Microgrid control method and device, power supply control method and device

Abstract

Provided are a microgrid control method and device, and a power supply control method and device. The microgrid control method comprises: obtaining impedance values ​​of each power supply cluster in the microgrid; determining whether a dynamic disturbance occurs in the microgrid according to the obtained impedance values; when it is determined that a dynamic disturbance occurs in the microgrid, controlling the microgrid according to the obtained impedance values ​​so as to restore the microgrid to a stable operating state, wherein each power supply cluster comprises at least one group of supporting power supplies and / or at least one group of main supporting power supplies.

Description

Technical Field

[0001] The present disclosure generally relates to the field of electric power technology, and more specifically, to a control method and device for a microgrid, and a control method and device for a power supply. Background Art

[0002] With the development of regional power systems (e.g., regional zero-carbon power systems), system uncertainty and stability are increasingly challenged. Due to the high proportion of renewable energy (hereinafter, also referred to as new energy) access, regional power systems are characterized by weak system inertia, weak stability, weak anti-disturbance capability, and weakened stability recovery capability after faults. How to maintain system stability under disturbance while increasing the penetration rate of renewable energy is an important issue facing people.

[0003] Fluctuations in the output power of large loads or a large number of distributed power sources, as well as faults (such as the occurrence or clearing of faults) will cause serious disturbances to the system. For disturbances, the microgrid dynamic disturbance control system should accurately identify them, and the fault detection signal will quickly return to normal values ​​to ensure that the circuit breaker does not trip. Especially in microgrids of 35kV and below that consume new energy locally, when the penetration rate of new energy is high, it is easy to cause dynamic voltage oscillations and power angle swing problems, which seriously endanger the stable operation of the system and the insulation of the equipment. Summary of the invention

[0004] The exemplary embodiments of the present disclosure provide a microgrid control method and device, and a power supply control method and device, which can quickly and accurately identify whether a dynamic disturbance occurs in the microgrid, and when a dynamic disturbance occurs in the microgrid, control the microgrid to return to a stable operating state.

[0005] According to a first aspect of an embodiment of the present disclosure, a microgrid control method is provided, comprising: obtaining impedance values ​​of each power cluster in the microgrid; determining whether a dynamic disturbance occurs in the microgrid based on the obtained impedance values; when it is determined that a dynamic disturbance occurs in the microgrid, controlling the microgrid based on the obtained impedance values ​​to restore the microgrid to a stable operating state, wherein each power cluster includes at least one group of supporting power supplies and / or at least one group of main supporting power supplies.

[0006] Optionally, based on the acquired impedance value, the step of determining whether a dynamic disturbance occurs in the microgrid includes: when the impedance value at at least one power cluster meets a first preset condition, determining that a dynamic disturbance occurs in the microgrid, wherein the first preset condition is that the duration of being in the first impedance interval reaches a preset duration.

[0007] Optionally, based on the acquired impedance value, the step of controlling the microgrid includes: for each power cluster whose impedance value meets the second preset condition, controlling at least one group of power supplies in the power cluster according to the impedance value at the power cluster, wherein the second preset condition is that the duration of being in the second impedance interval reaches a preset duration, and the first impedance interval includes the second impedance interval.

[0008] Optionally, the step of controlling at least one group of power supplies in the power cluster according to the impedance value at the power cluster includes: performing reactive control on at least one group of supporting power supplies in the power cluster according to the impedance value at the power cluster; and / or performing active control and reactive control on at least one group of main supporting power supplies in the power cluster according to the impedance value at the power cluster.

[0009] Optionally, the step of performing reactive power control on at least one group of supporting power sources in the power cluster according to the impedance value at the power cluster includes: for at least one supporting power source in the at least one group of supporting power sources in the power cluster, determining an output voltage reference value of the corresponding supporting power source according to the impedance value at the power cluster and at least one of the following items, for controlling the supporting power source: the rated voltage of the microgrid, the maximum power tracking value, power factor, output current feedback value, and active output reference value of the corresponding supporting power source.

[0010] Optionally, for at least one supporting power source in at least one group of supporting power sources in the power source cluster, the step of determining the output voltage reference value of the corresponding supporting power source includes: determining the resistive component reference value and the inductive component reference value in the impedance reference value of the corresponding supporting power source based on the maximum power tracking value and the power factor of the corresponding supporting power source and the rated voltage of the microgrid; determining the d-axis component of the output current reference value of the corresponding supporting power source based on the resistive component reference value and the active output reference value of the corresponding supporting power source and the resistive component in the impedance value at the power source cluster; and determining the inductive component of the output current reference value of the corresponding supporting power source based on the maximum power tracking value and the power factor of the corresponding supporting power source and the rated voltage of the microgrid. The d-axis component of the output current reference value and the d-axis component of the output current feedback value are used to determine the d-axis voltage reference value of the corresponding supporting power supply; the q-axis component of the output current reference value of the corresponding supporting power supply is determined based on the inductive component reference value of the corresponding supporting power supply and the inductive component in the impedance value at the power supply cluster, and the q-axis voltage reference value of the corresponding supporting power supply is determined based on the q-axis component of the output current reference value of the corresponding supporting power supply and the q-axis component of the output current feedback value; the d-axis voltage reference value and the q-axis voltage reference value of the corresponding supporting power supply are transformed to obtain the AC output voltage reference value of the corresponding supporting power supply.

[0011] Optionally, the step of performing active control and reactive control on at least one group of main supporting power sources in the power cluster according to the impedance value at the power cluster includes: for at least one main supporting power source in the at least one group of main supporting power sources in the power cluster, determining an output voltage reference value of the corresponding main supporting power source according to the impedance value at the power cluster and at least one of the following items, so as to control the main supporting power source: the rated voltage of the microgrid, the maximum power tracking value, power factor, current feedback value, DC voltage set value, and DC voltage feedback value of the corresponding main supporting power source.

[0012] Optionally, for at least one main supporting type power supply in the at least one group of main supporting type power supplies in the power supply cluster, the step of determining the output voltage reference value of the corresponding main supporting type power supply includes: determining the resistive component reference value and the inductive component reference value in the impedance reference value of the corresponding main supporting type power supply based on the maximum power tracking value and the power factor of the corresponding main supporting type power supply and the rated voltage of the microgrid; determining the d-axis component of the output current reference value of the corresponding main supporting type power supply based on the resistive component reference value, the DC voltage setting value and the DC voltage feedback value of the corresponding main supporting type power supply and the resistive component in the impedance value at the power supply cluster; and determining the inductive ... maximum power tracking value and the power factor of the corresponding main supporting type power supply and the rated voltage of the microgrid. The d-axis component of the output current reference value of the corresponding main supporting type power supply and the d-axis component of the output current feedback value are used to determine the d-axis voltage reference value of the corresponding main supporting type power supply; the q-axis component of the output current reference value of the corresponding main supporting type power supply is determined based on the inductive component reference value of the corresponding main supporting type power supply and the inductive component in the impedance value at the power supply cluster, and the q-axis voltage reference value of the corresponding main supporting type power supply is determined based on the q-axis component of the output current reference value of the corresponding main supporting type power supply and the q-axis component of the output current feedback value; the d-axis voltage reference value and the q-axis voltage reference value of the corresponding main supporting type power supply are transformed to obtain the AC output voltage reference value of the corresponding main supporting type power supply.

[0013] According to a second aspect of an embodiment of the present disclosure, a method for controlling a power supply is provided, comprising: obtaining an impedance value of a power supply cluster where the power supply is located; when the impedance value meets a preset condition, controlling the power supply according to the impedance value so that the microgrid where the power supply cluster is located is restored to a stable operating state, wherein the preset condition includes: a duration of being in a preset impedance interval for a preset duration.

[0014] Optionally, the step of controlling the power supply according to the impedance value includes: when the power supply is a supporting power supply, performing reactive control on the power supply according to the impedance value; and / or, when the power supply is a main supporting power supply, performing active control and reactive control on the power supply according to the impedance value.

[0015] Optionally, when the power supply is a supported power supply, the step of performing reactive power control on the power supply according to the impedance value includes: determining an output voltage reference value of the power supply according to the impedance value and at least one of the following items for controlling the power supply: the rated voltage of the microgrid, the maximum power tracking value, power factor, output current feedback value, and active output reference value of the power supply.

[0016] Optionally, when the power supply is a support type power supply, the step of determining the output voltage reference value of the power supply includes: determining the resistive component reference value and the inductive component reference value in the impedance reference value of the power supply based on the maximum power tracking value and the power factor of the power supply and the rated voltage of the microgrid; determining the d-axis component of the output current reference value of the power supply based on the resistive component reference value and the active output reference value of the power supply and the resistive component in the impedance value, and determining the d-axis voltage reference value of the power supply based on the d-axis component of the output current reference value of the power supply and the d-axis component of the output current feedback value; determining the q-axis component of the output current reference value of the power supply based on the inductive component reference value of the power supply and the inductive component in the impedance value, and determining the q-axis voltage reference value of the power supply based on the q-axis component of the output current reference value of the power supply and the q-axis component of the output current feedback value; transforming the d-axis voltage reference value and the q-axis voltage reference value of the power supply to obtain the AC output voltage reference value of the power supply.

