Flexible interconnection system control method and system based on adaptive droop control

Abstract

The invention provides a control method and system for a flexible interconnection system based on adaptive droop control, and the method comprises the steps: determining an initial droop coefficient of a voltage source converter in the flexible interconnection system according to an obtained steady-state operation parameter of the flexible interconnection system; when the flexible interconnection system is in a power imbalance state, updating an initial droop coefficient by using an adaptive droop control method according to the obtained margin capacity of the voltage source converter and the initial droop coefficient of the voltage source converter to obtain an updated droop coefficient; controlling the power transmission of the flexible interconnection system based on the updated droop coefficient; when power transmission control is carried out on the flexible interconnection system, the droop coefficient capable of being adaptively updated and adjusted according to the change of the working condition is introduced, the transmission power of the flexible interconnection system can be reasonably distributed, the direct-current voltage is kept stable, and therefore the adjusting capacity of the flexible interconnection system under power fluctuation is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of direct current voltage control, and in particular to a control method and system of a flexible interconnection system based on adaptive droop control. Background Art

[0002] At present, with the continuous development of renewable energy technology, the focus of energy research at home and abroad has gradually shifted to new energy sources such as distributed photovoltaics and wind power. The penetration rate of renewable energy power generation has continued to increase. At the same time, the elements in the power grid are becoming increasingly rich, and large-scale energy storage and various power loads such as electric vehicle charging piles and data centers have gradually appeared, which has increased the uncertainty of power grid source and load, and the flow change has become more complicated. Therefore, it is difficult for traditional distribution methods to ensure the stable operation of the power system, and it is impossible to achieve efficient consumption of renewable energy. In addition, the distribution network urgently needs new technologies and equipment to cope with the challenges of safety and stability brought about by the high proportion of renewable energy penetration and the access of a large number of new loads. Against this background, flexible interconnection technology has gradually become a research hotspot in the field of medium-voltage distribution networks. Flexible interconnection is a new technology based on power electronics. Compared with conventional switches, flexible interconnection technology is easier to achieve fault isolation, thereby greatly improving the flexibility and safety of distribution network control. When flexible interconnection technology is used for medium-voltage feeder interconnection, asynchronous closed-loop operation between multiple AC distribution feeders can be completed without increasing short-circuit capacity, which plays a role in flow transfer, load rate balancing, network loss reduction, fault isolation and power supply recovery, and realizes multi-terminal closed-loop operation between feeders and optimal configuration of adjustable resources.

[0003] The key to the control level of multi-terminal flexible interconnection technology is to maintain the stability of the system DC voltage. The current mainstream DC voltage control methods are master-slave control, voltage deviation control, and voltage droop control. All three methods are difficult to effectively solve the DC voltage stability under the condition of high penetration of distributed energy: the master-slave control method relies on an additional station-to-station communication system, and its economy and reliability are poor; the voltage deviation control method is not good at selecting the voltage deviation margin capacity, which can easily cause problems such as high grid loss and voltage instability; the droop control method is that multiple converter stations in the system jointly adopt a droop control strategy to complete the task of balancing power and stabilizing voltage. If external disturbances or converter station switching occur, the system can also quickly adjust to a stable operating point without the need for an additional communication system, and has strong reliability. However, in conventional droop control methods under large-scale power fluctuations, the selection of the slope characteristic curves of each voltage source converter is difficult, resulting in the flexible interconnection system losing its power regulation capability and therefore being unable to operate stably. Summary of the invention

[0004] In order to solve the problem that in the existing flexible interconnection system, the conventional droop control method cannot cope with complex power fluctuations when performing power transmission control, resulting in the system being unable to operate stably, the present invention proposes a control method for a flexible interconnection system based on adaptive droop control, comprising:

[0005] Determining an initial droop coefficient of a voltage source converter in the flexible interconnection system according to the acquired steady-state operating parameters of the flexible interconnection system;

[0006] When the flexible interconnection system is in a power imbalance state, the initial droop coefficient is updated by using an adaptive droop control method according to the obtained margin capacity of the voltage source converter and the initial droop coefficient of the voltage source converter to obtain an updated droop coefficient;

[0007] Based on the updated droop coefficient, power transmission of the flexible interconnection system is controlled.

[0008] Optionally, updating the initial droop coefficient by using an adaptive droop control method according to the obtained margin capacity of the voltage source converter and the initial droop coefficient of the voltage source converter comprises:

[0009] When the obtained margin capacity of the voltage source converter is 0, setting the updated droop coefficient of the voltage source converter to a preset value, and switching the control mode of the voltage source converter to a constant power and constant DC voltage mode;

[0010] When the obtained margin capacity of the voltage source converter is not 0, the initial droop coefficient is updated according to the initial droop coefficient of the voltage source converter using an adaptive droop coefficient update expression.

[0011] Optionally, when the obtained margin capacity of the voltage source converter is not 0, updating the initial droop coefficient according to the initial droop coefficient of the voltage source converter by using an adaptive droop coefficient update expression comprises:

[0012] When the obtained margin capacity of the voltage source converter is not 0, determining the margin capacity of the voltage source converter according to the port type to which the voltage source converter belongs;

[0013] According to the initial droop coefficient of the voltage source converter and the margin capacity, the initial droop coefficient is updated using the adaptive droop coefficient update expression.

[0014] Optionally, determining the margin capacity of the voltage source converter according to the port type to which the voltage source converter belongs includes:

[0015] When the port type to which the voltage source converter belongs is an output power port, calculating the corresponding operating power according to the operating data of the voltage source converter, and determining the capacity margin of the voltage source converter according to the operating power;

[0016] When the port type to which the voltage source converter belongs is an input power port, the corresponding power consumption is calculated according to the operation data of the voltage source converter, and the capacity margin of the voltage source converter is determined according to the power consumption.

