Multi-energy micro-grid negative sequence voltage treatment method

Abstract

The invention provides a multi-energy micro-grid negative sequence voltage treatment method. The method comprises the steps that three-phase voltage information of a common connection point is collected and separated to obtain a negative sequence voltage component; calculating to obtain the voltage unbalance degree of the common connection point; monitoring the three-phase output current of the execution end to obtain a single-phase maximum effective value; dynamically adjusting a control coefficient according to a logic scene; calculating to obtain a negative sequence voltage reference signal; calculating to obtain a voltage control reference signal; and collecting the grid-connected voltage of the execution end, generating a modulation signal by adopting a closed-loop control algorithm, controlling the output of the execution end through the modulation signal, and correcting the deviation between the grid-connected voltage and the voltage control reference signal. The method has the beneficial effects that an active treatment framework is constructed, an additional sensor is not needed to detect load current, the method is adaptive to a distributed multi-load and multi-energy microgrid scene, and the universality is high; double parameters of the voltage unbalance degree and the current effective value are linked, the driving control coefficient is dynamically adjusted, the dynamic balance between the treatment effect and the equipment safety is realized, and the equipment overload is avoided.

Description

Technical Field

[0001] This invention belongs to the field of power grid operation technology, and in particular relates to a method for managing negative sequence voltage in multi-energy microgrids. Background Technology

[0002] Microgrids, as an important way to effectively integrate and utilize distributed power sources, have broad application prospects in mountainous areas, remote villages, and the end of urban power distribution networks. However, when an independent microgrid is in operation, unbalanced loads can introduce unbalanced currents, causing the voltage at the point of common coupling to contain negative sequence components and resulting in excessive voltage imbalance, which seriously threatens the stable operation of the microgrid.

[0003] Existing negative sequence voltage mitigation technologies mainly fall into two categories: one is the negative sequence current compensation method, which requires additional sensors to detect load current and is only suitable for scenarios with a simple system structure and concentrated negative sequence current sources, making it unsuitable for distributed multi-load scenarios; the other is the inverter passive voltage control method, whose mitigation effect depends on other voltage source equipment such as diesel generators. However, as rotating equipment, the negative sequence component of diesel generators increases their losses and generates mechanical vibrations. Furthermore, this method has conservative parameter design, weak mitigation capabilities, and does not consider the impact of line impedance-inductance ratio on the mitigation effect, leading to decreased mitigation efficiency and failing to fully exploit the mitigation potential of grid-connected inverters. Therefore, there is an urgent need for a microgrid negative sequence voltage mitigation method that addresses the above problems. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a method for mitigating negative sequence voltage in multi-energy microgrids, which is particularly suitable for addressing the problem of grid-connected voltage containing negative sequence components caused by asymmetrical current.

[0005] The technical solution adopted in this invention is as follows: Firstly, a method for managing negative sequence voltage in multi-energy microgrids is provided, comprising the following steps:

[0006] Collect the three-phase voltage information at the point of common coupling and separate the negative sequence voltage component;

[0007] Based on the three-phase voltage information, the voltage imbalance at the point of common coupling is calculated.

[0008] By monitoring the three-phase output current at the actuator, the maximum effective value of a single phase can be obtained;

[0009] Based on the voltage imbalance and the maximum effective value of a single phase, the control coefficient is dynamically adjusted according to different logic scenarios;

[0010] Based on the negative sequence voltage component and the control coefficient, the negative sequence voltage reference signal is calculated.

[0011] Based on the negative sequence voltage reference signal and the reference voltage reference signal, the voltage control reference signal is calculated;

[0012] The grid-connected voltage of the actuator is collected, and a modulation signal is generated using a closed-loop control algorithm with the voltage control reference signal as the control target. The output of the actuator is controlled by the modulation signal to correct the deviation between the grid-connected voltage and the voltage control reference signal.

[0013] Furthermore, dynamically adjusting the control coefficients according to different logical scenarios includes the following steps:

[0014] The preset unbalance reference value, current threshold value, amplitude gradient step size, phase angle gradient step size, and limit value of the maximum effective value of the single phase are set.

