Fusion system of new energy power station phase modifier and in-station energy storage

Abstract

The embodiment of the application provides a fusion system of a phase modifier and an in-station energy storage of a new energy power station, comprising: a phase modifier and an energy storage system arranged in the new energy power station, the fusion system comprises an energy storage independent excitation mode, an energy storage excitation and self-parallel excitation complementary mode, an energy storage independent starting mode and an energy storage standby starting mode, the application can effectively fuse the phase modifier and the energy storage system in the new energy power station, improve the reliability of the phase modifier equipment and the utilization rate of the energy storage system, and fully play the supporting role of the phase modifier on the new energy power grid.

Description

Technical Field

[0001] This application relates to the field of new energy power systems, specifically to an integrated system of synchronous condenser and on-site energy storage in a new energy power plant. Background Technology

[0002] Power systems primarily powered by new energy sources (wind and solar power) will become the main power source in future power systems. Simultaneously, with the increasing proportion of new energy sources, the power grid will experience problems such as transient reactive power shortages, inertia deficiencies, and insufficient short-circuit capacity. Synchronous condensers, as a type of synchronous motor, have advantages such as strong transient reactive power capacity, large rotational inertia, and large short-circuit capacity. Configuring a certain proportion of distributed synchronous condensers in new energy power plants will be an effective solution. Due to the volatility and intermittency of wind and solar power, their frequency regulation and peak shaving performance for the power grid is poor. Energy storage is gradually becoming a standard feature in newly built wind farms and solar power plants, especially electrochemical energy storage. Synchronous condensers and energy storage respectively support the reactive power inertia and frequency regulation / peak shaving of new energy power plants, smoothing active and reactive power fluctuations to meet grid requirements, while simultaneously supporting the reliable operation of wind and solar power sources, representing a relatively ideal model.

[0003] In the traditional model, synchronous condensers are installed on the low-voltage side of the main transformer to provide reactive power, inertia, and short-circuit capacity support for renewable energy power generation. On one hand, they work with other reactive power compensation devices within the station (such as SVG) to provide steady-state reactive power support. Most importantly, they provide transient reactive power support. This is because renewable energy stations are generally located at the end of the main grid, with weak connections to the system, making them prone to transient voltage drops and rises. In such cases, the synchronous condenser, with its rapid dynamic response and overload capacity, provides strong excitation and rapid phase advance, reducing the risk of wind turbines and photovoltaic systems disconnecting from the grid due to transient voltage disturbances. Synchronous condensers typically use self-excited static excitation, meaning the power supply for rotor excitation is taken from the stator of the synchronous condenser, stepped down by an excitation transformer, and then converted to DC voltage by a rectifier to provide excitation current to the rotor windings. This structure is relatively simple and is currently the most widely used excitation method for synchronous motors. Its excitation control employs a mature excitation regulator, which receives voltage control commands from the receiver or the power grid to output the conduction angle of the controllable rectifier, thereby controlling the DC excitation voltage and regulating the excitation current. Furthermore, since the synchronous condenser lacks a prime mover, a dedicated starting device is required. Currently, the most commonly used is the SFC (Static Starter Converter). By connecting an external starting converter to the stator winding of the synchronous condenser and simultaneously applying a small amount of excitation to the rotor winding, soft starting of the synchronous condenser is achieved through frequency conversion control, driving it to above its rated speed. Then, the starting circuit is disconnected, and the synchronous condenser is connected to the grid when it coasts to near its rated speed. This starting method does not require an external drive disconnect device on the rotor shaft, offers reliable control, and boasts excellent performance. Its starting power comes from the station's power supply system, typically connected to the station's low-voltage 380V busbar.

[0004] Meanwhile, all renewable energy power stations are currently equipped with a certain proportion of energy storage, primarily electrochemical energy storage. This energy storage system is generally installed on the station's low-voltage 380V busbar, mainly serving to smooth out renewable energy output. When renewable energy output surges due to favorable weather conditions, exceeding the grid's load requirements, the excess electricity is stored in the station's energy storage devices. Conversely, when renewable energy output is low and cannot meet the grid's load needs, the energy storage devices discharge back into the grid. In summary, energy storage participates in peak shaving and valley filling for the power grid, smoothing out the volatility and intermittency of renewable energy, thus enabling it to achieve synchronous performance similar to traditional thermal power units. Through an energy management system, the energy storage system rationally allocates the charging and discharging modes of each module according to system commands and the equipment's own status, achieving efficient utilization and extended lifespan.

