Self-adaptive voltage support control method and device for high-inertia energy storage type synchronous phase modifier

Abstract

The invention relates to the technical field of high-inertia energy storage type synchronous phase modifier control, and particularly discloses a self-adaptive voltage support control method and device for a high-inertia energy storage type synchronous phase modifier. The power grid voltage is supported by adjusting the active power and the reactive power of the high-inertia energy storage type synchronous phase modifier, the reactive power is adjusted preferentially, the active power is adjusted when necessary, and the deviation of the generator terminal voltage can be reduced as much as possible; the influence of machine end voltage and rotor speed change on the power control capability of the phase modifier is considered, so that the control capability of the high-inertia energy storage type synchronous phase modifier can be fully exerted, and the machine end voltage change is reduced; active and reactive power output of the synchronous phase modifier can be flexibly adjusted by adopting different strategies according to the change degree of the grid-connected point voltage of the high-inertia energy storage type synchronous phase modifier, various disturbance conditions can be adapted, and the power grid voltage can be effectively supported; constant power control is adopted to realize voltage control of the high-inertia energy storage type synchronous phase modifier, communication and complex calculation are not needed, the principle is simple, and the reliability is high. According to the invention, self-adaptive voltage support control of the high-inertia energy storage type synchronous phase modifier can be realized.

Description

Technical Field

[0001] The present invention relates to the technical field of high inertia energy storage type synchronous condenser control, and in particular to a high inertia energy storage type synchronous condenser adaptive voltage support control method and device. Background Art

[0002] With the national energy transformation, new energy will gradually become the main power supply. At the same time, UHV DC transmission is widely used as an important way to transmit new energy over long distances in my country. The development of new energy and UHV DC has intensified the trend of power grid electronicization, the system voltage support capacity has dropped sharply, and the transient overvoltage and low voltage problems at the UHV DC sending and receiving ends are prominent. At present, the voltage control of the power system mainly includes three measures: adjusting the excitation current of the generator to change the generator terminal voltage, changing the transformation ratio by adjusting the transformer tap, and changing the power network parameters and reactive power distribution to reduce voltage loss.

[0003] Adjusting the bus voltage of individual power plants will cause the redistribution of reactive power in the system, which may conflict with the economic distribution of reactive power. Therefore, in large power systems, generator voltage regulation is only used as an auxiliary voltage regulation measure. In addition, due to the large peak-to-valley difference in load, frequent tap adjustment is required, which not only causes voltage fluctuations but also affects the life of the equipment. Reactive compensation devices are usually used to change power network parameters and reactive power distribution, including parallel static compensators (SVCs), parallel static synchronous compensators (STATCOMs), parallel synchronous condensers, etc. SVC emits or absorbs reactive power by controlling the trigger angle of its thyristors, but frequent switching of thyristors will cause unnecessary harmonic injection. STATCOM changes and emits the nature and size of reactive power by adjusting the amplitude and phase of the output voltage on the AC side of the bridge circuit or directly adjusting the current on the AC side. However, when the system voltage decreases, the reactive output capacity of STATCOM is affected by the system voltage and may not be able to compensate in time. When the system voltage increases, STATCOM cannot absorb reactive power in time.

[0004] The synchronous condenser currently used is a synchronous motor in a special operating state. It can automatically increase reactive 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. The control of the synchronous condenser is mainly composed of a fast voltage loop for rapid voltage regulation and a slow reactive loop for reactive reserve. In transient state, the system is rapidly excited by voltage-dominant control, and in steady state, the reactive-dominant control maintains stable output. However, the existing synchronous condenser cannot output active power and cannot take into account the active and reactive power requirements of the grid. The high-inertia energy storage type synchronous condenser is a new type of condenser based on a doubly fed induction generator. Its rotor is connected to the grid through a back-to-back converter, and the machine-side converter is used to provide AC excitation. Through the control of the rotor-side converter, the high-inertia energy storage type synchronous condenser can change speed over a wide range and adjust active and reactive output at the same time to provide support for the grid. However, the structure and operation principle of high-inertia energy storage synchronous condensers are essentially different from those of existing synchronous condensers. In addition, the electromagnetic process is coupled with the electromechanical process during the large-range change of the rotor speed of high-inertia energy storage synchronous condensers, and the relationship between active and reactive power is complex, making it impossible for existing voltage control technologies to be directly applied to high-inertia energy storage synchronous condensers. Therefore, it is urgent to explore the influence of speed and terminal voltage changes on the power control capability of the condenser, and realize voltage control of high-inertia energy storage synchronous condensers. Summary of the invention

