Main power supply type new energy power station and multi-mode autonomous cooperative operation control method thereof

Abstract

The invention provides a main power supply type new energy power station and a multi-mode autonomous cooperative operation control method, and the method comprises the steps: enabling all power generation units to be in a normal operation mode during grid-connected operation, and enabling a voltage sensor to detect the voltage of a PCC point; when the power grid has a short-circuit fault, all the power generation units enter a fault ride-through state through the local controller; judging according to the voltage amplitude of the PCC point, and executing grid-connected or off-grid operation; in the off-grid operation state, judgment is made according to the voltage amplitude of the PCC point, and a grid-connected instruction is sent out or the off-grid operation state is kept; according to an instruction returned by the power grid dispatching system, executing to enter a pre-synchronization state or keep in an off-grid operation state; and making a judgment according to the pre-synchronization state, and executing grid connection when a condition is met. According to the invention, the voltage support and frequency response characteristics of the grid-forming type power generation unit are fully exerted, so that the new energy station can continuously operate during a permanent fault or an operational off-grid period, power is continuously supplied to a local load, and the power grid is seamlessly switched to a grid-connected state in an electrified manner after the power grid is recovered.

Description

Technical Field

[0001] The present invention relates to the cross-technical field of renewable energy power generation and power electronics technology, and in particular to a main power supply type renewable energy power station and a multi-mode autonomous coordinated operation control method thereof. Background Art

[0002] In the near future, wind and solar power sources will surpass synchronous generators in both quantity and total volume, becoming the main power source in the power system. However, what does not match this volume is that the power conversion and grid-connected interface used by current wind power and photovoltaic grid-connected power, namely "grid-connected converters", still use "grid-following control" technology. The main feature of this technology is that it must rely on strong grid conditions to achieve good operation, otherwise it may cause instability, such as broadband oscillations and transient voltage instability that have occurred at home and abroad in recent years. These problems usually trigger protection actions, resulting in reduced power generation.

[0003] From the perspective of the underlying principle, grid-following control cannot operate independently without the grid, and cannot achieve natural inertia response and grid frequency regulation without adding additional control overhead. Therefore, at present, renewable energy power generation must also arrange certain traditional power generation forms (such as hydropower and thermal power) to provide sufficiently strong voltage support and sufficient active power response capabilities. It can be seen that under the currently commonly used grid-following control method, renewable energy power generation such as wind power and photovoltaic power is unlikely to become the dominant power source in the future.

[0004] To this end, a new type of converter grid-connected control architecture has gradually attracted the attention of the industry, namely "grid-building control" (also known as "self-synchronous voltage source control"). The characteristics of this control method are that it can independently establish voltage and frequency in the control link without relying on external grid conditions, and realize it through the converter. This control method is close to the synchronous generator device commonly used by traditional energy in terms of external characteristics. It can independently support node voltage and respond to grid frequency changes. Compared with the grid-following control method, it has better frequency domain characteristics, so it is more stable under weak grids. Based on the above advantages, the grid-building control technology has been widely studied in recent years, mainly for wind power, photovoltaic and energy storage power stations. At present, many grid-building new energy power generation demonstration projects have been built at home and abroad. In addition, according to the requirements of industry standards, newly built wind power and photovoltaic stations need to be equipped with no less than 20% of on-site energy storage at the same time. In summary, with the support of grid-type control and on-site energy storage, new energy power plants represented by wind power and photovoltaic power, on the basis of undertaking basic power generation, at least have the characteristics of conventional power sources such as independently establishing voltage and frequency, providing active and reactive power support, and providing short-term and long-term frequency support. They have the potential to become the dominant power source in the power system.

[0005] To this end, new energy power generation stations that use grid-connected control technology for the grid-connected converter interfaces of some or all of the power generation devices in the station are called "main power source type new energy stations."