[0005] The inventors have discovered that existing synchronous condensers in new energy power plants have at least the following problems:

[0006] 1. The most important function of a synchronous condenser is to provide transient reactive power support for the system, known as the forced excitation mode. This means that when the grid voltage drops, the rotor excitation voltage is increased to three times or even higher than the rated excitation voltage, causing the synchronous condenser to output a large amount of instantaneous reactive power. This is to support the grid voltage in a timely manner when a grid fault causes a voltage drop, ensuring grid voltage stability. However, the self-excited static excitation method used in existing technologies experiences a significant drop in the primary voltage of the excitation transformer when the grid voltage drops. This means the power supply voltage of the excitation system is far below normal levels, yet a higher amplitude DC voltage is still required. This indirectly places higher demands on the capacity and voltage level of the excitation system, increasing system complexity and affecting the dynamic performance of the excitation system. Especially in weak grid scenarios such as renewable energy power plants, the forced excitation function of the synchronous condenser cannot be fully utilized. Furthermore, since the excitation power comes from the generator end and is coupled with the synchronous condenser, it cannot inherently provide 100% reliability support. For example, when the excitation system itself fails, there is a lack of a corresponding backup excitation power supply.

[0007] 2. When using an SFC device (static start frequency converter) to start the synchronous condenser, the starting power comes from the station's AC system. Using frequency conversion starting will cause adverse effects such as harmonic pollution and current surges to the station's power system. In addition, when the system loses power, the SFC will be unable to start the synchronous condenser, making it difficult to restore the system voltage.

[0008] Therefore, based on years of experience and practice in related industries, the inventor proposes an integrated system of synchronous condenser and on-site energy storage in new energy power plants to overcome the shortcomings of existing technologies. Summary of the Invention

[0009] To address the problems in the existing technology, this application provides an integrated system for synchronous condensers and energy storage in new energy power plants. This system can effectively integrate synchronous condensers and energy storage systems within new energy power plants, improve the reliability of synchronous condenser equipment and the utilization rate of energy storage systems, and fully leverage the supporting role of synchronous condensers in the new energy power grid.

[0010] To solve at least one of the above-mentioned technical problems, this application provides the following technical solution:

[0011] In a first aspect, this application provides an integrated system of synchronous condenser and on-site energy storage in a new energy power plant, comprising: a synchronous condenser and an energy storage system installed in the new energy power plant;

[0012] The fusion system includes an independent excitation mode for energy storage. When the fusion system adopts the independent excitation mode for energy storage, the energy storage system is connected to the rotor winding of the synchronous condenser through an excitation voltage converter for adjusting the excitation current, so as to independently provide excitation current to the rotor winding.

[0013] The integrated system also includes a complementary mode of energy storage excitation and self-excitation. When the integrated system adopts the complementary mode of energy storage excitation and self-excitation, the excitation circuit of energy storage excitation and self-excitation is switched by an excitation switching device. When the grid voltage is within the normal operating range, the self-excitation system performs excitation. When the grid voltage drops, the excitation switching device switches to the energy storage system for excitation.

[0014] The fusion system also includes an independent energy storage start-up mode. When the fusion system adopts the independent energy storage start-up mode, the energy storage system is connected to the stator winding of the synchronous condenser through a static start inverter for frequency conversion control. The energy storage system is used to provide energy to independently soft-start the synchronous condenser.

[0015] The integrated system also includes an energy storage backup start-up mode. The energy storage system and the station power system switch power supply circuits through a power switching device. When the station power system and the static start inverter are in normal condition, the station power system provides start-up power to the static start inverter. When the station power system and the static start inverter are in abnormal condition and cannot meet the start-up requirements, the energy storage backup start-up mode is adopted, and the energy storage system provides backup power to the static start inverter.