[0017] Optionally, when the power supply is a main support type power supply, the step of performing active control and reactive control on the power supply according to the impedance value includes: determining an output voltage reference value of the power supply according to the impedance value and at least one of the following items for controlling the power supply: the rated voltage of the microgrid, the maximum power tracking value, power factor, current feedback value, DC voltage set value, and DC voltage feedback value of the power supply.

[0018] Optionally, when the power supply is a main support type power supply, the step of determining the output voltage reference value of the power supply includes: determining the resistive component reference value and the inductive component reference value in the impedance reference value of the power supply based on the maximum power tracking value and the power factor of the power supply and the rated voltage of the microgrid; determining the d-axis component of the output current reference value of the power supply based on the resistive component reference value, the DC voltage setting value and the DC voltage feedback value of the power supply, and the resistive component in the impedance value, and determining the d-axis voltage reference value of the power supply based on the d-axis component of the output current reference value of the power supply and the d-axis component of the output current feedback value; determining the q-axis component of the output current reference value of the power supply based on the inductive component reference value of the power supply and the inductive component in the impedance value, and determining the q-axis voltage reference value of the power supply based on the q-axis component of the output current reference value of the power supply and the q-axis component of the output current feedback value; transforming the d-axis voltage reference value and the q-axis voltage reference value of the power supply to obtain the AC output voltage reference value of the power supply.

[0019] According to a third aspect of an embodiment of the present disclosure, a control device for a microgrid is provided, comprising: an impedance acquisition unit, configured to acquire impedance values ​​of each power cluster in the microgrid; a dynamic disturbance judgment unit, configured to determine whether a dynamic disturbance occurs in the microgrid based on the acquired impedance values; and a control unit, configured to control the microgrid based on the acquired impedance values ​​when it is determined that a dynamic disturbance occurs in the microgrid, so as to restore the microgrid to a stable operating state, wherein each power cluster includes at least one group of supporting power supplies and / or at least one group of main supporting power supplies.

[0020] Optionally, the dynamic disturbance judgment unit is configured to: determine that a dynamic disturbance occurs in the microgrid when the impedance value at at least one power cluster meets a first preset condition, wherein the first preset condition is that the duration of being in the first impedance interval reaches a preset duration.

[0021] Optionally, the control unit is configured to: for each power supply cluster whose impedance value meets a second preset condition, control at least one group of power supplies in the power supply cluster according to the impedance value at the power supply cluster, wherein the second preset condition is that the duration of being in the second impedance interval reaches a preset duration, and the first impedance interval includes the second impedance interval.

[0022] Optionally, the control unit is configured to: for each power supply cluster whose impedance value meets the second preset condition, perform reactive control on at least one group of supporting power supplies in the power supply cluster according to the impedance value at the power supply cluster; and / or perform active control and reactive control on at least one group of main supporting power supplies in the power supply cluster according to the impedance value at the power supply cluster.

[0023] Optionally, the control unit is configured to: for at least one supporting power supply in at least one group of supporting power supplies in the power supply cluster, determine the output voltage reference value of the corresponding supporting power supply according to the impedance value at the power supply cluster and at least one of the following items, so as to control the supporting power supply: the rated voltage of the microgrid, the maximum power tracking value, power factor, output current feedback value, and active output reference value of the corresponding supporting power supply.

[0024] Optionally, the control unit is configured to: determine the resistive component reference value and the inductive component reference value in the impedance reference value of the corresponding supporting power supply based on the maximum power tracking value and the power factor of the corresponding supporting power supply and the rated voltage of the microgrid; determine the d-axis component of the output current reference value of the corresponding supporting power supply based on the resistive component reference value and the active output reference value of the corresponding supporting power supply and the resistive component in the impedance value at the power supply cluster, and determine the d-axis voltage reference value of the corresponding supporting power supply based on the d-axis component of the output current reference value of the corresponding supporting power supply and the d-axis component of the output current feedback value; determine the q-axis component of the output current reference value of the corresponding supporting power supply based on the inductive component reference value of the corresponding supporting power supply and the inductive component in the impedance value at the power supply cluster, and determine the q-axis voltage reference value of the corresponding supporting power supply based on the q-axis component of the output current reference value of the corresponding supporting power supply and the q-axis component of the output current feedback value; transform the d-axis voltage reference value and the q-axis voltage reference value of the corresponding supporting power supply to obtain the AC output voltage reference value of the corresponding supporting power supply.

[0025] Optionally, the control unit is configured to: for at least one main supporting type power supply in at least one group of main supporting type power supplies in the power supply cluster, determine the output voltage reference value of the corresponding main supporting type power supply according to the impedance value at the power supply cluster and at least one of the following items, so as to control the main supporting type power supply: the rated voltage of the microgrid, the maximum power tracking value, power factor, current feedback value, DC voltage set value, and DC voltage feedback value of the corresponding main supporting type power supply.

[0026] Optionally, the control unit is configured to: determine the resistive component reference value and the inductive component reference value in the impedance reference value of the corresponding main supporting type power supply based on the maximum power tracking value and the power factor of the corresponding main supporting type power supply and the rated voltage of the microgrid; determine the d-axis component of the output current reference value of the corresponding main supporting type power supply based on the resistive component reference value, the DC voltage setting value and the DC voltage feedback value of the corresponding main supporting type power supply and the resistive component in the impedance value at the power supply cluster; and determine the d-axis component of the output current reference value and the output current feedback value of the corresponding main supporting type power supply based on the d-axis component of the output current reference value and the output current feedback value of the corresponding main supporting type power supply. The d-axis component of the corresponding main supporting type power supply is used to determine the d-axis voltage reference value of the corresponding main supporting type power supply; the q-axis component of the output current reference value of the corresponding main supporting type power supply is determined based on the inductive component reference value of the corresponding main supporting type power supply and the inductive component in the impedance value at the power supply cluster, and the q-axis voltage reference value of the corresponding main supporting type power supply is determined based on the q-axis component of the output current reference value of the corresponding main supporting type power supply and the q-axis component of the output current feedback value; the d-axis voltage reference value and the q-axis voltage reference value of the corresponding main supporting type power supply are transformed to obtain the AC output voltage reference value of the corresponding main supporting type power supply.

[0027] According to a fourth aspect of an embodiment of the present disclosure, a control device for a power supply is provided, comprising: an impedance acquisition unit, configured to acquire an impedance value of a power supply cluster where the power supply is located; and a control unit, configured to control the power supply according to the impedance value when the impedance value meets a preset condition, so as to restore the microgrid where the power supply cluster is located to a stable operating state, wherein the preset condition includes: a duration of being continuously in a preset impedance interval reaches a preset duration.

[0028] Optionally, the control unit is configured to: when the power supply is a supporting power supply, perform reactive control on the power supply according to the impedance value; and / or, when the power supply is a main supporting power supply, perform active control and reactive control on the power supply according to the impedance value.

[0029] Optionally, the control unit is configured to: when the power supply is a supporting power supply, determine the output voltage reference value of the power supply based on the impedance value and at least one of the following items for controlling the power supply: the rated voltage of the microgrid, the maximum power tracking value, power factor, output current feedback value, and active output reference value of the power supply.

[0030] Optionally, the control unit is configured to: determine the resistive component reference value and the inductive component reference value in the impedance reference value of the power supply based on the maximum power tracking value and the power factor of the power supply, and the rated voltage of the microgrid; determine the d-axis component of the output current reference value of the power supply based on the resistive component reference value and the active output reference value of the power supply, and the resistive component in the impedance value, and determine the d-axis voltage reference value of the power supply based on the d-axis component of the output current reference value of the power supply and the d-axis component of the output current feedback value; determine the q-axis component of the output current reference value of the power supply based on the inductive component reference value of the power supply and the inductive component in the impedance value, and determine the q-axis voltage reference value of the power supply based on the q-axis component of the output current reference value of the power supply and the q-axis component of the output current feedback value; transform the d-axis voltage reference value and the q-axis voltage reference value of the power supply to obtain the AC output voltage reference value of the power supply.

[0031] Optionally, the control unit is configured to: when the power supply is a main support type power supply, determine the output voltage reference value of the power supply according to the impedance value and at least one of the following items, so as to control the power supply: the rated voltage of the microgrid, the maximum power tracking value, power factor, current feedback value, DC voltage set value, and DC voltage feedback value of the power supply.

[0032] Optionally, the control unit is configured to: determine the resistive component reference value and the inductive component reference value in the impedance reference value of the power supply based on the maximum power tracking value and the power factor of the power supply, and the rated voltage of the microgrid; determine the d-axis component of the output current reference value of the power supply based on the resistive component reference value, the DC voltage setting value and the DC voltage feedback value of the power supply, and the resistive component in the impedance value, and determine the d-axis voltage reference value of the power supply based on the d-axis component of the output current reference value of the power supply and the d-axis component of the output current feedback value; determine the q-axis component of the output current reference value of the power supply based on the inductive component reference value of the power supply and the inductive component in the impedance value, and determine the q-axis voltage reference value of the power supply based on the q-axis component of the output current reference value of the power supply and the q-axis component of the output current feedback value; transform the d-axis voltage reference value and the q-axis voltage reference value of the power supply to obtain the AC output voltage reference value of the power supply.

[0033] According to a fifth aspect of an embodiment of the present disclosure, a computer-readable storage medium storing a computer program is provided. When the computer program is executed by a processor, it prompts the processor to execute the microgrid control method as described above or the power supply control method as described above.