[0017] Optionally, calculating the corresponding operating power according to the operating data of the voltage source converter, and determining the capacity margin of the voltage source converter according to the operating power includes:

[0018] calculating the available power of the voltage source converter according to the operating data of the voltage source converter;

[0019] calculating the operating power of the voltage source converter according to the available power;

[0020] The available power and the operating power are subtracted to obtain a capacity margin of the voltage source converter.

[0021] Optionally, calculating the corresponding power consumption according to the operation data of the voltage source converter, and determining the capacity margin of the voltage source converter according to the power consumption includes:

[0022] calculating the power consumption of the voltage source converter according to the operation data of the voltage source converter;

[0023] calculating the actual operating power of the voltage source converter according to the consumed power;

[0024] The power consumption and the actual operating power are subtracted to obtain the capacity margin of the voltage source converter. Optionally, the adaptive droop coefficient update expression is as follows:

[0025] β j =β 0 ×α×H j ;

[0026] Among them, β j represents the updated droop coefficient of voltage source converter j; β 0 represents the initial droop coefficient; H j represents the margin capacity of voltage source converter j; α represents a constant value.

[0027] Optionally, determining an initial droop coefficient of a voltage source converter in the flexible interconnection system according to the acquired steady-state operating parameters of the flexible interconnection system includes:

[0028] According to the acquired steady-state operation parameters of the flexible interconnection system, a steady-state operation target is set;

[0029] Calculating an initial droop coefficient of a voltage source converter in the flexible interconnection system according to the steady-state operation target;

[0030] The steady-state operation targets include: power allocation ratio, node voltage operation range and frequency control range.

[0031] Based on the same inventive concept, the present invention also provides a control system for a flexible interconnection system based on adaptive droop control, comprising:

[0032] An initial coefficient determination module, used to determine an initial droop coefficient of a voltage source converter in the flexible interconnection system according to the acquired steady-state operation parameters of the flexible interconnection system;

[0033] a droop coefficient updating module, configured to update the initial droop coefficient by using an adaptive droop control method according to the obtained margin capacity of the voltage source converter and the initial droop coefficient of the voltage source converter when the flexible interconnection system is in a power imbalance state, so as to obtain an updated droop coefficient;

[0034] A power control module is used to control power transmission of the flexible interconnection system based on the updated droop coefficient.

[0035] Optionally, the droop coefficient updating module includes:

[0036] a mode switching submodule, configured to set the updated droop coefficient of the voltage source converter to a preset value and switch the control mode of the voltage source converter to a constant power and constant DC voltage mode when the obtained margin capacity of the voltage source converter is 0;

[0037] The coefficient updating submodule is used to update the initial droop coefficient of the voltage source converter by using an adaptive droop coefficient updating expression according to the initial droop coefficient of the voltage source converter when the obtained margin capacity of the voltage source converter is not 0.

[0038] Optionally, the coefficient updating submodule includes:

[0039] a capacity determining unit, configured to determine the margin capacity of the voltage source converter according to the port type to which the voltage source converter belongs when the obtained margin capacity of the voltage source converter is not 0;

[0040] An adaptive updating unit is used to update the initial droop coefficient of the voltage source converter according to the initial droop coefficient and the margin capacity using the adaptive droop coefficient updating expression.

[0041] Optionally, the capacity determination unit includes:

[0042] a sending-end calculation subunit, configured to calculate the corresponding operating power according to the operating data of the voltage source converter when the port type to which the voltage source converter belongs is an output power port, and determine the capacity margin of the voltage source converter according to the operating power;

[0043] The receiving-end calculation subunit is used to calculate the corresponding power consumption according to the operation data of the voltage source converter when the port type to which the voltage source converter belongs is an input power port, and to determine the capacity margin of the voltage source converter according to the power consumption.

[0044] Optionally, the sending-end computing subunit is used to:

[0045] calculating the available power of the voltage source converter according to the operating data of the voltage source converter;

[0046] calculating the operating power of the voltage source converter according to the available power;

[0047] The available power and the operating power are subtracted to obtain a capacity margin of the voltage source converter.

[0048] Optionally, the receiving-end computing subunit is configured to:

[0049] calculating the power consumption of the voltage source converter according to the operation data of the voltage source converter;

[0050] calculating the actual operating power of the voltage source converter according to the consumed power;

[0051] The power consumption and the actual operating power are subtracted to obtain the capacity margin of the voltage source converter. Optionally, the adaptive droop coefficient update expression is as follows:

[0052] β j =β 0 ×α×H j ;

[0053] Among them, β j represents the updated droop coefficient of voltage source converter j; β 0 represents the initial droop coefficient; H j represents the margin capacity of voltage source converter j; α represents a constant value.

[0054] Optionally, the initial coefficient determination module includes:

[0055] A target setting submodule is used to set a steady-state operation target according to the acquired steady-state operation parameters of the flexible interconnection system;

[0056] An initial coefficient calculation submodule, used to calculate an initial droop coefficient of the voltage source converter in the flexible interconnection system according to the steady-state operation target;

[0057] The steady-state operation targets include: power allocation ratio, node voltage operation range and frequency control range.

[0058] In another aspect, the present invention further provides an electronic device, comprising: at least one processor and a memory; the memory and the processor are connected via a bus;

[0059] The memory is used to store one or more programs;

[0060] When the one or more programs are executed by the at least one processor, a control method for a flexible interconnection system based on adaptive droop control as described above is implemented.

[0061] On the other hand, the present invention further provides a computer-readable storage medium having an execution program stored thereon, and when the execution program is executed, the control method of the flexible interconnection system based on adaptive droop control as described above is implemented.

