A main power supply type new energy power station and a multi-mode autonomous collaborative operation control method thereof

Abstract

The application provides a main power supply type new energy power station and a multi-mode autonomous collaborative operation control method, which comprises the following steps: when operating in parallel with the power grid, all power generation units are in a normal operation mode, and a voltage sensor detects the voltage of a PCC point; when a short-circuit fault occurs in the power grid, all power generation units enter a fault ride-through state through a local controller; the voltage amplitude of the PCC point is judged to execute grid-connected operation or off-grid operation; when operating in off-grid mode, the voltage amplitude of the PCC point is judged to execute a grid-connected instruction or maintain the off-grid operation state; a return instruction of a power grid dispatching system is executed to enter a pre-synchronization state or maintain the off-grid operation state; the pre-synchronization state is judged, and when the conditions are met, the grid-connected operation is executed. The application fully utilizes the voltage support and frequency response characteristics of the grid-connected power generation unit, so that the new energy power station can continuously operate during permanent faults or operational off-grid, continuously supply power to the local load, and seamlessly switch to the grid-connected state after the power grid is restored.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of new energy power generation and power electronics technology, in particular to a main power source type new energy power station and a multi-mode autonomous cooperative operation control method thereof. BACKGROUND

[0002] In the near future, wind and solar power will exceed synchronous generators in both quantity and total amount, becoming the most important power source in the power system. However, the power conversion and grid-connected interface, i.e. the grid-connected converter, currently used by wind and solar power is still using the "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 the wide frequency oscillation and transient voltage instability that occurred in recent years at home and abroad. After these problems occur, protection actions are usually triggered, resulting in reduced power generation.

[0003] From the perspective of the underlying principles, grid-following control cannot operate independently of the grid, and without additional control overhead, it cannot achieve natural inertia response and grid frequency regulation. Therefore, current new energy power generation must arrange certain traditional power generation forms (such as hydropower and thermal power) to provide sufficient voltage support and sufficient active response capability. It can be seen that under the current widely used grid-following control mode, wind and solar power and other new energy power generation cannot become the dominant power source in the future.

[0004] Therefore, a new type of grid-connected converter control architecture has gradually attracted industry attention, namely "grid-forming control" (also known as "self-synchronous voltage source control"). The feature of this control mode is that it does not need to rely on external grid conditions, and can autonomously establish voltage and frequency through the control link and through the converter. This control mode is similar to the synchronous generator device commonly used by traditional energy sources in terms of external characteristics, and can autonomously support node voltage and respond to grid frequency changes, and has better frequency domain characteristics than grid-following control, thus having stronger stability under weak grids. Based on the above advantages, grid-forming control technology has received a lot of applied research in recent years, mainly targeting wind power, solar power and energy storage power stations. At present, many grid-forming 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 and solar power stations need to be equipped with at least 20% of in-station energy storage. In summary, with the help of grid-forming control and in-station energy storage, wind and solar power generation stations, as representatives of new energy power generation, at least have the characteristics of autonomously establishing voltage and frequency, providing active and reactive power support, providing short-term and long-term frequency support, and other characteristics of conventional power sources, and have the potential to become the dominant power source of the power system.

[0005] To this end, the grid-connected converter interface of part or all of the power generation devices in the station is a new energy power station adopting network-forming control technology, referred to as a "main power source type new energy station".

[0006] At present, there are many researches and engineering experiences to guide the steady-state operation and transient state crossing of the network-forming control power generation device itself. However, in the face of the main power source type new energy station composed of network-forming control power generation units, there is still a lack of relevant research and valuable engineering experience. At present, there is no upper control architecture for the main power source type new energy station at the station control level, and in the existing demonstration projects, the original station controller based on the network-following control mode is still mainly used. This not only leads to the adaptability problem of the control architecture, but also makes it difficult to fully exert the unique advantages of the main power source type new energy station. SUMMARY

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

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

[0009] When operating in parallel, all power generation units in the new energy station are in a normal operation mode, a voltage sensor detects the voltage of 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 a fault crossing state through the local controller and obtain the PCC point voltage amplitude during the fault;

