Wind-diesel-storage island direct-current networking system based on network-following wind generating sets

Abstract

The invention discloses a wind-diesel-storage island direct current networking system based on a structure following grid wind generating set, and relates to the field of power grid construction, and the system comprises a diesel generating set which comprises a diesel-electric controller and a plurality of diesel power generation branches, and part or all of the diesel power generation branches serve as a voltage source for power supply; the wind generating set comprises a wind power controller and a plurality of wind power generation branches, part or all of the wind power generation branches serve as a voltage source to supply power, and / or part of the wind power generation branches serve as a current source to supply power with a grid; the energy storage controller controls the network construction energy storage unit to obtain electric energy on the direct-current bus for charging or serve as a voltage source for power supply, and the network following energy storage unit obtains electric energy on the direct-current bus for charging or serve as a current source for network following power supply; the direct current networking device distributes power supplied by the diesel generating set, the wind generating set and / or the energy storage device to the power grid load. According to the technical scheme, the utilization rate of the wind generating set is increased, and the networking control difficulty is reduced.

Description

Technical Field

[0001] This application relates to the technical field of grid-connected control of wind turbines. Specifically, it relates to a wind-diesel-storage island DC networking system based on a structure-following grid-connected wind turbine generator set. Background Art

[0002] Currently, for power consumption in similar island microgrids and remote areas where non-fossil energy is produced, a microgrid mode of integrated networking including wind, storage, and diesel is often adopted. This type of microgrid usually uses diesel generator sets and wind turbine generator sets to build an AC grid to supply power to AC loads in the area. When connecting to the AC grid, the control difficulty is relatively high, and it is necessary to adjust the frequency, phase, etc. of each supply voltage to be consistent, which brings relatively high difficulty to grid control. Moreover, in the existing microgrid mode, wind turbine generator sets usually cannot build a power supply network alone and need to supply power following the grid in the form of a current source, that is, the existing solutions have a strong dependence on diesel generator sets and low utilization rate of wind resources. Summary of the Invention

[0003] The technical problem to be solved by this application is that the grid control is relatively difficult and the dependence on diesel power generation is relatively strong when constructing the existing microgrid. Furthermore, a wind-diesel-storage island DC networking system based on a structure-following grid-connected wind turbine generator set is provided.

[0004] The technical solution of this application provides a wind-diesel-storage island DC networking system based on a structure-following grid-connected wind turbine generator set, including: A DC networking device, connected to a grid load through a DC bus and: A diesel generator set, including a diesel-electric controller and a plurality of diesel power generation branches. Each of the diesel power generation branches includes a series-connected diesel generator and a diesel-electric rectifier-inverter; the diesel-electric controller controls some or all of the diesel power generation branches to supply power as a voltage source; A wind turbine generator set, including a wind-electric controller and a plurality of wind power generation branches. Each of the wind power generation branches includes a series-connected wind turbine generator and a wind-electric rectifier-inverter. A structure-following inverter and a grid-following inverter are arranged in the wind turbine generator; the wind-electric controller controls some or all of the wind power generation branches to supply power as a voltage source, and / or some of the wind power generation branches to supply power following the grid as a current source; A energy storage device, including an energy storage controller, a structure-following energy storage unit, and a grid-following energy storage unit; the energy storage controller controls the structure-following energy storage unit to obtain electric energy on the DC bus for charging, or controls the structure-following energy storage unit to supply power as a voltage source; the energy storage controller controls the grid-following energy storage unit to obtain electric energy on the DC bus for charging, or controls the grid-following energy storage unit to supply power following the grid as a current source; The diesel-electric controller, the wind power controller, and the energy storage controller are communicatively connected, and the DC networking device distributes the electric energy supplied by the diesel generator set, the wind turbine generator set, and / or the energy storage device to the grid load.

[0005] Preferably, in some embodiments of the wind-diesel-storage island DC networking system based on a grid-forming wind turbine generator set, the wind turbine generator set further includes a first standby power source, which supplies electric energy to the wind power controller and provides starting electric energy to the wind turbine under the control of the wind power controller.

