A high-inertia energy storage type synchronous condenser adaptive voltage support control method and device

Abstract

The present application relates to high inertia energy storage type synchronous condenser control technical field, specifically disclose a kind of high inertia energy storage type synchronous condenser adaptive voltage support control method and device.By adjusting the active and reactive power of high inertia energy storage type synchronous condenser to support grid voltage, reactive power is adjusted first, active power is adjusted when necessary, can reduce the deviation of machine terminal voltage as far as possible;Considering the influence of machine terminal voltage and rotor speed variation on the power control ability of condenser, the control ability of high inertia energy storage type synchronous condenser can be fully utilized, and the voltage variation of machine terminal voltage can be reduced;According to the variation degree of high inertia energy storage type synchronous condenser grid-connected point voltage, different strategies are used to flexibly adjust the active and reactive power output of synchronous condenser, which can adapt to various disturbance conditions and effectively support grid voltage;Fixed power control is used to realize the voltage control of high inertia energy storage type synchronous condenser, without communication and complex calculation, and the principle is simple, with high reliability.The present application can realize the adaptive voltage support control of high inertia energy storage type synchronous condenser.

Description

Technical Field

[0001] This invention relates to the field of high-inertia energy storage synchronous condenser control technology, specifically to an adaptive voltage support control method and device for a high-inertia energy storage synchronous condenser. Background Technology

[0002] With the national energy transition, new energy sources will gradually become the mainstay of power supply. Meanwhile, ultra-high voltage direct current (UHVDC) transmission is being widely used as an important method for long-distance transmission of new energy in my country. The development of new energy and UHVDC has intensified the trend of power grid electronicization, leading to a sharp decline in the system's voltage support capacity and highlighting transient overvoltage and undervoltage problems at the UHVDC sending and receiving ends. Currently, power system voltage control mainly includes three types of measures: adjusting the generator's excitation current to change the generator terminal voltage, changing the transformer ratio by adjusting the transformer tap changers, and reducing voltage loss by changing power network parameters and reactive power distribution.

[0003] Adjusting the bus voltage of individual power plants can cause a redistribution of reactive power in the system, potentially conflicting with the economic allocation of reactive power. Therefore, in large power systems, generator voltage regulation is only used as an auxiliary voltage regulation measure. Furthermore, due to the large peak-to-valley load difference, frequent tap adjustments are required, causing voltage fluctuations and affecting equipment lifespan. Changing power network parameters and reactive power distribution typically involves reactive power compensation devices, including parallel static compensators (SVCs), parallel static synchronous compensators (STATCOMs), and parallel synchronous condensers. SVCs generate or absorb reactive power by controlling the firing angle of their thyristors, but frequent thyristor switching can lead to unnecessary harmonic injection. STATCOMs change the nature and magnitude of reactive power generation by adjusting the amplitude and phase of the AC output voltage of the bridge circuit or by directly adjusting the AC current. However, when the system voltage decreases, the reactive power output capability of STATCOMs is affected by the system voltage and may not be able to compensate in time; conversely, when the system voltage increases, STATCOMs may not be able to absorb reactive power in time.

[0004] Currently, the main synchronous condensers used are synchronous motors operating under special conditions. They can automatically increase reactive power output when the grid voltage drops and absorb reactive power when the grid voltage rises to maintain voltage, according to the needs of the power system. Synchronous condenser control mainly consists of a fast voltage loop for rapid voltage regulation and a slow reactive power loop for reactive power storage. During system transients, voltage-driven control enables rapid excitation, while reactive power-driven control maintains stable output during steady-state operation. However, existing synchronous condensers cannot output active power and cannot simultaneously meet the active and reactive power demands of the grid. High-inertia energy storage synchronous condensers are a new type of condenser based on doubly-fed induction generators. Their rotors are connected to the grid via back-to-back converters, and AC excitation is provided by generator-side converters. Through the control of the rotor-side converters, high-inertia energy storage synchronous condensers can achieve a wide range of speed variations and simultaneously regulate active and reactive power output, providing support to the grid. However, the structure and operating principle of high-inertia energy storage synchronous condensers differ fundamentally from existing synchronous condensers. Furthermore, the electromagnetic and electromechanical processes are coupled during large-scale rotor speed variations in high-inertia energy storage synchronous condensers, resulting in complex active and reactive power relationships. This makes existing voltage control technologies unsuitable for high-inertia energy storage synchronous condensers. Therefore, it is urgent to investigate the impact of speed and terminal voltage variations on the power control capability of the condenser to achieve voltage control for high-inertia energy storage synchronous condensers. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the actual problem that this invention needs to solve is: how to explore the impact of transient large slip speed change and voltage change on the power control capability of synchronous condenser, so as to realize adaptive voltage support control of high inertia energy storage synchronous condenser.