[0011] According to the PCC point voltage amplitude, a judgment is made, if the PCC point voltage waveform during the fault meets the voltage recovery curve required by the national standard, the entire new energy station will re-enter the parallel operation state from the fault crossing state; otherwise, according to the national standard, the new energy station is allowed to be disconnected from the grid, at this time, it enters the off-grid operation state;

[0012] During the off-grid operation state, according to the PCC point voltage amplitude, a judgment is made, if the PCC point voltage returns to the normal level, a grid connection instruction is sent to the grid dispatching system; otherwise, it continues to remain in the off-grid operation state;

[0013] According to the returned instruction of the grid dispatching system, a judgment is made, if the grid dispatching system returns a grid connection instruction, it enters a pre-synchronization state; otherwise, it continues to remain in the off-grid operation state and listens to the dispatching instruction issued by the grid;

[0014] According to the data results of the pre-synchronization state, a judgment is made, when the judgment meets the conditions, grid connection is performed.

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

[0016] Preferably, the operation after entering the off-grid running state includes:

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

[0018] According to the load power P L , the maximum power generation of new energy P ava , the minimum technical output of new energy P min , the maximum power generation of energy storage P Bout , the maximum charging power of energy storage P Bin , the off-grid running mode is determined.

[0019] The dispatching instructions issued by the power grid dispatching system are monitored.

[0020] Preferably, the off-grid running mode includes a double power supply mode, a single power supply mode, an underpower supply mode and an overpower generation mode;

[0021] In the double power supply mode stage, new energy and energy storage supply power at the same time to ensure sufficient power supply for the load, and at this time, P ava <P L <P ava +P Bout ;

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

[0023] In the underpower supply mode stage, new energy and energy storage supply maximum power at the same time, which cannot meet the demand of the load, and at this time, the load shedding action will be triggered, and at this time, P L >P ava +P Bout ;

[0024] In the overpower generation mode stage, when the local load is very small, the new energy maintains the minimum technical output, and the power generated is still higher than the sum of the total amount absorbed by the energy storage device and consumed by the load, and at this time, P min >P L +P Bin , the system power balance must be realized by cutting off the unit or running the unit at a low power.

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

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

[0027] Based on the voltage amplitude difference ΔU across the circuit breaker at point PCC, the reactive power increment command value ΔQ for each power generation unit is generated. ref,i .

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

[0029] Define the phase and frequency pre-synchronization control law: 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 the PCC on the station side, and θ2 is the voltage phase angle of the PCC on the grid side; this control law adopts cascaded proportional-integral (PI) control, k p,p The proportional gain is controlled by active power; k i,p It is the integral gain of active power control; k p,ω It is the frequency-controlled proportional gain, k i,ω It is the integral gain controlled by frequency.

[0032] ΔP is allocated to each grid-connected power generation unit according to the droop coefficient, as follows:

[0033]

[0034] The reactive power increment command value ΔQ for each power generation unit is generated based on the voltage amplitude difference ΔU across the circuit breaker at the PCC point. ref,i ,include:

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

[0036] ΔQ=k p,q ΔU+k i,q ∫ΔUdt

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

[0038] The ΔQ is allocated to each generating unit according to the available reactive power capacity, and is:

[0039]

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

[0041] Preferably, the judging, executing grid-connection, or continuing to maintain the pre-synchronization state according to the data result of the pre-synchronization state comprises:

[0042] If |Δθ| < ε1, |Δω| < ε2, |ΔU| < ε3 are satisfied, wherein Δω is the difference between the voltage frequencies on both sides of the PCC point breaker, and ε1, ε2, and ε3 are all positive numbers set, then the breaker of the PCC point is closed, and the grid-connection operation state is entered; otherwise, the pre-synchronization state is continued to maintain.

[0043] According to a second aspect of the present application, a main power source type new energy power station is provided, comprising a new energy station main controller, and the main controller adopts the multi-mode autonomous cooperative operation control method of the main power source type new energy power station.

[0044] Preferably, the main power source type new energy power station further comprises:

[0045] a medium-voltage bus, which serves as a common connection point PCC;

[0046] a wind turbine, which is connected to the medium-voltage bus through a medium-voltage feeder;

[0047] an energy storage device, which is directly connected to the medium-voltage bus;

[0048] a local load, which is connected to the medium-voltage bus;

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

[0050] a breaker, which is located between the medium-voltage bus and the transformer and has different physical quantities on both sides.