[0006] Preferably, in some embodiments of the wind-diesel-storage island DC networking system based on a grid-forming wind turbine generator set, the first standby power source is a standby diesel generator or a first inverter, where: the first inverter converts the electric energy on the DC bus to obtain electric energy adapted to the wind power controller or the wind turbine.

[0007] Preferably, in some embodiments of the wind-diesel-storage island DC networking system based on a grid-forming wind turbine generator set, among the wind turbine generator sets, the wind turbine with the grid-forming converter connected in the working state is defined as a wind turbine acting as a voltage source, and the wind turbine with the grid-following converter connected in the working state is defined as a wind turbine acting as a current source: the wind turbine acting as a voltage source supplies electric energy to the wind turbine acting as a current source under the control of the wind power controller.

[0008] Preferably, in some embodiments of the wind-diesel-storage island DC networking system based on a grid-forming wind turbine generator set, the energy storage device further includes a second standby power source, which supplies electric energy to the energy storage controller.

[0009] Preferably, in some embodiments of the wind-diesel-storage island DC networking system based on a grid-forming wind turbine generator set, the second standby power source is a standby diesel generator or a second inverter, where: the second inverter converts the electric energy on the DC bus to obtain electric energy adapted to the energy storage controller.

[0010] Preferably, in some embodiments of the wind-diesel-storage island DC networking system based on a grid-forming wind turbine generator set, the grid-forming energy storage unit includes a grid-forming energy storage battery, a grid-forming energy storage controller, and a grid-forming rectifier-inverter. The grid-forming energy storage battery is electrically connected to the DC bus through the grid-forming rectifier-inverter; the second standby power source supplies electric energy to the grid-forming energy storage controller.

[0011] Preferably, in some embodiments, for the wind-diesel-storage islanded DC networking system based on a configured-grid-connected wind turbine generator set, the grid-connected energy storage unit includes a grid-connected energy storage battery, a grid-connected energy storage controller, and a grid-connected rectifier-inverter. The grid-connected energy storage battery is electrically connected to the DC bus through the grid-connected rectifier-inverter; the second standby power supply provides electrical energy for the grid-connected energy storage controller.

[0012] Preferably, in some embodiments, for the wind-diesel-storage islanded DC networking system based on a configured-grid-connected wind turbine generator set, the forms of the power grid constructed by the system include: the power grid construction form of the wind turbine generator set, the power grid construction form of the configured energy storage unit, and the multi-source power grid construction form, where: The power grid construction form of the wind turbine generator set includes: Some or all of the wind turbines in the wind turbine generator set supply power independently, and some of the wind turbines supply power as voltage sources; some of the wind turbines in the wind turbine generator set and / or the grid-connected energy storage unit supply power to the grid as current sources; The power grid construction form of the configured energy storage unit includes: The configured energy storage unit supplies power as a reference voltage source, and the grid-connected energy storage unit supplies power to the grid as a current source; or, The configured energy storage unit supplies power as a reference voltage, and the grid-connected energy storage unit and some or all of the wind turbines in the wind turbine generator set supply power to the grid; The multi-source power grid construction form includes: Among some or all of the diesel generators in the diesel generator set, some or all of the wind turbines in the wind turbine generator set, and the configured energy storage unit, at least two components supply power synchronously as voltage sources to output the same reference voltage; The grid-connected energy storage unit and / or some of the wind turbines in the wind turbine generator set supply power to the grid.

[0013] Preferably, in some embodiments, for the wind-diesel-storage islanded DC networking system based on a configured-grid-connected wind turbine generator set, when the wind turbine generator set supplies power, if the electrical energy output by the DC networking device exceeds the power consumption demand of the power grid load, then some of the electrical energy provided by the wind turbines charges the configured energy storage unit and / or the grid-connected energy storage unit.