[0006] To address the aforementioned technical problems, this invention employs a high-inertia energy storage type synchronous condenser adaptive voltage support control method and apparatus, which may include the following technical solutions:

[0007] In a first aspect of the present invention, a high-inertia energy storage type synchronous condenser adaptive voltage support control method is provided, comprising the following steps:

[0008] S101. Collect the grid connection point voltage and rotor speed of the high-inertia energy storage synchronous condenser. If the grid connection point voltage is less than the minimum allowable voltage when the grid is operating normally, start adaptive voltage support control to support the grid voltage and execute step 102.

[0009] S102. Based on the grid connection point voltage, calculate the controllable range of active and reactive power of the high-inertia energy storage synchronous condenser considering speed variation.

[0010] S103. Based on the grid connection point rated voltage, grid voltage, and line reactance, calculate the reactive power required to restore the grid connection point voltage to its rated value.

[0011] S104. Determine whether the high-inertia energy storage synchronous condenser can restore the grid connection point voltage by only outputting reactive power. If it meets the requirement, proceed to step S105; otherwise, proceed to step S106.

[0012] S105. Set the active power control reference value of the high-inertia energy storage synchronous condenser to zero, and set the reactive power control reference value to the reactive power required to restore the grid connection point voltage to the rated value, thereby implementing control.

[0013] S106. Determine whether the output active and reactive power of the high-inertia energy storage synchronous condenser can restore the grid connection point voltage. If it is satisfied, proceed to step S107; otherwise, proceed to step S108.

[0014] S107. Based on the real-time voltage and real-time speed of the high-inertia energy storage synchronous condenser, calculate the active and reactive power required to restore the grid connection point voltage to the rated voltage, and set them as the control reference values ​​for the active and reactive power of the high-inertia energy storage synchronous condenser, and implement control.

[0015] S108. Based on the real-time voltage and real-time rotational speed of the high-inertia energy storage synchronous condenser, calculate the active and reactive power that maximizes the grid connection point voltage, and set them as control reference values ​​for the active and reactive power of the high-inertia energy storage synchronous condenser, and implement control. In a second aspect of the invention, the invention also proposes an adaptive voltage support control device for a high-inertia energy storage synchronous condenser, the control device comprising:

[0016] The acquisition module is used to collect the grid connection point voltage and rotor speed of the high-inertia energy storage synchronous condenser;

[0017] The first calculation module is used to calculate the controllable range of active and reactive power of high-inertia energy storage synchronous condensers considering rotational speed changes.

[0018] The second calculation module is used to calculate the reactive power required to restore the grid connection point voltage to its rated value.

[0019] The first judgment module is used to determine whether the high-inertia energy storage synchronous condenser can restore the grid connection point voltage by only outputting reactive power. If the high-inertia energy storage synchronous condenser can restore the grid connection point voltage by only outputting reactive power, the first control module is called; otherwise, the second judgment module is called.

[0020] The first control module is used to set the active power control reference value of the high-inertia energy storage synchronous condenser to zero and the reactive power reference value to the reactive power required to restore the grid connection point voltage to the rated value, and to implement control.

[0021] The second judgment module is used to determine whether the active and reactive power output by the high-inertia energy storage synchronous condenser can restore the grid connection point voltage. If it meets the requirements, the third calculation module is called; otherwise, the fourth calculation module is called.

[0022] The third calculation module is used to calculate the active and reactive power that can restore the grid connection point voltage to the rated voltage.

[0023] The second control module is used to set the active and reactive power control reference values ​​of the high-inertia energy storage synchronous condenser to the active and reactive power that can restore the grid connection point voltage to the rated voltage, and to implement control.

[0024] The fourth calculation module is used to calculate the target values ​​of active and reactive power that maximize the voltage at the grid connection point.

[0025] The third control module is used to set the active and reactive power control reference values ​​of the high-inertia energy storage synchronous condenser to the active and reactive power that maximizes the voltage at the grid connection point, and to implement control.

[0026] Existing methods control grid voltage solely by adjusting reactive power, neglecting the impact of active power on the grid. This may result in insufficient reactive power capacity and poor voltage support. The present invention offers the following advantages:

[0027] 1. This invention supports the grid voltage by adjusting the active and reactive power of a high-inertia energy storage synchronous condenser, prioritizing the adjustment of reactive power and adjusting active power when necessary, thereby minimizing the deviation of the generator terminal voltage.

[0028] 2. This invention takes into account the impact of changes in terminal voltage and rotor speed on the power control capability of the synchronous condenser, and can fully utilize the control capability of the high-inertia energy storage synchronous condenser, thereby reducing changes in terminal voltage.

[0029] 3. This invention can flexibly adjust the active and reactive power output of the synchronous condenser according to the degree of change in the grid connection voltage of the high-inertia energy storage synchronous condenser, and can adapt to various disturbance conditions, effectively supporting the grid voltage.

