CN-122026480-A - Multi-terminal heterogeneous new energy collection and delivery system, layered control architecture and cooperative control method

CN122026480ACN 122026480 ACN122026480 ACN 122026480ACN-122026480-A

Abstract

A multi-terminal heterogeneous new energy collection and delivery system, a layered control architecture and a cooperative control method are provided, wherein the system comprises at least one first new energy cluster and at least one second new energy cluster, the two new energy clusters are respectively connected with a receiving end alternating current main network through a corresponding first collection and delivery branch and a corresponding second collection and delivery branch, the first collection and delivery branch comprises a low-frequency alternating current collection bus, a low-frequency alternating current transmission line and a first collection device, the second collection and delivery branch comprises an alternating current collection bus, a delivery end converter, a direct current transmission line and a receiving end converter, and the direct current transmission line corresponding to the at least one second new energy cluster is connected to the low-frequency alternating current transmission line corresponding to the at least one first new energy cluster through the cooperative device. The invention improves the stability, economy and operation flexibility of large-scale collection and delivery of new energy by establishing a power mutual-aid and cooperative control mechanism between the low-frequency alternating current delivery branch and the direct current delivery branch.

Inventors

ZHOU SHAOZE
WEI CHENG
JIANG YUNTONG
XING WEIKANG
WANG WEI
LING JINGWEN
LI SISI
SHEN YANJUN
LIU KAIWEN
ZHANG JINGYI
HUANG MENGQI
WANG JIAHUI

Assignees

国电南瑞科技股份有限公司
南瑞集团有限公司
国网电力科学研究院有限公司

Dates

Publication Date: 20260512
Application Date: 20260410

Claims (20)