[0006] At present, there have been many studies and engineering experiences to provide guidance on the steady-state operation and transient ride-through of the grid-type control power generation device itself. However, facing the main power source type new energy station composed of grid-type power generation units, there is still a lack of relevant research and valuable engineering experience. At present, at the station control level, the upper-level control architecture for the main power source type new energy station has not been developed. In the existing demonstration projects, the original station controller based on the grid-following control method is still mainly used. This not only leads to the adaptability problem of the control architecture, but also makes it difficult to give full play to the unique advantages of the main power source type new energy station. Summary of the invention

[0007] In view of the defects in the prior art, the purpose of the present invention is to provide a main power supply type new energy power station and a multi-mode autonomous collaborative operation control method thereof.

[0008] According to one aspect of the present invention, a multi-mode autonomous collaborative operation control method for a main power source type new energy power station is provided, comprising:

[0009] When connected to the grid, all power generation units in the new energy station are in normal operation mode, and the voltage sensor detects the voltage at the PCC point and records the voltage amplitude;

[0010] After a short-circuit fault occurs in the power grid, all power generation units spontaneously enter the fault ride-through state through the local controller and obtain the voltage amplitude of the PCC point during the fault period;

[0011] A judgment is made based on the voltage amplitude of the PCC point. If the voltage waveform of the PCC point during the fault period meets the voltage recovery curve required by the national standard, the entire new energy station will re-enter the grid-connected operation state from the fault ride-through state; otherwise, the new energy station is allowed to disconnect from the grid according to the national standard, and enters the off-grid operation state at this time;

[0012] During the off-grid operation, the voltage amplitude of the PCC point is judged. If the voltage of the PCC point returns to the normal level, a grid connection request is sent to the grid dispatching system; otherwise, the off-grid operation state is maintained.

[0013] Make a judgment based on the instructions returned by the power grid dispatching system. If the power grid dispatching system returns the instruction to allow grid connection, enter the pre-synchronization state; otherwise, continue to remain in the off-grid operation state and listen to the dispatching instructions issued by the power grid;

[0014] A judgment is made based on the data results of the pre-synchronization state, and when the judgment meets the conditions, grid connection is executed.

[0015] Preferably, the main power source type new energy station realizes operational off-grid operation by accepting instructions issued by the power grid dispatching system.

[0016] Preferably, the operations after entering the off-grid operation state include:

[0017] The circuit breaker at the PCC point is disconnected;

[0018] According to the load power consumption P L 、The maximum power generation capacity of new energy P ava 、Minimum technical output of new energy P min 、Maximum power generation of energy storage P Bout 、Maximum charging power of energy storage P Bin , determine the off-grid operation mode.

[0019] Monitor the dispatching instructions issued by the power grid dispatching system.

[0020] Preferably, the off-grid operation mode includes a dual power supply mode, a single power supply mode, an under-power supply mode and an over-power supply mode;

[0021] Among them, in the dual power supply mode stage, new energy and energy storage are used to supply power at the same time to ensure sufficient power supply for the load. At this time, there are: P ava <P L <P ava +P Bout ;

[0022] In the single power supply mode stage, the new energy output is surplus, part of the power generation is absorbed by the energy storage device, and part is provided to the load. At this time, there is: P L <P ava ;

[0023] In the under-powered mode, new energy and energy storage provide maximum power at the same time, which cannot meet the load demand. At this time, the load shedding action will be triggered. L >P ava +P Bout ;

[0024] In the over-generation mode, when the local load is very small, the new energy maintains the minimum technical output, and the power it generates is still higher than the sum of the total power absorbed by the energy storage device and the total power consumed by the load. At this time, P min >P L +P Bin , system power balance must be achieved by cutting off units or reducing the power of units.

[0025] Preferably, during the pre-synchronization state, the operations performed include:

[0026] According to the voltage phase angle difference Δθ on both sides of the PCC point circuit breaker, the active power increment command value ΔP of each generating unit is generated. ref,i ;

[0027] According to the voltage amplitude difference ΔU on both sides of the PCC point circuit breaker, the reactive power increment command value ΔQ of each generating unit is generated. ref,i .

