Network construction control method and system based on cascaded SVG (Static Var Generator)

Abstract

The invention provides a cascaded SVG-based networking control method and system, and relates to the technical field of new energy grid-connected control, and the method comprises the steps: obtaining an active reference value through DC total voltage deviation; according to the active reference value, calculating an internal potential phase angle of the network-forming SVG, and obtaining an internal potential amplitude of the SVG; obtaining a three-phase voltage instruction of the SVG through the internal potential amplitude and the internal potential phase angle; obtaining the total modulation wave of the SVG according to the three-phase voltage instruction of the SVG; and obtaining a driving signal according to the total modulation wave, and controlling a primary loop of the SVG according to the driving signal. According to the invention, the internal potential amplitude and phase angle of the SVG are optimized by accurately controlling the direct-current total voltage deviation, so that efficient and stable three-phase voltage output and primary loop control are realized, and the electric energy quality and response speed of the SVG are comprehensively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy grid-connected control, and in particular to a cascaded SVG-based network control method and system. Background Art

[0002] At present, new energy power sources mostly adopt typical grid-following control methods when they are connected to the grid, that is, voltage vector orientation and power decoupling control based on phase-locked loops. However, new energy power sources cannot autonomously respond to and damp the fluctuations of grid frequency and voltage. This has led to problems such as weak inertia and weak damping in power systems with a high proportion of new energy, affecting the stability of the power system and becoming an important factor restricting the further improvement of the new energy grid connection rate.

[0003] In order to improve the grid support capability of new energy power sources, especially to enhance its reactive power support capability, traditional static VAR generators (SVG) are widely used. However, traditional SVGs have obvious weaknesses when providing reactive power support and there is a risk of system resonance with the grid. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a cascaded SVG-based network control method and system to promote the efficient operation of the new energy power grid.

[0005] In order to solve the above technical problems, the technical solution of the present invention is as follows:

[0006] In a first aspect, a cascaded SVG network control method is provided, the method comprising:

[0007] Obtain active power reference value through total DC voltage deviation;

[0008] Calculate the potential phase angle in the network SVG according to the active reference value, and obtain the potential amplitude in the SVG;

[0009] The three-phase voltage command of SVG is obtained through the internal potential amplitude and the internal potential phase angle;

[0010] According to the three-phase voltage command of SVG, the total modulation wave of SVG is obtained;

[0011] According to the total modulation wave, a driving signal is obtained, and the primary circuit of the SVG is controlled according to the driving signal.

[0012] Furthermore, the calculation formula of the active reference value is:

[0013]

[0014] Among them, P ref Indicates the active power command value; K prepresents proportional gain; Ki represents integral gain; S represents Laplace operator; C represents SVG equivalent DC capacitance; G M represents virtual admittance; Indicates the voltage reference value of the SVG DC side; U dc 2 Indicates the actual voltage value on the DC side of the SVG.

[0015] Furthermore, the calculation formula of the potential phase angle in the network SVG is:

[0016] θ = ∫(w-wg)dt;

[0017] Among them, θ represents the phase angle; w represents the grid frequency; wg represents the grid frequency; ∫(w-wg)dt represents the time integration of the frequency difference w-wg.

[0018] Furthermore, the calculation formula of the potential amplitude in SVG is:

[0019] Eq=((Qref-Q)*Kq+(Vref-V))*Kp;

[0020] Among them, Eq represents the internal potential amplitude; Qref represents the reactive power command; Q represents the actual reactive power value; Kq represents the reactive power control coefficient; Vref represents the voltage target value; V represents the actual output voltage; and Kp represents the proportionality coefficient.

[0021] Furthermore, the three-phase voltage instructions of SVG are obtained through the internal potential amplitude and the internal potential phase angle, including:

[0022] Obtain the internal potential amplitude and internal potential phase angle of SVG;

[0023] Convert the internal potential amplitude and the internal potential phase angle into a three-phase coordinate system;

[0024] Using trigonometric functions, the internal potential amplitude is decomposed onto each axis of the three-phase coordinate system to obtain the voltage amplitude of each phase;

[0025] In the three-phase coordinate system, the three-phase voltage command of SVG is obtained according to the voltage amplitude of each phase.