[0016] Furthermore, it also includes an energy storage excitation regulator that is signal-connected to the excitation voltage converter, the energy storage excitation regulator being used to send control signals to the excitation voltage converter.

[0017] Furthermore, when a complementary mode of energy storage excitation and self-excitation excitation is adopted, the excitation switching device is connected to the excitation transformer and rectifier of the synchronous condenser.

[0018] Furthermore, when the energy storage system is a DC power supply type, the excitation voltage converter is a DC / DC power electronic converter.

[0019] Furthermore, when the energy storage system is an AC power source, the excitation voltage converter is an AC / DC rectifier converter.

[0020] Furthermore, when the energy storage system is a DC power supply type, the energy storage system is connected to the DC side of the static start inverter to provide power to the static start inverter.

[0021] Furthermore, when the energy storage system is an AC power source, the energy storage system is connected to the AC side of the static start inverter to provide power to the static start inverter.

[0022] Furthermore, the power switching device is located on the AC side or DC side of the static start inverter.

[0023] Furthermore, a voltage converter for adapting the output voltage is also provided between the energy storage system and the static start frequency converter.

[0024] As can be seen from the above technical solution, this application provides an integrated system of synchronous condenser and on-site energy storage in a new energy power plant. By using an on-site energy storage system to replace the traditional excitation system to excite the rotor winding of the synchronous condenser, the strong excitation performance of the synchronous condenser is improved. At the same time, the energy storage system is used as the starting power supply for the synchronous condenser, ensuring the reliability of the synchronous condenser's start-up. Thus, the synchronous condenser and energy storage system in the new energy power plant are effectively integrated, improving the reliability of the synchronous condenser equipment and the utilization rate of the energy storage system, and giving full play to the supporting role of the synchronous condenser in the new energy power grid. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the independent excitation mode of the energy storage in the integrated system of synchronous condenser and on-site energy storage of the new energy power plant described in this application.

[0027] Figure 2 This is a schematic diagram of the complementary excitation mode of energy storage and self-excitation in the integrated system of synchronous condenser and on-site energy storage of the new energy power plant described in this application.

[0028] Figure 3This is a schematic diagram of the independent start-up mode of the integrated system of synchronous condenser and on-site energy storage in the new energy power plant described in this application;

[0029] Figure 4 This is a schematic diagram of the energy storage backup start-up mode of the integrated system of synchronous condenser and on-site energy storage in the new energy power plant described in this application. Detailed Implementation

[0030] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0031] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0032] In this application, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0033] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0034] Furthermore, the terms "installation," "setup," "equipped with," "connection," "linking," and "socketing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0035] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0036] Considering the lack of existing technologies that integrate synchronous condensers and energy storage systems, which leads to higher requirements on the capacity and voltage level of the excitation system when the grid voltage drops, increasing system complexity and affecting the dynamic performance of the excitation system, and the inability of the SFC to start the synchronous condenser when the system loses power, resulting in difficulties in system voltage recovery, this application provides an embodiment of an integrated system of synchronous condensers and on-site energy storage in a new energy power plant to effectively integrate synchronous condensers and energy storage systems in the new energy power plant, improve the reliability and utilization rate of synchronous condenser equipment, and give full play to the supporting role of synchronous condensers in the new energy power grid. In this embodiment, the integrated system of synchronous condensers and on-site energy storage in the new energy power plant specifically includes: a synchronous condenser and an energy storage system installed in the new energy power plant.

[0037] Specifically, this can be a synchronous condenser installed on the low-voltage side of the main transformer and an energy storage system connected to the low-voltage busbar within the station.

[0038] See Figure 1 The fusion system includes an independent excitation mode for energy storage. When the fusion system adopts the independent excitation mode for energy storage, the energy storage system is connected to the rotor winding of the synchronous condenser through an excitation voltage converter for adjusting the excitation current, replacing the conventional static self-excitation, so as to independently provide excitation current to the rotor winding.