[0005] In view of the above-mentioned deficiencies of the prior art, the problem that the present invention actually needs to solve is: how to explore the influence of transient large slip speed change and voltage change on the power control capability of the phase regulator, so as to realize adaptive voltage support control of high inertia energy storage type synchronous phase regulator.

[0006] In order to solve the above technical problems, the present invention adopts a high inertia energy storage type synchronous condenser adaptive voltage support control method and device, which may include the following technical solutions:

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

[0008] S101, collecting 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 during normal operation of the power grid, start the adaptive voltage support control to support the grid voltage, and execute step 102;

[0009] S102, calculating the controllable range of active and reactive power of a high-inertia energy storage type synchronous condenser taking into account speed changes according to the grid connection point voltage;

[0010] S103, calculating the reactive power required to restore the grid connection point voltage to the rated value according to the grid connection point rated voltage, the grid voltage and the line reactance;

[0011] S104, judging whether the high inertia energy storage synchronous condenser can restore the grid connection point voltage by only outputting reactive power, if satisfied, executing step S105, otherwise executing step S106;

[0012] S105, setting the active power control reference value of the high inertia energy storage type synchronous condenser to zero, and setting 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, judging whether the grid connection point voltage can be restored by outputting active and reactive power using the high inertia energy storage type synchronous condenser, if satisfied, executing step S107, otherwise executing step S108;

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

[0015] S108, according to the real-time voltage and real-time speed of the high-inertia energy storage type synchronous condenser, calculate the active and reactive power that can make the grid connection point voltage as large as possible, and set them as the active and reactive power control reference values ​​of the high-inertia energy storage type synchronous condenser, and implement control. In the second aspect of the present invention, the present invention also proposes an adaptive voltage support control device for high-inertia energy storage type synchronous condenser, the control device comprising:

[0016] Acquisition module, used to collect the grid connection point voltage and rotor speed of high inertia energy storage synchronous condenser;

[0017] The first calculation module is used to calculate the controllable range of active and reactive power of the high inertia energy storage type synchronous condenser taking into account the speed change;

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

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

[0021] The second judgment module is used to judge whether the grid connection point voltage can be restored by outputting active and reactive power using the high inertia energy storage type synchronous condenser. If the determination is satisfied, 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 type synchronous condenser to active and reactive power that can restore the grid connection point voltage to the rated voltage, and implement control;

[0024] A fourth calculation module is used to calculate active and reactive power target values ​​that can make the grid connection point voltage as large as possible;

[0025] The third control module is used to set the active and reactive power control reference values ​​of the high-inertia energy storage type synchronous phase condenser to the active and reactive power that can make the grid connection point voltage as large as possible, and implement control.

[0026] The existing method of controlling the grid voltage only by adjusting reactive power ignores the influence of active power on the grid, which may result in insufficient reactive capacity and poor voltage support effect. The present invention has the following beneficial effects:

[0027] 1. The present invention supports the grid voltage by adjusting the active and reactive power of the high-inertia energy storage type synchronous condenser, giving priority to adjusting the reactive power, and adjusting the active power when necessary, so as to minimize the deviation of the terminal voltage.

[0028] 2. The present invention takes into account the influence of the machine terminal voltage and rotor speed changes on the power control capability of the phase shifter, and can give full play to the control capability of the high inertia energy storage type synchronous phase shifter and reduce the machine terminal voltage changes.

[0029] 3. The present invention can flexibly adjust the active and reactive power output of the synchronous condenser according to the degree of change of the voltage at the grid connection point of the high-inertia energy storage synchronous condenser by adopting different strategies, can adapt to various disturbance conditions, and effectively support the grid voltage.