[0026] Furthermore, according to the three-phase voltage command of SVG, the total modulation wave of SVG is obtained, including:

[0027] Get the three-phase voltage command of SVG;

[0028] According to the three-phase voltage command of SVG, the number of levels of each power unit in SVG is determined;

[0029] Compare each phase voltage command in the three-phase voltage command with a preset level threshold to determine a final level;

[0030] Assigning the level to each power unit and comparing the voltage command of each phase with the selected PWM carrier to obtain the PWM waveform;

[0031] Distribute PWM waveform to each power unit of SVG;

[0032] The PWM waveforms obtained from each power unit are combined to obtain the total modulation wave of the SVG.

[0033] Further, a driving signal is obtained according to the total modulation wave, and a primary circuit of the SVG is controlled according to the driving signal, including:

[0034] Analyze the total modulation wave to determine the voltage at each time point;

[0035] The voltage at each time point is converted into a switching signal to obtain a driving signal;

[0036] Amplifying the driving signal through the driving circuit and transmitting the amplified driving signal to the power unit;

[0037] The power unit obtains the driving signal and controls the primary circuit of the SVG.

[0038] In a second aspect, a cascaded SVG-based network control system includes:

[0039] The acquisition module is used to obtain the active reference value through the total DC voltage deviation; calculate the potential phase angle of the network SVG according to the active reference value, and obtain the potential amplitude of the SVG; obtain the three-phase voltage command of the SVG through the internal potential amplitude and the internal potential phase angle;

[0040] The processing module is used to obtain the total modulation wave of the SVG according to the three-phase voltage instruction of the SVG; obtain the driving signal according to the total modulation wave, and control the primary circuit of the SVG according to the driving signal.

[0041] According to a third aspect, a computing device includes:

[0042] one or more processors;

[0043] The storage device is used to store one or more programs. When the one or more programs are executed by the one or more processors, the one or more processors implement the method described.

[0044] In a fourth aspect, a computer-readable storage medium stores a program, and when the program is executed by a processor, the method described is implemented.

[0045] The above solution of the present invention includes at least the following beneficial effects:

[0046] By obtaining the active reference value through the total DC voltage deviation, the potential phase angle and amplitude of the SVG can be accurately calculated, and then the accurate three-phase voltage command can be obtained, realizing the precise control of the SVG output. By directly calculating the potential phase angle of the SVG according to the active reference value, the power change in the power grid can be quickly responded to, and the dynamic response capability of the SVG is improved. Through the precise control of the internal potential amplitude and phase angle, this method can ensure the stable operation of the SVG in a complex power grid environment and effectively prevent the occurrence of power grid instability. According to the three-phase voltage command of the SVG, the total modulation wave is obtained, and then the accurate drive signal is obtained, which can ensure the precise control of the primary circuit of the SVG and improve the working efficiency of the SVG. It can adapt to the operation requirements under different power grid conditions, and optimize the power quality and stability of the power grid by flexibly adjusting the output of the SVG. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 It is a flow chart of a cascaded SVG networking control method provided by an embodiment of the present invention.

[0048] Figure 2 It is a schematic diagram of a control system based on cascaded SVG networking provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0049] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0050] like Figure 1 As shown, an embodiment of the present invention proposes a cascaded SVG network control method, the method comprising the following steps:

[0051] Step 1, obtaining an active power reference value through a total DC voltage deviation;

[0052] Step 2, calculating the potential phase angle of the network SVG according to the active reference value, and obtaining the potential amplitude of the SVG;

[0053] Step 3, obtaining the three-phase voltage command of SVG through the internal potential amplitude and the internal potential phase angle;

[0054] Step 4, obtaining the total modulation wave of the SVG according to the three-phase voltage command of the SVG;

[0055] Step 5: Obtain a driving signal according to the total modulation wave, and control the primary circuit of the SVG according to the driving signal.