[0034] According to a sixth aspect of an embodiment of the present disclosure, a controller of a microgrid is provided, the controller comprising: a processor; and a memory storing a computer program, wherein when the computer program is executed by the processor, the processor is prompted to execute the control method of the microgrid as described above.

[0035] According to a seventh aspect of an embodiment of the present disclosure, a controller of a power supply is provided, the controller comprising: a processor; and a memory storing a computer program, wherein when the computer program is executed by the processor, the processor is prompted to execute the power supply control method as described above.

[0036] According to the control method and device of the microgrid and the control method and device of the power supply of the exemplary embodiments of the present disclosure, whether a dynamic disturbance occurs in the microgrid is identified by measuring the impedance value at the main supporting power supply and / or the supporting power supply point of the microgrid, and when a dynamic disturbance occurs in the microgrid, the microgrid is controlled to return to a stable operating state based on the measured impedance value.

[0037] Additional aspects and / or advantages of the present general inventive concept will be set forth in part in the following description and in part will be apparent from the description or may be learned through practice of the present general inventive concept. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The above and other objects and features of the exemplary embodiments of the present disclosure will become more apparent through the following description in conjunction with the accompanying drawings which exemplarily illustrate the embodiments, in which:

[0039] Figure 1 A topology diagram showing a microgrid system according to an exemplary embodiment of the present disclosure;

[0040] Figure 2 shows a measured voltage curve in a stable operation state of a microgrid according to an exemplary embodiment of the present disclosure;

[0041] Figure 3 A voltage and current vector diagram is shown in a microgrid in a stable operation state according to an exemplary embodiment of the present disclosure;

[0042] Figure 4 shows a measured voltage and current curve in a microgrid dynamically unstable operating state according to an exemplary embodiment of the present disclosure;

[0043] Figure 5 A voltage and current vector diagram is shown in a microgrid under a dynamic unstable operation state according to an exemplary embodiment of the present disclosure;

[0044] Figure 6 A flow chart showing a control method of a microgrid according to an exemplary embodiment of the present disclosure;

[0045] Figure 7 An impedance calculation equivalent diagram according to an exemplary embodiment of the present disclosure is shown;

[0046] Figure 8 A measured impedance diagram showing a microgrid system when it is dynamically unstable according to an exemplary embodiment of the present disclosure;

[0047] Fig. 9 A schematic diagram showing various ranges of oscillation intervals according to an exemplary embodiment of the present disclosure;

[0048] Fig.10 A flowchart showing a method for determining an output voltage reference value of a supporting power supply in a power cluster according to an impedance value at the power cluster according to an exemplary embodiment of the present disclosure;

[0049] Fig.11 and Fig.12 A block diagram showing a method of determining an output voltage reference value of a supporting power supply in a power supply cluster according to an impedance value at the power supply cluster according to an exemplary embodiment of the present disclosure;

[0050] Fig.13 A flowchart showing a method for determining an output voltage reference value of a main support type power supply in a power cluster according to an impedance value at the power cluster according to an exemplary embodiment of the present disclosure;

[0051] Fig.14 and Fig.15 A block diagram showing a method of determining an output voltage reference value of a main support type power supply in a power cluster according to an impedance value at the power cluster according to an exemplary embodiment of the present disclosure;

[0052] Fig.16 A flow chart showing a method of controlling a power supply according to an exemplary embodiment of the present disclosure;

[0053] Fig.17 A flow chart showing a method for determining an output voltage reference value of a power supply according to an impedance value according to an exemplary embodiment of the present disclosure;

[0054] Fig.18 A flow chart showing a method for determining an output voltage reference value of a power supply according to an impedance value according to another exemplary embodiment of the present disclosure;

[0055] Fig.19 A structural block diagram showing a control device of a microgrid according to an exemplary embodiment of the present disclosure;

[0056] Fig. 20 A structural block diagram of a power supply control device according to an exemplary embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0057] Reference will now be made in detail to the embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like parts throughout. The embodiments will be described below with reference to the drawings in order to explain the present disclosure.

[0058] The voltage level of a larger-capacity microgrid is generally a local power system below 35kV. In addition to the traditional power system and substation, the rest is mainly a power system consisting of loads, distributed renewable energy, energy storage and other primary systems, as well as protection, stability and control and other secondary systems. Figure 1 A topology diagram of a microgrid system according to an exemplary embodiment of the present disclosure is shown. The microgrid system can operate independently or in weak connection with a grid system.

[0059] like Figure 1 As shown in the figure, the microgrid system mainly includes a grid main supporting converter type generator (Grid forming CBG, referred to as the grid main supporting power source), a grid following converter type generator (Grid following CBG, referred to as the grid following power source), a grid supporting converter type generator (Grid supporting CBG, referred to as the grid supporting power source), a microgrid internal load, and a transmission and distribution line. The bus voltage level of each section of the microgrid system is usually 10kV to 35kV. The grid main supporting power source (Grid forming CBG) can be defined as: a generator connected to the grid through a controllable voltage source converter, which has the ability to control the grid voltage and frequency. The grid supporting power source (Grid supporting CBG) can be defined as: a generator connected to the grid through a voltage source or current source converter, which has the ability to actively assist in regulating the grid frequency and voltage. The grid following power source (Grid following CBG) can be defined as: a generator connected to the grid through a current source converter, which does not have the ability to actively assist in regulating the grid frequency and voltage.

[0060] Below Figure 1Each node in the microgrid system topology shown is explained. Bus I represents the first section of the microgrid bus segment, bus II represents the second section of the microgrid bus segment, and bus III represents the third section of the microgrid bus segment. The microgrid is connected to the main grid through bus II section, and the voltage of the grid connection point (POC) is generally at a voltage level of 10kV to 35kV. CB4, CB8, and CB12 on each section of the bus are load circuit breakers, and the outgoing lines on the bus are powered by low voltage through step-down transformers. CB2, CB6, and CB10 on each section of the bus are photovoltaic power generation circuit breakers, and the photovoltaic power generation units are connected to each section of the bus through step-up transformers. CB1, CB5, and CB9 on each section of the bus are wind turbine outgoing line circuit breakers, and wind turbine generator sets are connected to each section of the bus through step-up transformers. CB3, CB7, and CB11 on each section of the bus are energy storage circuit breakers, and energy storage is connected to each section of the bus through step-up transformers. CB15 is the grid connection point where the microgrid is located (i.e. Figure 1 CB13 and CB44 represent busbar circuit breakers. Figure 1 In this system, energy storage is used as the main supporting power source of the grid (Grid forming CBG), photovoltaic and wind turbines can be used as grid supporting power sources (Grid supporting CBG), and photovoltaic or wind turbines can also be used as grid following power sources (Grid following CBG).

[0061] It should be understood that the present disclosure is not limited to a voltage level of 10 kV, but is still applicable to other voltage levels such as 20 kV, 35 kV, 400 V, etc. Figure 1 The main connection form shown can also be applied to single bus without segmentation, other single bus with multiple segments, double bus connection, ring network power supply line structure and radial area structure. At the same time, the voltage level of the load node is not limited to 10kV, and it is still applicable to other nodes that meet the medium and low voltage level specifications. The grid main supporting power supply (Grid forming CBG) involved in the present disclosure is not limited to energy storage, and it is still applicable to other forms of stable power supplies, such as micro-turbines and gas turbines. The grid supporting power supply (Grid supporting CBG) and grid following power supply (Grid following CBG) involved in the present disclosure are also not limited to photovoltaic and wind turbines. All other power supplies that meet the definition are within the protection scope.

[0062] When the microgrid operates in normal mode, for example, the penetration rate of new energy is low and the load is small, for example, at this time, one wind turbine generator and one photovoltaic generator are connected to the microgrid system. Since the load power matches the power generation power and energy storage capacity, the change law of the voltage and current of the microgrid relative to the large grid in this operating state can be as follows: Figure 2 and3 shown.

[0063] When the load in the microgrid increases and the penetration rate of renewable energy increases, for example, the number of wind turbines and photovoltaic generators increases to two each, the microgrid system may experience dynamic instability (dynamic disturbance). The change law of the voltage and current of the microgrid relative to the large grid in this operating state can be shown as follows: Figure 4 and Figure 5 Microgrid dynamic disturbance refers to severe changes in microgrid voltage and current caused by factors such as a sufficiently high proportion of renewable energy generation, nonlinear loads, planned islands, intermittent renewable energy and output power fluctuations, and grid-side faults. The duration of the change is between 50 milliseconds and 2 seconds.

[0064] Figure 4 The dotted line in the figure represents the voltage of the microgrid in a dynamic unstable state, and the solid line represents the corresponding current. It can be seen that relative to Figure 2 , Figure 4 The voltage and current in the circuit repeat once after three cycles, that is, the power angle changes once every three cycles; and, compared with Figure 3 ,from Figure 5 It can also be seen that the ratio of voltage to current (impedance value) and the angle between voltage and current (power factor angle) are changing, both changing once every three cycles, and returning to the initial value after three cycles. It can be seen that too high a penetration rate of new energy sources can easily induce dynamic instability in microgrids, resulting in dynamic voltage oscillations accompanied by power angle swings, which seriously endangers the stable operation of the system and the insulation of the equipment.

