used here is the load transfer process of an AC system. When the AC system is transmitting 3MW of active power in steady state, 1MW of active power is transferred in 12 seconds. Comparative tests were conducted with and without the power regulation function engaged during this process. The resulting waveforms are shown below. Figure 10 and Figure 11 As shown.

[0092] from Figure 10 and Figure 11 The waveform shows that under this operating condition, when the AC system is supplied with 1MW of active power, the system frequency fluctuates significantly. However, by employing this active power regulation method, the system can quickly adjust its active power output in response to these frequency fluctuations, achieving good frequency regulation functionality. Figure 12 As shown.

[0093] In summary, this invention provides a power regulation method based on SVG and energy storage technology, which, in particular, can dynamically support system inertia and maintain system frequency stability when system frequency fluctuations occur. This method, based on the reactive power compensation and harmonic suppression functions of SVG, dynamically adjusts active power according to system frequency fluctuations, achieving excellent dynamic performance. This method is simple in structure, fast, accurate, and easy to implement.

[0094] This invention also provides a power regulation device based on SVG and energy storage technology, as described in the following embodiments. Since the principle by which this device solves the problem is similar to that of the power regulation method based on SVG and energy storage technology, the implementation of this device can refer to the implementation of the power regulation method based on SVG and energy storage technology; repeated details will not be elaborated further.

[0095] Figure 14 This is a schematic diagram of a power regulation device (regulator) based on SVG and energy storage technology in an embodiment of the present invention. Multiple energy storage units are connected to the SVG power module circuit of a cascaded H-bridge reactive power compensation generator via a DC / DC converter. The energy storage units are used to support or compensate for power fluctuations in the AC system, such as... Figure 14 As shown, the device includes:

[0096] Interphase SOC equalization control unit 01 (e.g.) Figure 5 The "phase-to-phase SOC equalization control" shown is used to perform phase-to-phase SOC equalization control of energy storage units based on the average state of charge of all energy storage units, the average state of charge of the three phases of the energy storage units, and the three-phase current value of the converter, to obtain the zero-sequence voltage reference value converted from the state of charge of the energy storage units; the zero-sequence voltage reference value is injected into the three-phase reference voltage value output by the inner loop controller to obtain the three-phase reference voltage value containing phase-to-phase SOC equalization adjustment; the three-phase current value of the converter is obtained by detecting the AC system frequency at the access point of the cascaded H-bridge converter;

[0097] SOC equalization control unit 02 inside the bridge arm (e.g.) Figure 5 The "SOC equalization control within the bridge arm" shown is used to perform SOC equalization control of the energy storage units within the bridge arm based on the state of charge of each energy storage unit and the average SOC of all energy storage units, thereby obtaining the additional voltage adjustment amount for each energy storage unit within the phase. The additional voltage adjustment amount for each energy storage unit within the phase, together with the three-phase reference voltage value containing the inter-phase SOC equalization adjustment, obtains the reference voltage command for each module of the corresponding three phases after the SOC adjustment of the energy storage unit. The trigger pulse of the three-phase cascaded H-bridge power module obtained by the reference voltage command being phase-shifted by the carrier is used to input the cascaded H-bridge converter to ensure that the AC system frequency at the access point is kept within the target range.

[0098] In one embodiment, the outer loop controller (such as...) Figure 5 The “outer loop control PI control” shown can be used to regulate the active power of the connected AC system by adopting a dual PI control method that takes into account the frequency dead zone.

[0099] In one embodiment, the interphase SOC equalization control unit is specifically used to obtain the zero-sequence voltage reference value according to the following relationship:

[0100]

[0101] in, K0 is the zero-sequence voltage reference value, K0 is the proportionality constant, and ΔSOC is the three-phase unbalance component ΔSOC. x The square root of the sum of the squares of , For alternating current and three-phase unbalance component ΔSOC x The initial phase angle is obtained by transformation.

[0102] In one embodiment, the SOC equalization control unit within the bridge arm is specifically used to obtain the additional voltage regulation of each energy storage unit within the phase according to the following relationship:

[0103]

[0104] in, K1 is the additional voltage regulation of each energy storage unit within the phase, and ΔSOC is the proportional constant. xi For the three-phase unbalanced components, δ is taken as 0 in the charging state and π in the discharging state.

[0105] In one embodiment, the energy storage unit (such as...) Figure 2 The Battery shown can be a new energy power generation system.

[0106] This invention also provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the above-described power regulation method based on SVG and energy storage technology.

[0107] This invention also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the aforementioned power regulation method based on SVG and energy storage technology.

[0108] This invention also provides a computer program product, which includes a computer program that, when executed by a processor, implements the aforementioned power regulation method based on SVG and energy storage technology.

[0109] In this embodiment of the invention, the power regulation scheme based on SVG and energy storage technology proceeds as follows: The AC system frequency at the access point of the cascaded H-bridge converter is detected to obtain the three-phase current value of the converter; multiple energy storage units are connected to the SVG power module loop of the cascaded H-bridge reactive power compensation generator via a DC / DC converter, and the energy storage units are used to support or compensate for power fluctuations in the AC system; based on the average state of charge (SOC) of all energy storage units, the average SOC of the three phases of the energy storage units, and the three-phase current value of the converter, inter-phase SOC balancing control is performed to obtain the zero-sequence voltage reference value converted from the SOC of the energy storage units; the zero-sequence voltage reference value is injected into the three-phase reference voltage value output by the inner loop controller to obtain a three-phase reference voltage value containing inter-phase SOC balancing adjustment; based on the SOC of each energy storage unit and the average SOC of all energy storage units... The average state of charge (SOC) of the energy storage units is used to perform SOC equalization control within the bridge arm, resulting in the additional voltage adjustment for each energy storage unit in the phase. Based on the three-phase reference voltage values ​​containing inter-phase SOC equalization control and the additional voltage adjustment for each energy storage unit in the phase, the reference voltage command for each module of the corresponding three phases after SOC adjustment of the energy storage units is obtained. The trigger pulses of the three-phase cascaded H-bridge power modules obtained by carrier phase shift modulation of the reference voltage command are used to input the cascaded H-bridge converter to ensure that the AC system frequency at the access point remains within the target range. This provides a frequency modulation method for AC systems in the combined structure of energy storage units and SVG power modules, realizing dynamic adjustment of active power based on system frequency fluctuations on the basis of SVG reactive power compensation and harmonic suppression functions, achieving good dynamic performance.