[0014] The above technical solutions provided by the present application, compared with the prior art, have the following technical effects: The wind-diesel-storage island DC networking system based on the wind turbine generator set with a grid connection provided by the present application includes a DC networking device, a diesel generator set, a wind turbine generator set and an energy storage device. Rectifier converters are provided in both the diesel generator set and the wind turbine generator set, which can convert the AC power generated by the diesel generator and the wind turbine generator into DC power and then transmit it to the DC bus; the output of the energy storage system is originally DC power. Therefore, the DC networking device is connected to DC power through the DC bus. When the electric energy provided by each component is networked, only the DC power is put in or cut out, which simplifies the control of the power grid and reduces the difficulty of networking. A grid connection converter and a grid connection converter are configured in the wind turbine of the wind turbine generator set. Depending on whether the grid connection converter and the grid connection converter are in working state, different wind turbines can participate in power supply as voltage sources or current sources, thereby forming a wind turbine generator set with a grid connection. The energy storage device includes a grid-building energy storage unit and a grid-following energy storage unit. The grid-building energy storage unit can be used as a voltage source to supply power, and the grid-following energy storage unit can be used as a current source to supply power to the grid. Therefore, even if the diesel generator set is disconnected from the grid, the networking system in the present application can use the wind turbine as a voltage source in the grid-building wind generator set and one or two of the grid-building energy storage units as a voltage source in the energy storage system as voltage sources to supply power to realize network building, thereby reducing the dependence on the diesel generator set and improving the utilization rate of the wind generator set. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a structural block diagram of a wind-diesel-storage island DC networking system based on a wind turbine generator set in a grid-connected manner according to an embodiment of the present application; Figure 2 This is a block diagram of the internal structure of a wind turbine generator set according to an embodiment of the present application; Figure 3 This is a block diagram of the internal structure of the energy storage device according to one embodiment of the present application; Figure 4 This is a structural block diagram of a wind-diesel-storage island DC networking system based on a grid-connected wind turbine generator set as described in another embodiment of the present application. DETAILED DESCRIPTION

[0016] The specific implementation of the present application is further described below with reference to the accompanying drawings.

[0017] It is easy to understand that according to the technical solution of the present application, without changing the essential spirit of the present application, a variety of structural modes and implementation modes that can be replaced by those skilled in the art can be replaced with each other. Therefore, the following specific implementation modes and drawings are only exemplary descriptions of the technical solution of the present application, and should not be regarded as the entirety of the present application or as a limitation or restriction on the technical solution of the application.

[0018] This embodiment provides a wind-diesel-storage island DC networking system based on a grid-forming wind turbine generator set, as Figure 1 shown, including: A DC networking device, which is connected to a grid load, a diesel generator set, a wind turbine generator set, and a energy storage device through a DC bus. Among them, the diesel generator set, the wind turbine generator set, and the energy storage device are in a parallel connection relationship. As shown in the figure: The diesel generator set includes a diesel-electric controller and multiple diesel power generation branches. Each diesel power generation branch includes a series-connected diesel generator and a diesel-electric rectifier-inverter. The diesel-electric controller controls some or all of the diesel power generation branches to supply power as a voltage source. Among them, the diesel-electric rectifier-inverter is the rectifier-inverter. The rectifier-inverter has rectification and inversion functions and can convert the alternating current output by the diesel generator into direct current. Different diesel power generation branches can be either in a working state or a non-working state. The diesel power generation branches in the working state output direct current to the DC bus, and the diesel generators in the non-working state are equivalent to being disconnected from the grid, which can reduce diesel consumption.

[0019] The wind turbine generator set includes a wind-electric controller and multiple wind power generation branches. Each wind power generation branch includes a series-connected wind turbine generator and a wind-electric rectifier-inverter. A grid-forming inverter and a grid-following inverter are arranged in the wind turbine generator. The wind-electric controller controls some or all of the wind power generation branches to supply power as a voltage source, and / or some of the wind power generation branches to supply power following the grid as a current source. As mentioned above, the wind-electric rectifier-inverter is similar to the diesel-electric rectifier-inverter, and its function is to convert the alternating current generated by the wind turbine generator into direct current. In addition, there are multiple wind turbine generators. The inverters in different wind turbine generators entering the working state can be the same or different. If the grid-forming inverter in the wind turbine generator works, the wind turbine generator can directly participate in building the network as a voltage source and output DC voltage to the DC bus. If the grid-following inverter in the wind turbine generator works, the wind turbine generator can supply power following the grid as a current source. Specifically, a full-power inverter can be arranged in the wind turbine generator. Taking a 10MW full-power inverter as an example, it includes 2 groups of 5MW inverters in parallel control. One group of 5MW inverters adopts grid-forming control, and the other group of 5MW inverters adopts grid-following control. Each group of inverters includes a rectifier-side inverter and an inverter-side inverter. For the inverter adopting grid-forming control, it is used as the controlled voltage source and directly generates the voltage amplitude and frequency according to the requirements. At this time, phase synchronization does not need to be considered, which is equivalent to a reference voltage source. For the inverter adopting grid-following control, it is used as the controlled current source, synchronizes with the grid voltage phase through the phase-locked loop technology, and controls the output power by controlling the current amplitude. In this application, through the fan controller, the working states of different wind turbine generators are controlled according to the networking requirements.