[0030] 4. This invention uses constant power control to achieve voltage control of high-inertia energy storage synchronous condensers, which eliminates the need for communication and complex calculations. The principle is simple and the reliability is high. Attached Figure Description

[0031] To make the objectives, technical solutions, and advantages of the invention clearer, the invention will now be described in further detail with reference to the accompanying drawings, wherein:

[0032] Figure 1 This is a flowchart of an adaptive voltage support control method for a high-inertia energy storage synchronous condenser disclosed in this invention;

[0033] Figure 2 This is a structural diagram of a high-inertia energy storage type synchronous condenser adaptive voltage support control device disclosed in this invention;

[0034] Figure 3 This is a schematic diagram of a simulation model of an adaptive voltage support control scenario for a high-inertia energy storage synchronous condenser according to an embodiment of the present invention.

[0035] Figure 4 This is a schematic diagram illustrating the simulation effect of the adaptive voltage support control scenario for the high-inertia energy storage synchronous condenser according to an embodiment of the present invention. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] like Figure 1 As shown, this invention discloses an adaptive voltage support control method for a high-inertia energy storage type synchronous condenser, comprising the following steps:

[0038] S101. Collect the grid connection point voltage and rotor speed of the high-inertia energy storage synchronous condenser. If the grid connection point voltage is less than the minimum allowable voltage when the grid is operating normally, start adaptive voltage support control to support the grid voltage and execute step 102.

[0039] S102. Based on the grid connection point voltage, calculate the controllable range of active and reactive power of the high-inertia energy storage synchronous condenser considering speed variation.

[0040] S103. Based on the grid connection point rated voltage, grid voltage, and line reactance, calculate the reactive power required to restore the grid connection point voltage to its rated value.

[0041] S104. Determine whether the high-inertia energy storage synchronous condenser can restore the grid connection point voltage by only outputting reactive power. If it meets the requirement, proceed to step S105; otherwise, proceed to step S106.

[0042] S105. Set the active power control reference value of the high-inertia energy storage synchronous condenser to zero, and set the reactive power control reference value to the reactive power required to restore the grid connection point voltage to the rated value, thereby implementing control.

[0043] S106. Determine whether the output active and reactive power of the high-inertia energy storage synchronous condenser can restore the grid connection point voltage. If it is satisfied, proceed to step S107; otherwise, proceed to step S108.

[0044] S107. Based on the real-time voltage and real-time speed of the high-inertia energy storage synchronous condenser, calculate the active and reactive power required to restore the grid connection point voltage to the rated voltage, and set them as the control reference values ​​for the active and reactive power of the high-inertia energy storage synchronous condenser, and implement control.

[0045] S108. Based on the real-time voltage and real-time rotational speed of the high-inertia energy storage synchronous condenser, calculate the active and reactive power that maximizes the grid connection point voltage, and set these as reference values ​​for the active and reactive power control of the high-inertia energy storage synchronous condenser, then implement control. In this embodiment of the invention, based on the collected grid connection point voltage and rotor speed of the high-inertia energy storage synchronous condenser, when the grid connection point voltage is less than the minimum allowable voltage for normal grid operation, adaptive voltage support control is initiated to support the grid voltage. The controllable range of active and reactive power of the high-inertia energy storage synchronous condenser considering rotational speed changes is calculated, and the active and reactive power required to restore the grid connection point voltage to its rated value is calculated.

[0046] In specific implementation, in step S101, the minimum allowable voltage is generally (1 ± 10%) times the rated voltage to (1 ± 5%) times the rated voltage.

[0047] It should be noted that the high-inertia energy storage synchronous condenser is a device without a prime mover. Unlike conventional generators that rely on prime movers (such as water turbines and steam turbines), this type of condenser provides AC excitation to the rotor windings through back-to-back converters and adopts a doubly-fed induction generator structure. This design makes the condenser more flexible in operation, freeing it from dependence on traditional prime movers. Simultaneously, the AC excitation method lays the foundation for more precise power regulation. Active and reactive power regulation is achieved through generator-side converter control. The generator-side converter acts as an intelligent bridge between the condenser and the internal generator mechanism. Through precise control, the active and reactive power output of the condenser can be flexibly adjusted. When the grid load changes, the active power output can be adjusted in a timely manner to ensure the balance between power supply and demand; by adjusting reactive power, the grid voltage can be effectively maintained to meet the power demand of the grid under different operating conditions. Grid-side converter control stabilizes the DC voltage of the back-to-back converters, which is a key link in ensuring the stable operation of the condenser and effective control of the grid. A stable DC voltage is the foundation for the stable operation of the entire system. The grid-side converter ensures that the DC voltage is within the normal range through real-time monitoring and adjustment, thereby guaranteeing the normal operation of the generator-side converter and ensuring the stable operation of the entire synchronous condenser system.

[0048] By employing a high-inertia energy storage synchronous condenser control method, it is possible to achieve support control of grid frequency and voltage. When grid frequency fluctuates, its high inertia characteristics and active power regulation capability can provide an inertial response to suppress frequency changes; when voltage fluctuates, its reactive power regulation capability can respond quickly to adjust grid voltage, ensuring stable grid operation, improving power quality, and enhancing grid stability and reliability.