[0065] The current methods to solve the problems of voltage oscillation and power angle swing in power systems mainly focus on increasing system inertia and damping. However, the power system dominated by new energy sources mainly uses power electronic equipment as converters, and the system has low rotational inertia. The system damping can be improved by directly connecting the rotating generator to the power system. However, the energy input of the rotating generator mainly relies on traditional oil and gas, which is not conducive to carbon emissions and environmental indicators. Secondly, the disturbance source and non-important loads can also be removed by relay protection devices, but doing so will reduce the reliability and economy of the system power supply on the one hand, and on the other hand, the control and protection cannot form a good coordination, which will further expand the scope of the accident. Third, improve the quality of the power supply of the system by installing filters. However, in the case of dynamic voltage oscillation accompanied by power angle swing, harmonics may not be the main cause, and harmonic control may not be effective.

[0066] In view of the above problems, the present disclosure proposes a control method and device for a microgrid, and a control method and device for a power supply, which can identify whether a dynamic oscillation occurs in the microgrid system according to the impedance values ​​measured at the microgrid main support type power supply and the microgrid support type power supply point, and when dynamic oscillation occurs in the microgrid system, control the microgrid system to recover to a stable operating state. Thus, the microgrid system can operate stably even at a high penetration rate, avoiding the phenomena of relay protection tripping, safety automatic device operation decoupling, and power frequency overvoltage damage to insulation caused by unstable dynamic oscillation.

[0067] It should be understood that the microgrid control method and device, and the power supply control method and device according to the present disclosure can be applied not only to the above-mentioned exemplified scenarios, but also to other suitable scenarios, and the present disclosure does not limit this.

[0068] Figure 6 A flow chart showing a control method of a microgrid according to an exemplary embodiment of the present disclosure is shown. As an example, the control method of a microgrid according to an exemplary embodiment of the present disclosure may be executed by a controller of the microgrid.

[0069] Reference Figure 6 , in step S101, the impedance value of each power cluster in the microgrid is obtained.

[0070] Each power supply cluster includes at least one group of supporting power supplies and / or at least one group of main supporting power supplies. Each group of supporting power supplies may include at least one supporting power supply. Each group of main supporting power supplies may include at least one main supporting power supply.

[0071] As an example, the type of supporting power source may include but is not limited to at least one of the following items: a wind turbine generator set, a photovoltaic power generation unit. It should be understood that other types of new energy power generation units may also be included, and the present disclosure does not limit this.

[0072] As an example, the type of the main support type power source may include but is not limited to at least one of the following items: energy storage device, micro-turbine, gas turbine. It should be understood that other types of stable power sources may also be included, and the present disclosure does not limit this.

[0073] As an example, the above-mentioned power clusters in the microgrid may be pre-divided according to an appropriate division method, and a corresponding impedance measurement device may be installed for each power cluster to measure the impedance value at each power cluster.

[0074] As an example, the impedance value at the output end of each power cluster may be measured. For example, the impedance value at the output end (ie, the high-voltage side output end) of the boost transformer of each power cluster may be measured.

[0075] It should be understood that the types of supporting power sources included in the same power cluster may be the same or different, and the types of main supporting power sources included in the same power cluster may be the same or different. For example, a cluster consisting of multiple wind turbines can be divided into a power cluster, and multiple photovoltaic power generation units can be divided into a power cluster; or, multiple wind turbines and multiple photovoltaic power generation units can be divided into a power cluster. For example, at least one energy storage device can be divided into a power cluster.

[0076] As an example, see Figure 1 , Figure 1 The "wind turbine" on each bus section in the figure may refer to a power cluster composed of at least one wind turbine generator set, the "photovoltaic" on each bus section may refer to a power cluster composed of at least one photovoltaic power generation unit, and the "energy storage" on each bus section may refer to a power cluster composed of at least one energy storage device. Accordingly, an impedance measuring device may be provided near the output end of the step-up transformer of each power cluster to measure the impedance value at each power cluster in real time. In addition, as another example, the main supporting power source and the supporting power source under each bus section may be divided into a power cluster.

[0077] In step S102, it is determined whether a dynamic disturbance occurs in the microgrid according to the acquired impedance value.

[0078] As an example, when the impedance value at at least one power cluster satisfies a first preset condition, it is determined that the microgrid has a dynamic disturbance. For example, the first preset condition may be that the duration of being in the first impedance interval reaches a preset duration.

[0079] The present disclosure takes into account that the dynamic instability of the microgrid is mainly manifested in that the oscillation frequency is not fixed and is basically in the subsynchronous range, and the power angle swings quickly. Figure 4 and Figure 5 , it can be calculated that during the period of dynamic instability, the measured impedance will change. In order to more clearly describe the principle of measuring impedance determination, the equivalent schematic diagram is used as follows Figure 7 As shown, oscillation occurs during the operation of the microgrid, and the current can be expressed as follows:

[0080]

[0081] in, Represents the generator output current, Indicates the generator terminal voltage, Represents the voltage at the grid bus N, M represents the generator bus, N represents the grid bus, Z M represents the generator impedance, Z L Represents the line impedance, Z N Represents the grid impedance, Z Σ=Z M +Z L +Z N ,

[0082] Bus voltage at point M It is expressed as:

[0083]

[0084] The measured impedance at point M can be expressed as:

[0085]

[0086] Among them, Z MM represents the measured impedance at the machine end, h represents the ratio of the bus voltage at point M to the bus voltage at point N, and δ represents the power angle; due to the short lines in the microgrid, it can be approximately considered that h=1 in the above formula. Then further deduction is:

[0087]

[0088] From this, we can get the measured impedance value when the microgrid system oscillates. Figure 8 As shown, according to the above content and Figure 8 When the microgrid system is dynamically unstable and oscillating, the measured impedance will move quickly along the dotted line. Figure 8 At point O in the graph, the maximum oscillation amplitude under this operating condition will occur.

[0089] return Figure 6 When it is determined in step S102 that a dynamic disturbance occurs in the microgrid, step S103 is executed to control the microgrid according to the acquired impedance value so as to restore the microgrid to a stable operating state.

[0090] As an example, the stable operation state of the microgrid may mean that the frequency of the microgrid is within a specific frequency range, and the voltage of the microgrid is within a specific voltage range.

[0091] As an example, for each power cluster whose impedance value meets the second preset condition, at least one group of power supplies in the power cluster may be controlled according to the impedance value at the power cluster. In other words, when the impedance value at a power cluster meets the second preset condition, at least one power supply in at least one group of power supplies in the power cluster is controlled according to the impedance value at the power cluster. It should be understood that all or part of the power supplies in the power cluster may be controlled according to the impedance value at the power cluster.

[0092] As an example, the second preset condition may be that the duration of being in the second impedance interval reaches a preset duration, the first impedance interval includes the second impedance interval, that is, the range of the first impedance interval is greater than the range of the second impedance interval, and the range of the second impedance interval is within the range of the first impedance interval.

[0093] As an example, step S103 may include: for each power cluster whose impedance value meets the second preset condition, performing reactive control on at least one group of supporting power sources in the power cluster according to the impedance value at the power cluster; and / or performing active control and reactive control on at least one group of main supporting power sources in the power cluster according to the impedance value at the power cluster.

[0094] By performing reactive power auxiliary control on microgrid-supported power sources, the reactive output characteristics and active flexible regulation advantages of distributed wind turbines and photovoltaic power sources can be fully utilized, and a reasonable control strategy is designed for dynamic stability control of microgrids. The reactive support characteristics and flexible active auxiliary characteristics of renewable energy are fully utilized, and the resources and capabilities of renewable energy are fully utilized, ensuring the improvement of the high quality and high penetration rate of green energy, and guaranteeing the economic benefits of electricity use for users.

[0095] By performing active and reactive power control on the grid-generated power source (i.e., the main supporting power source) in the microgrid, the grid-generated power source in the microgrid is composed of a stable power source, which can ensure the frequency stability and voltage stability of the system over a long period of time. For rapid swings in the power angle, the swing in the power angle can be quickly smoothed by controlling the power source that can quickly respond to active output.

[0096] Fig. 9 A schematic diagram showing various ranges of oscillation intervals according to an exemplary embodiment of the present disclosure.

[0097] The first case: Usually when the microgrid is running at low load and the penetration rate of new energy is less than 30%, the more power electronic equipment in the system is connected in parallel, the more likely it is to cause the system dynamic oscillation instability, which manifests as continuous oscillation and obvious noise. In this stage, the measured impedance is large, and the oscillation power angle swing range is usually around 30°, corresponding to Fig. 9 In (a), the measured impedance at this time will only be in the oscillation interval 1. In this oscillation mode, the oscillation can be eliminated by stopping part of the grid-following power supplies and increasing the output power of the grid-generated power supplies. The control scheme of the main supporting power supply and / or the supporting power supply as described in the above exemplary embodiment can also be used to smooth it out to ensure stable operation of the system.

[0098] The second case: When the load of the microgrid system increases, the penetration rate of new energy is between 30% and 70%, and multiple power supplies are required to supply power at the same time, the microgrid system is prone to dynamic unstable oscillation. The oscillation amplitude and power angle swing are more serious than the previous case. At this time, the measured impedance is smaller than that in the first case, and the oscillation power angle swing can reach about 60°, corresponding to Fig. 9 In (b), the measured impedance at this time enters the oscillation interval 2, but does not enter the oscillation interval 3. In this oscillation mode, reliable power supply of the load must be ensured, so the power supply cannot be cut off first, and the control scheme of the main supporting power supply and / or the supporting power supply as described in the above exemplary embodiment needs to be adopted to smooth it out and ensure stable operation of the system.