[0020] The energy storage device includes an energy storage controller, a grid-building energy storage unit and a grid-following energy storage unit; the energy storage controller controls the grid-building energy storage unit to obtain electric energy from the DC bus for charging, or controls the grid-building energy storage unit to supply power as a voltage source; the energy storage controller controls the grid-following energy storage unit to obtain electric energy from the DC bus for charging, or controls the grid-following energy storage unit to supply power to the grid as a current source. As mentioned above, the grid-building energy storage unit can be regarded as a voltage source, and the grid-following energy storage unit can be regarded as a current source. When it needs to be charged, electric energy is obtained from the DC bus and converted into a voltage value suitable for charging the energy storage unit to achieve charging. When it needs to be powered, the grid-building energy storage unit can directly supply power as a voltage source, and the grid-following energy storage unit can supply power to the grid as a current source.

[0021] The diesel-electric controller, the wind power controller and the energy storage controller are communicatively connected, and the DC networking device distributes the power supplied by the diesel generator set, the wind power generator set and / or the energy storage device to the grid load. The DC networking completes the DC networking after obtaining the DC power provided by each power supply component from the bus, and then supplies the power to the grid load. If the grid load requires DC power, it can directly use the power provided by the DC networking device. If the grid load requires AC power, it can convert the DC power output by the DC bus into AC power by setting an inverter in front of the power load for use by the load.

[0022] In the above scheme of this embodiment, the system includes a DC networking device, a diesel generator set, a wind generator set and an energy storage device. In the diesel generator set and the wind generator set, a rectifier converter is provided, which can convert the AC power generated by the diesel generator and the wind generator into DC power and then transmit it to the DC bus; the output of the energy storage system is originally DC power. Therefore, the DC networking device is connected to DC power through the DC bus. When the electric energy provided by each component is networked, only the DC power is put in or cut out, which simplifies the grid control and reduces the difficulty of networking. A grid-building converter and a grid-following converter are configured in the wind turbine of the wind turbine generator set. Depending on whether the grid-building converter and the grid-following converter are in working state, different wind turbines can participate in power supply as voltage sources or current sources, thereby forming a grid-building wind turbine generator set. The energy storage device includes a grid-building energy storage unit and a grid-following energy storage unit. The grid-building energy storage unit can be used as a voltage source to supply power, and the grid-following energy storage unit can be used as a current source to supply power to the grid. Therefore, even if the diesel generator set is disconnected from the grid, the networking system in this application can use the wind turbine as a voltage source in the grid-forming wind turbine generator set and one or two of the grid-forming energy storage units in the energy storage system as voltage sources to supply power to realize network formation, thereby reducing the dependence on the diesel generator set and improving the utilization rate of the wind generator set. The above technical solution of this application fills the gap in wind-diesel-storage integrated DC networking and multi-voltage source DC island power grid technology.

[0023] Preferably, as Figure 2 shown, the wind turbine generator set further includes a first backup power source, which supplies power to the wind power controller and provides starting power to the wind turbine generator under the control of the wind power controller. The backup power source can be realized by a pre-set component with power generation function, such as a large-capacity battery, a small power generation unit, etc. By setting the backup power source, the self-start of the wind turbine generator set can be realized, and the independent power supply of the wind turbine generator set can be completed. Further preferably, the first backup power source is a backup diesel generator or a first inverter AC converter, where: as Figure 4 shown, the first inverter AC converter converts the electric energy on the DC bus to obtain electric energy adapted to the wind power controller or the wind turbine generator. According to the power supply mode of the wind turbine generator set, when self-starting is required, the first backup power source can supply power to the wind power controller, so that the wind power controller can control each wind turbine generator, such as controlling the start and stop of the wind turbine generator, unit protection, control of the grid-forming converter and grid-following converter in each wind turbine generator, etc. If there is no wind or the wind force is very small and difficult to drive the blades of the wind turbine generator, the first backup power source can also be used to drive the wind turbine blades to start, etc. During this process, the first backup power source can receive the control of the wind power controller and change its power supply magnitude to match the electric energy required by the power supply target.