[0051] Preferably, the energy storage device adopts a single-star chain type topology, a plurality of cascaded sub-modules are connected in series to each phase bridge arm, each of the sub-modules has a battery pack, and is 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 an industrial Ethernet, is connected to a wind farm control host, a SCADA server and a data storage of a station control layer, and is connected to each terminal equipment through a switch; information of a sensor in the new energy station is connected to an internal network of the wind farm through the industrial Ethernet;

[0053] The industrial Ethernet is also connected to an external power grid and a local load through a router to realize telemetry, remote signaling, remote control, remote adjustment and off-grid operation control of the local load.

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

[0055] The main power type new energy power station and the multi-mode autonomous collaborative operation control method thereof in the embodiment of the application make the new energy station uninterrupted under permanent fault or during operational off-grid by giving full play to the voltage support and pre-synchronization frequency response characteristics of the network-constructed power generation unit, continuously supply power to the local load, and seamlessly switch to the grid-connected state after the power grid is restored. BRIEF DESCRIPTION OF DRAWINGS

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

[0057] Figure 1 The flow chart of the multi-mode autonomous collaborative operation control method of the main power type new energy power station of an embodiment of the application;

[0058] Figure 2 The schematic diagram of the pre-synchronization control law in a preferred embodiment of the application;

[0059] Figure 3 The topology diagram of the main power type wind farm in another embodiment of the application;

[0060] Figure 4 The control topology of the network-constructed permanent magnet wind turbine in a preferred embodiment of the application;

[0061] Figure 5 The controller structure of the network-constructed energy storage device in a preferred embodiment of the application;

[0062] Figure 6 The wind farm communication architecture in a preferred embodiment of the application. DETAILED DESCRIPTION

[0063] The application will be described in detail below with specific examples. The following examples will help those skilled in the art to further understand the application, but do not limit the application in any form. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the application. These are within the scope of the present application.

[0064] Referring to Figure 1 As shown in the figure, it is a multi-mode autonomous cooperative operation control method flow chart of the main power type new energy power station of an embodiment of the application. Specifically, the multi-mode autonomous cooperative operation control method of the main power type new energy power station in the embodiment includes:

[0065] S100, the default state is a 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 at the PCC continuously detects the voltage at this point and records the amplitude of the voltage.

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

[0067] S300, judgment 1: if the voltage waveform at the PCC during the fault 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 the requirements of the national standard, the new energy station is allowed to be off-grid, at this time, it enters the off-grid operation state;

[0068] S400, judgment 2: if the PCC point voltage is detected to recover to the normal level, send a grid-connected instruction to the grid dispatching system; otherwise, continue to remain in the off-grid operation state;

[0069] S500, judgment 3: if the grid dispatching system returns a grid-connected instruction, enter the following pre-synchronization state; otherwise, continue to remain in the off-grid operation state and listen to the dispatching instruction issued by the grid.

[0070] S600, judgment 4: make a judgment according to the data results of the pre-synchronization state, and execute grid connection when the conditions are met.

[0071] Wherein, the selection of the national standard (Chinese national standard) depends on the type of the new energy station, such as: wind farm: GB / T19963.1-2021, Technical Regulation for Wind Farm Integration into Power System Part 1: Land-based Wind Power[S]: 28; such as: photovoltaic power station: GB19964-2012, Technical Regulation for Photovoltaic Power Station Integration into Power System[S].

[0072] The embodiment is aimed at the problem that the new energy station must be stopped under the permanent fault of the sending line, and proposes a multi-mode autonomous cooperative operation control method for the main power type new energy station adopting network type control, so that the new energy station can be switched to off-grid operation mode during the permanent fault of the sending line, and the new energy generation can continue to supply power to the local load under the cooperation of the energy storage without stopping; in addition, the new energy station can be reconnected to the grid after the power grid fault is recovered.

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

[0074] In a preferred embodiment of the present application, 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 of new energy P ava , the minimum technical output of new energy P min , the maximum power generation of energy storage P Bout , the maximum charging power of energy storage P Bin , the off-grid operation mode is determined.