[0099] The third case: When the system load increases and the penetration rate of new energy reaches more than 70%, the microgrid system is very likely to cause dynamic oscillation problems. The oscillation phenomenon caused may be the most serious. At this time, the measured impedance is smaller, the oscillation power swing is larger, and even the oscillation center appears inside the main supporting power supply of the microgrid, corresponding to Fig. 9 (c), the measured impedance at this time enters the oscillation interval 3. In this oscillation mode, it should be coordinated with the microgrid relay protection to ensure the safe and stable operation of the system.

[0100] As an example, the first impedance interval may include: oscillation interval 1, oscillation interval 2, and oscillation interval 3. As an example, the second impedance interval may include: oscillation interval 1 and oscillation interval 2.

[0101] As an example, according to the impedance value at the power cluster, the step of performing reactive power control on at least one group of supporting power sources in the power cluster may include: for at least one supporting power source in the at least one group of supporting power sources in the power cluster, determining the output voltage reference value of the corresponding supporting power source according to the impedance value at the power cluster and at least one of the following items, so as to control the supporting power source: the rated voltage of the microgrid, the maximum power tracking value, power factor, output current feedback value, and active output reference value of the corresponding supporting power source. Figures 10 to 12 An exemplary embodiment of this step is described below.

[0102] As an example, according to the impedance value at the power supply cluster, the step of performing active control and reactive control on at least one group of main supporting power supplies in the power supply cluster may include: for at least one main supporting power supply in at least one group of main supporting power supplies in the power supply cluster, determining the output voltage reference value of the corresponding main supporting power supply according to the impedance value at the power supply cluster and at least one of the following items, so as to control the main supporting power supply: the rated voltage of the microgrid, the maximum power tracking value, power factor, current feedback value, DC voltage setting value, and DC voltage feedback value of the corresponding main supporting power supply. Figures 13 to 15An exemplary embodiment of this step is described below.

[0103] Fig.10 A flow chart illustrating a method of determining an output voltage reference value of a supporting power supply in a power cluster according to an impedance value at the power cluster according to an exemplary embodiment of the present disclosure.

[0104] Reference Fig.10 In step S201, based on the maximum power tracking value MPPT and the power factor PF of the supporting power source and the rated voltage of the microgrid, the resistive component reference value and the inductive component reference value in the impedance reference value of the supporting power source are determined.

[0105] In step S202, based on the resistive component reference value and active output reference value of the supporting power supply and the resistive component in the impedance value at the power supply cluster, the d-axis component of the output current reference value of the supporting power supply is determined, and based on the d-axis component of the output current reference value of the supporting power supply and the d-axis component of the output current feedback value, the d-axis voltage reference value of the supporting power supply is determined.

[0106] Reference Fig.11 , the output of the conventional control outer loop of the new energy (i.e., the supporting power source) is: the active output reference value of the supporting power source. As an example, Fig.11 As shown, the d-axis component i of the output current reference value of the supporting power supply can be obtained based on the resistive component in the impedance value at the power supply cluster, the resistive component reference value of the supporting power supply after filtering, and the active output reference value of the supporting power supply after limiting processing. fdref ; Then, the d-axis component i of the output current reference value of the supporting power supply fdref The d-axis component i of the output current feedback value fd The difference between the two is input into the first PI controller, and the output of the first PI controller after the limiting process is used as the d-axis voltage reference value v of the supporting power supply. fd .

[0107] In step S203, based on the inductive component reference value of the supporting power supply and the inductive component in the impedance value at the power supply cluster, the q-axis component of the output current reference value of the supporting power supply is determined, and based on the q-axis component of the output current reference value of the supporting power supply and the q-axis component of the output current feedback value, the q-axis voltage reference value of the supporting power supply is determined.

[0108] As an example, Fig.12 As shown, the q-axis component i of the output current reference value of the supporting power supply can be obtained based on the inductive component in the impedance value at the power supply cluster and the filtered inductive component reference value of the supporting power supply. fqref ; Then, the q-axis component i of the output current reference value of the supporting power supply fqrefThe q-axis component i of the output current feedback value fq The difference between the two is input into the second PI controller, and the output of the second PI controller after the limiting process is used as the q-axis voltage reference value v of the supporting power supply. fq .

[0109] In step S204, the d-axis voltage reference value and the q-axis voltage reference value of the supporting power supply are transformed to obtain an AC output voltage reference value of the supporting power supply.

[0110] As an example, the obtained AC output voltage reference value of the supporting power supply can act on the converter of the supporting power supply. As another example, the supporting power supply can also include additional auxiliary equipment (for example, a reactive power compensation device). When the supporting power supply includes the auxiliary equipment, the obtained AC output voltage reference value of the supporting power supply can act on the auxiliary equipment.

[0111] According to an exemplary embodiment of the present disclosure, supporting power sources with "intermittency, uncertainty and volatility" such as wind turbines and photovoltaic power generation units are used as disturbance sources, and the disturbance amount injected into the microgrid is extracted, that is, the measured impedance of the real-time operation of the disturbance source is used as the feedback value, and the real-time maximum power tracking value, power factor and rated voltage of the microgrid system are used as references to control the system stability.

[0112] Fig.13 A flow chart illustrating a method of determining an output voltage reference value of a main support-type power supply in a power cluster according to an impedance value at the power cluster according to an exemplary embodiment of the present disclosure.

[0113] Reference Fig.13 In step S301, based on the maximum power tracking value and power factor of the main supporting power source and the rated voltage of the microgrid, the resistive component reference value and the inductive component reference value in the impedance reference value of the main supporting power source are determined.

[0114] In step S302, based on the resistive component reference value, the DC voltage setting value and the DC voltage feedback value of the main supporting type power supply, and the resistive component in the impedance value at the power supply cluster, the d-axis component of the output current reference value of the main supporting type power supply is determined, and based on the d-axis component of the output current reference value of the main supporting type power supply and the d-axis component of the output current feedback value, the d-axis voltage reference value of the corresponding main supporting type power supply is determined.

[0115] As an example, Fig.14As shown, the difference between the DC voltage setting value (i.e., DC voltage reference) and the DC voltage feedback value of the main supporting power supply can be input into the third PI controller; based on the resistive component in the impedance value at the power supply cluster, the resistive component reference value of the main supporting power supply after filtering, and the output of the third PI controller after the limiting process, the d-axis component i of the output current reference value of the main supporting power supply can be obtained. fdref Then, the d-axis component i of the output current reference value of the main support power supply is fdref The d-axis component i of the output current feedback value fd The difference between the two is input into the fourth PI controller, and the output of the fourth PI controller after the limiting process is used as the d-axis voltage reference value v of the main support type power supply fd .

[0116] In step S303, based on the inductive component reference value of the main supporting type power supply and the inductive component in the impedance value at the power supply cluster, the q-axis component of the output current reference value of the main supporting type power supply is determined, and based on the q-axis component of the output current reference value of the main supporting type power supply and the q-axis component of the output current feedback value, the q-axis voltage reference value of the main supporting type power supply is determined.

[0117] As an example, Fig.15 As shown, the q-axis component i of the output current reference value of the main support type power supply can be obtained based on the inductive component in the impedance value at the power supply cluster and the filtered inductive component reference value of the main support type power supply. fqref Then, the q-axis component i of the output current reference value of the main support power supply is fqref The q-axis component i of the output current feedback value fq The difference between the two values ​​is input into the fifth PI controller, and the output of the fifth PI controller after the limiting process is used as the q-axis voltage reference value v of the main support type power supply. fq .

[0118] In step S304, the d-axis voltage reference value and the q-axis voltage reference value of the main support type power supply are transformed to obtain an AC output voltage reference value of the main support type power supply.

[0119] As an example, the obtained AC output voltage reference value of the main support type power supply can act on the converter of the main support type power supply. As another example, the main support type power supply can also include additional auxiliary equipment. When the main support type power supply includes the auxiliary equipment, the obtained AC output voltage reference value of the main support type power supply can act on the auxiliary equipment.

[0120] According to an exemplary embodiment of the present disclosure, supporting power sources with "intermittency, uncertainty and volatility" such as wind turbines and photovoltaic power generation units are used as disturbance sources, and the disturbance amount injected into the microgrid is extracted, that is, the measured impedance of the real-time operation of the disturbance source is used as the feedback value, and the real-time maximum power tracking value, power factor and rated voltage of the microgrid system are used as references to control the system stability.

[0121] In addition, as an example, for each power cluster whose impedance value meets the second preset condition, the impedance value at the power cluster can be sent to at least one power supply in at least one group of power supplies in the power cluster, so that the power supply adjusts its own output voltage reference value according to the received impedance value to help the microgrid return to a stable state. The power supply can determine its own output voltage reference value according to the impedance value using the method described in the above exemplary embodiment according to its own type (i.e., main support type power supply or supporting type power supply).

[0122] Fig.16 A flow chart showing a control method of a power supply according to an exemplary embodiment of the present disclosure is shown. As an example, the control method of a power supply according to an exemplary embodiment of the present disclosure may be executed by a converter controller or a main controller of the power supply.

[0123] Reference Fig.16 , in step S401, the impedance value of the power supply cluster where the power supply is located is obtained.

[0124] As an example, the impedance value may be obtained from an impedance measuring device for measuring an impedance value at a power supply cluster.

[0125] As another example, an impedance value of a power cluster in which the power source is located may be received from a controller of the microgrid.