[0110] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0111] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0112] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0113] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0114] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A power regulation method based on SVG and energy storage technology, characterized in that, Multiple energy storage units are connected to the SVG power module circuit of a cascaded H-bridge reactive power compensation generator via a DC / DC converter. The energy storage units are used to support or compensate for power fluctuations in the AC system. The power regulation method based on SVG and energy storage technology includes: Based on the average state of charge (SOC) of all energy storage units, the average SOC of the three phases of the energy storage units, and the three-phase current of the converter, SOC balancing control of the phase-to-phase energy storage units is performed to obtain the zero-sequence voltage reference value converted from the SOC of the energy storage units. This zero-sequence voltage reference value is obtained according to the following relationship: ;in, This is the zero-sequence voltage reference value. It is a proportionality constant. Three-phase unbalanced components The square root of the sum of the squares of , For alternating current and three-phase unbalanced components The initial phase angle is obtained by transformation; the zero-sequence voltage reference value is injected into the three-phase reference voltage value output by the inner loop controller to obtain a three-phase reference voltage value containing inter-phase SOC equalization adjustment; the three-phase current value of the converter is obtained by detecting the AC system frequency at the access point of the cascaded H-bridge converter. Based on the state of charge (SOC) of each energy storage unit and the average SOC of all energy storage units, SOC balance control is performed on the energy storage units within the bridge arm to obtain the additional voltage regulation for each energy storage unit within the phase. This additional voltage regulation is obtained according to the following formula: ;in, This refers to the additional voltage regulation of each energy storage unit within the phase. It is a proportionality constant. This refers to the three-phase unbalanced components. It is set to 0 during charging and to 0 during discharging. The additional voltage adjustment of each energy storage unit within the phase, together with the three-phase reference voltage value containing the inter-phase SOC equalization adjustment, obtains the reference voltage command for each module of the corresponding three phases after the state of charge adjustment of the energy storage unit; the trigger pulse of the three-phase cascaded H-bridge power module obtained by the reference voltage command after carrier phase shift modulation is used to input the cascaded H-bridge converter to ensure that the AC system frequency at the access point is kept within the target range.

2. The power regulation method based on SVG and energy storage technology as described in claim 1, characterized in that, Also includes: A dual-PI control method that takes into account the frequency dead zone is used to regulate the active power of the connected AC system.

3. The power regulation method based on SVG and energy storage technology as described in claim 1, characterized in that, The energy storage unit is a new energy power generation system.

4. A power regulation device based on SVG and energy storage technology, characterized in that, Multiple energy storage units are connected to the SVG power module circuit of a cascaded H-bridge reactive power compensation generator via a DC / DC converter. The energy storage units are used to support or compensate for power fluctuations in the AC system. The power regulation device based on SVG and energy storage technology includes: The inter-phase SOC balancing control unit is used to perform inter-phase SOC balancing control of energy storage units based on the average state of charge of all energy storage units, the average state of charge of the three phases of the energy storage units, and the three-phase current of the converter, to obtain the zero-sequence voltage reference value converted from the state of charge of the energy storage units. This zero-sequence voltage reference value is obtained according to the following formula: ;in, This is the zero-sequence voltage reference value. It is a proportionality constant. Three-phase unbalanced components The square root of the sum of the squares of , For alternating current and three-phase unbalanced components The initial phase angle is obtained by transformation; the zero-sequence voltage reference value is injected into the three-phase reference voltage value output by the inner loop controller to obtain a three-phase reference voltage value containing inter-phase SOC equalization adjustment; the three-phase current value of the converter is obtained by detecting the AC system frequency at the access point of the cascaded H-bridge converter. The SOC balancing control unit within the bridge arm is used to perform SOC balancing control of the energy storage units within the bridge arm based on the state of charge of each energy storage unit and the average SOC of all energy storage units, to obtain the additional voltage regulation amount for each energy storage unit within the phase. This includes obtaining the additional voltage regulation amount for each energy storage unit within the phase according to the following formula: ;in, This refers to the additional voltage regulation of each energy storage unit within the phase. It is a proportionality constant. This refers to the three-phase unbalanced components. It is set to 0 during charging and to 0 during discharging. The additional voltage adjustment of each energy storage unit within the phase, together with the three-phase reference voltage value containing the inter-phase SOC equalization adjustment, obtains the reference voltage command for each module of the corresponding three phases after the state of charge adjustment of the energy storage unit; the trigger pulse of the three-phase cascaded H-bridge power module obtained by the reference voltage command after carrier phase shift modulation is used to input the cascaded H-bridge converter to ensure that the AC system frequency at the access point is kept within the target range.

5. The power regulation device based on SVG and energy storage technology as described in claim 4, characterized in that, The outer loop controller is specifically used to regulate the active power of the connected AC system using a dual PI control method that takes into account the frequency dead zone.

6. A computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the method of any one of claims 1 to 3.

7. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the method of any one of claims 1 to 3.

8. A computer program product, characterized in that, The computer program product includes a computer program that, when executed by a processor, implements the method of any one of claims 1 to 3.

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