[0077] 3. Listen to the dispatching instruction issued by the power grid.

[0078] In this step, the minimum technical output refers to the minimum output power of the power generation maintenance operation. The minimum technical output of the wind turbine is generally 5% to 10%; the maximum power generation of the energy storage refers to the maximum wind power that can be captured under the current wind speed; the maximum charging power of the energy storage refers to the maximum active power that can be generated by the energy storage power under the current state of charge (SOC).

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

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

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

[0082] Under power supply mode: in this stage, even if the new energy and energy storage simultaneously provide maximum power, still cannot meet the demand of load, at this time will trigger load cutout action, 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 keeps the minimum technical output, the power it emits may still be higher than the sum of the total amount of energy storage device absorption plus load consumption, at this time: P min >P L +P Bin Therefore, system power balance must be achieved by cutting off the unit or unit power running.

[0084] Through the above operation, the working mode of off-grid system can be determined according to the maximum power generation of energy storage, the maximum charging power of energy storage and the size of local load, prevent wind power blockage from causing off-grid system overvoltage or frequency overshoot, at the same time, avoid the frequency collapse caused by too large local load.

[0085] In a preferred embodiment of the present application, greater than 0.9pu is used as the judgment mark of grid voltage recovery. After off-grid operation, 0.9pu indicates that the grid is electrified, at this time, it is used as the mark of grid connection, but whether to perform grid connection operation still needs the grid dispatching to give the permission of grid connection instruction.

[0086] In a preferred embodiment of the present application, the operation after step S500 enters the pre-synchronization state is provided, including:

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

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

[0089] Further, please refer to Figure 2 , which shows the pre-synchronization control law. Figure 2 The phase and frequency pre-synchronization control law shown in (a) is shown as follows:

[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, and θ2 is the voltage phase angle of PCC at the grid side; k p,ω is the proportional gain of frequency control, k i,ω is the integral gain of frequency control;

[0095] ΔP is distributed to each grid-forming generating unit according to the droop coefficient, specifically:

[0096]

[0097] On the other hand, Figure 2 (b) shown in 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 distributed to each generating unit according to the available reactive power capacity, specifically:

[0100]

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

[0102] Through the above operation, the frequency, phase and voltage of the new energy generating unit and the energy storage device in the station using the network construction type control can be adjusted to be consistent with the grid connection point, thereby realizing the synchronization control of the entire new energy station. Unlike the conventional grid-connected new energy station, the synchronization process under the network construction type control needs to change the power reference instruction to realize the alignment of the phase, frequency and voltage, otherwise a large grid connection impact and power oscillation will be caused, and in severe cases, overvoltage and overcurrent will also be caused. The pre-synchronization control method proposed in the above embodiments of the application can avoid the occurrence of the above problems.

[0103] In a preferred embodiment of the application, a preferred process of step S600 is provided, specifically: if |Δθ| < ε1, |Δω| < ε2, |ΔU| < ε3 are satisfied, wherein Δω is the difference between the voltage frequencies on both sides of the PCC point breaker, and ε1, ε2, ε3 are all small positive numbers, then the PCC point breaker is closed, and the grid-connected operation state is entered; otherwise, the pre-synchronization state is continued to be maintained.

[0104] In some other embodiments of the application, the control method can accept the instructions issued by the power grid dispatching system, so that the main power type new energy station realizes the operational off-grid.

[0105] The control method in the above embodiments of the application can also be extended to the doubly-fed wind turbine generator station and the photovoltaic power station using the network construction type control, and the relevant principles are the same, which will not be described here.

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

[0107] As shown in Figure 3 Fig. 1, which is a topology of the main power type new energy power station in a preferred embodiment of the application, mainly showing the equipment of the medium voltage level power grid layer. Specifically, the medium voltage bus is taken as the point of common coupling (PCC), the wind turbine generator 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 also some local loads connected to the medium voltage bus, such as electrolytic hydrogen, etc. The medium voltage bus is connected to the power grid through a transformer, and there is a breaker between the medium voltage bus and the transformer, and the physical quantities on both sides of the breaker are represented by subscripts 1 and 2, respectively.