[0049] In specific implementation, in step S102, the controllable range of active and reactive power of the high-inertia energy storage synchronous condenser takes into account the influence of speed change and is calculated according to the following method;

[0050] The controllable range of active and reactive power of a high-inertia energy storage synchronous condenser is the intersection of the stator-side power domain and the rotor-side power domain. The stator-side power domain is determined by the grid connection point voltage, while the rotor-side power domain is determined by the grid connection point voltage and the rotational speed. As the grid connection point voltage and rotational speed change, the controllable range of active and reactive power of the high-inertia energy storage synchronous condenser changes.

[0051] The stator-side power domain is determined as follows:

[0052] The abscissa of the center of the power domain circle on the stator side is calculated based on the stator voltage amplitude, stator resistance, and stator impedance.

[0053] The ordinate of the center of the power domain circle on the stator side is calculated based on the stator voltage amplitude, stator resistance, and stator impedance.

[0054] The radius of the power domain on the stator side is calculated based on the stator voltage amplitude, stator resistance, stator-side impedance, and allowable rotor current.

[0055] Based on the x and y coordinates of the center of the stator-side power domain, the inner region of the circle constructed with the radius of the stator-side power domain is taken as the stator-side power domain.

[0056] It is understood that this embodiment takes into account factors such as stator voltage, resistance, reactance, and allowable rotor current. The stator-side power domain determined by the above calculations limits the feasible range of active and reactive power output from the stator side of the synchronous condenser, which is of great significance for the reasonable control of the synchronous condenser's operating status in the power system.

[0057] Specifically, the formula for calculating the power domain on the stator side can be expressed as:

[0058]

[0059] In the formula, These are the x and y coordinates of the center and radius of the power domain circle on the stator side, respectively. s Q sThese represent the active and reactive power outputs of the synchronous condenser, U. sm R is the stator voltage amplitude. s X is the stator resistance. ms For the magnetizing reactance, X s For stator reactance, I rmax This is the allowable value for rotor current.

[0060] The rotor-side power domain is determined as follows:

[0061] The abscissa of the center of the rotor-side power domain circle is calculated based on the first power domain coefficient, the second power domain coefficient, and the stator voltage amplitude.

[0062] The ordinate of the center of the rotor-side power domain circle is calculated based on the first power domain coefficient, the third power domain coefficient, and the stator voltage amplitude.

[0063] The radius of the rotor-side power domain is calculated based on the first power domain coefficient, the second power domain coefficient, the third power domain coefficient, the stator voltage amplitude, and the allowable rotor current.

[0064] Based on the horizontal and vertical coordinates of the rotor-side power domain, the inner region of the circle constructed with the radius of the rotor-side power domain is taken as the rotor-side power domain.

[0065] It is understood that this embodiment comprehensively considers factors such as the inductance, resistance, slip, stator voltage amplitude, and allowable rotor current of the stator and rotor. The rotor-side power domain determined by the above calculations limits the range of active and reactive power output by the synchronous condenser rotor side, which helps to reasonably control the operating status of the synchronous condenser rotor side in the power system operation.

[0066] Specifically, the formula for calculating the rotor-side power domain can be expressed as:

[0067]

[0068] In the formula, P s Q s These represent the active and reactive power outputs of the synchronous condenser, R. r X is the rotor resistance. r For rotor reactance, X mr =ω r L m L m For magnetizing inductance, L s P is the stator inductance, s is the slip. s ′ r Q s ′ r R s ′ rThe x and y coordinates of the center of the rotor-side power domain circle and the radius are determined as follows:

[0069]

[0070] Among them, K sr M sr N sr The rotor-side power domain coefficient is determined as follows:

[0071]

[0072] Among them, K sr M represents the first power domain coefficient on the rotor side. sr N represents the rotor-side second power domain coefficient. sr This represents the coefficient of the third power domain on the rotor side.

[0073] In specific implementation, in step S105, the following method is used to determine whether the high-inertia energy storage synchronous condenser can restore the grid connection point voltage by only outputting reactive power:

[0074] Compare the maximum adjustable reactive power of the high-inertia energy storage synchronous condenser with the reactive power required to restore the grid connection point voltage to its rated value. If the maximum adjustable reactive power of the high-inertia energy storage synchronous condenser is greater than or equal to the reactive power required to restore the grid connection point voltage to its rated value, then it is determined that the high-inertia energy storage synchronous condenser can restore the grid connection point voltage by outputting reactive power alone; otherwise, it is determined that the high-inertia energy storage synchronous condenser cannot restore the grid connection point voltage by outputting reactive power alone.

[0075] In specific implementation, the reactive power required to restore the grid connection point voltage to its rated value in this embodiment of the invention is calculated using the following method:

[0076] Based on the square of the rated voltage at the grid connection point of the high-inertia energy storage synchronous condenser and the square of the grid voltage, the square of the deviation of the actual grid voltage from the rated voltage at the grid connection point is calculated.