[0039] See Figure 2 The integrated system also includes a complementary mode of energy storage excitation and self-excitation. An excitation switching device is provided between the energy storage system and the rotor winding of the synchronous condenser. When the integrated system adopts the complementary mode of energy storage excitation and self-excitation, the excitation circuit of the energy storage excitation and the self-excitation is switched through the excitation switching device. When the grid voltage is within the normal operating range, the self-excitation system performs excitation. When the grid voltage drops, the excitation switching device switches to the energy storage system for excitation. In this way, the supporting role of the synchronous condenser in grid voltage is fully utilized through the external excitation method.

[0040] See Figure 3 The integrated system also includes an independent energy storage start-up mode. When the integrated system adopts the independent energy storage start-up mode, the energy storage system is connected to the stator winding of the synchronous condenser through a static start inverter for frequency conversion control. The energy storage system is used to provide energy to independently soft-start the synchronous condenser.

[0041] refer to Figure 4 The integrated system also includes an energy storage backup start-up mode. A static starter inverter is installed between the energy storage system and the stator winding. A power switching device is installed between the static starter inverter and the energy storage system. The energy storage system and the station power system switch power supply circuits through the power switching device. When the station power system and the static starter inverter are in normal condition, the station power system provides start-up power to the static starter inverter. When the station power system and the static starter inverter are in abnormal condition and cannot meet the start-up requirements, the energy storage backup start-up mode is adopted, and the energy storage system provides backup power to the static starter inverter.

[0042] exist Figure 3 and Figure 4 In this configuration, if the energy storage system is an AC system, it is connected to the AC input side of the SFC; if it is a DC system, it is connected to the DC side of the SFC. The voltage converter is used to adapt the output voltage of the energy storage system to the input voltage of the SFC.

[0043] Understandably, synchronous condensers in renewable energy power plants employ self-excited static excitation. When the grid voltage drops, the primary voltage of the excitation transformer also drops significantly, meaning the excitation system's power supply voltage is far below normal levels. Yet, a higher amplitude DC voltage is still required, indirectly placing higher demands on the excitation system's capacity and voltage level, increasing system complexity, and affecting its dynamic performance. This is especially problematic in weak grid scenarios like renewable energy power plants, where the strong excitation effect of the synchronous condenser cannot be fully utilized. Furthermore, since the excitation power originates from the generator and is coupled with the synchronous condenser, it inherently cannot provide 100% reliability. For example, in the event of a fault in the excitation system itself, there is a lack of a corresponding backup excitation power supply.

[0044] Optionally, this application directly uses an energy storage system to replace the traditional excitation system to provide excitation current for the rotor winding of the synchronous condenser. This allows the use of existing self-contained energy storage power supplies at the power station, eliminating the need for excitation transformers and rectifiers in the traditional excitation circuit in the primary electrical system structure. Only a voltage converter needs to be added, utilizing the capacity of the energy storage device itself and improving energy utilization efficiency.

[0045] Optionally, a combination of an energy storage excitation system and a traditional self-excited excitation system can be used. Only under necessary circumstances, such as a voltage dip in the grid, can the excitation switching device switch to the energy storage system for external excitation, fully utilizing the transient non-functional capacity of the synchronous condenser. In this case, the energy storage excitation system operates in an intermittent mode. Specifically, an excitation switching device is also provided between the energy storage system and the rotor winding. This device is used to connect the energy storage system and the rotor winding when a transient voltage dip is detected, and to close the connection circuit when the system voltage returns to normal. This allows the stator winding of the synchronous condenser to provide excitation current to the rotor winding. In other words, when a transient voltage dip occurs, the energy storage system automatically engages and the traditional self-excited system is locked out. Utilizing the constant potential of the energy storage system, it provides external excitation to the synchronous condenser, fully leveraging its strong excitation function. When the system voltage returns to normal, the energy storage excitation system automatically disengages and switches back to the traditional self-excited system. In this approach, the capacity requirements for the energy storage system are reduced, but the requirements for rapid deployment are higher, along with a faster discharge rate and higher discharge current or power. This method uses energy storage as a backup excitation power source in the forced excitation mode, which can improve the forced excitation performance of the synchronous condenser and reduce the performance and capacity requirements for the voltage converter and energy storage device.