[0126] In step S402, when the impedance value meets a preset condition, the power source is controlled according to the impedance value so that the microgrid where the power source cluster is located is restored to a stable operating state.

[0127] The preset condition includes: the duration of being in the preset impedance interval reaches the preset duration. As an example, the preset impedance interval may be the second impedance interval in the above exemplary embodiment.

[0128] As an example, step S402 may include: when the power supply is a supporting power supply, performing reactive power control on the power supply according to the impedance value; and / or, when the power supply is a main supporting power supply, performing active power control and reactive power control on the power supply according to the impedance value.

[0129] As an example, when the power supply is a support type power supply, the step of performing reactive power control on the power supply according to the impedance value may include: determining an output voltage reference value of the power supply according to the impedance value and at least one of the following items, for controlling the power supply: a rated voltage of the microgrid, a maximum power tracking value, a power factor, an output current feedback value, and an active output reference value of the power supply. Fig.17 An exemplary embodiment of this step is described below.

[0130] As an example, when the power supply is a main support type power supply, the step of performing active control and reactive control on the power supply according to the impedance value may include: determining an output voltage reference value of the power supply according to the impedance value and at least one of the following items for controlling the power supply: a rated voltage of the microgrid, a maximum power tracking value, a power factor, a current feedback value, a DC voltage setting value, and a DC voltage feedback value of the power supply. Fig.18 An exemplary embodiment of this step is described below.

[0131] As an example, the obtained AC output voltage reference value of the power supply can act on the converter of the power supply. As another example, the power supply can also include additional auxiliary equipment (for example, a reactive power compensation device). When the power supply includes the auxiliary equipment, the obtained AC output voltage reference value of the power supply can act on the auxiliary equipment.

[0132] Fig.17 A flow chart illustrating a method of determining an output voltage reference value of a power supply according to an impedance value according to an exemplary embodiment of the present disclosure.

[0133] Reference Fig.17 In step S501, based on the maximum power tracking value and the power factor of the power supply and the rated voltage of the microgrid, the resistive component reference value and the inductive component reference value in the impedance reference value of the power supply are determined.

[0134] In step S502, based on the resistive component reference value and active output reference value of the power supply and the resistive component in the impedance value, the d-axis component of the output current reference value of the power supply is determined, and based on the d-axis component of the output current reference value of the power supply and the d-axis component of the output current feedback value, the d-axis voltage reference value of the power supply is determined.

[0135] In step S503, the q-axis component of the output current reference value of the power supply is determined based on the inductive component reference value of the power supply and the inductive component in the impedance value, and the q-axis voltage reference value of the power supply is determined based on the q-axis component of the output current reference value of the power supply and the q-axis component of the output current feedback value.

[0136] In step S504, the d-axis voltage reference value and the q-axis voltage reference value of the power supply are transformed to obtain an AC output voltage reference value of the power supply.

[0137] Fig.18 A flow chart illustrating a method of determining an output voltage reference value of a power supply according to an impedance value according to another exemplary embodiment of the present disclosure.

[0138] Reference Fig.18 In step S601, based on the maximum power tracking value and the power factor of the power supply and the rated voltage of the microgrid, the resistive component reference value and the inductive component reference value in the impedance reference value of the power supply are determined.

[0139] In step S602, based on the resistive component reference value, the DC voltage setting value and the DC voltage feedback value of the power supply, and the resistive component in the impedance value, the d-axis component of the output current reference value of the power supply is determined, and based on the d-axis component of the output current reference value of the power supply and the d-axis component of the output current feedback value, the d-axis voltage reference value of the power supply is determined.

[0140] In step S603, based on the inductive component reference value of the power supply and the inductive component in the impedance value, the q-axis component of the output current reference value of the power supply is determined, and based on the q-axis component of the output current reference value of the power supply and the q-axis component of the output current feedback value, the q-axis voltage reference value of the power supply is determined.

[0141] In step S604, the d-axis voltage reference value and the q-axis voltage reference value of the power supply are transformed to obtain an AC output voltage reference value of the power supply.

[0142] It should be understood that the specific processing involved in the power control method according to the exemplary embodiment of the present disclosure has been referred to. Figures 1 to 17 The details have been described in detail and will not be repeated here.

[0143] Fig.19 A structural block diagram of a control device of a microgrid according to an exemplary embodiment of the present disclosure is shown.

[0144] like Fig.19 As shown, a control device 10 of a microgrid according to an exemplary embodiment of the present disclosure includes: an impedance acquisition unit 101 , a dynamic disturbance determination unit 102 , and a control unit 103 .

[0145] Specifically, the impedance acquisition unit 101 is configured to acquire the impedance value of each power supply cluster in the microgrid. Each power supply cluster includes at least one group of supporting power supplies and / or at least one group of main supporting power supplies.

[0146] The dynamic disturbance determination unit 102 is configured to determine whether a dynamic disturbance occurs in the microgrid according to the acquired impedance value.

[0147] The control unit 103 is configured to control the microgrid according to the acquired impedance value when it is determined that a dynamic disturbance occurs in the microgrid, so as to restore the microgrid to a stable operating state.

[0148] As an example, the impedance acquisition unit 101 may receive the impedance value of each power supply cluster from each impedance measurement device used to measure the impedance value of the power supply cluster. It should be understood that Fig.19 In the figure, only one impedance measuring device is exemplarily connected to the impedance acquisition unit 101. In fact, each impedance measuring device can be connected to the impedance acquisition unit 101 in a wired or wireless manner to provide the impedance acquisition unit 101 with the measured impedance value.

[0149] As an example, the "wind turbine" on each bus section may refer to a power cluster consisting of at least one wind turbine generator set, the "photovoltaic" on each bus section may refer to a power cluster consisting of at least one photovoltaic power generation unit, and the "energy storage" on each bus section may refer to a power cluster consisting of at least one energy storage device.

[0150] As an example, the dynamic disturbance judgment unit 102 can be configured to: determine that a dynamic disturbance occurs in the microgrid when the impedance value at at least one power cluster meets a first preset condition, wherein the first preset condition is that the duration of being in the first impedance interval reaches a preset duration.

[0151] As an example, the control unit 103 can be configured to: for each power supply cluster whose impedance value meets the second preset condition, control at least one group of power supplies in the power supply cluster according to the impedance value at the power supply cluster, wherein the second preset condition is that the duration of being in the second impedance interval reaches a preset duration, and the first impedance interval includes the second impedance interval.

[0152] As an example, the control unit 103 may be connected to each power supply (e.g., a main controller or a converter controller of each power supply) in a wired or wireless manner to control each power supply. For example, the control unit 103 may send a control instruction to each power supply in the power supply cluster that meets the second preset condition.

[0153] As an example, the control unit 103 can be configured to: for each power supply cluster whose impedance value meets the second preset condition, perform reactive control on at least one group of supporting power supplies in the power supply cluster according to the impedance value at the power supply cluster; and / or perform active control and reactive control on at least one group of main supporting power supplies in the power supply cluster according to the impedance value at the power supply cluster.

[0154] As an example, the control unit 103 can be configured to: for at least one supporting power supply in at least one group of supporting power supplies in the power supply cluster, determine the output voltage reference value of the corresponding supporting power supply according to the impedance value at the power supply cluster and at least one of the following items, so as to control the supporting power supply: the rated voltage of the microgrid, the maximum power tracking value, power factor, output current feedback value, and active output reference value of the corresponding supporting power supply.

[0155] As an example, the control unit 103 may be configured to: determine the resistive component reference value and the inductive component reference value in the impedance reference value of the corresponding supporting power source based on the maximum power tracking value and the power factor of the corresponding supporting power source and the rated voltage of the microgrid; determine the d-axis component of the output current reference value of the corresponding supporting power source based on the resistive component reference value and the active output reference value of the corresponding supporting power source and the resistive component in the impedance value at the power source cluster, and determine the d-axis voltage reference value of the corresponding supporting power source based on the d-axis component of the output current reference value of the corresponding supporting power source and the d-axis component of the output current feedback value; determine the q-axis component of the output current reference value of the corresponding supporting power source based on the inductive component reference value of the corresponding supporting power source and the inductive component in the impedance value at the power source cluster, and determine the q-axis voltage reference value of the corresponding supporting power source based on the q-axis component of the output current reference value of the corresponding supporting power source and the q-axis component of the output current feedback value; transform the d-axis voltage reference value and the q-axis voltage reference value of the corresponding supporting power source to obtain the AC output voltage reference value of the corresponding supporting power source.

[0156] As an example, the control unit 103 can be configured to: for at least one main supporting type power supply in at least one group of main supporting type power supplies in the power supply cluster, determine the output voltage reference value of the corresponding main supporting type power supply according to the impedance value at the power supply cluster and at least one of the following items, so as to control the main supporting type power supply: the rated voltage of the microgrid, the maximum power tracking value, power factor, current feedback value, DC voltage set value, and DC voltage feedback value of the corresponding main supporting type power supply.