[0062] Compared with the prior art, the present invention has the following beneficial effects:

[0063] The present invention provides a control method and system for a flexible interconnection system based on adaptive droop control, comprising: determining an initial droop coefficient of a voltage source converter in the flexible interconnection system according to acquired steady-state operating parameters of the flexible interconnection system; when the flexible interconnection system is in a power imbalance state, updating the initial droop coefficient by using an adaptive droop control method according to the acquired margin capacity of the voltage source converter and the initial droop coefficient of the voltage source converter to obtain an updated droop coefficient; and controlling the power transmission of the flexible interconnection system based on the updated droop coefficient. The present application introduces a droop coefficient that can be adaptively updated and adjusted according to changes in working conditions when controlling the power transmission of the flexible interconnection system, which is beneficial to reasonably allocating the transmission power of the flexible interconnection system and maintaining the stability of the DC voltage, thereby increasing the regulation capability of the flexible interconnection system under power fluctuations. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Figure 1 A schematic flow chart of a control method for a flexible interconnection system based on adaptive droop control provided by the present invention;

[0065] Figure 2 A schematic diagram of the overall framework of a control method for a flexible interconnection system based on adaptive droop control provided by the present invention;

[0066] Figure 3 A four-port flexible interconnection system provided in a specific embodiment of the present invention;

[0067] Figure 4 A control block diagram of a control method for a flexible interconnection system based on adaptive droop control provided by a specific embodiment of the present invention;

[0068] Figure 5 A schematic diagram of the structure of a control system of a flexible interconnection system based on adaptive droop control provided by the present invention;

[0069] Figure 6 The present invention provides a schematic structural diagram of an electronic device. DETAILED DESCRIPTION

[0070] The present invention proposes a control method, system, device and medium for a flexible interconnection system based on adaptive droop control. The specific implementation modes of the present invention are further described in detail below with reference to the accompanying drawings.

[0071] Embodiment 1:

[0072] The present invention provides a control method for a flexible interconnection system based on adaptive droop control, the flow chart is as follows: Figure 1 As shown, including:

[0073] Step 1: Determine an initial droop coefficient of a voltage source converter in the flexible interconnection system according to the acquired steady-state operating parameters of the flexible interconnection system;

[0074] Step 2: When the flexible interconnection system is in a power imbalance state, the initial droop coefficient is updated by using an adaptive droop control method according to the obtained margin capacity of the voltage source converter and the initial droop coefficient of the voltage source converter to obtain an updated droop coefficient;

[0075] Step 3: Based on the updated droop coefficient, the power transmission of the flexible interconnection system is controlled.

[0076] The flexible interconnection system mentioned in the present invention refers to an efficient, reliable and environmentally friendly DC transmission system based on a voltage source converter (VSC). VSC can realize flexible conversion between DC and AC, which is the basis for the flexible interconnection system to realize bidirectional energy flow and optimized configuration. VSC has the advantages of fast response speed, flexible control and little impact on system stability. By setting the adaptive update adjustment droop coefficient, the power of the flexible interconnection system is controlled, so that the flexible interconnection system can operate efficiently and stably. First, starting from initialization, the flexible interconnection system needs to determine an initial droop coefficient (for example, β can be used) according to the steady-state operation parameters. 0 The initial droop coefficient is fixed and is used when the flexible DC interconnection system enters a continuous monitoring and adjustment process (also called entering a cycle). If the system is currently in a power balance state, the VSC will control the power transmission of the system with the initial droop coefficient. The arbitrary constant distributes and adjusts the transmission power of the flexible interconnection system by affecting the control parameters of the VSC. For example, the steady-state operating parameters of the flexible interconnection system may include: power distribution ratio (active power, reactive power), voltage level (DC, AC), current level (DC, AC), power factor (active power, reactive power) and load (static, dynamic) conditions, etc. The steady-state operating parameters can be directly measured by installing sensors or instruments (such as voltage transformers, current transformers, power factor meters, etc.) at key positions of the flexible interconnection system; the operating status of the flexible interconnection system can also be monitored in real time using online monitoring equipment, and the steady-state operating parameters of the system can also be obtained by analyzing the monitoring data. After the steady-state operating parameters of the flexible interconnection system are obtained, it is necessary to determine the initial droop coefficient of the voltage source converter in the system and the value of the arbitrary constant, specifically:

[0077] In one implementation, the process of determining the initial droop coefficient of the voltage source converter in the flexible interconnection system according to the acquired steady-state operating parameters of the flexible interconnection system may include:

[0078] According to the acquired steady-state operation parameters of the flexible interconnection system, a steady-state operation target is set;

[0079] According to the steady-state operation target, the initial droop coefficient of the voltage source converter in the flexible interconnection system is calculated;

[0080] In this implementation, in order to ensure the accuracy and completeness of the collected steady-state operation parameters, before setting the steady-state operation target, it is necessary to clean and verify them, and set the steady-state operation target according to the steady-state operation parameters after cleaning and verification. For example, the steady-state operation target may include: power distribution ratio, node voltage operation range and frequency control range; for example, in terms of power distribution ratio, it is necessary to determine the active power and reactive power distribution ratio between each voltage source converter in the flexible interconnection system, such as the first voltage source converter can be set to bear 40% of the total load, and the second voltage source converter can be set to bear 60% of the total load; in terms of node voltage operation range, it is necessary to ensure that the voltage of all nodes fluctuates within the allowable range, such as setting the range to 0.95pu to 1.05pu; in terms of frequency control range, it is necessary to ensure that the frequency of the system fluctuates within the allowable range, such as setting the range to 49.5Hz to 50.5Hz; after setting the steady-state operation target, the initial droop coefficient of the voltage source converter can be calculated;

[0081] Taking the frequency control range as an example, the initial droop coefficient of the voltage source converter in the flexible interconnection system can be determined as follows:

[0082] Assuming that the frequency reference value of the flexible interconnection system is 50 Hz and the allowable range is 49.5 Hz to 50.5 Hz, the frequency of the system can be controlled by the following calculation formula:

[0083] f=f ref +m j (P j -P ref );

[0084] Where, f represents the system frequency; f ref Indicates the reference frequency; P j is the active power provided by the jth voltage source converter; P ref Indicates reference active power; m j represents the initial droop coefficient of the jth voltage source converter; by adjusting m j , the frequency of the flexible interconnection system can be kept within the allowable range. For example, if the system frequency is too high, the corresponding active power droop coefficient can be appropriately increased to reduce the active power output and the frequency. Through the above steps, the steady-state operation target can be set according to the steady-state operation parameters of the flexible interconnection system, and the initial droop coefficient of the voltage source converter can be calculated, which is conducive to ensuring that the power distribution of the system is reasonable and the node voltage or frequency is within the allowable range when the system is in steady-state operation, thereby improving the stability and reliability of the system.