1. A multi-terminal heterogeneous new energy collection and delivery system comprises at least one first new energy cluster and at least one second new energy cluster, and is characterized in that: each first new energy cluster and each second new energy cluster are connected to the receiving-end alternating current main network through corresponding first collecting and sending-out branches and second collecting and sending-out branches respectively; The first collecting and sending-out branch comprises a low-frequency alternating current collecting bus, a low-frequency alternating current transmission line and a first collecting device which are sequentially connected between the first new energy cluster and the receiving-end alternating current main network; The second collecting and delivering branch comprises an alternating current collecting bus, a delivering end converter, a direct current transmission line and a receiving end converter which are sequentially connected between the second type new energy cluster and the receiving end alternating current main network; The direct current transmission lines corresponding to the at least one second type of new energy clusters are connected to the low-frequency alternating current transmission lines corresponding to the at least one first type of new energy clusters through the mutual-aid cooperative device.
2. The multi-terminal heterogeneous new energy collection and delivery system according to claim 1, wherein: The multi-terminal heterogeneous new energy collection and delivery system further comprises at least one third new energy cluster; each third type of new energy source is connected with the receiving end alternating current main network through a corresponding third collecting and sending branch; The third collecting and delivering branch circuit comprises a power frequency alternating current collecting bus and a power frequency alternating current transmission line, wherein the power frequency alternating current collecting bus collects third new energy cluster electric energy, and the power frequency alternating current transmission line transmits the electric energy to the receiving end alternating current main network.
3. The multi-terminal heterogeneous new energy collection and delivery system according to claim 1, wherein: The first collecting device is a motor-generator set, wherein the motor is a synchronous motor, the generator is a synchronous generator, the motor and the generator are matched in capacity and are coaxially connected, one side of the motor is connected with the low-frequency alternating current transmission line, and one side of the generator is connected with the receiving-end alternating current main network.
4. The multi-terminal heterogeneous new energy collection and delivery system according to claim 3, wherein: and realizing the power mutual aid of the connected second collecting and delivering branch circuit to the first collecting and delivering branch circuit and the soft start control of the connected first collecting device through the mutual aid cooperative device.
5. The multi-terminal heterogeneous new energy collection and delivery system according to claim 4, wherein: The mutual aid cooperative device is a modularized reversing type converter MCC or a modularized multi-level converter MMC.
6. The multi-terminal heterogeneous new energy collection and delivery system according to any one of claims 3-5, wherein: When the first collecting device is started, the mutual-compensation cooperative device is controlled to output low-frequency low-voltage alternating current to the synchronous motor side of the first collecting device, the motor-generator set is subjected to variable-frequency soft start, in the starting process, the frequency and voltage of the output alternating current are gradually increased, so that the synchronous motor drives the synchronous generator to stably speed up, when the rotating speed of the motor-generator set meets the synchronous grid-connected rotating speed condition, the amplitude, the frequency and the phase of the end voltage of the synchronous generator are adjusted, so that the synchronous grid-connected condition is met with the receiving-end alternating current main network, and after the synchronous grid-connected condition is met, the first collecting device is put into operation.
7. The multi-terminal heterogeneous new energy collection and delivery system according to claim 6, wherein: When the change quantity of the output power of the first new energy cluster in a preset time interval exceeds a set fluctuation threshold value, calculating a difference value between the target running power and the actual running power of the first collecting device motor-generator set as a power tracking instruction of the mutual-aid cooperative device, and controlling the second new energy cluster to inject power or absorb power to a low-frequency alternating current collecting bus corresponding to the first new energy cluster through the mutual-aid cooperative device so as to realize quasi-constant power running of the first collecting device motor-generator set.
8. The multi-terminal heterogeneous new energy collection and delivery system according to claim 6, wherein: When the multi-terminal heterogeneous new energy collection and delivery system operates normally, the first collection device corresponding to each first type of new energy cluster calculates and delivers a unit control instruction according to the scheduling control instruction and the current operation electric parameter, so that active output adjustment, voltage support and reactive power support of the receiving end alternating current main network are realized.
9. The multi-terminal heterogeneous new energy collection and delivery system according to claim 6, wherein: When the voltage drop fault of the receiving-end alternating-current bus is detected, the synchronous generator in the first collecting device is controlled to enter a forced excitation running state to provide dynamic reactive power support for the receiving-end alternating-current bus, meanwhile, the mechanical inertia of the motor-generator set is utilized to provide frequency support, and after the voltage of the receiving-end alternating-current bus is recovered, the exciting current of the synchronous generator is gradually recovered to the level before the fault according to a preset recovery rate.
10. The multi-terminal heterogeneous new energy collection and delivery system according to claim 1, wherein: The transmitting end converter is a modularized reversing type converter MCC, and the receiving end converter is a modularized multi-level converter MMC or a modularized reversing type converter MCC.
11. The multi-terminal heterogeneous new energy collection and delivery system according to claim 10, wherein: In the second collecting and sending branch, the direct current side of the sending end MCC adopts double closed loop control, a sub-module average capacitor voltage outer ring is constructed, a direct current reference value is generated based on the deviation between the sub-module average capacitor voltage reference value and an actual value, a direct current inner ring is constructed, and the amplitude of a third harmonic component introduced in the modulating voltage of the alternating current side of the sending end MCC is regulated based on the deviation between the direct current reference value and the actual direct current so as to change the equivalent power exchange relation of the alternating current side and the direct current side, realize the internal energy balance of the sending end MCC and enable the output power of new energy to be smoothly transmitted to a direct current bus.
12. The multi-terminal heterogeneous new energy collection and delivery system according to claim 10, wherein: in the second collecting and sending branch, the direct current side of the receiving end converter adopts a constant direct current voltage control mode irrelevant to topology, and the direct current is regulated by constructing a direct current voltage closed loop link, so that the direct current bus voltage is stabilized at a preset reference value.