[0108] As shown in Figure 4 Fig. 2, which is a topology and control mode of the wind turbine generator in a preferred embodiment of the application. Specifically, taking a full power type wind turbine generator as an example, the grid-side converter adopts the network construction type control mode, and the reference value is realized by the maximum power tracking control (MPPT) link; the machine side adopts the conventional vector control to control the direct current side voltage to remain constant.

[0109] As shown in Figure 5 , it is the topology and control method of the energy storage device in a preferred embodiment of the present application. Specifically, the energy storage device adopts a single-star chain topology, and each phase bridge arm is connected with a plurality of cascaded sub-modules in series, and each sub-module 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 network construction type control, and the bottom layer generates the switching signal of each sub-module through SOC control and multi-level modulation.

[0110] As shown in Figure 6 , it is the preferred communication architecture of the main power type new energy power station in an embodiment of the present application. The multi-mode autonomous collaborative operation control method proposed in the above embodiment can play a role through the 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 of the station control layer, and connected to each wind turbine generator, energy storage device, 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 a high-level application program 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 the local load through a router to realize the four remote functions (telemetry, remote signaling, remote control, remote adjustment), and coordinate the local load for off-grid operation control.

[0111] The station-level control architecture suitable for the main power type new energy station in the above embodiment is built on the basis of existing communication facilities (such as the SCADA system in the station), and 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 embodiment, so that the main power type wind farm can provide more advanced functions, such as uninterrupted operation function under permanent fault, off-grid multi-mode operation function, and autonomous collaborative grid-connected function after grid recovery; also makes the total power generation time of the main power type new energy station be improved, and ensures the power supply of the local load (such as electric hydrogen) during permanent fault or operational off-grid to the greatest extent.

[0112] The specific embodiments of the present application are described above. It should be understood that the present application is not limited to the above specific embodiments, and those skilled in the art can make various modifications or modifications within the scope of the claims, which does not affect the essential content of the present application. The above preferred features can be used in combination in the case of not conflicting with each other.

Claims

1. A multi-mode autonomous collaborative operation control method for a main power supply type new energy power plant, characterized in that, The method comprises the following steps: When grid-connected operation, all power generation units in the new energy station are in normal operation mode, the voltage sensor detects the voltage of the PCC point and records the voltage amplitude; After a short-circuit fault occurs in the power grid, all power generation units enter a fault ride-through state through the local controller and obtain the voltage amplitude of the PCC point during the fault; According to the PCC point voltage amplitude, if the PCC point voltage waveform during the fault 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 the national standard, the new energy station is allowed to be off-grid, and at this time, it enters an off-grid operation state; During the off-grid operation state, according to the PCC point voltage amplitude, if the PCC point voltage returns to the normal level, a request for grid-connected instruction is sent to the power grid dispatching system; otherwise, the off-grid operation state is maintained; According to the returned instruction of the power grid dispatching system, if the power grid dispatching system returns a grid-connected instruction, the pre-synchronization state is entered; otherwise, the off-grid operation state is maintained, and the dispatching instruction issued by the power grid is listened to; According to the data results of the pre-synchronization state, when the conditions are met, the grid connection is performed; During the pre-synchronization state, the operations performed include: According to the difference Δθ of the phase angles of the voltages on both sides of the PCC point breaker, the active power increment command value ΔP of each generating unit is generated ref,i ; According to the difference ΔU between the voltage amplitudes on both sides of the PCC point breaker, the reactive power increment command value ΔQ of each power generation unit is generated ref,i ; The active power increment command value ΔP of each power generation unit is generated according to the difference Δθ between the phase angles of the voltages on both sides of the PCC point breaker ref,i , comprising: Define phase and frequency pre-synchronization 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: ω ref = k p,ω Δθ + k i,ω ∫Δθdt where Δθ = θ2- θ1, θ1is the voltage phase angle of the PCC at the plant side, and θ2is the voltage phase angle of the PCC at the grid side;k p,p is the proportional gain of the active control;k i,p is the integral gain of the active control;k p,ω is the proportional gain of the frequency control;k i,ω is the integral gain of the frequency control; ΔP is distributed to each grid-forming power generation unit according to the droop coefficient, and ΔQ is distributed to each power generation unit according to the reactive power available capacity, and the main power supply type new energy station realizes the operational off-grid by accepting the instruction issued by the power grid dispatching system. The reactive power increment instruction value ΔQ of each power generation unit is generated according to the difference ΔU between the voltage amplitudes on both sides of the PCC point breaker ref,i , comprising: The operations after entering the off-grid operation state include: ΔQ = k p,q ΔU + k i,q ∫ΔU dt The circuit breaker at the PCC point is opened; The dispatching instruction issued by the power grid dispatching system is listened to. wherein S is the available reactive capacity of each generating unit i n,i P is the rated capacity of generating unit i i P is the active power output of generating unit i.