[0157] As an example, the control unit 103 can be configured to: determine the resistive component reference value and the inductive component reference value in the impedance reference value of the corresponding main supporting type power supply based on the maximum power tracking value and the power factor of the corresponding main supporting type power supply and the rated voltage of the microgrid; determine the d-axis component of the output current reference value of the corresponding main supporting type power supply based on the resistive component reference value, the DC voltage setting value and the DC voltage feedback value of the corresponding main supporting type power supply, and the resistive component in the impedance value at the power supply cluster; and determine the d-axis component of the output current reference value of the corresponding main supporting type power supply based on the d-axis component and the output current feedback value of the corresponding main supporting type power supply. The d-axis component of the feedback value is used to determine the d-axis voltage reference value of the corresponding main supporting type power supply; the q-axis component of the output current reference value of the corresponding main supporting type power supply is determined based on the inductive component reference value of the corresponding main supporting type power supply and the inductive component in the impedance value at the power supply cluster, and the q-axis voltage reference value of the corresponding main supporting type power supply is determined based on the q-axis component of the output current reference value of the corresponding main supporting type power supply and the q-axis component of the output current feedback value; the d-axis voltage reference value and the q-axis voltage reference value of the corresponding main supporting type power supply are transformed to obtain the AC output voltage reference value of the corresponding main supporting type power supply.

[0158] Fig. 20 A structural block diagram of a power supply control device according to an exemplary embodiment of the present disclosure is shown.

[0159] like Fig. 20 As shown, the power supply control device 20 according to the exemplary embodiment of the present disclosure includes: an impedance acquisition unit 201 and a control unit 202 .

[0160] Specifically, the impedance acquisition unit 201 is configured to acquire the impedance value of the power supply cluster where the power supply is located.

[0161] The control unit 202 is configured to control the power supply according to the impedance value when the impedance value meets the preset conditions so as to restore the microgrid where the power supply cluster is located to a stable operating state, wherein the preset conditions include: the duration of being in the preset impedance interval reaches a preset duration.

[0162] As an example, the control unit 202 may be configured to: when the power supply is a supporting power supply, perform reactive control on the power supply according to the impedance value; and / or, when the power supply is a main supporting power supply, perform active control and reactive control on the power supply according to the impedance value.

[0163] As an example, the impedance acquisition unit 201 may receive the impedance value of the power cluster from an impedance measurement device for measuring the impedance value of the power cluster where the power is located, and the control unit 202 is used to control the power according to the received impedance value.

[0164] Fig. 20Only one power source (eg, a wind turbine generator set, a photovoltaic power generation unit, an energy storage device) included in the power source cluster is exemplarily shown. It should be understood that each power source cluster may include at least one power source.

[0165] Fig. 20 The control device 20 of a wind turbine generator set, the control device 20 of a photovoltaic power generation unit, and the control device 20 of an energy storage device are only shown as examples. It should be understood that for each supporting power source and / or each main supporting power source in the microgrid, a control device 20 can be provided for it one by one. For example, the control device 20 of each power source can be provided in the converter controller and / or the main controller of the power source.

[0166] As an example, the control unit 202 can be configured to: when the power supply is a supporting power supply, determine the output voltage reference value of the power supply based on the impedance value and at least one of the following items for controlling the power supply: the rated voltage of the microgrid, the maximum power tracking value, power factor, output current feedback value, and active output reference value of the power supply.

[0167] As an example, the control unit 202 may be configured to: determine the resistive component reference value and the inductive component reference value in the impedance reference value of the power supply based on the maximum power tracking value and the power factor of the power supply and the rated voltage of the microgrid; determine the d-axis component of the output current reference value of the power supply based on the resistive component reference value and the active output reference value of the power supply and the resistive component in the impedance value, and determine the d-axis voltage reference value of the power supply based on the d-axis component of the output current reference value of the power supply and the d-axis component of the output current feedback value; determine the q-axis component of the output current reference value of the power supply based on the inductive component reference value of the power supply and the inductive component in the impedance value, and determine the q-axis voltage reference value of the power supply based on the q-axis component of the output current reference value of the power supply and the q-axis component of the output current feedback value; transform the d-axis voltage reference value and the q-axis voltage reference value of the power supply to obtain the AC output voltage reference value of the power supply.

[0168] As an example, the control unit 202 can be configured to: when the power supply is a main support type power supply, determine the output voltage reference value of the power supply according to the impedance value and at least one of the following items for controlling the power supply: the rated voltage of the microgrid, the maximum power tracking value, power factor, current feedback value, DC voltage set value, and DC voltage feedback value of the power supply.

[0169] As an example, the control unit 202 may be configured to: determine the resistive component reference value and the inductive component reference value in the impedance reference value of the power supply based on the maximum power tracking value and the power factor of the power supply and the rated voltage of the microgrid; determine the d-axis component of the output current reference value of the power supply based on the resistive component reference value, the DC voltage setting value and the DC voltage feedback value of the power supply, and the resistive component in the impedance value, and determine the d-axis voltage reference value of the power supply based on the d-axis component of the output current reference value of the power supply and the d-axis component of the output current feedback value; determine the q-axis component of the output current reference value of the power supply based on the inductive component reference value of the power supply and the inductive component in the impedance value, and determine the q-axis voltage reference value of the power supply based on the q-axis component of the output current reference value of the power supply and the q-axis component of the output current feedback value; transform the d-axis voltage reference value and the q-axis voltage reference value of the power supply to obtain the AC output voltage reference value of the power supply.

[0170] It should be understood that the specific processing performed by the control device of the microgrid and the control device of the power supply according to the exemplary embodiment of the present disclosure has been referred to. Figures 1 to 18 The details have been described in detail and will not be repeated here.

[0171] It should be understood that each unit in the control device of the microgrid according to the exemplary embodiment of the present disclosure can be implemented as a hardware component and / or a software component. Those skilled in the art can implement each unit, for example, using a field programmable gate array (FPGA) or an application specific integrated circuit (ASIC) according to the processing performed by each defined unit.

[0172] It should be understood that the various units in the control device of the power supply according to the exemplary embodiment of the present disclosure can be implemented as hardware components and / or software components. Those skilled in the art can implement the various units, for example, using a field programmable gate array (FPGA) or an application specific integrated circuit (ASIC), according to the processing performed by the defined various units.

[0173] An exemplary embodiment of the present disclosure provides a computer-readable storage medium storing a computer program, which, when executed by a processor, causes the processor to execute the control method of the microgrid as described in the above exemplary embodiment. The computer-readable storage medium is any data storage device that can store data read by a computer system. Examples of computer-readable storage media include: read-only memory, random access memory, read-only optical disk, magnetic tape, floppy disk, optical data storage device, and carrier wave (such as data transmission through the Internet via a wired or wireless transmission path).

[0174] An exemplary embodiment of the present disclosure provides a computer-readable storage medium storing a computer program, which, when executed by a processor, causes the processor to execute the control method of the power supply as described in the above exemplary embodiment. The computer-readable storage medium is any data storage device that can store data read out by a computer system. Examples of computer-readable storage media include: read-only memory, random access memory, read-only optical disk, magnetic tape, floppy disk, optical data storage device, and carrier wave (such as data transmission through the Internet via a wired or wireless transmission path).

[0175] According to an exemplary embodiment of the present disclosure, a controller of a microgrid includes: a processor (not shown) and a memory (not shown), wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor is prompted to execute the control method of the microgrid as described in the above exemplary embodiment.

[0176] According to an exemplary embodiment of the present disclosure, a controller of a power supply includes: a processor (not shown) and a memory (not shown), wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor is prompted to execute the control method of the power supply as described in the above exemplary embodiment. As an example, the controller may be set in a converter controller and / or a main controller of the power supply.

[0177] Although some exemplary embodiments of the present disclosure have been shown and described, it will be appreciated by those skilled in the art that modifications may be made to these embodiments without departing from the principles and spirit of the present disclosure, the scope of which is defined by the claims and their equivalents.

Claims

1. A microgrid control method, characterized in that: include: Obtain the impedance value of each power cluster in the microgrid; According to the obtained impedance value, determine whether the microgrid has a dynamic disturbance; When it is determined that a dynamic disturbance occurs in the microgrid, the microgrid is controlled according to the obtained impedance value to restore the microgrid to a stable operating state. Wherein, each power supply cluster includes at least one group of supporting power supplies and / or at least one group of main supporting power supplies; The step of controlling the microgrid according to the acquired impedance value includes: for each power cluster whose impedance value meets the second preset condition, controlling at least one group of power supplies in the power cluster according to the impedance value at the power cluster; The step of controlling at least one group of power supplies in the power cluster according to the impedance value at the power cluster includes: performing reactive power control on at least one group of supporting power supplies in the power cluster according to the impedance value at the power cluster; Among them, the step of performing reactive power control on at least one group of supporting power sources in the power cluster according to the impedance value at the power cluster includes: for at least one supporting power source in the at least one group of supporting power sources in the power cluster, determining the output voltage reference value of the corresponding supporting power source according to the impedance value at the power cluster and at least one of the following items, so as to control the supporting power source: the rated voltage of the microgrid, the maximum power tracking value, power factor, output current feedback value, and active output reference value of the corresponding supporting power source.

2. The control method according to claim 1, characterized in that: According to the obtained impedance value, the steps of determining whether a dynamic disturbance occurs in the microgrid include: When the impedance value at at least one power cluster satisfies a first preset condition, it is determined that a dynamic disturbance occurs in the microgrid. The first preset condition is that the duration of being in the first impedance interval continuously reaches a preset duration.

3. The control method according to claim 2, characterized in that: The second preset condition is that the duration of being in the second impedance interval reaches a preset duration, and the first impedance interval includes the second impedance interval.