13. The multi-terminal heterogeneous new energy collection and delivery system according to claim 12, wherein: When the receiving end converter is a modularized reversing converter MCC, a controllable third harmonic component is introduced into an alternating current output voltage waveform, and the amplitude of the third harmonic component is regulated based on direct current bus voltage deviation so as to change the equivalent conversion relation between alternating current voltage and direct current voltage, thereby realizing the regulation and stabilization of the direct current bus voltage.
14. A layered control architecture for the multi-terminal heterogeneous new energy collection and delivery system of any of claims 1-13, comprising a dispatch control center, a local system controller, and a plurality of device controllers, wherein: The dispatching control center is positioned at the upper layer of the control framework and used for issuing a start-stop instruction, an AGC active dispatching instruction and an AVC voltage/reactive dispatching instruction to the multi-terminal heterogeneous new energy collecting and sending system according to the operation requirement of the receiving end alternating current main network; The local system controller is positioned at the middle layer of the control framework and is used for receiving an instruction issued by the dispatching control center, combining the real-time running states of the first new energy cluster, the second new energy cluster, the first collecting device, the mutual-aid cooperative device and the transmitting-receiving end converter, identifying and switching the current running mode of the multi-end heterogeneous new energy collecting-transmitting system, issuing corresponding control setting values to each device controller, and realizing the coordinated running between the first collecting device and the second collecting-transmitting branch.
15. The hierarchical control architecture for a multi-terminal heterogeneous new energy collection and delivery system according to claim 14, wherein: The device controller comprises a mutual cooperation device controller, an M-G controller, a transmitting end converter controller and a receiving end converter controller.
16. The hierarchical control architecture for a multi-terminal heterogeneous new energy collection and delivery system according to claim 15, wherein: when the motor-generator set rotating speed of the first collecting device meets the synchronous grid-connected rotating speed condition, the M-G controller adjusts the amplitude, frequency and phase of the synchronous generator terminal voltage to control the first collecting device to put into operation, then the local system controller exits the soft start mode, and the system is switched to the normal operation mode.
17. The hierarchical control architecture for a multi-terminal heterogeneous new energy collection and delivery system according to claim 16, wherein: The normal operation mode comprises an AGC/AVC conventional tracking mode, a mutual power stabilizing mode and a fault collaborative traversing mode; in the AGC/AVC conventional tracking mode, a local system controller performs target allocation according to an AGC active scheduling instruction and an AVC voltage/reactive scheduling instruction, and an M-G controller performs active and voltage/reactive tracking control; in the mutual-power stabilizing mode, the local system controller sends a power tracking instruction to the mutual-power cooperative device controller according to the detected fluctuation of the output power of the first type of new energy clusters, and the mutual-power cooperative device controller controls the second type of new energy clusters to inject power or absorb power to the low-frequency alternating current collecting buses corresponding to the first type of new energy clusters through the mutual-power cooperative device; In the fault co-traversing mode, the local system controller issues a co-fault co-traversing operation instruction to the M-G controller, and the M-G controller switches the first collecting device to a fault support operation state.
18. A method for cooperatively controlling a multi-terminal heterogeneous new energy collection and delivery system based on the hierarchical control architecture of any one of claims 14-17, the method comprising: step 1, a local system controller detects the grid-connected state of a first collecting device, if the first collecting device is not connected with the grid, the soft start mode of the step 2 is entered, otherwise, the step 3 is entered; Step 2, the local system controller controls the mutual-aid cooperative device to carry out soft start on the first collecting device, after the grid-connected condition is met, the first collecting device is controlled to be put into operation, and then step 3 is carried out; step 3, continuously monitoring the running state of the system, entering a step 4 when judging that the system fails, executing a cooperative fault ride-through mode, and entering a step 5 otherwise; Step 4, the local system controller issues a cooperative fault ride-through operation instruction, the first collecting device is switched to a fault support operation state, if the fault is cleared, the step 5 is entered, otherwise, the cooperative fault ride-through mode is kept to operate; Step 5, enabling an AGC/AVC conventional tracking mode by a local system controller and monitoring a first new energy cluster output power fluctuation event in real time, and entering a step 6 if power fluctuation occurs, otherwise, controlling a motor-generator set in a first collecting device to track active setting or tracking voltage/reactive setting according to an AGC active scheduling instruction and an AVC voltage/reactive scheduling instruction; And 6, controlling the mutual-power cooperative device to enter a mutual-power stabilizing mode by the local system controller, and controlling the second type of new energy clusters to inject power or absorb power to the low-frequency alternating current collecting buses corresponding to the first type of new energy clusters through the mutual-power cooperative device so as to enable the first collecting device to keep a quasi-constant power running state.
19. The multi-terminal heterogeneous new energy collection and delivery system cooperative control method according to claim 18, wherein the method comprises the following steps: In step 2, the mutual-aid cooperative device is controlled to output low-frequency low-voltage alternating current to the synchronous motor side of the first collecting device, the motor-generator set is subjected to variable-frequency soft start, the frequency and voltage of the output alternating current are gradually increased, when the rotating speed of the motor-generator set meets the synchronous grid-connected rotating speed condition, the amplitude, frequency and phase of the synchronous generator terminal voltage are adjusted to enable the synchronous generator terminal voltage and the receiving terminal alternating current main network to meet the synchronous grid-connected condition, and after the synchronous grid-connected condition is met, the first collecting device is put into operation to achieve grid connection of the first collecting device.
20. The collaborative control method for the multi-terminal heterogeneous new energy collection and delivery system according to claim 19, wherein the collaborative control method comprises the following steps: In step 3, when the voltage of the bus of the receiving end alternating current main network drops to a set drop fault threshold value and the set delay is continuously set, judging that the system has a voltage drop fault, and enabling a fault collaborative traversing mode by the local system controller.