[0046] Specifically, energy storage systems require dedicated voltage converters to meet the needs of excitation current regulation. For DC power sources such as batteries and supercapacitors, the excitation converter is a DC / DC power electronic converter, which regulates the DC output excitation voltage by adjusting the duty cycle. For flywheel energy storage, since it uses a motor drive and outputs three-phase AC power, the excitation converter is an AC / DC rectifier converter, with a basic principle similar to a traditional self-excited excitation system.

[0047] Furthermore, the control strategy of this application is similar to that of a traditional self-excited system. The excitation regulator receives the system voltage AVC or the generator terminal voltage command, and obtains the conduction angle of the AC / DC rectifier converter or the duty cycle of the DC / DC converter through PI negative feedback. This generates trigger pulses for the power electronic switches, realizing corresponding switching control, regulating the output DC voltage, and thus regulating the excitation current. When using a DC / DC power electronic converter, the boost factor should be fully considered to ensure that the maximum excitation voltage of the synchronous condenser is greater than three times the rated excitation voltage, and the capacity of the device should meet the requirement of the maximum excitation voltage's duration.

[0048] Understandably, when using an SFC (Stop Starter Variable Frequency) device to start a synchronous condenser, the starting power comes from the station's AC system. Using variable frequency starting will cause adverse effects such as harmonic pollution and current surges on the station's voltage. In addition, when the system loses power, the SFC will be unable to start the synchronous condenser, making it difficult to restore the system voltage.

[0049] In response, this application uses an energy storage system as the starting power source for the synchronous condenser. This allows the energy storage system to play its black start role while simultaneously starting the synchronous condenser in a timely manner, providing reactive inertia support for system recovery under special operating conditions. It also prevents the synchronous condenser from failing to start when the SFC (Self-Fueled Controller) fails.

[0050] Optionally, this application directly uses the energy storage system instead of the station power system as the starting power source for the synchronous condenser, which improves the energy utilization rate of the energy storage system and reduces harmonic pollution and current surges to the station power system.

[0051] Optionally, the energy storage system and the station power system switch power supply circuits through a power switching device. When the station power system and the static starter inverter are in normal condition, the station power system provides starting power to the static starter inverter. When the station power system and the static starter inverter are in abnormal condition and cannot meet the starting requirements, an energy storage backup starting mode is adopted, in which the energy storage system provides backup power to the static starter inverter to improve the starting reliability of the camera equipment under extreme conditions.

[0052] Understandably, regarding the capacity adaptation of the energy storage system, the energy storage system of this application can adopt a single electrochemical energy storage method or a combination of electrochemical energy storage with supercapacitors and flywheel energy storage. Electrochemical energy storage has a large capacity and long discharge time, making it suitable for long-term operation. However, considering that the proportion of new energy configuration energy storage is generally around 10%, while the proportion of synchronous condenser capacity configuration is generally around 10% to 20%, and the excitation capacity of the synchronous condenser accounts for about 1% of the total capacity, the excitation capacity accounts for no more than 2% of the energy storage. The rated capacity of electrochemical energy storage is much larger than the excitation capacity, so it can fully meet the requirements of short-term excitation power and can cover both long-term and intermittent operation modes. Generally, the starting capacity of the synchronous condenser accounts for less than 10% of the synchronous condenser capacity, so its proportion of the energy storage capacity is less than 20%, which is feasible.

[0053] As can be seen from the above description, the integrated system of synchronous condenser and on-site energy storage in the new energy power plant provided in the embodiments of this application improves the excitation performance of the synchronous condenser by using the on-site energy storage system to replace the traditional excitation system for exciting the rotor winding of the synchronous condenser. At the same time, the use of the energy storage system as the starting power supply for the synchronous condenser ensures the reliability of the synchronous condenser's start-up. Thus, the synchronous condenser and energy storage system in the new energy power plant are effectively integrated, improving the reliability of the synchronous condenser equipment and the utilization rate of the energy storage system, and giving full play to the supporting role of the synchronous condenser in the new energy power grid.