[0028] Preferably, the active power increment command value ΔP of each power generation unit is generated according to the voltage phase angle difference Δθ on both sides of the PCC point circuit breaker. ref,i ,include:

[0029] Define the phase and frequency presynchronization control rate: ΔP = k p,p (ω ref -Δω)+k i,p ∫(ω ref -Δω)dt, where Δω=ω2-ω1,ω ref The expression is:

[0030] ω ref =k p,ω Δθ+k i,ω ∫Δθdt

[0031] Where Δθ=θ2-θ1, θ1 is the voltage phase angle of PCC at the station side, θ2 is the voltage phase angle of PCC at the grid side; the control rate adopts cascade proportional integral control (PI), k p,p is the proportional gain of active power control; k i,p is the integral gain of active power control; k p,ω is the proportional gain of the frequency control, k i,ω is the integral gain of frequency control;

[0032] Allocate ΔP to each grid-connected power generation unit according to the droop coefficient:

[0033]

[0034] The reactive power increment command value ΔQ of each generating unit is generated according to the voltage amplitude difference ΔU on both sides of the PCC point circuit breaker. ref,i ,include:

[0035] Define the voltage amplitude pre-synchronization control rate:

[0036] ΔQ=k p,q ΔU+k i,q ∫ΔUdt

[0037] Where ΔU = U2-U1, U1 is the voltage amplitude of the PCC on the station side, and U2 is the voltage amplitude of the PCC on the grid side;

[0038] Allocate ΔQ to each generating unit according to the reactive available capacity:

[0039]

[0040] in is the available reactive capacity of each generating unit i, S n,i is the rated capacity of power generation unit i, P i is the active output of power generation unit i.

[0041] Preferably, making a judgment based on the data result of the pre-synchronization state, executing the grid connection, or continuing to remain in the pre-synchronization state includes:

[0042] If |Δθ|<ε1, |Δω|<ε22, |ΔU|<ε3, where Δω is the voltage-frequency difference between the two sides of the PCC point circuit breaker, and ε1, ε2, and ε3 are all set positive numbers, then close the PCC point circuit breaker and enter the grid-connected operation state; otherwise, continue to remain in the pre-synchronization state.

[0043] According to a second aspect of the present invention, there is provided a main power supply type new energy power station, comprising a new energy station main controller, wherein the main controller adopts any one of the multi-mode autonomous collaborative operation control methods of the main power supply type new energy power station.

[0044] Preferably, the main power source type new energy power station also includes:

[0045] A medium voltage busbar, the medium voltage busbar serving as a common connection point PCC;

[0046] A wind turbine generator set, wherein the wind turbine generator set is connected to the medium voltage busbar via a medium voltage feeder;

[0047] An energy storage device, the energy storage device being directly connected to the medium voltage bus;

[0048] A local load, wherein the local load is connected to the medium voltage bus;

[0049] A transformer, through which the medium voltage bus is connected to a power grid;

[0050] A circuit breaker is located between the medium voltage bus and the transformer, and the physical quantities on both sides of the circuit breaker are different.

[0051] Preferably, the energy storage device adopts a single star chain topology, with each phase bridge arm connecting several cascaded submodules in series, each of the submodules having a battery pack connected to the bridge arm through an LC filter circuit and a full-bridge converter;

[0052] The communication architecture of the new energy power station is based on industrial Ethernet, connected to the wind farm control host, SCADA server and data storage device at the station control layer, and connected to each terminal equipment through a switch; the information of the sensors in the new energy station is connected to the wind farm intranet through the industrial Ethernet;

[0053] The industrial Ethernet is also connected to the external power grid and local loads through a router to achieve telemetry, telesignaling, remote control, remote regulation, and coordinate local loads for off-grid operation control.