[0056] In the embodiment of the present invention, the deviation of the total DC voltage is first detected. According to the deviation of the total DC voltage, the system calculates an active reference value. This value represents the active power that the SVG (static reactive generator) needs to output in order to maintain the power balance of the system. Using the calculated active reference value, the system further calculates the phase angle of the potential inside the SVG. This phase angle determines the relative relationship between the output voltage of the SVG and the grid voltage, and is the key to achieving power control. At the same time, the system also obtains the amplitude of the potential inside the SVG, and generates the three-phase voltage instructions of the SVG in combination with the phase angle and amplitude of the internal potential. These instructions specify the voltage magnitude and phase that each phase of the SVG should output. According to the three-phase voltage instructions, the total modulation wave of the SVG is calculated. This modulation wave is the basis for the switch control of the SVG inverter. According to the total modulation wave, the system generates specific drive signals. These signals are used to control the switch state of the SVG inverter, thereby achieving precise control of the primary circuit of the SVG. Through this control, the SVG can accurately output the required three-phase voltage to maintain the power balance and voltage stability of the system.

[0057] By monitoring and adjusting the output of SVG in real time, it is possible to respond quickly to power fluctuations in the system, thereby maintaining the power balance of the system. The precise control of SVG helps stabilize the grid voltage and reduce the impact of voltage fluctuations on sensitive equipment. The fast response characteristics of SVG can effectively reduce harmonics and voltage flicker and improve power quality. By optimizing the output of SVG, system losses can be reduced and overall energy efficiency can be improved. SVG can flexibly adjust its output according to system requirements, and can quickly adapt whether it needs to increase reactive power support or perform active power regulation. The real-time control and fast response capabilities of SVG help improve the stability and reliability of the power grid under abnormal conditions.

[0058] In a preferred embodiment of the present invention, the calculation formula of the active reference value is:

[0059]

[0060] Among them, P ref Indicates the active power command value; K p represents proportional gain; Ki represents integral gain; S represents Laplace operator; C represents SVG equivalent DC capacitance; G M represents virtual admittance; Indicates the voltage reference value of the SVG DC side; U dc 2 Indicates the actual voltage value on the DC side of the SVG.

[0061] In the embodiment of the present invention, the voltage reference value of the SVG DC side is It is the DC voltage level that the system expects to maintain. The actual voltage value U on the DC side of SVG dc 2 is the result of real-time measurement. The difference between the two (i.e., voltage deviation) is a key parameter that the control system needs to pay attention to and adjust. Proportional gain K p Used to quickly respond to deviations in DC voltage. When the actual voltage deviates from the reference value, the proportional control immediately generates a control signal proportional to the deviation. The integral gain Ki is related to the Laplace operator S, the SVG equivalent DC capacitance C, and the virtual admittance G. M Combined, an integral control link is formed. This link is designed to eliminate long-term voltage deviations. Through the integral effect, even small deviations will gradually accumulate and generate corresponding control signals. According to the voltage deviation, the active reference value P is calculated through the proportional and integral control links. ref This value represents the active power that the SVG needs to output to maintain the DC voltage near the reference value. The Laplace operator S represents the dynamic characteristics of the system, which is related to the SVG equivalent DC capacitance C and virtual admittance G. M Together, the stability and rapid response of the control system are ensured. By continuously monitoring the DC voltage and adjusting the active reference value, the system can dynamically maintain the stability of the DC side voltage of the SVG.

[0062] By using the calculation formula of the active reference value, the voltage on the DC side of the SVG can be accurately controlled. This precise control helps ensure the stable operation of the SVG and avoid damage to the equipment due to voltage fluctuations. p This enables the control system to quickly respond to changes in the SVG DC voltage. When the voltage deviates, the system can quickly adjust the active reference value to correct the voltage deviation and maintain system stability. It plays a role in eliminating steady-state errors in the control system. Through the integration effect, the system can gradually eliminate the long-term deviation of the DC voltage and ensure the stability of the SVG during long-term operation. The SVG equivalent DC capacitance C and virtual admittance G are taken into account. M This makes the control system robust to changes in the internal parameters of the SVG. Even if the parameters of the SVG change within a certain range, the control system can still maintain a good control effect. Stable DC voltage is the basis for the normal operation of SVG. By accurately controlling the active reference value, the quality of the power output by SVG can be ensured. In addition, stable DC voltage also helps to improve the working efficiency of SVG and reduce unnecessary energy loss.