[0024] Preferably, in the wind-diesel-storage island DC networking system based on the grid-forming and grid-following wind turbine generator set in the solution, in the wind turbine generator set, the wind turbine generator with the grid-forming converter connected to the working state is defined as the wind turbine generator as a voltage source, and the wind turbine generator with the grid-following converter connected to the working state is defined as the wind turbine generator as a current source: the wind turbine generator as a voltage source supplies power to the wind turbine generator as a current source under the control of the wind power controller. When the wind turbine generator as a voltage source operates normally and outputs a stable reference voltage, it can supply excitation power to the wind turbine generator as a current source. Further, the wind turbine generator as a voltage source can also supply power to the wind power controller and other components or devices that require electric energy. Through this solution, the utilization rate of wind power is further improved, and the consumption of resources such as diesel is reduced.

[0025] As Figure 3As shown, in the wind-diesel-storage island DC networking system based on the structure-following network wind turbine generator set, the energy storage device further includes a second backup power supply, and the second backup power supply provides electrical energy for the energy storage controller. In this way, under the power supply of the second backup power supply, the energy storage controller can control the structure-following network energy storage unit to supply power as a voltage source and control the grid-following network energy storage unit to supply power as a current source for grid connection. After the networking is completed, the structure-following network energy storage unit can replace the second backup power supply to supply power to devices or components such as the energy storage controller. Further preferably, the second backup power supply is a standby diesel generator or a second inverter, where: As Figure 4 shown, the second inverter converts the electrical energy on the DC bus to obtain electrical energy adapted to the energy storage controller. Generally, the first backup power supply and the second backup power supply are preferably realized by converting the voltage with an inverter. To avoid insufficient electrical energy on the DC bus affecting the system networking, a standby diesel generator can be used as an auxiliary device.

[0026] Preferably, as Figure 3 shown, the structure-following network energy storage unit includes a structure-following network energy storage battery, a structure-following network energy storage controller, and a structure-following network rectifier and converter. The structure-following network energy storage battery is electrically connected to the DC bus through the structure-following network rectifier and converter; the second backup power supply provides electrical energy for the structure-following network energy storage controller. The structure-following network rectifier and converter can realize the function of bidirectional voltage conversion. When it is necessary to charge the structure-following network energy storage battery, the structure-following network rectifier and converter converts the electrical energy on the DC bus into a voltage value adapted to the charging requirement of the structure-following network energy storage battery. When it is necessary for the structure-following network energy storage battery to supply power as a voltage source, the structure-following network rectifier and converter can boost the voltage value output by the structure-following network energy storage battery and then supply it to the DC bus. Similarly, as Figure 3 shown, the grid-following network energy storage unit includes a grid-following network energy storage battery, a grid-following network energy storage controller, and a grid-following network rectifier and converter. The grid-following network energy storage battery is electrically connected to the DC bus through the grid-following network rectifier and converter; the second backup power supply provides electrical energy for the grid-following network energy storage controller. The grid-following network rectifier and converter can also convert the electrical energy on the DC bus into a voltage suitable for charging the grid-following network energy storage battery, and convert the electrical energy output by the grid-following network energy storage battery into electrical energy suitable for grid-following power supply and then transport it to the DC bus.