[0077] The reactive power associated with the high-inertia energy storage synchronous condenser is obtained by using the ratio of the square of the deviation voltage to the line reactance.

[0078] The embodiments of the present invention comprehensively consider factors such as the rated voltage of the synchronous condenser's grid connection point, the actual grid voltage, and the line reactance. By calculating these parameters, it is possible to determine the amount of reactive power that the synchronous condenser should output or absorb to meet the system operation requirements. This is of great significance for rationally controlling the operating status of the synchronous condenser and maintaining grid voltage stability.

[0079] Specifically, the formula for calculating the reactive power required for the grid connection point voltage to recover to its rated value is as follows:

[0080]

[0081] In the formula, U pcc U is the rated voltage at the grid connection point. G X is the grid voltage. L This refers to the line reactance.

[0082] The maximum adjustable reactive power of a high-inertia energy storage synchronous condenser includes the maximum reactive power it can generate and the maximum reactive power it can absorb. Based on the real-time voltage and rated speed, and utilizing the controllable range of active and reactive power of the high-inertia energy storage synchronous condenser, it is calculated using the following method:

[0083] The maximum adjustable reactive power of the stator-side power domain is calculated based on the ordinate and abscissa of the center of the stator-side power domain and the radius.

[0084] The maximum adjustable reactive power of the rotor-side power domain can be calculated based on the ordinate and abscissa of the center of the rotor-side power domain and the radius.

[0085] The maximum reactive power that the synchronous condenser can generate is calculated based on the minimum value between the maximum adjustable reactive power in the stator power domain and the maximum adjustable reactive power in the rotor power domain.

[0086] The minimum adjustable reactive power of the stator-side power domain is calculated based on the ordinate and abscissa of the center of the stator-side power domain and the radius.

[0087] The minimum adjustable reactive power of the rotor-side power domain is calculated based on the ordinate, abscissa, and radius of the center of the rotor-side power domain.

[0088] The maximum reactive power that the synchronous condenser can absorb is calculated based on the maximum value between the minimum adjustable reactive power in the stator-side power domain and the minimum adjustable reactive power in the rotor-side power domain.

[0089] Specifically, by taking the minimum value, we ensure that the calculated maximum reactive power that the synchronous condenser can generate is the maximum reactive power that the synchronous condenser can generate under the combined constraints of the stator and rotor sides. By taking the maximum value, we determine that, under the combined constraints of the stator and rotor sides, the calculated maximum reactive power that the synchronous condenser can absorb is the maximum reactive power that the synchronous condenser can absorb under the combined constraints of the stator and rotor sides.

[0090] Specifically, the formula for calculating the maximum adjustable reactive power of a high-inertia energy storage synchronous condenser is as follows:

[0091]

[0092] In the formula, Q sf To adjust the maximum reactive power that the camera can generate, Q sx To adjust the maximum reactive power that the camera can absorb, These represent the maximum adjustable reactive power in the stator-side power domain and the rotor-side power domain, respectively. These are the minimum adjustable reactive power in the stator-side power domain and the rotor-side power domain, respectively.

[0093] In specific implementation, in step S106, the following method is used to determine whether the active and reactive power output by the high-inertia energy storage synchronous condenser can restore the grid connection point voltage:

[0094] Compare whether the output power function of the high-inertia energy storage synchronous condenser that can restore the grid connection point voltage overlaps with the power range of the high-inertia energy storage synchronous condenser under real-time speed and grid connection point voltage. If there is an overlap, it is determined that the output active and reactive power of the high-inertia energy storage synchronous condenser can restore the grid connection point voltage; otherwise, it is determined that the output active and reactive power of the high-inertia energy storage synchronous condenser cannot restore the grid connection point voltage.

[0095] The output power function of the high-inertia energy storage synchronous condenser capable of restoring the grid connection point voltage is determined as follows:

[0096]

[0097] This function reflects the relationship between the active and reactive power output of the synchronous condenser, the rated voltage at the grid connection point, the grid voltage, and the line reactance. Its purpose is to clarify the mathematical relationships between various electrical quantities during the process of the synchronous condenser restoring the grid connection point voltage, thereby facilitating the analysis and control of the synchronous condenser's output power.

[0098] In specific implementation, in step S107, the active and reactive power required to restore the grid connection point voltage to the rated voltage are determined as follows:

[0099] By combining the output power function and power control range of the high-inertia energy storage synchronous condenser, the intersection point is calculated, and the point with the minimum active power among the two intersection points is selected. The active and reactive power at this point are the active and reactive power that restore the grid connection point voltage to the rated voltage.