[0063] In a preferred embodiment of the present invention, the calculation formula of the potential phase angle in the network SVG is:

[0064] θ = ∫(w-wg)dt;

[0065] Among them, θ represents the phase angle; w represents the grid frequency; wg represents the grid frequency; ∫(w-wg)dt represents the time integration of the frequency difference w-wg.

[0066] In the embodiment of the present invention, w represents the internal frequency set by the networking SVG, and wg represents the detected grid frequency, that is, the real-time frequency of the external power system. w-wg calculates the difference between the internal frequency of the networking SVG and the external grid frequency. This frequency difference is a key parameter for phase adjustment. ∫(w-wg)dt represents the time integration of the frequency difference. The purpose of integration is to accumulate the frequency difference and reflect the change in phase. Simply put, if the frequency of the networking SVG is higher than the grid frequency, the integral value will gradually increase; conversely, if the frequency of the networking SVG is lower than the grid frequency, the integral value will gradually decrease. Through the above integration process, the phase angle θ is obtained. The phase angle represents the relative position relationship between the internal potential of the networking SVG and the grid voltage. In order to maintain synchronization with the grid, the SVG adjusts the phase of its internal potential to match the phase of the grid. The networking SVG ensures synchronization with the grid by continuously adjusting the phase angle θ of its internal potential.

[0067] ∫(w-wg)dt enables the grid-forming SVG to dynamically adjust its internal potential phase angle to maintain synchronization with the grid frequency. This dynamic synchronization capability ensures that the SVG can still operate stably when the grid frequency fluctuates, effectively reducing energy loss and system instability caused by frequency mismatch. By calculating the frequency difference in real time and integrating it over time, the SVG can quickly sense and respond to changes in the grid frequency. This rapid response capability is essential to maintaining the stability and reliability of the power system, especially in the face of emergencies or grid failures. Accurate phase angle control helps reduce harmonics and distortion in the SVG output. By maintaining precise synchronization with the grid, potential interference to power equipment can be reduced and power quality can be improved. Accurate phase angle adjustment can optimize the energy exchange between the SVG and the grid, thereby improving energy utilization efficiency. This helps reduce energy waste, reduce operating costs, and promote sustainable energy utilization. By adjusting its internal potential phase angle to match the phase of the grid, it helps to enhance the stability of the entire grid. It broadens the scope of application of SVG and enables it to play an important role in various power systems.

[0068] In a preferred embodiment of the present invention, the calculation formula of the potential amplitude in SVG is:

[0069] Eq=((Qref-Q)*Kq+(Vref-V))*Kp;

[0070] Among them, Eq represents the internal potential amplitude; Qref represents the reactive power command; Q represents the actual reactive power value; Kq represents the reactive power control coefficient; Vref represents the voltage target value; V represents the actual output voltage; and Kp represents the proportionality coefficient.

[0071] In the embodiment of the present invention, Qref is the target value of reactive power, and Q is the reactive power value actually measured. The difference between them, Qref-Q, represents the deviation of reactive power. Qref is the target value of output voltage, and V is the output voltage value actually measured. The difference between them, Vref-V, represents the deviation of output voltage. The deviation is adjusted by two coefficients. Kq is the reactive control coefficient, which is used to adjust the influence of reactive power deviation. Kp is the proportional coefficient, which is used to adjust the amplification degree of the entire deviation signal (including reactive and voltage deviations). First, the product of reactive deviation and Kq is calculated, that is, (Qref-Q)*Kq, which means that a part of the internal potential is adjusted according to the deviation of reactive power. Then, this part is added to the voltage deviation Vref-V to obtain a total deviation adjustment value. Finally, this total deviation adjustment value is multiplied by the proportional coefficient Kp to obtain the final internal potential amplitude adjustment amount Eq. As the output of the control system, Eq will affect the output voltage and reactive power of SVG, thereby forming a feedback loop. When the actual reactive power q and output voltage V deviate from their target values, the Eq will be adjusted accordingly to drive the SVG output close to the target value. By continuously monitoring the difference between the actual value and the target value and adjusting the Eq accordingly, the control system can achieve stable control of the SVG output voltage and reactive power, ensuring that they can quickly respond to and track changes in the target value.