[0054] Compared with the prior art, the present invention has the following beneficial effects:

[0055] The main power supply type new energy power station and its multi-mode autonomous collaborative operation control method in the embodiment of the present invention make full use of the voltage support and pre-synchronization frequency response characteristics of the grid-building type power generation unit to enable the new energy station to operate uninterruptedly under permanent faults or during operational off-grid operation, provide continuous power supply to local loads, and seamlessly switch to the grid-connected state after the power grid is restored. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0057] Figure 1 This is a flow chart of a multi-mode autonomous collaborative operation control method of a main power source type new energy power station according to an embodiment of the present invention;

[0058] Figure 2 is a schematic diagram of a pre-synchronization control law in a preferred embodiment of the present invention;

[0059] Figure 3 A topological diagram of a main power source type wind farm in another embodiment of the present invention;

[0060] Figure 4 A control topology of a grid-type permanent magnet wind turbine in a preferred embodiment of the present invention;

[0061] Figure 5 A controller structure of a grid-type energy storage device in a preferred embodiment of the present invention;

[0062] Figure 6 This is a wind farm communication architecture in a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0063] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several variations and improvements may be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0064] See also Figure 1 , which is a flow chart of a multi-mode autonomous collaborative operation control method of a main power source type new energy power station according to an embodiment of the present invention. Specifically, the multi-mode autonomous collaborative operation control method of a main power source type new energy power station in this embodiment includes:

[0065] S100, the default state is the grid-connected operation state: in this state, all power generation units (including energy storage) in the station are in normal operation mode; the voltage sensor located at the PCC continuously detects the voltage here and records the voltage amplitude.

[0066] S200, fault ride-through state: When a short circuit occurs in the power grid, each power generation unit (including energy storage) spontaneously enters the fault ride-through mode, which is spontaneously implemented by the local controller of each power generation unit; the voltage sensor at the PCC will record the abnormal voltage during the fault.

[0067] S300, judgment 1: if the voltage waveform at the PCC during the fault period meets the voltage recovery curve required by the national standard, then the entire new energy station will re-enter the grid-connected operation state from the fault ride-through state; otherwise, the new energy station is allowed to disconnect from the grid according to the requirements of the national standard, and enters the off-grid operation state at this time;

[0068] S400, judgment 2: if it is detected that the voltage at the PCC point has returned to a normal level, a grid connection request instruction is sent to the grid dispatching system; otherwise, the off-grid operation state is maintained;

[0069] S500, judgment 3: If the grid dispatching system returns a grid connection permission instruction, then enter the following pre-synchronization state; otherwise continue to maintain the off-grid operation state and monitor the dispatching instructions issued by the grid.

[0070] S600, judgment 4: make a judgment based on the data result of the pre-synchronization state, and execute grid connection when the judgment condition is met.

[0071] Among them, the choice of national standard (Chinese national standard) depends on the type of new energy site, such as: wind farm: GB / T19963.1-2021, Technical regulations for wind farm access to power system Part 1: Onshore wind power [S]: 28; such as: photovoltaic power station: GB19964-2012, Technical regulations for photovoltaic power station access to power system [S].

[0072] In this embodiment, in order to solve the problem that the current new energy stations must shut down due to permanent faults in the transmission lines, a multi-mode autonomous collaborative operation control method is proposed for the main power source type new energy stations using grid-type control. The method can enable the new energy stations to switch to an off-grid operation mode during the period when a permanent fault occurs in the transmission line. During this period, the new energy power generation can continue to supply power to the local load with the cooperation of energy storage without shutting down; in addition, it can be reconnected to the grid after the grid fault is restored.

[0073] In a preferred embodiment of the present invention, S200 is implemented. Generally, in the grid connection of new energy, the grid connection point voltage less than 0.9 pu is generally used as a judgment mark of grid fault. Therefore, when the grid connection point voltage is less than 0.9, the entire new energy power station enters the fault ride-through mode.

[0074] In a preferred embodiment of the present invention, in step S300, after entering the off-grid operation state, the following operations are performed when entering the off-grid operation state:

[0075] 1. The circuit breaker at the PCC point is disconnected;

[0076] 2. According to the load power consumption P L 、The maximum power generation capacity of new energy P ava 、Minimum technical output of new energy P min 、Maximum power generation of energy storage P Bout 、Maximum charging power of energy storage P Bin , determine the off-grid operation mode.