[0100] In specific implementation, step S108 involves determining the active and reactive power that maximize the grid connection point voltage by combining the combined power control range with the normal function of the power demand curve. The normal function of the power demand curve is calculated as follows:

[0101]

[0102] Among them, Q sr P represents the active and reactive power that maximize the grid connection point voltage. It is the target value calculated by this formula, and its magnitude works in conjunction with other parameters to meet the requirement of maximizing the grid connection point voltage. s0 With Qs0 The x and y coordinates are the horizontal and vertical coordinates of the point on the power demand curve closest to the power control range, respectively.

[0103] This invention prioritizes reactive power adjustment and adjusts active power when necessary, minimizing terminal voltage deviation. It fully utilizes the control capabilities of high-inertia energy storage synchronous condensers, reducing terminal voltage fluctuations. By employing different strategies to flexibly adjust the active and reactive power output of the synchronous condenser, it can adapt to various disturbances and effectively support grid voltage. It requires no communication or complex calculations, has a simple principle, and high reliability.

[0104] Figure 2 This is a structural diagram of a high-inertia energy storage type synchronous condenser adaptive voltage support control device according to an embodiment of the present invention, as shown below. Figure 2 As shown, the control device includes:

[0105] The acquisition module is used to collect the grid connection point voltage and rotor speed of the high-inertia energy storage synchronous condenser;

[0106] The first calculation module is used to calculate the controllable range of active and reactive power of high-inertia energy storage synchronous condensers considering rotational speed changes.

[0107] The second calculation module is used to calculate the reactive power required to restore the grid connection point voltage to its rated value.

[0108] The first judgment module is used to determine whether the high-inertia energy storage synchronous condenser can restore the grid connection point voltage by only outputting reactive power. If the high-inertia energy storage synchronous condenser can restore the grid connection point voltage by only outputting reactive power, the first control module is called; otherwise, the second judgment module is called.

[0109] The first control module is used to set the active power control reference value of the high-inertia energy storage synchronous condenser to zero and the reactive power reference value to the reactive power required to restore the grid connection point voltage to the rated value, and to implement control.

[0110] The second judgment module is used to determine whether the active and reactive power output by the high-inertia energy storage synchronous condenser can restore the grid connection point voltage. If it meets the requirements, the third calculation module is called; otherwise, the fourth calculation module is called.

[0111] The third calculation module is used to calculate the active and reactive power that can restore the grid connection point voltage to the rated voltage.

[0112] The second control module is used to set the active and reactive power control reference values ​​of the high-inertia energy storage synchronous condenser to the active and reactive power that can restore the grid connection point voltage to the rated voltage, and to implement control.

[0113] The fourth calculation module is used to calculate the target values ​​of active and reactive power that maximize the voltage at the grid connection point.

[0114] The third control module is used to set the active and reactive power control reference values ​​of the high-inertia energy storage synchronous condenser to the active and reactive power that maximizes the voltage at the grid connection point, and to implement control.

[0115] Through the coordinated operation of the acquisition module, various calculation modules, various judgment modules, and various control modules in this embodiment of the invention, the active and reactive power of the high-inertia energy storage synchronous condenser can be adjusted to support the grid voltage. Reactive power is adjusted first, and active power is adjusted when necessary, minimizing the deviation of the generator terminal voltage. Considering the impact of changes in generator terminal voltage and rotor speed on the power control capability of the condenser, the control capability of the high-inertia energy storage synchronous condenser can be fully utilized, reducing voltage fluctuations at the generator terminal. Based on the degree of voltage variation at the grid connection point of the high-inertia energy storage synchronous condenser, different strategies can be used to flexibly adjust the active and reactive power output of the synchronous condenser, adapting to various disturbance conditions and effectively supporting the grid voltage. Constant power control is used to achieve voltage control of the high-inertia energy storage synchronous condenser, eliminating the need for communication and complex calculations; the principle is simple and the reliability is high.

[0116] Create such a structure in MATLAB / Simulink Figure 3 The simulation model of the high-inertia energy storage synchronous condenser has a rated capacity of 11.11 MVA, an inertial time constant of 20.3 s, a pole pair count of 1, a stator rated voltage of 10.5 kV, a rotor rated voltage of 3.3 kV, stator and rotor resistances of 0.074 Ω and 0.0275 Ω respectively, total stator and rotor leakage inductances of 6.11 mH and 6.4 mH respectively, excitation inductance of 234.93 mH, a stator / rotor turns ratio of 0.6, a DC bus voltage of 7000 V, and a DC bus capacitance of 30 mF. The high-inertia doubly-fed synchronous condenser and each renewable energy power station are connected to the common junction point B1 via their respective busbars, and then connected to the grid via a high-voltage AC transmission line through a step-up substation. B2 is the low-voltage side busbar, PCC is the grid connection point between the doubly-fed synchronous condenser and the renewable energy power station, and B3 is the high-voltage access point. The effectiveness of the present invention is verified by comparing the control method of the traditional synchronous condenser that only provides reactive power under transient conditions with the method of the present invention.