[0072] By comparing the reactive power command Qref with the actual reactive power value Q, and combining the difference between the voltage target value Vref and the actual output voltage V, the required internal potential amplitude Eq can be calculated. This precise control method helps maintain the stability of the power system, ensures that the reactive power and voltage fluctuate around the set value, and thus improves the power quality. By adjusting the reactive power command Qref, reactive compensation can be flexibly performed to meet the changing reactive power demand in the power grid. This flexibility helps to optimize the power factor of the power grid, reduce line losses, and improve energy efficiency. The proportional coefficient Kp can amplify the deviation signals of reactive power and voltage, so that the internal potential amplitude Eq can respond quickly to changes in the power grid. This fast dynamic response capability helps to correct the unbalanced state in the power grid in time and maintain the stable operation of the power grid. Through the precise control of the internal potential amplitude Eq, it helps to reduce voltage fluctuations and reactive power imbalance in the power grid, thereby improving the stability of the power grid. This stability is of great significance to prevent the collapse or failure of the power grid when facing load changes or external disturbances. It has a concise and clear form, which is easy to implement in the control system. At the same time, by adjusting the reactive control coefficient Kq and the proportional coefficient Kp, the performance of the control system is optimized to adapt to the operation requirements under different power grid conditions, and applied to different types of static VAR generators SVG, the compatibility and versatility of the equipment are improved. This helps to reduce the cost of equipment research and development and maintenance, and promote the widespread application of SVG technology.

[0073] In a preferred embodiment of the present invention, the three-phase voltage command of SVG is obtained by the internal potential amplitude and the internal potential phase angle, including:

[0074] Obtain the internal potential amplitude and internal potential phase angle of SVG;

[0075] Convert the internal potential amplitude and the internal potential phase angle into a three-phase coordinate system;

[0076] Using trigonometric functions, the internal potential amplitude is decomposed onto each axis of the three-phase coordinate system to obtain the voltage amplitude of each phase;

[0077] In the three-phase coordinate system, the three-phase voltage command of SVG is obtained according to the voltage amplitude of each phase.

[0078] In the embodiment of the present invention, the amplitude and phase angle of the internal potential are first obtained. These parameters are usually obtained by internal algorithms or external sensors, and reflect the current working state of the SVG and the synchronization with the power grid. The amplitude and phase angle of the internal potential are described in a single-phase or polar coordinate system. In order to obtain a three-phase voltage command, these parameters need to be converted into a three-phase coordinate system (such as an abc coordinate system). This is usually achieved by Park's transformation or its inverse transformation. In the three-phase coordinate system, the internal potential amplitude is decomposed into three phases using trigonometric functions (such as sine and cosine functions). Since the phase difference between the three-phase voltages is 120 degrees, the specific voltage value of each phase can be calculated by the phase angle and amplitude. According to the voltage amplitude decomposed from each phase, the SVG control system generates a three-phase voltage command. These instructions will instruct the inverter of the SVG on how to adjust its output voltage to maintain synchronization with the power grid and output the required reactive power or active power.

[0079] By calculating the voltage command for each phase, the SVG output is precisely controlled. This helps ensure that the SVG can respond quickly and accurately to changes in grid demand. Using the internal potential amplitude and phase angle to generate three-phase voltage commands helps the SVG maintain strict synchronization with the grid. Synchronization is the basis for stable operation of the power system and is essential for preventing faults and protecting equipment. Accurate three-phase voltage command generation can reduce voltage fluctuations and harmonic distortion, thereby improving the power quality of the SVG output. This is very important for the normal operation of sensitive loads and power equipment. By optimizing the three-phase voltage command, imbalances and oscillations in the system can be reduced, thereby enhancing the stability of the entire power system. A stable power system can transmit and distribute electrical energy more efficiently and reduce energy losses. Accurate three-phase voltage commands can prevent the SVG and connected equipment from being damaged by overvoltage or overcurrent. By adjusting the output voltage in a timely manner, the equipment can be protected from grid faults or abnormal conditions.