[0077] 3. Monitor the dispatching instructions issued by the power grid.

[0078] In this step, the minimum technical output refers to the minimum output power required for power generation to maintain operation. The minimum technical output of a wind turbine is generally 5% to 10%; the maximum power generation power of energy storage refers to the maximum wind power that can be captured at the current wind speed; the maximum charging power of energy storage refers to the maximum active power that the energy storage power source can generate at the current state of charge (SOC).

[0079] In a preferred embodiment, it is further provided that during off-grid operation, the operating mode is established through the following relationship, and corresponding actions (cutting off the unit, shedding the load, charging the energy storage, discharging the energy storage) are performed:

[0080] Dual power supply mode: In this stage, new energy and energy storage are used to supply power at the same time to ensure sufficient power supply for the load. At this time, there are: P ava <P L <P ava +P Bout

[0081] Single power supply mode: In this stage, the new energy output is surplus, part of the power generation is absorbed by the energy storage device, and part is provided to the load. At this time: P L <P ava

[0082] Underpowered mode: In this stage, even if new energy and energy storage provide maximum power at the same time, they still cannot meet the load demand. At this time, the load shedding action will be triggered. At this time, P L >P ava +P Bout ;

[0083] Over-generation mode: When the local load is very small, even if the new energy maintains the minimum technical output, the power it generates may still be higher than the sum of the total amount absorbed by the energy storage device plus the total amount consumed by the load. At this time, P min >P L +P Bin Therefore, system power balance must be achieved by cutting off units or reducing the power of units.

[0084] Through the above operations, the working mode of the off-grid system can be determined according to the maximum power generation power of the energy storage, the maximum charging power of the energy storage and the size of the local load, so as to prevent the off-grid system from overvoltage or frequency overshoot caused by wind turbine power blocking, and avoid frequency collapse caused by excessive local load.

[0085] In a preferred embodiment of the present invention, a voltage greater than 0.9 pu is used as a sign of grid voltage recovery. After off-grid operation, 0.9 pu indicates that the grid is energized, which is a sign that grid connection is possible. However, whether to execute the grid connection operation still requires the grid dispatcher to give a grid connection permission instruction.

[0086] In a preferred embodiment of the present invention, operations after entering the pre-synchronization state in step S500 are provided, including:

[0087] According to the voltage phase angle difference Δθ on both sides of the PCC point circuit breaker, the active power increment command value ΔP of each generating unit is generated. ref,i ;

[0088] According to the voltage amplitude difference ΔU on both sides of the PCC point circuit breaker, the reactive power increment command value ΔQ of each generating unit is generated. ref,i .

[0089] For further information, see Figure 2 , which shows the pre-synchronization control law. Figure 2 (a) shows the phase and frequency pre-synchronization control rate, and its mathematical expression is:

[0090] ΔP=k p,p (ω ref -Δω)+k i,p ∫(ωref -Δω)dt

[0091] The control rate adopts cascade proportional integral control (PI), k p,p is the proportional gain of active power control, k i,p is the integral gain of active power control;

[0092] Where Δω=ω2-ω1,ω ref The expression is:

[0093] ω ref =k p,ω Δθ+k i,ω ∫Δθdt

[0094] Where Δθ=θ2-θ1, θ1 is the voltage phase angle of PCC at the station side, θ2 is the voltage phase angle of PCC at the grid side; k p,ω is the proportional gain of the frequency control, k i,ω is the integral gain of frequency control;

[0095] Allocate ΔP to each grid-connected power generation unit according to the droop coefficient, specifically:

[0096]

[0097] on the other hand, Figure 2 (b) shows the voltage amplitude pre-synchronization control rate:

[0098] ΔQ=k p,q ΔU+k i,q ∫ΔUdt

[0099] Where ΔU = U2-U1, U1 is the voltage amplitude of PCC at the station side, and U2 is the voltage amplitude of PCC at the grid side; ΔQ is allocated to each generating unit according to the reactive available capacity, specifically:

[0100]

[0101] in is the available reactive capacity of each generating unit i, S n,i is the rated capacity of power generation unit i, P i is the active output of power generation unit i.