2. The multi-mode autonomous cooperative operation control method of the main power source type new energy power station according to claim 1, characterized in that, The off-grid operation mode includes a double power supply mode, a single power supply mode, an under power supply mode, and an over power generation mode; 3. The multi-mode autonomous cooperative operation control method of a main power source type new energy power station according to claim 1, characterized in that, According to the data results of the pre-synchronization state, the grid connection is performed or the pre-synchronization state is maintained, which includes: If |Δθ|<ε1, |Δω|<ε2, |ΔU|<ε3 are met, where Δω is the difference between the voltage frequencies on both sides of the PCC point circuit breaker, and ε1, ε2, and ε3 are all positive numbers, then the PCC point circuit breaker is closed, and the grid-connected operation state is entered; otherwise, the pre-synchronization state is maintained. According to the load power consumption P L , the maximum new energy power generation P ava , the minimum new energy technical output P min , the maximum energy storage power generation P Bout , the maximum energy storage charging power P Bin , determine the off-grid operation mode; The method comprises the following steps:

4. The multi-mode autonomous cooperative operation control method of a main power source type new energy power plant according to claim 3, characterized in that, The main controller of the new energy station adopts the multi-mode autonomous cooperative operation control method of the main power supply type new energy power station according to any one of claims 1-5. Wherein, in the double power supply mode stage, new energy and energy storage supply power at the same time, so as to ensure sufficient power supply of load, at this time, P ava <P L <P ava +P Bout ; In the single power supply mode stage, new energy output surplus, part of the power generation is absorbed by the energy storage device, part of the power supply to the load, at this time: P L <P ava ; In the underpower mode stage, the new energy and the energy storage simultaneously provide the maximum power, which cannot meet the demand of the load, at this time the load shedding action is triggered, at this time there are P L > P ava + P Bout ; In the over-generation mode phase, when the local load is very small, the new energy keeps the minimum technical output, and the power generated is still higher than the sum of the total amount absorbed by the energy storage device and consumed by the load. At this time, there is: P min > P L + P Bin The system power balance must be achieved by cutting off the unit or running the unit at a reduced power.

5. The multi-mode autonomous cooperative operation control method of a main power source type new energy power plant according to claim 1, characterized in that, Further comprising: A medium voltage bus serving as a public connection point PCC; 6. A main power supply type new energy power plant, characterized in that, A wind turbine connected to the medium voltage bus through a medium voltage feeder; 7. A main power supply type new energy power plant according to claim 6, characterized in that, An energy storage device directly connected to the medium voltage bus; A local load connected to the medium voltage bus; A transformer connecting the medium voltage bus to the power grid; A circuit breaker between the medium voltage bus and the transformer, the physical quantities on both sides of the circuit breaker being different. ​ ​ ​ 8. The new energy power station of claim 6, characterized in that, the energy storage device adopts a single-star chain topology, each phase bridge arm is connected with a plurality of cascaded sub-modules in series, each of the sub-modules has a battery pack, and is 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 an industrial Ethernet, a wind farm control host, a SCADA server and a data storage connected to a station control layer, and each terminal equipment connected through a switch; information of sensors in the new energy station is connected to an internal network of the wind farm through the industrial Ethernet; the industrial Ethernet is also connected to an external power grid and a local load through a router to realize telemetry, remote signaling, remote control, remote adjustment, and off-grid operation control coordinated with the local load.

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