[0085] In one implementation, any of the above-mentioned constants can be determined by using a simulation optimization method, including:

[0086] Establish mathematical models of flexible interconnection systems in simulation software (such as MATLAB / Simulink, PSCAD, etc.);

[0087] Set different constant values, perform multiple simulations, and record the system's performance indicators (such as DC voltage stability, power regulation capability, etc.) under different working conditions;

[0088] According to the simulation results, the system performance under different values ​​is evaluated and the optimal value is selected. In this implementation, the constant value that minimizes the DC voltage deviation can be found through simulation optimization. When the system power fluctuates greatly, the optimized constant value can more effectively adjust the droop coefficient, which is conducive to reducing oscillation and overshoot during the transition process, thereby maintaining the stability of the DC voltage.

[0089] After the initial droop coefficient and constant value are determined by the above method, it is necessary to judge the current power state of the flexible interconnection system. When the system is in a power balanced state, the voltage source converter controls the power of the system through the initial droop coefficient determined above. When the flexible interconnection system is in a power unbalanced state, the initial droop coefficient can be adaptively updated according to the margin capacity of the voltage source converter, and the power of the flexible interconnection system can be controlled according to the updated droop coefficient (also called adaptive droop coefficient) so as to reasonably allocate the transmission power of each port and keep the DC voltage of the system stable. Specifically:

[0090] In one implementation, the process of updating the initial droop coefficient using the adaptive droop control method according to the obtained margin capacity of the voltage source converter and the initial droop coefficient of the voltage source converter may include:

[0091] When the obtained margin capacity of the voltage source converter is 0, the updated droop coefficient of the voltage source converter is set to a preset value, and the control mode of the voltage source converter is switched to a constant power and constant DC voltage mode;

[0092] When the obtained margin capacity of the voltage source converter is not 0, the initial droop coefficient is updated according to the initial droop coefficient of the voltage source converter by using an adaptive droop coefficient update expression;

[0093] In this implementation, if the current power imbalance of the system is detected (i.e., the flexible interconnection system is in a power imbalance state), the system first determines whether the voltage source converter has a power margin capacity to transmit power. If there is no margin capacity, the adaptive droop coefficient β of the jth voltage source converter is set to jSet to 0, the control mode of the voltage source converter is switched to constant power and constant DC voltage mode; if there is margin capacity, the adaptive droop coefficient update expression is used to update the initial droop coefficient, specifically:

[0094] In this implementation, when the margin capacity of the voltage source converter obtained is not 0, the process of updating the initial droop coefficient according to the initial droop coefficient of the voltage source converter by using an adaptive droop coefficient update expression may include:

[0095] When the obtained margin capacity of the voltage source converter is not 0, determining the margin capacity of the voltage source converter according to the port type to which the voltage source converter belongs;

[0096] According to the initial droop coefficient and margin capacity of the voltage source converter, the initial droop coefficient is updated by using an adaptive droop coefficient update expression; in this implementation, by dynamically adjusting the droop coefficient according to the margin capacity of the voltage source converter, the voltage source converter can be flexibly adjusted according to the actual operating conditions, and this flexibility is conducive to improving the stability and reliability of the power system; and the application of the adaptive droop coefficient can optimize the distribution of power among multiple voltage source converters. For example, in a microgrid or distributed power generation system, multiple voltage source converters may need to operate in parallel to jointly support the grid voltage and provide power. By adaptively adjusting the droop coefficient, it can ensure that the power distribution between the voltage source converters is more balanced, which is conducive to the reasonable distribution of the transmission power of each port, maintaining the stability of the system DC voltage, and avoiding the situation where some converters are overloaded while other converters are lightly loaded; in addition, in this implementation, by optimizing the droop coefficient, the operating efficiency of the voltage source converter can also be improved, and the energy loss of the voltage source converter during the conversion process can be reduced. When the system load changes, the voltage source converter can quickly respond and maintain the stability of the grid voltage by adjusting the droop coefficient, ultimately improving the voltage regulation performance and improving the energy utilization efficiency.

[0097] For example, the adaptive droop coefficient update expression above can be as follows:

[0098] β j =β 0 ×α×H j ;

[0099] Among them, β j represents the updated droop coefficient of voltage source converter j; β 0 represents the initial droop coefficient; H jrepresents the margin capacity of voltage source converter j (i.e., the difference between the rated capacity of the voltage source converter and the actual load); α represents a constant value; In this example, by introducing the margin capacity into the update expression of the droop coefficient, the system can dynamically adjust the droop coefficient according to the actual load of the voltage source converter. When the load changes, the margin capacity will change accordingly, thereby triggering the update of the droop coefficient, so that the system can respond to load changes more quickly and maintain the stability of the grid voltage. In addition, the adaptive droop coefficient can enhance the stability of the system, especially when the grid is disturbed or fails, each voltage source converter can quickly adjust the droop coefficient according to its own margin capacity, thereby jointly maintaining the stable operation of the grid. This mechanism is conducive to reducing grid fluctuations and improving the robustness of the system.