Description

Multi-terminal heterogeneous new energy collection and delivery system, layered control architecture and cooperative control method Technical Field The invention belongs to the technical field of new energy power systems, and particularly relates to a multi-terminal and heterogeneous collection and delivery system suitable for a high-proportion new energy access scene and a cooperative stable control method thereof, which are particularly suitable for high-efficiency collection, stable grid connection and flexible regulation scenes of open sea, offshore and onshore new energy. Background With the promotion of the 'double carbon' target, the new energy power generation permeability represented by wind power and photovoltaic is continuously improved. New energy power systems are evolving from traditional structures with synchronous power sources as main bodies to heterogeneous systems with power electronic converters and synchronous power sources mixed and coexistent. The safety, stability and economy of new energy collection and delivery become industry core requirements. At present, a single power frequency alternating current transmission mode, a flexible direct current transmission mode or a low frequency alternating current transmission mode is mainly adopted for collecting and transmitting new energy, but a plurality of technical bottlenecks are faced in practical application, and the high-efficiency grid connection requirement of large-scale new energy is difficult to meet. In the existing new energy collection and delivery scheme, the power frequency alternating current transmission technology is mature, the system is relatively simple in structure, but under the condition of concentrated collection and delivery of new energy, the system is easy to be restricted by factors such as line charging power, reactive power balance, voltage stability and the like, the delivery capacity and the application range are limited, the low-frequency alternating current transmission can improve the delivery characteristics of alternating current transmission to a certain extent, the problems of limited delivery capacity, higher reactive compensation requirement, complex system configuration and the like still exist, and the flexible direct current transmission has stronger long-distance and large-scale delivery capacity and good power flow control capability, but has high investment of a converter platform, a converter valve and matched offshore facilities, complex engineering implementation and higher requirements on project economy and engineering feasibility. Especially, under the scene that multiple types of new energy coexist and the difference of the sending-out requirements is obvious, the single sending-out mode is difficult to simultaneously consider the economical efficiency, flexibility, stable supporting capacity and fault adaptability. The new energy power generation has the characteristics of volatility, intermittence and uncertainty, and under the condition of large-scale collection and delivery of the new energy clusters, rapid fluctuation of delivery power, disturbance of voltage of an alternating current bus at a receiving end and unbalance of power distribution among alternating current and direct current branches are easy to cause. Especially, under the condition that different new energy clusters have differences in sending distance, capacity scale and sending mode, the dynamic response capability of each branch to the power grid is inconsistent, and a single branch is difficult to independently bear multiple functions such as power stabilization, scheduling tracking and fault support. Meanwhile, most of existing new energy collecting and delivering systems mainly use power electronic interfaces, the inertia and short-circuit supporting capacity of the system are insufficient, and when a receiving-end alternating-current main network is in a weak network state or is subjected to fault disturbance, the problems of insufficient voltage supporting, power fluctuation amplification, continuous grid-connected operation capacity reduction and the like are easy to occur. The Chinese patent application CN118232397A (publication date is 2024.06.21) discloses a low-frequency alternating current-power frequency alternating current mutual aid offshore wind power delivery system, wherein the low-frequency wind power field in a low-frequency alternating current delivery unit and the power frequency wind power field in a power frequency alternating current power delivery unit are connected or not connected through controlled closing or controlled closing of a source side bidirectional interconnection switch, and the alternating current is subjected to frequency conversion through a first frequency conversion link or a second frequency conversion link, so that mutual aid between the low-frequency alternating current delivery unit and the power frequency alternating current delivery unit is realized. The scheme mai