[0080] In a preferred embodiment of the present invention, according to the three-phase voltage instruction of SVG, the total modulation wave of SVG is obtained, including:

[0081] Get the three-phase voltage command of SVG;

[0082] According to the three-phase voltage command of SVG, the number of levels of each power unit in SVG is determined;

[0083] Compare each phase voltage command in the three-phase voltage command with a preset level threshold to determine a final level;

[0084] Assigning the level to each power unit and comparing the voltage command of each phase with the selected PWM carrier to obtain the PWM waveform;

[0085] Distribute PWM waveform to each power unit of SVG;

[0086] The PWM waveforms obtained from each power unit are combined to obtain the total modulation wave of the SVG.

[0087] In the embodiment of the present invention, three-phase voltage instructions are first received. These instructions are calculated based on the grid demand and the operating state of the SVG and are used to guide the output voltage of the SVG. According to the design of the SVG and the amplitude of the three-phase voltage instructions, the system will determine the number of levels that each power unit needs to output. This is usually related to the topology and control method of the SVG. The voltage instruction of each phase will be compared with the preset level threshold to determine the final level that each power unit should output. This process is to convert the continuous voltage instruction into a discrete level signal. The determined level will be allocated to each power unit. At the same time, the voltage instruction of each phase will be compared with the selected PWM (pulse width modulation) carrier to generate a PWM waveform. The PWM waveform determines the on and off time of the power unit switch device. The generated PWM waveform will be allocated to each power unit of the SVG to guide the switching operation of each unit, thereby realizing the output control of the voltage. The PWM waveform obtained by each power unit will finally be merged to form the total modulation wave of the SVG. This modulation wave is the basis of the final output voltage of the SVG.

[0088] By converting the three-phase voltage command into a precise PWM waveform, the output voltage of the SVG can be precisely controlled to meet the requirements of the power grid for voltage quality and stability. The use of PWM modulation technology can improve the energy conversion efficiency of the SVG, reduce unnecessary energy loss, and contribute to energy conservation and environmental protection. Accurate PWM modulation can reduce the harmonic components in the SVG output, thereby reducing harmonic pollution to the power grid and protecting the purity of the power grid. PWM modulation technology enables the SVG to quickly respond to changes in power grid demand, adjust the output voltage in a timely manner, and maintain the stable operation of the power grid. By dividing the SVG into multiple power units and merging PWM waveforms, the modular design of the SVG can be achieved, improving the flexibility and scalability of the system.

[0089] In a preferred embodiment of the present invention, a driving signal is obtained according to the total modulation wave, and a primary circuit of the SVG is controlled according to the driving signal, including:

[0090] Analyze the total modulation wave to determine the voltage at each time point;

[0091] The voltage at each time point is converted into a switching signal to obtain a driving signal;

[0092] Amplifying the driving signal through the driving circuit and transmitting the amplified driving signal to the power unit;

[0093] The power unit obtains the driving signal and controls the primary circuit of the SVG.

[0094] In an embodiment of the present invention, the control system first analyzes the total modulation wave, and this process involves determining the corresponding voltage value at each time point. These voltage values ​​represent the voltage level that the SVG should output. Next, the system converts the voltage values ​​at these time points into corresponding switching signals. These switching signals, i.e., drive signals, are used to directly control the on and off of power switching devices (such as IGBTs, etc.) in the SVG. The converted drive signal is then amplified by the drive circuit to ensure that the signal has sufficient strength and stability to drive the power switching device. The amplified drive signal is transmitted to each power unit of the SVG. After receiving the amplified drive signal, the power unit controls the switch device inside it according to the state of the signal (high level or low level), thereby realizing precise control of the primary circuit of the SVG. This control can adjust the voltage and current output by the SVG to meet the needs of the power grid.