[0100] In this implementation, the process of determining the margin capacity of the voltage source converter according to the port type to which the voltage source converter belongs may include:

[0101] When the port type to which the voltage source converter belongs is an output power port, the corresponding operating power is calculated according to the operating data of the voltage source converter, and the capacity margin of the voltage source converter is determined according to the operating power;

[0102] When the port type to which the voltage source converter belongs is an input power port, the corresponding power consumption is calculated according to the operation data of the voltage source converter, and the capacity margin of the voltage source converter is determined according to the power consumption; in this implementation, when the system determines that the voltage source converter has a margin capacity for transmitting power, the system then determines whether the voltage source converter is a receiving-end VSC (corresponding to the input power port) or a sending-end VSC (corresponding to the output power port), and the system estimates the available power according to the power input of the receiving-end VSC, and determines the capacity margin (for example, using ΔH DV According to the power output of the sending-end VSC, the consumed power is estimated and the capacity margin ΔH is determined. DV , the capacity margin is expressed in the form of DC voltage deviation. For example, the calculation formula of the capacity margin can be as follows:

[0103]

[0104] in, Indicates the DC voltage deviation at the maximum capacity of the voltage source converter; Indicates the DC voltage deviation under the rated capacity of the voltage source converter; in this implementation, by distinguishing the port type (output power or input power) of the voltage source converter and calculating the capacity margin according to its operating data (operating power or consumed power), the actual operating status of the voltage source converter can be more accurately reflected. This precise calculation method is conducive to avoiding the problem of inaccurate margin capacity calculation caused by misjudging the port type or ignoring the operating data, and by accurately calculating the capacity margin and adjusting the droop coefficient accordingly, the operating state of the voltage source converter can be optimized and unnecessary energy loss can be reduced; at the same time, with the development of the power system, new voltage source converters may continue to be added to the flexible interconnection system. By introducing the process of port type judgment and margin capacity calculation, the function of the system can be easily expanded to adapt to the addition of new voltage source converters and different operating requirements. In addition, this adaptive adjustment mechanism is also conducive to improving the reliability of the system, because when the margin capacity of the voltage source converter changes, the system can respond quickly and adjust the droop coefficient to maintain the stable operation of the power grid.

[0105] In this implementation, the above process of calculating the corresponding operating power according to the operating data of the voltage source converter and determining the capacity margin of the voltage source converter according to the operating power may include:

[0106] calculating the available power of the voltage source converter according to the operating data of the voltage source converter;

[0107] Calculate the operating power of the voltage source converter based on the available power;

[0108] The capacity margin of the voltage source converter is obtained by subtracting the available power from the operating power.

[0109] In this implementation, the above process of calculating the corresponding power consumption according to the operation data of the voltage source converter and determining the capacity margin of the voltage source converter according to the power consumption may include:

[0110] Calculating the power consumption of the voltage source converter according to the operating data of the voltage source converter;

[0111] Calculate the actual operating power of the voltage source converter based on the consumed power;

[0112] The consumed power and the actual operating power are subtracted to obtain the capacity margin of the voltage source converter;

[0113] In this implementation, by calculating the available power or consumed power of the voltage source converter based on the operating data, and further calculating the operating power, the current operating state of the voltage source converter can be accurately quantified. This quantification method provides a direct evaluation of the performance of the voltage source converter, which helps the operation and maintenance personnel to understand the health status of the equipment in a timely manner; by performing a difference between the available power (or consumed power) and the operating power, the capacity margin of the voltage source converter can be accurately calculated. The capacity margin is an important indicator to measure the remaining capacity of the voltage source converter, which reflects the reserve capacity of the equipment in response to load changes or failures; by accurately calculating the capacity margin and adjusting the droop coefficient accordingly, the operating state of the voltage source converter can be optimized and unnecessary energy losses can be reduced. At the same time, this adaptive adjustment mechanism is also conducive to improving the reliability of the system, because when the capacity margin of the voltage source converter changes, the system can respond quickly and adjust the droop coefficient to maintain the stable operation of the power grid;

[0114] After completing the above steps, the system will return to the beginning of the loop and check again whether the system power is balanced. When the system power reaches balance or meets other end conditions, the process will end and update the state of the flexible interconnection system according to the initial droop coefficient and the determined constant value.

[0115] In summary, the present invention aims at the problem that the conventional droop control method used to control power transmission in the existing flexible interconnection system cannot cope with complex power fluctuations. When the power fluctuation of the flexible interconnection system is large, the capacity margin of the voltage source converter will change, resulting in a deviation in the DC voltage and the system cannot operate stably. In order to increase the power regulation capability of the flexible interconnection system under complex fluctuations, a control method for the flexible interconnection system based on adaptive droop control is proposed by utilizing the characteristic that the adaptive droop coefficient of the flexible interconnection system is proportional to the capacity margin of the voltage source converter and the DC voltage deviation. Figure 2 As shown, first, according to the steady-state operating parameters of the flexible interconnection system, the initial droop coefficient and constant value are determined, and the power balance state of the flexible interconnection system and the margin capacity of the voltage source converter are judged. If the flexible interconnection system is in a power balance state, the voltage source converter uses a constant droop coefficient to control the flexible interconnection system; if the flexible interconnection system is in a power imbalance state and the voltage source converter has no margin capacity, the droop coefficient is set to 0 and the operation mode of the flexible interconnection system is switched to control. If the voltage source converter has margin capacity, the adaptive droop coefficient is continuously iterated and adjusted according to the port type to which the voltage source converter belongs; the present invention adaptively adjusts the droop coefficient by adaptively adjusting the droop coefficient so that the droop coefficient is adaptively adjusted according to the margin capacity of the voltage source converter and the size of the DC voltage deviation, and switches the operation mode of the voltage source converter according to the actual working conditions when the distributed power generation is connected, so as to reasonably distribute the transmission power of each port; compared with the traditional droop control method, the control method of the present invention has the following advantages:

[0116] 1. Strong power regulation capability: The adaptive droop coefficient can be adaptively adjusted according to changes in operating conditions, so that the controller of the flexible interconnection system has stronger power regulation capability. By iteratively updating the value of the adaptive droop coefficient and continuously monitoring the system power distribution, it can respond to system changes in real time and quickly adjust control parameters to ensure that the system is always in the optimal operating state and effectively respond to large-scale power fluctuations under the access of renewable energy.