4. The control method according to claim 1, characterized in that: The step of controlling at least one group of power supplies in the power supply cluster according to the impedance value at the power supply cluster further includes: According to the impedance value at the power supply cluster, active power control and reactive power control are performed on at least one group of main support type power supplies in the power supply cluster.

5. The control method according to claim 1, characterized in that: For at least one supporting power supply in at least one group of supporting power supplies in the power supply cluster, the step of determining an output voltage reference value of the corresponding supporting power supply includes: Determine a resistive component reference value and an inductive component reference value in an impedance reference value of the corresponding supporting power source based on a maximum power tracking value and a power factor of the corresponding supporting power source and a rated voltage of the microgrid; Determine the d-axis component of the output current reference value of the corresponding supporting power source based on the resistive component reference value and the active output reference value of the corresponding supporting power source, and the resistive component in the impedance value at the power source cluster, and determine the d-axis voltage reference value of the corresponding supporting power source based on the d-axis component of the output current reference value of the corresponding supporting power source and the d-axis component of the output current feedback value; Determine the q-axis component of the output current reference value of the corresponding supporting power source based on the inductive component reference value of the corresponding supporting power source and the inductive component in the impedance value at the power source cluster, and determine the q-axis voltage reference value of the corresponding supporting power source based on the q-axis component of the output current reference value of the corresponding supporting power source and the q-axis component of the output current feedback value; The d-axis voltage reference value and the q-axis voltage reference value of the corresponding supporting power supply are transformed to obtain the AC output voltage reference value of the corresponding supporting power supply.

6. The control method according to claim 4, characterized in that: The step of performing active control and reactive control on at least one group of main support type power sources in the power source cluster according to the impedance value at the power source cluster includes: For at least one main supporting type power supply in at least one group of main supporting type power supplies in the power supply cluster, the output voltage reference value of the corresponding main supporting type power supply is determined according to the impedance value at the power supply cluster and at least one of the following items, so as to control the main supporting type power supply: the rated voltage of the microgrid, the maximum power tracking value, power factor, current feedback value, DC voltage set value, and DC voltage feedback value of the corresponding main supporting type power supply.

7. The control method according to claim 6, characterized in that: For at least one main supporting type power supply in the at least one group of main supporting type power supplies in the power supply cluster, the step of determining an output voltage reference value of the corresponding main supporting type power supply comprises: Determine a resistive component reference value and an inductive component reference value in an impedance reference value of the corresponding main supporting power source based on a maximum power tracking value and a power factor of the corresponding main supporting power source and a rated voltage of the microgrid; Determine the d-axis component of the output current reference value of the corresponding main supporting type power supply based on the resistive component reference value, the DC voltage setting value and the DC voltage feedback value of the corresponding main supporting type power supply, and the resistive component in the impedance value at the power supply cluster, and determine the d-axis voltage reference value of the corresponding main supporting type power supply based on the d-axis component of the output current reference value and the d-axis component of the output current feedback value of the corresponding main supporting type power supply; Determine the q-axis component of the output current reference value of the corresponding main supporting type power supply based on the inductive component reference value of the corresponding main supporting type power supply and the inductive component in the impedance value at the power supply cluster, and determine the q-axis voltage reference value of the corresponding main supporting type power supply based on the q-axis component of the output current reference value of the corresponding main supporting type power supply and the q-axis component of the output current feedback value; The d-axis voltage reference value and the q-axis voltage reference value of the corresponding main support type power supply are transformed to obtain the AC output voltage reference value of the corresponding main support type power supply.

8. A method for controlling a power supply, characterized in that: include: Get the impedance value of the power cluster where the power supply is located; When the impedance value meets the preset condition, the power supply is controlled according to the impedance value so that the microgrid where the power supply cluster is located is restored to a stable operating state. The preset conditions include: the duration of being in the preset impedance interval reaches a preset duration; The step of controlling the power source according to the impedance value includes: when the power source is a support type power source, performing reactive power control on the power source according to the impedance value; Among them, when the power supply is a supported power supply, the step of performing reactive power control on the power supply according to the impedance value includes: determining the output voltage reference value of the power supply according to the impedance value and at least one of the following items for controlling the power supply: the rated voltage of the microgrid, the maximum power tracking value, power factor, output current feedback value, and active output reference value of the power supply.

9. The control method according to claim 8, characterized in that: The step of controlling the power supply according to the impedance value comprises: When the power source is a main support type power source, active power control and reactive power control are performed on the power source according to the impedance value.

10. The control method according to claim 8, characterized in that: When the power supply is a supporting power supply, the step of determining the output voltage reference value of the power supply includes: Determine a resistive component reference value and an inductive component reference value in an impedance reference value of the power supply based on a maximum power tracking value and a power factor of the power supply and a rated voltage of the microgrid; Determine a d-axis component of an output current reference value of the power supply based on a resistive component reference value and an active output reference value of the power supply, and a resistive component in the impedance value, and determine a d-axis voltage reference value of the power supply based on the d-axis component of the output current reference value of the power supply and a d-axis component of an output current feedback value; Determine a q-axis component of an output current reference value of the power supply based on an inductive component reference value of the power supply and an inductive component in the impedance value, and determine a q-axis voltage reference value of the power supply based on the q-axis component of the output current reference value of the power supply and the q-axis component of the output current feedback value; The d-axis voltage reference value and the q-axis voltage reference value of the power supply are transformed to obtain an AC output voltage reference value of the power supply.

11. The control method according to claim 9, characterized in that: When the power supply is a main support type power supply, the steps of performing active control and reactive control on the power supply according to the impedance value include: An output voltage reference value of the power supply is determined based on the impedance value and at least one of the following items for controlling the power supply: a rated voltage of the microgrid, a maximum power tracking value, a power factor, a current feedback value, a DC voltage set value, and a DC voltage feedback value of the power supply.

12. The control method according to claim 11, characterized in that: When the power supply is a main support type power supply, the step of determining the output voltage reference value of the power supply includes: Determine a resistive component reference value and an inductive component reference value in an impedance reference value of the power supply based on a maximum power tracking value and a power factor of the power supply and a rated voltage of the microgrid; Determine the d-axis component of the output current reference value of the power supply based on the resistive component reference value, the DC voltage setting value and the DC voltage feedback value of the power supply, and the resistive component in the impedance value, and determine the d-axis voltage reference value of the power supply based on the d-axis component of the output current reference value of the power supply and the d-axis component of the output current feedback value; Determine a q-axis component of an output current reference value of the power supply based on an inductive component reference value of the power supply and an inductive component in the impedance value, and determine a q-axis voltage reference value of the power supply based on the q-axis component of the output current reference value of the power supply and the q-axis component of the output current feedback value; The d-axis voltage reference value and the q-axis voltage reference value of the power supply are transformed to obtain an AC output voltage reference value of the power supply.

13. A control device for a microgrid, characterized in that: include: An impedance acquisition unit is configured to acquire impedance values ​​of each power cluster in the microgrid; A dynamic disturbance judgment unit is configured to determine whether a dynamic disturbance occurs in the microgrid according to the acquired impedance value; The control unit is configured to control the microgrid according to the acquired impedance value when it is determined that a dynamic disturbance occurs in the microgrid, so as to restore the microgrid to a stable operating state. Wherein, each power supply cluster includes at least one group of supporting power supplies and / or at least one group of main supporting power supplies; The control unit is configured to: for each power supply cluster whose impedance value meets the second preset condition, control at least one group of power supplies in the power supply cluster according to the impedance value at the power supply cluster; The process of controlling at least one group of power supplies in the power cluster according to the impedance value at the power cluster includes: performing reactive power control on at least one group of supporting power supplies in the power cluster according to the impedance value at the power cluster; Among them, according to the impedance value at the power supply cluster, the processing of reactive power control of at least one group of supporting power supplies in the power supply cluster includes: for at least one supporting power supply in the at least one group of supporting power supplies in the power supply cluster, determining the output voltage reference value of the corresponding supporting power supply according to the impedance value at the power supply cluster and at least one of the following items, so as to control the supporting power supply: the rated voltage of the microgrid, the maximum power tracking value, power factor, output current feedback value, and active output reference value of the corresponding supporting power supply.

14. A power supply control device, characterized in that: include: An impedance acquisition unit is configured to acquire an impedance value of a power supply cluster where the power supply is located; The control unit is configured to control the power supply according to the impedance value when the impedance value meets a preset condition, so as to restore the microgrid where the power supply cluster is located to a stable operating state, The preset conditions include: the duration of being in the preset impedance interval reaches a preset duration; Wherein, the control unit is configured to: when the power supply is a supporting power supply, perform reactive power control on the power supply according to the impedance value; Among them, according to the impedance value, the processing of reactive power control of the power supply includes: determining the output voltage reference value of the power supply according to the impedance value and at least one of the following items for controlling the power supply: the rated voltage of the microgrid, the maximum power tracking value of the power supply, the power factor, the output current feedback value, and the active output reference value.

15. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the processor is prompted to execute the microgrid control method according to any one of claims 1 to 7 or the power supply control method according to any one of claims 8 to 12.

16. A microgrid controller, characterized in that: The controller comprises: processor; A memory storing a computer program, which, when executed by a processor, prompts the processor to execute the microgrid control method according to any one of claims 1 to 7.

17. A power supply controller, characterized in that: The controller comprises: processor; A memory storing a computer program, which, when executed by a processor, prompts the processor to execute the power supply control method according to any one of claims 8 to 12.

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