[0095] By accurately analyzing and converting the total modulation wave, precise control of the SVG primary circuit can be achieved. This helps ensure that the output of the SVG matches the needs of the power grid, improving the power quality and the stability of the power grid. Using the switch signal as the drive signal can ensure the rapid response capability of the SVG. When the grid conditions change, the SVG can quickly adjust its output to maintain the stable operation of the grid. By optimizing the generation and transmission process of the drive signal, unnecessary energy loss can be reduced, thereby improving the operating efficiency of the SVG. This helps to reduce operating costs and reduce energy waste. Using an amplified drive signal can ensure the reliable conduction and shutdown of the power switching device and reduce the possibility of misoperation. This helps to enhance the reliability and stability of the SVG, extend the service life of the equipment, and make flexible adjustments under different grid conditions. Whether facing load changes or grid failures, the SVG can adapt to the new operating environment by adjusting its drive signal.

[0096] like Figure 2 As shown, an embodiment of the present invention further provides a cascaded SVG-based network control system 20, comprising:

[0097] The acquisition module 21 is used to obtain the active reference value through the total DC voltage deviation; calculate the potential phase angle of the network SVG according to the active reference value, and obtain the potential amplitude of the SVG; obtain the three-phase voltage command of the SVG through the internal potential amplitude and the internal potential phase angle;

[0098] The processing module 22 is used to obtain the total modulation wave of the SVG according to the three-phase voltage instruction of the SVG; obtain the driving signal according to the total modulation wave, and control the primary circuit of the SVG according to the driving signal.

[0099] It should be noted that the system is a system corresponding to the above method, and all implementation methods in the above method embodiment are applicable to this embodiment and can achieve the same technical effect.

[0100] The embodiment of the present invention further provides a computing device, comprising: a processor, a memory storing a computer program, wherein when the computer program is executed by the processor, the method described above is executed. All implementations in the above method embodiment are applicable to this embodiment and can achieve the same technical effect.

[0101] The embodiment of the present invention also provides a computer-readable storage medium storing instructions, which, when executed on a computer, enable the computer to execute the method described above. All implementations in the above method embodiment are applicable to this embodiment and can achieve the same technical effect.

[0102] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0103] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0104] In the embodiments provided by the present invention, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0105] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0106] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0107] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: various media that can store program codes, such as USB flash drives, mobile hard disks, ROM, RAM, magnetic disks, or optical disks.

[0108] In addition, it should be noted that in the apparatus and method of the present invention, it is obvious that each component or each step can be decomposed and / or recombined. These decompositions and / or recombinations should be regarded as equivalent schemes of the present invention. Moreover, the steps of performing the above-mentioned series of processing can naturally be performed in chronological order according to the order of description, but it is not necessary to perform them in chronological order, and some steps can be performed in parallel or independently of each other. For those of ordinary skill in the art, it is understood that all or any steps or components of the method and apparatus of the present invention can be implemented in any computing device (including processors, storage media, etc.) or a network of computing devices in hardware, firmware, software or a combination thereof, which can be achieved by those of ordinary skill in the art using basic programming skills after reading the description of the present invention.

[0109] Therefore, the purpose of the present invention can also be achieved by running a program or a group of programs on any computing device. The computing device can be a well-known general device. Therefore, the purpose of the present invention can also be achieved by simply providing a program product containing a program code that implements the method or device. That is to say, such a program product also constitutes the present invention, and the storage medium storing such a program product also constitutes the present invention. Obviously, the storage medium can be any well-known storage medium or any storage medium developed in the future. It should also be pointed out that in the device and method of the present invention, it is obvious that each component or each step can be decomposed and / or recombined. These decompositions and / or recombinations should be regarded as equivalent schemes of the present invention. In addition, the steps of performing the above-mentioned series of processing can naturally be performed in chronological order according to the order of description, but it is not necessary to perform them in chronological order. Some steps can be performed in parallel or independently of each other.