[0117] 2. Good DC voltage stability: The design of the adaptive droop coefficient in the present invention takes into account the margin capacity and DC voltage deviation of the voltage source converter, and can switch the working modes of the voltage source converters on the rectifier side and the inverter side when the voltage source converter shuts down or fails. Compared with the conventional droop control method, it can prevent the voltage source converter from being overloaded when the system is highly powered, thereby improving the system's operating efficiency and safety. By reasonably allocating the transmission power of each port, it can smooth out the system's DC voltage fluctuations caused by the volatility and randomness of renewable energy, thereby improving the system's robustness and reliability.

[0118] 3. Strong adaptability: It does not rely on specific system structures and fixed control parameters, but can be adaptively adjusted according to the actual working conditions of the system. The controller can cope with various complex and sudden working conditions, has a fast response speed, can maintain high control accuracy and stability, has strong adaptability and universality, and can be widely used in different types of multi-port flexible interconnection systems. It can also maintain the stability of the system DC voltage and enhance the power regulation capability of the controller, thereby effectively solving the problem of losing power regulation capability under large-scale power fluctuations, achieving power balance in the flexible interconnection system, and maintaining DC voltage stability.

[0119] Embodiment 2:

[0120] In a specific embodiment, a control method of a flexible interconnection system based on adaptive droop control proposed by the present invention is applied to Figure 3 In the four-terminal flexible interconnection system shown in the figure, distributed energy is connected to the system through VSC1 and VSC3 to transmit power to the system, and the two grid-side converters VSC2 and VSC4 absorb power from the system and transmit it to the AC power grid. In this embodiment, VSC1 and VSC3 use fixed active / reactive power control as the outer loop controller, and VSC2 and VSC4 use adaptive droop control / fixed reactive power control as the outer loop controller to generate current reference values ​​of the inner loop controller (for example, I sdref and I sqref ), which acts on the output voltage of the voltage source converter and performs decoupling control (i.e., according to I sdref and I sqref After decoupling control, the voltage reference values ​​U sdrefand U sqref Then perform three-phase conversion (i.e., convert from the dq coordinate system to the abc three-phase coordinate system) to generate the three-phase voltage command value U cref ), and finally, the on-off of the voltage source conversion switch tube is controlled by pulse width modulation (PWM) to adjust the DC voltage and power of the voltage source converter; specifically, the block diagram of the droop control in this embodiment is as follows Figure 4 As shown, the input parameters are: DC voltage reference value (for example, U dcref Indicated), actual value of DC voltage (for example, U dc ) and active power reference value (for example, P ref The output parameters are: droop coefficient and current reference value (for example, I sdref By obtaining the DC voltage reference value U dcref , Actual value of DC voltage U dc and active power reference value P ref , calculate the capacity margin ΔH of the flexible interconnection system DV =U dcref -U dc , and according to the predetermined constant value α and capacity margin ΔH DV , update the droop coefficient; then the active power reference value P ref The actual value of active power (for example, represented by P) is input into the proportional-integral (PI) controller, and the output current reference value I sdref Finally, according to the updated droop coefficient and the actual voltage value U dc Calculate the active power reference value P ref To adjust the active power distribution of each port of the flexible interconnection system, ensure the power balance of the system, and enhance the power regulation capability.

[0121] Therefore, this embodiment can illustrate that a control method for a flexible interconnected system based on adaptive droop control provided by the present invention makes the droop coefficient of the flexible interconnected system proportional to the margin capacity and DC voltage deviation of the voltage source converter, so that it can be adaptively adjusted according to the parameters that change in real time in the system. When the flexible interconnected system faces large-scale power fluctuations, the margin capacity of the voltage source converter will change accordingly, and the DC voltage will also have a corresponding deviation. The adaptive update adjustment of the droop coefficient is conducive to ensuring that the controller can respond to system changes in a timely and accurate manner, so that when facing complex and changeable working conditions, the flexible interconnected system can not only solve the problems of traditional droop controllers in power regulation and DC voltage stability, but also improve the safety and stability of the flexible interconnected system, thereby providing strong technical support for the efficient utilization and flexible configuration of distributed energy.

[0122] Embodiment 3:

[0123] The present invention based on the same inventive concept also provides a control system based on a flexible interconnection system with adaptive droop control, the structural composition diagram is as follows: Figure 5 As shown, including:

[0124] An initial coefficient determination module, used to determine an initial droop coefficient of a voltage source converter in the flexible interconnection system according to the acquired steady-state operation parameters of the flexible interconnection system;

[0125] A droop coefficient updating module is used to update the initial droop coefficient by using an adaptive droop control method according to the obtained margin capacity of the voltage source converter and the initial droop coefficient of the voltage source converter when the flexible interconnection system is in a power imbalance state, so as to obtain an updated droop coefficient;

[0126] The power control module is used to control power transmission of the flexible interconnection system based on the updated droop coefficient.

[0127] In one implementation, the initial coefficient determination module may include:

[0128] A target setting submodule is used to set a steady-state operation target according to the acquired steady-state operation parameters of the flexible interconnection system;

[0129] An initial coefficient calculation submodule, used to calculate an initial droop coefficient of a voltage source converter in a flexible interconnection system according to a steady-state operation target;

[0130] Among them, the steady-state operation targets include: power allocation ratio, node voltage operation range and frequency control range.