[0030] 4. The present invention adopts constant power control to realize voltage control of high inertia energy storage type synchronous phase condenser, which does not require communication and complex calculation, has simple principle and high reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to make the purpose, technical solution and advantages of the invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings, in which:

[0032] Figure 1 This is a flow chart of an adaptive voltage support control method for a high inertia energy storage type synchronous condenser disclosed in the present invention;

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

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

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

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

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

[0038] S101, collecting 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 during normal operation of the power grid, start the adaptive voltage support control to support the grid voltage, and execute step 102;

[0039] S102, calculating the controllable range of active and reactive power of a high-inertia energy storage type synchronous condenser taking into account speed changes according to the grid connection point voltage;

[0040] S103, calculating the reactive power required to restore the grid connection point voltage to the rated value according to the grid connection point rated voltage, the grid voltage and the line reactance;

[0041] S104, judging whether the high inertia energy storage synchronous condenser can restore the grid connection point voltage by only outputting reactive power, if satisfied, executing step S105, otherwise executing step S106;

[0042] S105, setting the active power control reference value of the high inertia energy storage type synchronous condenser to zero, and setting 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, judging whether the grid connection point voltage can be restored by outputting active and reactive power using the high inertia energy storage type synchronous condenser, if satisfied, executing step S107, otherwise executing step S108;

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

[0045] S108. According to the real-time voltage and real-time speed of the high-inertia energy storage type synchronous condenser, the active and reactive power that can make the grid connection point voltage as large as possible is calculated, and set as the active and reactive power control reference value of the high-inertia energy storage type synchronous condenser, and implement control. In the example of the present invention, the present invention collects the grid connection point voltage and rotor speed of the high-inertia energy storage type synchronous condenser, and when the grid connection point voltage is less than the minimum allowable voltage for normal operation of the power grid, starts the adaptive voltage support control to support the grid voltage, calculates the controllable range of the active and reactive power of the high-inertia energy storage type synchronous condenser considering the speed change, and calculates the active and reactive power required to restore the grid connection point voltage to the rated value.

[0046] During 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 type synchronous condenser is a prime mover-free device. Unlike conventional generators that rely on prime movers (such as turbines and steam turbines), this type of condenser provides AC excitation for the rotor winding through a back-to-back converter and adopts a double-fed induction generator structure. This design makes the condenser more flexible in operation and gets rid of the dependence on traditional prime movers. At the same time, the AC excitation method lays the foundation for more accurate power regulation. Active and reactive power regulation is achieved through machine-side converter control. The machine-side converter is like an intelligent bridge between the condenser and the internal generator mechanism. Through precise control, the active power and reactive power output of the condenser can be flexibly adjusted. When the grid load changes, the active power output can be adjusted in time to ensure the balance of power supply and demand; by adjusting the reactive power, the grid voltage can be effectively maintained to meet the power demand of the grid under different working conditions. The grid-side converter control realizes the stability of the DC voltage of the back-to-back converter, which is a key link to ensure the stable operation of the condenser and the effective control of the grid. Stable DC voltage is the basis 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 providing guarantee for the normal operation of the machine-side converter and ensuring the stable operation of the entire phase-shifting system.

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

[0049] In specific implementation, in step S102, the controllable range of active and reactive power of the high inertia energy storage type 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 high-inertia energy storage type synchronous phase condenser is the intersection of the stator side power domain and the rotor side power domain, where the stator side power domain is determined by the grid connection point voltage, and the rotor side power domain is determined by the grid connection point voltage and speed. As the grid connection point voltage and speed change, the controllable range of active and reactive power of high-inertia energy storage type synchronous phase condenser changes.

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

[0052] According to the stator voltage amplitude, the stator resistance and the impedance on the stator side, the abscissa of the center of the stator side power domain circle is calculated;

[0053] According to the stator voltage amplitude, the stator resistance and the impedance on the stator side, the ordinate of the center of the stator side power domain is calculated;

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

[0055] According to the abscissa and ordinate of the center of the stator side power domain, the inner area of ​​the circle is constructed as the stator side power domain with the radius of the stator side power domain.

[0056] It can be understood that this embodiment takes into account factors such as stator voltage, resistance, reactance and allowable value of rotor current. The stator side power domain determined by the above calculation limits the feasible range of active power and reactive power output on the stator side of the phase regulator, which is of great significance for the reasonable control of the operating state of the phase regulator during power system operation.