[0027] The system structure of the above wind turbine generator set and energy storage device is as Figure 4 shown. The forms of the system for constructing the power grid include: realizing the form of the diesel generator set for constructing the grid, the form of the wind turbine generator set for constructing the grid, the form of the structure-following network energy storage unit for constructing the grid, and the form of multi-source grid construction, where: The diesel engine controller in the diesel generator set can monitor the operating status of each diesel generator and determine whether the diesel generator set can operate normally to meet the networking requirements. At the same time, it can communicate with the wind power controller in the wind turbine generator set and the energy storage controller in the energy storage device. The three controllers can share information and cooperate in control. There is a device for monitoring wind conditions inside the wind turbine generator set. The wind conditions are sent to the wind turbine controller through monitoring. The wind turbine controller can independently judge whether the current wind conditions meet the startup requirements of the wind turbine generator set and how many wind turbine generators can be started. Thus, it can determine whether the wind turbine generator set can build a power grid. The energy storage controller in the energy storage device can monitor the stored electricity of the grid-forming energy storage unit and the grid-following energy storage unit, and judge whether the two energy storage units need to be charged or can participate in power supply. Since the above three controllers can transmit information to each other, they can share the status data of the diesel generator set, the wind turbine generator set, and the energy storage device, so as to achieve cooperative control. For example, when the diesel generator set has an abnormality, the wind turbine generator set judges whether it can build a power grid according to the wind conditions, and the energy storage device judges whether it can build a power grid according to the stored electricity of the grid-forming energy storage unit. If either of them can build a power grid, the power grid construction can still be completed. Another example is that even if the diesel generator set can currently form a power grid, but the wind turbine generator set can provide sufficient power under the current wind conditions, then at this time, the diesel generator set can bear a small load or even no load, and the wind turbine generator set completely forms the power grid and bears as much load as possible, improving the utilization efficiency of wind energy. Multiple switches can be configured in the DC networking device. The switch connected to the output of the diesel generator set is controlled by the diesel-electric controller, the switch connected to the output of the wind turbine generator set is controlled by the wind power controller, and the switch connected to the output of the energy storage device is controlled by the energy storage controller. The on or off of each switch is controlled according to the equipment components connected to the power grid, so as to realize the parallel connection of different power sources. Specifically, the networking situations of different grid-forming forms are as follows: I. The grid-forming form of the wind turbine generator set: By monitoring the wind conditions, when the wind conditions meet the operating conditions of the wind turbine generator, the wind turbine generator is preferentially used to build a power grid to improve the utilization efficiency of wind energy. The first standby power supply can supply power to the wind power controller. The wind turbine generator set starts and is connected to the grid for power generation. At this time, the first standby power supply supplies power to the startup of the wind turbine generator set and the wind power controller. The alternating current output by the wind turbine generator set is converted into direct current through the wind power rectifier-inverter. The wind turbine generator set builds a power grid system as a voltage source, and the wind turbine generator set can charge the grid-following energy storage unit and the grid-forming energy storage unit. Specifically, the working states of each component include: 1.1 Independent power supply of the wind turbine generator set By monitoring the wind conditions, when the wind conditions continuously meet the operating conditions of the wind turbines, the wind power generation unit independently forms a grid for power supply. Some wind turbines supply power as a voltage source through a grid-forming converter, outputting a stable reference voltage for the DC grid. Some wind turbines are connected to the grid as a grid-following current source through a grid-following converter. At this time, the wind turbines acting as voltage sources can supply excitation power to the wind turbines acting as current sources, and the wind turbines acting as voltage sources can also supply power to the wind power controller and other electrical components, such as various converters. Further, if there is redundancy in the power generation of the wind power generation unit, it can also charge the grid-following energy storage unit and the grid-forming energy storage unit. That is, when the wind power generation unit supplies power, if the electric energy output by the DC networking device exceeds the power consumption demand of the grid load, then part of the electric energy provided by the wind turbines charges the grid-forming energy storage unit and / or the grid-following energy storage unit. Thus, the maximum utilization efficiency of the wind power generation unit is achieved.

[0028] 1.2 Wind-diesel-battery integrated power supply with the wind power generation unit as the grid reference voltage source As mentioned above, the wind power generation unit constructs the grid as a voltage source and is the main power supply for the DC grid; The grid-following energy storage unit supplies power to the grid as a current source to ensure the power supply stability of the DC grid.