[0131] In one implementation, the droop coefficient updating module may include:

[0132] A mode switching submodule, for setting the updated droop coefficient of the voltage source converter to a preset value and switching the control mode of the voltage source converter to a constant power and constant DC voltage mode when the obtained margin capacity of the voltage source converter is 0;

[0133] The coefficient updating submodule is used to update the initial droop coefficient of the voltage source converter by using an adaptive droop coefficient updating expression according to the initial droop coefficient of the voltage source converter when the obtained margin capacity of the voltage source converter is not 0.

[0134] In this implementation, the above coefficient updating submodule may include:

[0135] a capacity determination unit, configured to determine the margin capacity of the voltage source converter according to the port type to which the voltage source converter belongs when the obtained margin capacity of the voltage source converter is not 0;

[0136] The adaptive updating unit is used to update the initial droop coefficient according to the initial droop coefficient and margin capacity of the voltage source converter by using an adaptive droop coefficient updating expression.

[0137] For example, the above adaptive droop coefficient update expression can be as follows:

[0138] β j =β 0 ×α×H j ;

[0139] Among them, β j represents the updated droop coefficient of voltage source converter j; β 0 represents the initial droop coefficient; H j represents the margin capacity of voltage source converter j; α represents a constant value.

[0140] In this implementation, the capacity determination unit may include:

[0141] The sending-end calculation subunit is used to calculate the corresponding operating power according to the operating data of the voltage source converter when the port type to which the voltage source converter belongs is an output power port, and determine the capacity margin of the voltage source converter according to the operating power;

[0142] The receiving end calculation subunit is used to calculate the corresponding power consumption according to the operation data of the voltage source converter when the port type to which the voltage source converter belongs is an input power port, and determine the capacity margin of the voltage source converter according to the power consumption.

[0143] In this implementation, the above-mentioned sending-end computing subunit can be used to:

[0144] calculating the available power of the voltage source converter according to the operating data of the voltage source converter;

[0145] Calculate the operating power of the voltage source converter based on the available power;

[0146] The capacity margin of the voltage source converter is obtained by subtracting the available power from the operating power.

[0147] In this implementation, the receiving end computing subunit may be used to:

[0148] Calculating the power consumption of the voltage source converter according to the operating data of the voltage source converter;

[0149] Calculate the actual operating power of the voltage source converter based on the consumed power;

[0150] The power consumption and the actual operating power are subtracted to obtain the capacity margin of the voltage source converter.

[0151] Embodiment 4:

[0152] like Figure 6 As shown, the present invention also provides an electronic device, which may be a computer device, a single-chip device, an intelligent mobile device, etc. The electronic device in this embodiment may include a processor, a memory, a transceiver component, etc. The memory, the processor, and the transceiver component are connected via a bus; the memory may be used to store an execution program, and an exemplary execution program may include instructions; the processor is used to execute the instructions stored in the memory. The memory may also be used to store data, which may be called and / or modified when the instructions are executed.

[0153] The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc. It is the computing core and control core of the terminal, which is suitable for implementing one or more instructions, specifically suitable for loading and executing one or more instructions in a storage medium to implement the corresponding method flow or corresponding functions, so as to implement the steps of a control method for a flexible interconnection system based on adaptive droop control in the above-mentioned embodiment.

[0154] Embodiment 5:

[0155] Based on the same inventive concept, the present invention also provides a readable storage medium, specifically an electronic device readable storage medium (Memory), which is a memory device in an electronic device for storing programs and data. It can be understood that the storage medium here can include both built-in storage media in the electronic device and, of course, extended storage media supported by the electronic device. The storage medium provides a storage space, which stores the operating system of the terminal. In addition, one or more instructions suitable for being loaded and executed by the processor are also stored in the storage space, and these instructions can be one or more execution programs (including program codes). It should be noted that the storage medium here can be a high-speed RAM memory or a non-volatile memory, such as at least one disk storage. The processor loads and executes one or more instructions stored in the storage medium, which can implement the steps of a control method for a flexible interconnection system based on adaptive droop control in the above embodiment.

[0156] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented 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.

[0157] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0158] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1A function specified in one or more boxes.

[0159] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process in the computer or other programmable device. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0160] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit its protection scope. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that after reading the present invention, those skilled in the art can still make various changes, modifications or equivalent substitutions to the specific implementation methods of the application, but these changes, modifications or equivalent substitutions are all within the protection scope of the claims to be approved.

Claims

1. A control method for a flexible interconnection system based on adaptive droop control, characterized in that: include: Determining an initial droop coefficient of a voltage source converter in the flexible interconnection system according to the acquired steady-state operating parameters of the flexible interconnection system; When the flexible interconnection system is in a power imbalance state, the initial droop coefficient is updated by using an adaptive droop control method according to the obtained margin capacity of the voltage source converter and the initial droop coefficient of the voltage source converter to obtain an updated droop coefficient; Based on the updated droop coefficient, power transmission of the flexible interconnection system is controlled.

2. The method according to claim 1, characterized in that The method of updating the initial droop coefficient by using an adaptive droop control method according to the obtained margin capacity of the voltage source converter and the initial droop coefficient of the voltage source converter comprises: When the obtained margin capacity of the voltage source converter is 0, setting the updated droop coefficient of the voltage source converter to a preset value, and switching the control mode of the voltage source converter to a constant power and constant DC voltage mode; When the obtained margin capacity of the voltage source converter is not 0, the initial droop coefficient is updated according to the initial droop coefficient of the voltage source converter using an adaptive droop coefficient update expression.

3. The method according to claim 2, characterized in that When the margin capacity of the voltage source converter obtained is not 0, updating the initial droop coefficient according to the initial droop coefficient of the voltage source converter by using an adaptive droop coefficient update expression, comprising: When the obtained margin capacity of the voltage source converter is not 0, determining the margin capacity of the voltage source converter according to the port type to which the voltage source converter belongs; According to the initial droop coefficient of the voltage source converter and the margin capacity, the initial droop coefficient is updated using the adaptive droop coefficient update expression.