[0015] If the voltage imbalance is less than the imbalance reference value, the control coefficient remains unchanged;

[0016] If the voltage imbalance is greater than or equal to the imbalance reference value and the maximum effective value of a single phase is less than the current threshold value, the amplitude of the control coefficient is gradually increased according to the amplitude gradient step size.

[0017] If the voltage imbalance is greater than or equal to the imbalance reference value and the maximum effective value of a single phase is greater than or equal to the current threshold value, stop adjusting the amplitude of the control coefficient and gradually adjust the phase angle of the control coefficient according to the phase angle gradient step size;

[0018] When the phase angle of the control coefficient is adjusted to make the maximum effective value of a single phase less than the current threshold value and the voltage imbalance greater than or equal to the imbalance reference value, the phase angle of the current control coefficient is fixed, and the amplitude of the control coefficient is gradually increased according to the gradient step size until the voltage imbalance is less than or equal to the imbalance reference value or the maximum effective value of a single phase exceeds the limit value, at which point the adjustment of the control coefficient is stopped.

[0019] Furthermore, the negative sequence voltage component is separated from the three-phase voltage information using a negative sequence extraction algorithm.

[0020] Furthermore, the mathematical properties of the control coefficients include both real and complex numbers.

[0021] Furthermore, the closed-loop control algorithm is a voltage closed-loop control algorithm, which dynamically outputs adjustment amount by comparing the instantaneous value or effective value of the grid-connected voltage with the voltage control reference signal in real time, so as to ensure that the deviation quickly converges to the allowable range.

[0022] In a second aspect, an electronic device is provided, comprising: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, the instructions being executed by the at least one processor to enable the at least one processor to execute the multi-energy microgrid negative sequence voltage management method provided herein.

[0023] Thirdly, a non-transient computer-readable storage medium storing computer instructions is provided, wherein the computer instructions are used to cause a computer to execute the negative sequence voltage management method for multi-energy microgrids provided in this disclosure.

[0024] Fourthly, a computer program product is provided, including a computer program / instructions, which are executed by a processor to provide the multi-energy microgrid negative sequence voltage management method disclosed herein.

[0025] The advantages and positive effects of this invention are as follows: By adopting the above technical solution, the dual parameters of voltage imbalance and current effective value are linked to achieve a dynamic balance between governance effect and equipment safety, and avoid equipment overload; by integrating negative sequence compensation and basic power supply requirements, the voltage quality of the microgrid is significantly improved, the utilization rate of execution equipment is increased, and the operating cost is reduced; by using the negative sequence extraction algorithm, the negative sequence voltage component is accurately separated, providing a clear and pure control target for subsequent negative sequence compensation. Attached Figure Description

[0026] Figure 1 This is a flowchart illustrating a negative sequence voltage mitigation method according to an embodiment of the present invention.

[0027] Figure 2 This is a schematic diagram of the simulation waveform of a microgrid system according to an embodiment of the present invention;

[0028] Figure 3 This is a schematic diagram of the control coefficient change waveform according to an embodiment of the present invention. Detailed Implementation

[0029] The present disclosure will now be described more fully with reference to the accompanying drawings, which illustrate exemplary embodiments of the present disclosure. The technical solutions of the embodiments of the present disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present disclosure, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present disclosure without creative effort are within the scope of protection of the present disclosure.

[0030] like Figure 1 As shown, this invention provides a method for managing negative sequence voltage in multi-energy microgrids, comprising the following steps:

[0031] S100: Collect the three-phase voltage information at the point of common coupling (PCC) and separate the negative sequence voltage component;

[0032] S200. Calculate the voltage imbalance at the point of common coupling based on the three-phase voltage information.

[0033] Specifically, the positive-sequence voltage RMS value is obtained by separating the three-phase voltage information using a negative-sequence extraction algorithm. and the effective value of negative sequence voltage (i.e., the effective value of the negative sequence voltage component), through the equation Calculate voltage unbalance .

[0034] S300: Monitor the three-phase output current at the execution end to obtain the maximum effective value of a single phase;

[0035] S400: Based on voltage imbalance and maximum effective value of single phase, the control coefficient is dynamically adjusted according to different logic scenarios;

[0036] S500. Multiply the negative sequence voltage component by the control coefficient to calculate the negative sequence voltage reference signal;

[0037] S600: Based on the negative sequence voltage reference signal and the preset reference voltage signal, the voltage control reference signal is calculated;

[0038] Specifically, the preset reference voltage signal is a three-phase positive sequence voltage signal, and the negative sequence voltage signal is a three-phase negative sequence voltage signal containing the amplitude and phase information required for compensation. According to the principle of "adding corresponding phases", the three-phase voltage signals are added separately by phasor addition to calculate the voltage control reference signal.