[0102] Through the above operations, the frequency, phase and voltage of the new energy power generation units and energy storage devices that adopt grid-type control in the station can be adjusted to be consistent with the grid connection point, thereby realizing the synchronous control of the entire new energy station. Unlike conventional grid-type new energy stations, the synchronization process under the grid-type control method needs to achieve the alignment of phase, frequency and voltage by changing the power reference instruction, otherwise it will cause a large grid connection shock and power oscillation, and in severe cases it will cause overvoltage and overcurrent. The pre-synchronization control method proposed in the above embodiment of the present invention can avoid the occurrence of the above problems.

[0103] In a preferred embodiment of the present invention, a preferred process of step S600 is provided, specifically: if |Δθ|<ε1, |Δω|<ε2, |ΔU|<ε3, where Δω is the voltage-frequency difference between the two sides of the PCC point circuit breaker, and ε1, ε2, ε3 are all small positive numbers, then close the PCC point circuit breaker and enter the grid-connected operation state; otherwise, continue to maintain the pre-synchronization state.

[0104] In some other embodiments of the present invention, the control method can accept instructions issued by the power grid dispatching system to enable the main power supply type new energy station to achieve operational off-grid operation.

[0105] The control method in the above embodiment of the present invention can also be extended to a doubly-fed wind turbine power station and a photovoltaic power station using grid-type control. The relevant principles are the same and will not be elaborated here.

[0106] Based on the same inventive concept, in other embodiments of the invention, a main power source type new energy power station is provided, and the main controller in the new energy station adopts the multi-mode autonomous collaborative operation control method of the main power source type new energy power station in the above embodiment.

[0107] like Figure 3 As shown, the topology of the main power source type new energy power station in a preferred embodiment of the present invention is mainly displayed, which mainly shows the equipment of the medium voltage level grid layer. Specifically: the medium voltage bus is used as the common connection point (PCC), the wind turbine is connected to the medium voltage bus through the medium voltage feeder, and the energy storage device is directly connected to the medium voltage bus; in addition, there are some local loads connected to the medium voltage bus, such as electrolytic hydrogen. The medium voltage bus is connected to the grid through a transformer, and there is a circuit breaker between the medium voltage bus and the transformer. The physical quantities on both sides of the circuit breaker are represented by subscripts 1 and 2 respectively.

[0108] like Figure 4 The figure shows the topology and control method of a wind turbine in a preferred embodiment of the present invention. Specifically, taking a full-power wind turbine as an example, the grid-side converter adopts a grid-type control method, and its reference value is realized by the maximum power tracking control (MPPT) link; the machine side adopts conventional vector control to control the DC side voltage to remain constant.

[0109] like Figure 5 As shown, the topology and control method of the energy storage device in a preferred embodiment of the present invention are shown. Specifically, the energy storage device adopts a single star chain topology, and each phase bridge arm is connected in series with several cascaded submodules. Each submodule has a battery pack connected to the bridge arm through an LC filter circuit and a full-bridge converter. The energy storage device also adopts a grid-type control, and the bottom layer generates the switching signal of each submodule through SOC control and multi-level modulation.

[0110] like Figure 6 As shown, it is a preferred wind farm communication architecture of the main power source type new energy power station in one embodiment of the present invention. The multi-mode autonomous collaborative operation control method proposed in the above embodiment can play a role through this communication architecture. Specifically, the communication architecture is based on industrial Ethernet, connected to the wind farm control host (main controller), SCADA server and data storage device of the station control layer, and connected to each wind turbine, energy storage device, and circuit breaker and other terminal equipment through a switch. In addition, the information of the main sensors in the station is also connected to the wind farm intranet through industrial Ethernet. It should be emphasized that the multi-mode autonomous collaborative operation control method can be used as an advanced application running in the wind farm control host. In addition, the industrial Ethernet of the wind farm intranet is also connected to the external power grid and local loads through a router to realize the four remote functions (telemetry, remote communication, remote control, and remote adjustment) and coordinate the local load for off-grid operation control.