[0117] Simulation results are as follows Figure 4As shown, Method 1 is the traditional control method for synchronous condensers to provide reactive current according to reactive power demand, while Method 2 is the method of this invention. Under grid fault conditions and grid connection point fluctuations, the grid connection point voltage drops to 0.75 pu under Method 1, and to 0.78 pu under Method 2, representing a 2% voltage increase compared to Method 1. The comparison results show that the adaptive voltage support control method for high-inertia energy storage synchronous condensers provides greater voltage support than the traditional synchronous condenser method.

[0118] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high-inertia energy-stored synchronous condenser adaptive voltage support control method, characterized by, The method comprises the following steps: S101, collecting the grid-connected point voltage and the rotor speed of the high-inertia energy storage synchronous compensator, and if the grid-connected point voltage is less than the minimum allowable voltage during normal operation of the power grid, starting adaptive voltage support control to support the power grid voltage, and performing step 102; S102, calculating the controllable range of the active and reactive power of the high-inertia energy storage synchronous compensator considering the speed change according to the grid-connected point voltage; S103, calculating the reactive power required to restore the grid-connected point voltage to the rated value according to the grid-connected point rated voltage, the power grid voltage and the line reactance; S104, judging whether the high-inertia energy storage synchronous compensator can restore the grid-connected point voltage by outputting only reactive power, if yes, performing step S105, otherwise performing step S106; S105, setting the active power control reference value of the high-inertia energy storage synchronous compensator to zero and setting the reactive power control reference value to the reactive power required to restore the grid-connected point voltage to the rated value, thereby implementing control; S106, judging whether the high-inertia energy storage synchronous compensator can restore the grid-connected point voltage by outputting active and reactive power, if yes, performing step S107, otherwise performing step S108; S107, calculating the active and reactive power required to restore the grid-connected point voltage to the rated voltage according to the real-time voltage and real-time speed of the high-inertia energy storage synchronous compensator, and setting the active and reactive power control reference value of the high-inertia energy storage synchronous compensator, thereby implementing control; S108, calculating the active and reactive power that can make the grid-connected point voltage as large as possible according to the real-time voltage and real-time speed of the high-inertia energy storage synchronous compensator, and setting the active and reactive power control reference value of the high-inertia energy storage synchronous compensator, thereby implementing control.

2. The adaptive voltage support control method for a high-inertia energy-stored synchronous condenser according to claim 1, wherein In step S102, the controllable range of the active and reactive power of the high-inertia energy storage synchronous compensator considers the influence of the speed change and is calculated by the following method: The controllable range of the active and reactive power of the high-inertia energy storage synchronous compensator is the intersection of the stator side power domain and the rotor side power domain, wherein the stator side power domain is determined by the grid-connected point voltage and the rotor side power domain is determined by the grid-connected point voltage and the speed.

3. The adaptive voltage support control method for a high-inertia energy-stored synchronous condenser according to claim 2, wherein In step S102, the stator side power domain is calculated by the following method: The horizontal coordinate of the center of the stator side power domain is calculated according to the stator voltage amplitude, the stator resistance and the impedance on the stator side; The vertical coordinate of the center of the stator side power domain is calculated according to the stator voltage amplitude, the stator resistance and the impedance on the stator side; The radius of the stator side power domain is calculated according to the stator voltage amplitude, the stator resistance, the impedance on the stator side and the rotor current allowable value; The circular internal region constructed by the horizontal coordinate and the vertical coordinate of the center of the stator side power domain with the radius of the stator side power domain is taken as the stator side power domain.

4. The adaptive voltage support control method for a high-inertia energy-stored synchronous condenser according to claim 2, wherein In step S102, the rotor side power domain is calculated by the following method: The horizontal coordinate of the center of the rotor side power domain is calculated according to the first power domain coefficient on the rotor side, the second power domain coefficient and the stator voltage amplitude; The vertical coordinate of the center of the rotor side power domain is calculated according to the first power domain coefficient on the rotor side, the third power domain coefficient and the stator voltage amplitude; According to the rotor-side first power domain coefficient, the rotor-side second power domain coefficient, the rotor-side third power domain coefficient, the stator voltage amplitude, and the rotor current allowable value, the radius of the rotor-side power domain is calculated; According to the abscissa and the ordinate of the rotor-side power domain, and the radius of the rotor-side power domain, the circular internal region obtained is constructed as the rotor-side power domain.

5. The adaptive voltage support control method of a high-inertia energy-stored synchronous condenser according to claim 1, wherein In step S105, whether the high-inertia energy storage type synchronous condenser only outputting reactive power can restore the grid point voltage is judged according to the following method: The maximum adjustable reactive power of the high-inertia energy storage type synchronous condenser is compared with the size of the reactive power required to restore the grid point voltage to the rated value. If the maximum adjustable reactive power of the high-inertia energy storage type synchronous condenser is greater than or equal to the reactive power required to restore the grid point voltage to the rated value, it is judged that the high-inertia energy storage type synchronous condenser only outputting reactive power can restore the grid point voltage; otherwise, it is judged that the high-inertia energy storage type synchronous condenser only outputting reactive power cannot restore the grid point voltage.