[0039] The S700 acquires the grid-connected voltage at the execution end, uses the voltage control reference signal as the control target, and generates a modulation signal using a closed-loop control algorithm. The output of the execution end is controlled by the modulation signal to correct the deviation between the grid-connected voltage and the voltage control reference signal.

[0040] Using the above methods, an active governance framework is constructed. It does not require additional sensors to detect load current, is adaptable to distributed microgrid scenarios with multiple loads and multiple energy sources, and has strong versatility. By linking the voltage imbalance and the effective value of the current as dual parameters, a dynamic balance between governance effect and equipment safety is achieved, avoiding equipment overload. By integrating negative sequence compensation and basic power supply requirements, the voltage quality of the microgrid is significantly improved, the utilization rate of the execution equipment is increased, and the operating cost is reduced.

[0041] To address the issues of unclear and ambiguous control coefficient adjustment logic and lack of explicit rules in existing technologies, which lead to disordered governance, overload, or failure to meet governance standards, this embodiment provides an implementation method.

[0042] In one embodiment, based on voltage imbalance and single-phase maximum effective value The dynamic adjustment of the control coefficient K according to different logical scenarios includes the following steps:

[0043] Preset unbalance reference value Current threshold Limits on amplitude gradient step size, phase angle gradient step size, and maximum effective value of a single phase;

[0044] like Keep K constant;

[0045] like and The amplitude of K is gradually increased according to the amplitude gradient step size;

[0046] like and Stop adjusting the magnitude of K, and gradually adjust the phase angle of K according to the phase angle gradient step size;

[0047] When the phase angle of K is adjusted to make ,and With the current phase angle of K fixed, the magnitude of K is gradually increased according to the gradient step size until... or Stop adjusting K when the limit is exceeded.

[0048] By adopting the above method, the triggering conditions and operation rules for coefficient adjustment in multiple scenarios are clarified, making the adjustment process reproducible and controllable, and improving the practicality of the technical solution. Through the progressive strategy of "amplitude priority, phase angle optimization, and amplitude readjustment", the current threshold limit is broken through to maximize the potential for governance. The equipment loss caused by blind adjustment is avoided, and the voltage imbalance is quickly reduced under the premise of ensuring equipment safety, taking into account both governance efficiency and stability.

[0049] In one embodiment, a negative sequence voltage component is separated from the three-phase voltage information using a negative sequence extraction algorithm.

[0050] In one embodiment, the mathematical properties of the control coefficients include real and complex numbers.

[0051] To address the problem that existing closed-loop control algorithms suffer from slow deviation convergence and low tracking accuracy, resulting in grid-connected voltage failing to effectively follow the reference signal and affecting the governance effect, this embodiment provides an implementation method.

[0052] In one embodiment, the closed-loop control algorithm is a voltage closed-loop control algorithm, which dynamically outputs the adjustment amount by comparing the instantaneous or effective value of the grid-connected voltage with the voltage control reference signal in real time, so as to ensure that the deviation quickly converges to the allowable range.

[0053] By using the above method, the instantaneous or effective voltage values ​​are compared in real time, and the adjustment amount is dynamically output to achieve rapid convergence of deviations, ensuring accurate tracking of the grid-connected voltage to the control reference signal; improving the response speed and stability of voltage regulation, avoiding excessive voltage fluctuations, and further optimizing the power supply quality of the microgrid; strengthening the reliability of closed-loop control in the governance process, ensuring the effective implementation of negative sequence compensation measures, and continuously maintaining the voltage balance of the microgrid.