[0054] As an optional implementation, a voltage converter for voltage adaptation is also provided between the energy storage system and the static start inverter.

[0055] As an optional implementation, in the complementary mode of energy storage excitation and self-excitation excitation, the excitation switching device is connected to the excitation transformer and rectifier of the synchronous condenser.

[0056] As an optional implementation, it also includes an energy storage excitation regulator that is signal-connected to the excitation voltage converter, the energy storage excitation regulator being used to send control signals to the excitation voltage converter.

[0057] As an optional implementation, when the energy storage system is a DC power supply type, the excitation voltage converter is a DC / DC power electronic converter; when the energy storage system is an AC power supply type, the excitation voltage converter is an AC / DC rectifier converter.

[0058] As an optional implementation, a static starter inverter (SFC) is also included, disposed between the energy storage system and the stator winding. The SFC is connected to the station's AC power supply. When the energy storage system is a DC power supply type, the energy storage system is connected to the DC side of the SFC via a voltage converter to provide power to the SFC. When the energy storage system is an AC power supply type, the energy storage system is connected to the AC side of the SFC via a voltage converter to provide power to the SFC.

[0059] As an optional implementation, a power switching device is provided between the static start inverter and the energy storage system. The power switching device is used to connect the connection circuit between the energy storage system and the static start inverter when a grid accident or power failure of the static start inverter is detected, so that the energy storage system provides backup power for the static start inverter.

[0060] As an optional implementation, the power switching device is located on the AC side or DC side of the static start inverter.

[0061] Optionally, the energy storage system of this application can not only be used directly as the starting power source for the synchronous condenser, but also as a backup power source for the existing SFC. For example, the energy storage system can be used as a backup power source for the AC or DC side of the SFC. For battery energy storage, it can be connected to the DC bus of the SFC to provide power. For flywheel energy storage, it can be connected to the AC side of the SFC to provide power. In this mode, the energy storage system only serves as a backup power source, suitable for emergency startup of the synchronous condenser in the event of a grid accident or SFC power failure. At the same time, a power switching device is set up to switch the power circuit to the energy storage system, which can be connected to the AC or DC side of the SFC depending on the actual situation.

[0062] It is understandable that in this application Figures 1 to 4 The fusion system further includes:

[0063] Wind turbines and photovoltaic (PV) power generation equipment;

[0064] A prefabricated transformer is a transformer that initially steps up the voltage on the wind turbine and photovoltaic sides.

[0065] Main transformer - A transformer that steps up the voltage at the renewable energy power plant before sending it to the main power grid;

[0066] Main grid - refers to the core area of ​​a power system in a certain region where the stability and reliability are relatively strong, relative to the power grid far away from this area where the stability and reliability are relatively weak (such as wind power generation sites).

[0067] Station service transformer - a step-down transformer that provides power to the loads within a new energy power station;

[0068] Synchronous condenser step-up transformer - A transformer that raises the stator side voltage of a synchronous condenser to the same voltage level as the low-voltage side of the main transformer;

[0069] Low-voltage busbar of main transformer: The busbar on the low-voltage side of the main transformer that serves as a collection point;

[0070] Station service voltage busbar: The busbar that supplies power to the low-voltage side (380V) loads within the station;

[0071] Outgoing lines: Outgoing lines from new energy power plants transmit the capacity of new energy power plants to the main grid;

[0072] Synchronous condenser: A type of synchronous motor that provides reactive power regulation for the power grid, consisting of a stator and a rotor.

[0073] Energy storage system: Energy storage system configured in new energy power stations to adapt to peak shaving and frequency regulation and to smooth out power output fluctuations, including but not limited to battery energy storage, supercapacitor energy storage, flywheel energy storage and their auxiliary systems.

[0074] SFC: Variable frequency starter for synchronous condensers;

[0075] Excitation transformer: A traditional self-excited step-down transformer;

[0076] Rectifier: A traditional self-excited device that converts AC voltage into DC voltage;

[0077] Energy storage excitation regulator: An excitation regulation device suitable for using energy storage as an excitation power source;

[0078] Self-excited excitation regulator: Excitation regulation device under traditional self-excited excitation method;

[0079] Excitation voltage converter: A device that performs excitation voltage conversion under energy storage excitation mode. Depending on the power supply type, it can be an AC-DC rectifier or a DC-DC converter.