[0110] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A cascaded SVG network control method, characterized in that: The method comprises: Obtain active power reference value through total DC voltage deviation; Calculate the potential phase angle in the network SVG according to the active reference value, and obtain the potential amplitude in the SVG; The three-phase voltage command of SVG is obtained through the internal potential amplitude and the internal potential phase angle; According to the three-phase voltage command of SVG, the total modulation wave of SVG is obtained; According to the total modulation wave, a driving signal is obtained, and the primary circuit of the SVG is controlled according to the driving signal.

2. The cascaded SVG network control method according to claim 1, characterized in that: The calculation formula of active reference value is: Among them, P ref Indicates the active power command value; K p represents proportional gain; Ki represents integral gain; S represents Laplace operator; C represents SVG equivalent DC capacitance; G M represents virtual admittance; Indicates the voltage reference value of the SVG DC side; U dc 2 Indicates the actual voltage value on the DC side of the SVG.

3. The cascaded SVG network control method according to claim 2 is characterized in that: The calculation formula of the potential phase angle in the SVG network is: θ = ∫(w-wg)dt; Among them, θ represents the phase angle; w represents the grid frequency; wg represents the grid frequency; ∫(w-wg)dt represents the time integration of the frequency difference w-wg.

4. The cascaded SVG network control method according to claim 3 is characterized in that: The calculation formula of the potential amplitude in SVG is: Eq=((Qref-Q)*Kq+(Vref-V))*Kp; Among them, Eq represents the internal potential amplitude; Qref represents the reactive power command; Q represents the actual reactive power value; Kq represents the reactive power control coefficient; Vref represents the voltage target value; V represents the actual output voltage; and Kp represents the proportionality coefficient.

5. The cascaded SVG network control method according to claim 4, characterized in that: The three-phase voltage instructions of SVG are obtained through the internal potential amplitude and internal potential phase angle, including: Obtain the internal potential amplitude and internal potential phase angle of SVG; Convert the internal potential amplitude and the internal potential phase angle into a three-phase coordinate system; Using trigonometric functions, the internal potential amplitude is decomposed onto each axis of the three-phase coordinate system to obtain the voltage amplitude of each phase; In the three-phase coordinate system, the three-phase voltage command of SVG is obtained according to the voltage amplitude of each phase.

6. The cascaded SVG network control method according to claim 5, characterized in that: According to the three-phase voltage command of SVG, the total modulation wave of SVG is obtained, including: Get the three-phase voltage command of SVG; According to the three-phase voltage command of SVG, the number of levels of each power unit in SVG is determined; Compare each phase voltage command in the three-phase voltage command with a preset level threshold to determine a final level; Assigning the level to each power unit and comparing the voltage command of each phase with the selected PWM carrier to obtain the PWM waveform; Distribute PWM waveform to each power unit of SVG; The PWM waveforms obtained from each power unit are combined to obtain the total modulation wave of the SVG.

7. The cascaded SVG network control method according to claim 6, characterized in that: According to the total modulation wave, the driving signal is obtained, and the primary circuit of the SVG is controlled according to the driving signal, including: Analyze the total modulation wave to determine the voltage at each time point; The voltage at each time point is converted into a switching signal to obtain a driving signal; Amplifying the driving signal through the driving circuit and transmitting the amplified driving signal to the power unit; The power unit obtains the driving signal and controls the primary circuit of the SVG.

8. A cascaded SVG network control system, characterized in that: include: An acquisition module is used to obtain an active power reference value through a DC total voltage deviation; Calculate the potential phase angle in the network SVG according to the active reference value, and obtain the potential amplitude in the SVG; The three-phase voltage command of SVG is obtained through the internal potential amplitude and the internal potential phase angle; The processing module is used to obtain the total modulation wave of the SVG according to the three-phase voltage instruction of the SVG; obtain the driving signal according to the total modulation wave, and control the primary circuit of the SVG according to the driving signal.

9. A computing device, characterized in that include: one or more processors; A storage device for storing one or more programs, when the one or more programs are executed by the one or more processors, the one or more processors implement the method as claimed in any one of claims 1 to 7.

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

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