6. The adaptive voltage support control method of the high-inertia energy storage type synchronous condenser according to claim 5, the size of the maximum adjustable reactive power of the high-inertia energy storage type synchronous condenser and the reactive power required to restore the grid point voltage to the rated value are calculated according to the following method respectively: According to the ordinate, the abscissa, and the radius of the center of the stator-side power domain, the maximum adjustable reactive power of the stator-side power domain is calculated; According to the ordinate, the abscissa, and the radius of the center of the rotor-side power domain, the maximum adjustable reactive power of the rotor-side power domain is calculated; According to the minimum value of the maximum adjustable reactive power of the stator-side power domain and the maximum adjustable reactive power of the rotor-side power domain, the maximum reactive power that the condenser can emit is calculated; According to the ordinate, the abscissa, and the radius of the center of the stator-side power domain, the minimum adjustable reactive power of the stator-side power domain is calculated; According to the ordinate, the abscissa, and the radius of the center of the rotor-side power domain, the minimum adjustable reactive power of the rotor-side power domain is calculated; According to the maximum value of the minimum adjustable reactive power of the stator-side power domain and the minimum adjustable reactive power of the rotor-side power domain, the maximum reactive power that the condenser can absorb is calculated; According to the grid point rated voltage square of the high-inertia energy storage type synchronous condenser and the grid voltage square, the deviation voltage square of the actual grid voltage relative to the grid point rated voltage is calculated; According to the ratio of the deviation voltage square to the line reactance, the related reactive power of the high-inertia energy storage type synchronous condenser is obtained.

7. The adaptive voltage support control method of a high-inertia energy-stored synchronous condenser according to claim 1, wherein In step S106, whether the high-inertia energy storage type synchronous condenser outputting active and reactive power can restore the grid point voltage is judged according to the following method: The output power function of the high-inertia energy storage type synchronous condenser capable of restoring the grid point voltage is compared with the intersection of the real-time speed and the grid point voltage of the high-inertia energy storage type synchronous condenser power range. If there is an intersection, it is judged that the high-inertia energy storage type synchronous condenser outputting active and reactive power can restore the grid point voltage; otherwise, it is judged that the high-inertia energy storage type synchronous condenser outputting active and reactive power cannot restore the grid point voltage.

8. The adaptive voltage support control method of a high-inertia energy-stored synchronous condenser according to claim 1, wherein, In step S107, the active and reactive power that makes the grid-connected point voltage recover to the rated voltage is determined in the following way: The intersection point is calculated by combining the high-inertia energy storage type synchronous condenser output power function and the power control range, and the active power minimum point in the intersection point is taken, and the active and reactive power of the point is the active and reactive power that makes the grid-connected point voltage recover to the rated voltage.

9. The adaptive voltage support control method of a high-inertia energy-stored synchronous condenser according to claim 1, wherein, In step S108, the active and reactive power that makes the grid-connected point voltage as large as possible is solved by combining the power control range and the power demand curve normal function.

10. A high-inertia energy-stored synchronous condenser adaptive voltage support control device, characterized by, The control device comprises: An acquisition module is configured to acquire the grid-connected point voltage and the rotor speed of the high-inertia energy storage type synchronous condenser; A first calculation module is configured to calculate the controllable range of the active and reactive power of the high-inertia energy storage type synchronous condenser considering the change of the speed; A second calculation module is configured to calculate the reactive power required to make the grid-connected point voltage recover to the rated value; A first judgment module is configured to judge whether the high-inertia energy storage type synchronous condenser can recover the grid-connected point voltage by outputting only the reactive power, and if the high-inertia energy storage type synchronous condenser can recover the grid-connected point voltage by outputting only the reactive power, a first control module is called, otherwise a second judgment module is called; The first control module is configured to set the active power control reference value of the high-inertia energy storage type synchronous condenser to zero, and set the reactive power reference value to the reactive power required to make the grid-connected point voltage recover to the rated value, and implement control; The second judgment module is configured to judge whether the high-inertia energy storage type synchronous condenser can recover the grid-connected point voltage by outputting the active and reactive power, and if yes, a third calculation module is called, otherwise a fourth calculation module is called; The third calculation module is configured to calculate the active and reactive power that can make the grid-connected point voltage recover to the rated voltage; The second control module is configured to set the active and reactive power control reference value of the high-inertia energy storage type synchronous condenser to the active and reactive power that can make the grid-connected point voltage recover to the rated voltage, and implement control; The fourth calculation module is configured to calculate the active and reactive power target value that can make the grid-connected point voltage as large as possible; The third control module is configured to set the active and reactive power control reference value of the high-inertia energy storage type synchronous condenser to the active and reactive power that can make the grid-connected point voltage as large as possible, and implement control.

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