[0080] Excitation switching device: A device that switches the excitation circuit as needed;

[0081] Voltage converter: A voltage conversion device that ensures the voltage of the energy storage system matches the AC or DC side voltage of the SFC;

[0082] Power switching device: A device that switches between the SFC's station power supply and energy storage power supply as needed.

[0083] The above description is merely an illustrative embodiment of the present invention and is not intended to limit the scope of the invention. Any equivalent changes and modifications made by those skilled in the art without departing from the concept and principles of the present invention should fall within the scope of protection of the present invention.

Claims

1. A system integrating synchronous condenser and on-site energy storage in a new energy power plant, characterized in that, include: Synchronous condensers and energy storage systems installed within new energy power plants; The fusion system includes an independent excitation mode for energy storage. When the fusion system adopts the independent excitation mode for energy storage, the energy storage system is connected to the rotor winding of the synchronous condenser through an excitation voltage converter for adjusting the excitation current, so as to independently provide excitation current to the rotor winding. The integrated system also includes a complementary mode of energy storage excitation and self-excitation. When the integrated system adopts the complementary mode of energy storage excitation and self-excitation, the excitation circuit of energy storage excitation and self-excitation is switched by an excitation switching device. When the grid voltage is within the normal operating range, the self-excitation system performs excitation. When the grid voltage drops, the excitation switching device switches to the energy storage system for excitation. The fusion system also includes an independent energy storage start-up mode. When the fusion system adopts the independent energy storage start-up mode, the energy storage system is connected to the stator winding of the synchronous condenser through a static start inverter for frequency conversion control. The energy storage system is used to provide energy to independently soft-start the synchronous condenser. The integrated system also includes an energy storage backup start-up mode. The energy storage system and the station power system switch power supply circuits through a power switching device. When the station power system and the static start inverter are in normal condition, the station power system provides start-up power to the static start inverter. When the station power system and the static start inverter are in abnormal condition and cannot meet the start-up requirements, the energy storage backup start-up mode is adopted, and the energy storage system provides backup power to the static start inverter.

2. The integrated system of synchronous condenser and on-site energy storage in a new energy power station according to claim 1, characterized in that, It also includes an energy storage excitation regulator that is signal-connected to the excitation voltage converter, the energy storage excitation regulator being used to send control signals to the excitation voltage converter.

3. The integrated system of synchronous condenser and on-site energy storage in a new energy power station according to claim 1, characterized in that, When the energy storage excitation and self-excitation complementary mode are adopted, the excitation switching device is connected to the excitation transformer and rectifier of the synchronous condenser.

4. The integrated system of synchronous condenser and on-site energy storage in a new energy power station according to claim 1, characterized in that, When the energy storage system is a DC power supply type, the excitation voltage converter is a DC / DC power electronic converter.

5. The integrated system of synchronous condenser and on-site energy storage in a new energy power station according to claim 1, characterized in that, When the energy storage system is an AC power source, the excitation voltage converter is an AC / DC rectifier converter.

6. The integrated system of synchronous condenser and on-site energy storage in a new energy power station according to claim 4, characterized in that, When the energy storage system is a DC power supply type, the energy storage system is connected to the DC side of the static start inverter to provide power to the static start inverter.

7. The integrated system of synchronous condenser and on-site energy storage in a new energy power station according to claim 5, characterized in that, When the energy storage system is an AC power source, the energy storage system is connected to the AC side of the static start inverter to provide power to the static start inverter.

8. The integrated system of synchronous condenser and on-site energy storage in a new energy power station according to claim 1, characterized in that, The power switching device is located on the AC or DC side of the static start inverter.

9. The integrated system of synchronous condenser and on-site energy storage in a new energy power station according to claim 1, characterized in that, A voltage converter for voltage adaptation is also provided between the energy storage system and the static start frequency converter.

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