[0029] II. Grid-forming form of the grid-forming energy storage unit: By monitoring the operating status of the diesel generator set and the wind conditions, it is judged whether there are abnormal situations such as fuel quantity alarms or equipment damage in the diesel generator set, and whether the wind conditions support the normal operation of the wind turbines to participate in grid construction. When both the operating status of the diesel generator set and the wind conditions do not support grid construction, the second standby power supply (standby diesel generator) supplies power to the energy storage controller of the energy storage device. The energy storage controller starts the grid-forming energy storage unit to provide a stable reference voltage for the DC grid as a voltage source, and the grid-following energy storage unit provides power output for the DC grid as a current source. At this time, the grid-forming energy storage unit supplies power as the only reference voltage source; when the DC grid formation is completed, the grid-forming energy storage unit supplies power to equipment such as the energy storage controller and various converters.

[0030] If the wind conditions improve and meet the start-up of some or all of the wind turbines, then some or all of the wind turbines can supply power to the grid as a current source.

[0031] III. Multi-source grid-forming form: If the operating status of the diesel generator set is stable and the wind conditions support the normal operation of the wind turbines, then multi-source grid formation can be achieved, that is, at least two components among some or all of the diesel generators in the diesel generator set, some or all of the wind turbines in the wind power generation unit, and the grid-forming energy storage unit output the same reference voltage synchronously as voltage sources; at this time, each voltage source outputs the same reference voltage uniformly.

[0032] The network-connected energy storage unit and / or some of the wind turbines in the wind power generation set are network-connected for power supply. That is, the network-connected energy storage unit always acts as a current source for network-connected power supply, and some wind turbines can also be separated to act as current sources for network-connected power generation. The multi-source network formation method forms a DC power grid through multiple voltage sources, which can effectively improve the stability of the DC power grid. At this time, the first standby power supply and the second standby power supply can be realized by converting the voltage on the DC bus through the first inverter and the second inverter respectively.

[0033] All the network formation methods in the above solutions of the present application adopt DC network formation technology. Compared with an AC power grid, problems such as frequency and phase do not need to be considered, and it is more convenient for power sources to be connected to the grid and load switching. It can realize the forms of independent network formation and collaborative network formation for wind power, energy storage, and diesel power respectively, and improve the stability of the DC power grid by increasing voltage sources of different types and different sources. Among them, in the wind power generation set, a network formation converter and a network-connected converter are used to divide the wind turbines into two power supply methods: voltage source and current source, so as to realize the independent DC network formation of the wind power generation set. At the same time, two sets of energy storage units are configured. The network formation energy storage unit can form a network independently as a voltage source, and the network-connected energy storage unit can supply power to the grid as a current source, realizing energy storage network formation and energy storage network connection in the same system.

[0034] According to needs, the above technical solutions can be combined to achieve the best technical effect.

[0035] The above are only the principles and preferred embodiments of the present application. It should be noted that for those of ordinary skill in the art, based on the principle of the present application, several other variations can also be made, which should also be regarded as the protection scope of the present application.

Claims

1. A wind-diesel-battery islanded DC networking system based on a pitch-controlled wind turbine generator set, characterized in that, Comprising: A DC networking device, which is connected to a grid load through a DC bus and: A diesel generator set, including a diesel-electric controller and a plurality of diesel power generation branches. Each of the diesel power generation branches includes a series-connected diesel generator and a diesel-electric rectifier-inverter. The diesel-electric controller controls some or all of the diesel power generation branches to supply power as a voltage source; A wind power generation set, including a wind power controller and a plurality of wind power generation branches. Each of the wind power generation branches includes a series-connected wind turbine generator and a wind power rectifier-inverter. A grid-forming inverter and a grid-following inverter are arranged in the wind turbine generator. The wind power controller controls some or all of the wind power generation branches to supply power as a voltage source, and / or some of the wind power generation branches to supply power following the grid as a current source; An energy storage device, including an energy storage controller, a grid-forming energy storage unit, and a grid-following energy storage unit. The energy storage controller controls the grid-forming energy storage unit to obtain electrical energy on the DC bus for charging, or controls the grid-forming energy storage unit to supply power as a voltage source. The energy storage controller controls the grid-following energy storage unit to obtain electrical energy on the DC bus for charging, or controls the grid-following energy storage unit to supply power following the grid as a current source; The diesel-electric controller, the wind power controller, and the energy storage controller are communicatively connected, and the DC networking device distributes the electrical energy supplied by the diesel generator set, the wind power generation set, and / or the energy storage device to the grid load.