[0054] To facilitate the use of the negative sequence voltage management method for multi-energy microgrids provided in this disclosure, this disclosure also provides a negative sequence voltage management system for multi-energy microgrids, including: an energy storage system, an unbalanced power load device, a new energy power generation device, and a diesel generator, all connected to a common coupling point;

[0055] Energy storage system: The core negative sequence voltage component treatment execution end, collects the common coupling point voltage (i.e. three-phase voltage information) and its own output current, generates modulation signal by dynamically adjusting the control coefficient, actively undertakes the negative sequence compensation task, and protects the diesel generator from the influence of negative sequence components;

[0056] Unbalanced power load devices: the main source of unbalanced current in microgrid systems. Their operation can cause negative sequence components in the point of common coupling voltage, leading to voltage imbalance. They are the target of negative sequence voltage management.

[0057] New energy power generation equipment: a core component of distributed power sources, providing power to microgrids and working in conjunction with other power sources to meet the power demand of loads. Its grid-connected operation needs to be adapted to the voltage quality management requirements of microgrids.

[0058] Diesel generators are important voltage source devices in microgrids, providing stable power support; however, negative sequence components increase their losses and cause mechanical vibrations, requiring energy storage systems to share the negative sequence management function to ensure their own stable operation.

[0059] The following description, in conjunction with a preferred embodiment, illustrates the content involved in the above embodiments.

[0060] like Figures 2-3 As shown, in a preferred embodiment, the test is performed in a MATLAB simulation system, and a reference value for the allowable voltage imbalance is set. The current threshold (the threshold for the maximum single-phase current) is: The entire simulation process is divided into four stages. Stage 1: Simulation time 0.5s~0.6s, control coefficient K=0. In this stage, the negative sequence voltage reference is zero, the voltage imbalance at the point of common coupling is 5.2%, and the maximum effective value of the single-phase energy storage output current is 17.6A. Stage 2: Simulation time 0.6s~0.8s, only the amplitude of coefficient K is adjusted. After the maximum effective value of the single phase reaches the threshold of 24.8A, the voltage imbalance decreases to 3.7%. Stage 3: Simulation time 0.8s~1.0s, keeping the amplitude of control coefficient K constant, the phase angle of the control coefficient is adjusted. The voltage imbalance continues to decrease. At the same time, due to the change in harmonic power flow, the maximum effective value of the single phase also decreases. After reaching a suitable phase angle, the voltage imbalance decreases to 2.9%, and the maximum effective value of the single phase decreases to 21.9A. Phase 4: Simulation time 1.0s~1.2s. Keep the phase angle of the control coefficient K unchanged, and continue to increase the amplitude of the control coefficient K until the voltage imbalance is reduced to 1.9%, which is less than the allowable value of 2%, thus achieving the control target. At this time, the maximum effective value of a single phase is 24.0A, which is still less than the current threshold.

[0061] Based on embodiments of this disclosure, this disclosure also provides an electronic device, a readable storage medium, and a computer program product.

[0062] An electronic device includes at least one processor and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, the instructions being executed by the at least one processor to enable the at least one processor to perform the multi-energy microgrid negative sequence voltage management method provided in this disclosure.

[0063] Electronic devices are intended to represent various forms of digital computers, such as laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. Electronic devices can also represent various forms of mobile devices, such as personal digital processors, cellular phones, smartphones, wearable devices, and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely illustrative and are not intended to limit the implementation of the present disclosure described and / or claimed herein.

[0064] A non-transitory computer-readable storage medium storing computer instructions, wherein the computer instructions are used to cause a computer to execute the negative sequence voltage management method for multi-energy microgrids provided in this disclosure.

[0065] The various embodiments of this disclosure can be implemented in digital electronic circuit systems, integrated circuit systems, field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), application-specific standard products (ASSPs), systems-on-a-chip (SoCs), complex programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various embodiments may include implementations in one or more computer programs that can be executed and / or interpreted on a programmable system including at least one programmable processor, which may be a dedicated or general-purpose programmable processor, capable of receiving data and instructions from a storage system, at least one input device, and at least one output device, and transmitting data and instructions to the storage system, the at least one input device, and the at least one output device.

[0066] A computer program product includes a computer program / instructions, which are executed by a processor to provide a method for managing negative sequence voltage in multi-energy microgrids.

[0067] The program code used to implement the methods of this disclosure may be written in any combination of one or more programming languages. This program code may be provided to a processor or controller of a general-purpose computer, special-purpose computer, or other programmable data processing apparatus, such that when executed by the processor or controller, the program code causes the functions / operations specified in the flowcharts and / or block diagrams to be implemented. The program code may be executed entirely on a machine, partially on a machine, as a standalone software package partially on a machine and partially on a remote machine, or entirely on a remote machine or server.