[0111] The above-mentioned embodiment is applicable to the station-level control architecture of the main power source type new energy station. This control architecture is established on the basis of existing communication facilities (such as the SCADA system in the station). By modifying the software control part of the main controller, the software part adopts the multi-mode autonomous collaborative operation control method in the above-mentioned embodiment, so that the main power source type wind farm can provide more advanced functions, such as uninterrupted operation under permanent faults, off-grid multi-mode operation function, and autonomous collaborative grid connection function after power grid restoration; it also increases the total power generation time of the main power source type new energy station, and ensures to the greatest extent that the power supply of local loads (such as hydrogen production) during permanent faults or operational off-grid periods is not affected.

[0112] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various modifications or variations within the scope of the claims, which does not affect the essence of the present invention. The above preferred features can be used in any combination without conflicting with each other.

Claims

1. A multi-mode autonomous collaborative operation control method for a main power source type new energy power station, characterized in that: include: When connected to the grid, all power generation units in the new energy station are in normal operation mode, and the voltage sensor detects the voltage at the PCC point and records the voltage amplitude; After a short-circuit fault occurs in the power grid, all power generation units spontaneously enter the fault ride-through state through the local controller and obtain the voltage amplitude of the PCC point during the fault period; A judgment is made based on the voltage amplitude of the PCC point. If the voltage waveform of the PCC point during the fault period meets the voltage recovery curve required by the national standard, the entire new energy station will re-enter the grid-connected operation state from the fault ride-through state; Otherwise, according to national standards, the new energy station is allowed to be disconnected from the grid, and then enters the off-grid operation state; During the off-grid operation, the voltage amplitude of the PCC point is judged. If the voltage of the PCC point returns to the normal level, a grid connection request is sent to the grid dispatching system; otherwise, the off-grid operation state is maintained. Make a judgment based on the instructions returned by the power grid dispatching system. If the power grid dispatching system returns the instruction to allow grid connection, enter the pre-synchronization state; otherwise, continue to remain in the off-grid operation state and listen to the dispatching instructions issued by the power grid; A judgment is made based on the data results of the pre-synchronization state, and when the judgment meets the conditions, grid connection is executed.

2. According to claim 1, a multi-mode autonomous collaborative operation control method for a main power source type new energy power station is characterized in that: The main power source type new energy station realizes operational off-grid operation by accepting instructions issued by the power grid dispatching system.

3. According to claim 1, a multi-mode autonomous collaborative operation control method for a main power source type new energy power station is characterized in that: Operations after entering the off-grid operation state include: The circuit breaker at the PCC point is disconnected; According to the load power consumption P L 、The maximum power generation capacity of new energy P ava 、Minimum technical output of new energy P min 、Maximum power generation of energy storage P Bout 、Maximum charging power of energy storage P Bin , determine the off-grid operation mode; Monitor the dispatching instructions issued by the power grid dispatching system.

4. The multi-mode autonomous collaborative operation control method of a main power source type new energy power station according to claim 3 is characterized in that: The off-grid operation modes include dual power supply mode, single power supply mode, under-power supply mode and over-power supply mode; Among them, in the dual power supply mode stage, new energy and energy storage are used to supply power at the same time to ensure sufficient power supply for the load. At this time, there are: P ava <P L <P ava +P Bout ; In the single power supply mode, the new energy output is surplus, part of the power generation is absorbed by the energy storage device, and part is provided to the load. At this time, there is: P L <P ava ; In the under-powered mode, new energy and energy storage provide maximum power at the same time, which cannot meet the load demand. At this time, the load shedding action will be triggered. L >P ava +P Bout ; In the over-generation mode, when the local load is very small, the new energy maintains the minimum technical output, and the power it generates is still higher than the sum of the total power absorbed by the energy storage device and the total power consumed by the load. At this time, P min >P L +P Bin , system power balance must be achieved by cutting off units or reducing the power of units.