2. The wind-diesel-storage island DC networking system based on a grid-forming and grid-following wind power generation set according to claim 1, wherein: The wind power generation set further includes a first standby power source, which supplies electrical energy to the wind power controller and provides starting electrical energy to the wind turbine generator under the control of the wind power controller.

3. The wind-diesel-storage island DC networking system based on a grid-forming and grid-following wind power generation set according to claim 2, wherein: The first standby power source is a standby diesel generator or a first inverter. Among them, the first inverter converts the electrical energy on the DC bus to obtain electrical energy adapted to the wind power controller or the wind turbine generator.

4. The wind-diesel-storage island DC networking system based on a grid-forming and grid-following wind power generation set according to claim 1, wherein: In the wind power generation set, the wind turbine generator with the grid-forming inverter connected to the working state is defined as the wind turbine generator as a voltage source, and the wind turbine generator with the grid-following inverter connected to the working state is defined as the wind turbine generator as a current source. The wind turbine generator as a voltage source supplies electrical energy to the wind turbine generator as a current source under the control of the wind power controller.

5. The wind-diesel-storage island DC networking system based on a grid-forming and grid-following wind power generation set according to claim 1, wherein: The energy storage device further includes a second standby power source, which supplies electrical energy to the energy storage controller.

6. The wind-diesel-storage island DC networking system based on a grid-forming and grid-following wind power generation set according to claim 5, wherein: The second backup power supply is a backup diesel generator or a second inverter, where: the second inverter converts the electric energy on the DC bus to obtain electric energy adapted to the energy storage controller.

7. The wind-diesel-storage island DC networking system based on a grid-forming and grid-following wind turbine generator set according to claim 6, characterized in that: The grid-forming energy storage unit includes a grid-forming energy storage battery, a grid-forming energy storage controller, and a grid-forming rectifier-inverter. The grid-forming energy storage battery is electrically connected to the DC bus through the grid-forming rectifier-inverter; The second backup power supply provides electric energy for the grid-forming energy storage controller.

8. The wind-diesel-storage island DC networking system based on a grid-forming and grid-following wind turbine generator set according to claim 7, characterized in that: The grid-following energy storage unit includes a grid-following energy storage battery, a grid-following energy storage controller, and a grid-following rectifier-inverter. The grid-following energy storage battery is electrically connected to the DC bus through the grid-following rectifier-inverter; The second backup power supply provides electric energy for the grid-following energy storage controller.

9. The wind-diesel-storage islanded DC networking system based on the structure-following network wind turbine generator set according to any one of claims 1-8, characterized in that, The forms of the power grid constructed by the system include: the grid-forming form of the wind turbine generator set, the grid-forming form of the grid-forming energy storage unit, and the multi-source grid-forming form, where: The grid-forming form of the wind turbine generator set includes: Some or all of the wind turbines in the wind turbine generator set are independently powered, and some of the wind turbines are powered as voltage sources; some of the wind turbines in the wind turbine generator set and / or the grid-following energy storage unit are grid-following powered as current sources; The grid-forming form of the grid-forming energy storage unit includes: The grid-forming energy storage unit is powered as a reference voltage source, and the grid-following energy storage unit is grid-following powered as a current source; or, The grid-forming energy storage unit is powered as a reference voltage, and the grid-following energy storage unit and some or all of the wind turbines in the wind turbine generator set are grid-following powered; The multi-source grid-forming form includes: Among some or all of the diesel generators in the diesel generator set, some or all of the wind turbines in the wind turbine generator set, and the grid-forming energy storage unit, at least two components are used as voltage sources to output the same reference voltage for synchronous power supply; The grid-following energy storage unit and / or some of the wind turbines in the wind turbine generator set are grid-following powered.

10. The wind-diesel-storage island DC networking system based on a grid-forming and grid-following wind turbine generator set according to claim 9, characterized in that: When the wind turbine generator set supplies power, if the electric energy output by the DC networking device exceeds the power consumption demand of the power grid load, then some of the electric energy provided by the wind turbines charges the grid-forming energy storage unit and / or the grid-following energy storage unit.

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