[0068] In the context of this disclosure, a machine-readable medium can be a tangible medium that may contain or store a program for use by or in conjunction with an instruction execution system, apparatus, or device. A machine-readable medium can be a machine-readable signal medium or a machine-readable storage medium. A machine-readable medium can be, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination of the foregoing. More specific examples of machine-readable storage media include electrical connections based on one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing.

[0069] The embodiments of the present invention have been described in detail above, but the content described is only a preferred embodiment of the present invention and should not be considered as limiting the scope of the present invention. All equivalent changes and improvements made in accordance with the scope of the present invention should still fall within the patent coverage of the present invention.

Claims

1. A method for governing negative sequence voltage of a multi-energy microgrid, characterized in that, Includes the following steps: Collect the three-phase voltage information at the point of common coupling and separate the negative sequence voltage component; Based on the three-phase voltage information, the voltage imbalance at the point of common coupling is calculated. By monitoring the three-phase output current at the actuator, the maximum effective value of a single phase can be obtained; Based on the voltage imbalance and the maximum effective value of a single phase, the control coefficient is dynamically adjusted according to different logic scenarios; Based on the negative sequence voltage component and the control coefficient, the negative sequence voltage reference signal is calculated. Based on the negative sequence voltage reference signal and the reference voltage reference signal, the voltage control reference signal is calculated; The grid-connected voltage of the actuator is collected, and a modulation signal is generated using the voltage control reference signal as the control target and a closed-loop control algorithm is used to control the output of the actuator through the modulation signal, thereby correcting the deviation between the grid-connected voltage and the voltage control reference signal.

2. The multi-energy microgrid negative sequence voltage governance method of claim 1, wherein, Dynamically adjusting the control coefficients according to different logical scenarios includes the following steps: The preset unbalance reference value, current threshold value, amplitude gradient step size, phase angle gradient step size, and limit value of the maximum effective value of the single phase are set. If the voltage imbalance is less than the imbalance reference value, the control coefficient remains unchanged; If the voltage imbalance is greater than or equal to the imbalance reference value and the maximum effective value of a single phase is less than the current threshold value, the amplitude of the control coefficient is gradually increased according to the amplitude gradient step size. If the voltage imbalance is greater than or equal to the imbalance reference value and the single-phase maximum effective value is greater than or equal to the current threshold value, stop adjusting the amplitude of the control coefficient and gradually adjust the phase angle of the control coefficient according to the phase angle gradient step size; When the phase angle of the control coefficient is adjusted to make the maximum effective value of a single phase less than the current threshold value and the voltage imbalance greater than or equal to the imbalance reference value, the phase angle of the current control coefficient is fixed, and the amplitude of the control coefficient is gradually increased according to the gradient step size until the voltage imbalance is less than or equal to the imbalance reference value or the maximum effective value of a single phase exceeds the limit value, at which point the adjustment of the control coefficient is stopped.

3. The multi-energy microgrid negative sequence voltage governance method of claim 1, wherein: The negative sequence voltage component is obtained from the three-phase voltage information by using a negative sequence extraction algorithm.

4. The multi-energy microgrid negative sequence voltage governance method of claim 1, wherein: The mathematical properties of the control coefficients include both real and complex numbers.

5. The multi-energy microgrid negative sequence voltage governance method of claim 1, wherein: The closed-loop control algorithm is a voltage closed-loop control algorithm. By comparing the instantaneous or effective value of the grid-connected voltage with the voltage control reference signal in real time, it dynamically outputs the adjustment amount to ensure that the deviation quickly converges to the allowable range.

6. An electronic device, comprising: At least one processor; as well as A memory that is communicatively connected to at least one processor; wherein, The memory stores instructions that can be executed by at least one processor to enable the at least one processor to perform the method of any one of claims 1 to 5.

7. A non-transitory computer readable storage medium having stored thereon computer instructions, wherein, Computer instructions are used to cause a computer to perform the method according to any one of claims 1 to 5.

8. A computer program product comprising a computer program / instructions that, when executed by a processor, implement the steps of the method according to any one of claims 1 to 5.

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