5. The multi-mode autonomous collaborative operation control method of a main power source type new energy power station according to claim 1 is characterized in that: During the pre-synchronization state, the operations performed include: According to the voltage phase angle difference Δθ on both sides of the PCC point circuit breaker, the active power increment command value ΔP of each generating unit is generated. ref,i ; According to the voltage amplitude difference ΔU on both sides of the PCC point circuit breaker, the reactive power increment command value ΔQ of each generating unit is generated. ref,i .

6. The multi-mode autonomous collaborative operation control method of a main power source type new energy power station according to claim 5 is characterized in that: The active power increment command value ΔP of each generating unit is generated according to the voltage phase angle difference Δθ on both sides of the PCC point circuit breaker. ref,i ,include: Define the phase and frequency presynchronization control rate: ΔP = k p,p (ω ref -Δω)+k i,p ∫(ω ref -Δω)dt, where Δω=ω2-ω1,ω ref The expression is: oh ref =k p,ω Δθ+k i,ω ∫Δθdt Where Δθ=θ2-θ1, θ1 is the voltage phase angle of PCC at the station side, θ2 is the voltage phase angle of PCC at the grid side; k p,p is the proportional gain of active power control; k i,p is the integral gain of active power control; k p,ω is the proportional gain of the frequency control, k i,ω is the integral gain of frequency control; Allocate ΔP to each grid-connected power generation unit according to the droop coefficient: The reactive power increment command value ΔQ of each generating unit is generated according to the voltage amplitude difference ΔU on both sides of the PCC point circuit breaker. ref,i ,include: Define the voltage amplitude pre-synchronization control rate: ΔQ=k p,q ΔU+k i,q ∫ΔUdt Where ΔU = U2-U1, U1 is the voltage amplitude of the PCC on the station side, and U2 is the voltage amplitude of the PCC on the grid side; Allocate ΔQ to each generating unit according to the reactive available capacity: in is the available reactive capacity of each generating unit i, S n,i is the rated capacity of power generation unit i, P i is the active output of power generation unit i.

7. The multi-mode autonomous collaborative operation control method of a main power source type new energy power station according to claim 6 is characterized in that: The step of making a judgment based on the data result of the pre-synchronization state, executing the grid connection, or continuing to stay in the pre-synchronization state includes: If |Δθ|<ε1, |Δω|<ε2, |ΔU|<ε3, where Δω is the voltage-frequency difference between the two sides of the PCC point circuit breaker, and ε1, ε2, and ε3 are all set positive numbers, then close the PCC point circuit breaker and enter the grid-connected operation state; otherwise, continue to remain in the pre-synchronization state.

8. A main power source type new energy power station, characterized in that: It includes a new energy station main controller, and the main controller adopts the multi-mode autonomous collaborative operation control method of the main power supply type new energy power station described in any one of claims 1-7.

9. A main power source type new energy power station according to claim 8, characterized in that: Also includes: A medium voltage busbar, the medium voltage busbar serving as a common connection point PCC; A wind turbine generator set, wherein the wind turbine generator set is connected to the medium voltage busbar via a medium voltage feeder; An energy storage device, the energy storage device being directly connected to the medium voltage bus; A local load, wherein the local load is connected to the medium voltage bus; A transformer, through which the medium voltage bus is connected to a power grid; A circuit breaker is located between the medium voltage bus and the transformer, and the physical quantities on both sides of the circuit breaker are different.

10. A main power source type new energy power station according to claim 8, characterized in that: The energy storage device adopts a single star chain topology, with each phase bridge arm connecting several cascaded submodules in series, each of the submodules having a battery pack connected to the bridge arm through an LC filter circuit and a full-bridge converter; The communication architecture of the new energy power station is based on industrial Ethernet, connected to the wind farm control host, SCADA server and data storage device at the station control layer, and connected to each terminal equipment through a switch; the information of the sensors in the new energy station is connected to the wind farm intranet through the industrial Ethernet; The industrial Ethernet is also connected to the external power grid and local loads through a router to achieve telemetry, telesignaling, remote control, remote regulation, and coordinate local loads for off-grid operation control.

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