4. The method according to claim 3, characterized in that The step of determining the margin capacity of the voltage source converter according to the port type to which the voltage source converter belongs comprises: When the port type to which the voltage source converter belongs is an output power port, calculating the corresponding operating power according to the operating data of the voltage source converter, and determining the capacity margin of the voltage source converter according to the operating power; When the port type to which the voltage source converter belongs is an input power port, the corresponding power consumption is calculated according to the operation data of the voltage source converter, and the capacity margin of the voltage source converter is determined according to the power consumption.

5. The method according to claim 4, characterized in that The step of calculating the corresponding operating power according to the operating data of the voltage source converter, and determining the capacity margin of the voltage source converter according to the operating power comprises: calculating the available power of the voltage source converter according to the operating data of the voltage source converter; calculating the operating power of the voltage source converter according to the available power; The available power and the operating power are subtracted to obtain a capacity margin of the voltage source converter.

6. The method according to claim 4, characterized in that The step of calculating the corresponding power consumption according to the operation data of the voltage source converter, and determining the capacity margin of the voltage source converter according to the power consumption includes: calculating the power consumption of the voltage source converter according to the operation data of the voltage source converter; calculating the actual operating power of the voltage source converter according to the consumed power; The power consumption and the actual operating power are subtracted to obtain a capacity margin of the voltage source converter.

7. The method according to any one of claims 2 to 6, characterized in that: The adaptive droop coefficient update expression is as follows: β j ＝β0×α×H j ； Among them, β j represents the updated droop coefficient of voltage source converter j; β0 represents the initial droop coefficient; H j represents the margin capacity of voltage source converter j; α represents a constant value.

8. The method according to claim 1, characterized in that The step of determining an initial droop coefficient of a voltage source converter in the flexible interconnection system according to the acquired steady-state operation parameters of the flexible interconnection system comprises: According to the acquired steady-state operation parameters of the flexible interconnection system, a steady-state operation target is set; Calculating an initial droop coefficient of a voltage source converter in the flexible interconnection system according to the steady-state operation target; The steady-state operation targets include: power allocation ratio, node voltage operation range and frequency control range.

9. A control system for a flexible interconnected system based on adaptive droop control, characterized in that: include: An initial coefficient determination module, used to determine an initial droop coefficient of a voltage source converter in the flexible interconnection system according to the acquired steady-state operation parameters of the flexible interconnection system; a droop coefficient updating module, configured to update the initial droop coefficient by using an adaptive droop control method according to the obtained margin capacity of the voltage source converter and the initial droop coefficient of the voltage source converter when the flexible interconnection system is in a power imbalance state, so as to obtain an updated droop coefficient; A power control module is used to control power transmission of the flexible interconnection system based on the updated droop coefficient.

10. The system according to claim 9, characterized in that The droop coefficient updating module comprises: a mode switching submodule, configured to set the updated droop coefficient of the voltage source converter to a preset value and switch the control mode of the voltage source converter to a constant power and constant DC voltage mode when the obtained margin capacity of the voltage source converter is 0; The coefficient updating submodule is used to update the initial droop coefficient of the voltage source converter by using an adaptive droop coefficient updating expression according to the initial droop coefficient of the voltage source converter when the obtained margin capacity of the voltage source converter is not 0.

11. The system according to claim 10, characterized in that The coefficient updating submodule comprises: a capacity determining unit, configured to determine the margin capacity of the voltage source converter according to the port type to which the voltage source converter belongs when the obtained margin capacity of the voltage source converter is not 0; An adaptive updating unit is used to update the initial droop coefficient of the voltage source converter according to the initial droop coefficient and the margin capacity using the adaptive droop coefficient updating expression.

12. The system according to claim 11, characterized in that The capacity determination unit includes: a sending-end calculation subunit, configured to calculate the corresponding operating power according to the operating data of the voltage source converter when the port type to which the voltage source converter belongs is an output power port, and determine the capacity margin of the voltage source converter according to the operating power; The receiving-end calculation subunit is used to calculate the corresponding power consumption according to the operation data of the voltage source converter when the port type to which the voltage source converter belongs is an input power port, and to determine the capacity margin of the voltage source converter according to the power consumption.

13. The system of claim 12, wherein: The sending-end computing subunit is used for: calculating the available power of the voltage source converter according to the operating data of the voltage source converter; calculating the operating power of the voltage source converter according to the available power; The available power and the operating power are subtracted to obtain a capacity margin of the voltage source converter.

14. The system of claim 12, wherein: The receiving end computing subunit is used for: calculating the power consumption of the voltage source converter according to the operation data of the voltage source converter; calculating the actual operating power of the voltage source converter according to the consumed power; The power consumption and the actual operating power are subtracted to obtain a capacity margin of the voltage source converter.

15. The system according to any one of claims 10 to 14, characterized in that: The adaptive droop coefficient update expression is as follows: β j ＝β0×α×H j ； Among them, β j represents the updated droop coefficient of voltage source converter j; β0 represents the initial droop coefficient; H j represents the margin capacity of voltage source converter j; α represents a constant value.

16. The system of claim 9, wherein: The initial coefficient determination module comprises: A target setting submodule is used to set a steady-state operation target according to the acquired steady-state operation parameters of the flexible interconnection system; An initial coefficient calculation submodule, used to calculate an initial droop coefficient of the voltage source converter in the flexible interconnection system according to the steady-state operation target; The steady-state operation targets include: power allocation ratio, node voltage operation range and frequency control range.

17. An electronic device, characterized in that: include: at least one processor and memory; The memory and the processor are connected via a bus; The memory is used to store one or more programs; When the one or more programs are executed by the at least one processor, a control method for a flexible interconnection system based on adaptive droop control as claimed in any one of claims 1 to 8 is implemented.

18. A computing device readable storage medium, characterized in that: An execution program is stored thereon, and when the execution program is executed, a control method for a flexible interconnection system based on adaptive droop control as described in any one of claims 1 to 8 is implemented.

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