[0057] Specifically, the calculation formula of the stator side power domain can be expressed as:

[0058]

[0059] In the formula, are the horizontal and vertical coordinates and radius of the center of the power domain circle on the stator side, P s , Q sare the active power and reactive power output by the phase regulator, U sm is the stator voltage amplitude, R s is the stator resistance, X ms is the magnetizing reactance, X s is the stator reactance, I rmax is the allowable value of rotor current.

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

[0061] The horizontal coordinate of the center of the power domain of the rotor side is calculated according to the first power domain coefficient, the second power domain coefficient and the stator voltage amplitude of the rotor side;

[0062] The ordinate of the center of the power domain of the rotor side is calculated according to the first power domain coefficient, the third power domain coefficient and the stator voltage amplitude of the rotor side;

[0063] The radius of the rotor side power domain is calculated according to the first power domain coefficient, the second power domain coefficient, the third power domain coefficient, the stator voltage amplitude, and the rotor current allowable value on the rotor side;

[0064] According to the abscissa and ordinate of the rotor side power domain and the radius of the rotor side power domain, the inner area of ​​the circle is constructed as the rotor side power domain.

[0065] It can be understood that this embodiment comprehensively considers factors such as the inductance, resistance, slip rate, stator voltage amplitude and allowable value of rotor current of the stator and rotor. The rotor side power domain determined by the above calculation limits the value range of active power and reactive power output on the rotor side of the phase regulator, which helps to reasonably regulate the operating state of the rotor side of the phase regulator during the operation of the power system.

[0066] Specifically, the calculation formula of the rotor side power domain can be expressed as:

[0067]

[0068] Where P s , Q s are the active power and reactive power output by the phase regulator, R r is the rotor resistance, X r is the rotor reactance, X mr =ω r L m , L m is the magnetizing inductance, L s is the stator inductance, s is the slip rate. s ' r , Q s ' r , R s ' rare the horizontal and vertical coordinates of the center of the power domain circle on the rotor side and the radius, which are determined as follows:

[0069]

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

[0071]

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

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

[0074] Compare the maximum adjustable reactive power of the high inertia energy storage type synchronous condenser with the reactive power required to restore the grid connection 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 connection point voltage to the rated value, then it is judged that the high inertia energy storage type synchronous condenser can restore the grid connection point voltage by only outputting reactive power; otherwise, it is judged that the high inertia energy storage type synchronous condenser cannot restore the grid connection point voltage by only outputting reactive power.

[0075] In specific implementation, the reactive power required to restore the grid connection point voltage to the rated value in the embodiment of the present invention is calculated as follows:

[0076] According to the square of the rated voltage of the grid connection point of the high inertia energy storage synchronous condenser and the square of the grid voltage, the square of the deviation voltage of the actual grid voltage relative to the rated voltage of the grid connection point is calculated;

[0077] According to the ratio of the square of the deviation voltage to the line reactance, the reactive power related to the high inertia energy storage type synchronous condenser is obtained.

[0078] The embodiment of the present invention comprehensively considers factors such as the rated voltage of the phase modulator grid-connected point, the actual grid voltage, and the line reactance. Through the calculation of these parameters, the reactive power that the phase modulator should output or absorb in order to meet the system operation requirements can be obtained, which is of great significance for reasonably controlling the operating state of the phase modulator and maintaining the stability of the grid voltage.

[0079] Specifically, the calculation formula for the reactive power required to restore the grid voltage to the rated value is expressed as:

[0080]

[0081] Where U pcc is the rated voltage of the grid connection point, U G is the grid voltage, X L is the line reactance.

[0082] The maximum adjustable reactive power of high inertia energy storage synchronous condenser includes the maximum reactive power that can be generated and the maximum reactive power that can be absorbed. According to the real-time voltage and rated speed, using the controllable range of active and reactive power of high inertia energy storage synchronous condenser, it is calculated as follows:

[0083] According to the ordinate, abscissa and radius of the center of the stator side power domain circle, the maximum adjustable reactive power of the stator side power domain is calculated;

[0084] According to the ordinate, abscissa and radius of the center of the rotor side power domain circle, the maximum adjustable reactive power in the rotor side power domain is calculated;

[0085] The maximum reactive power that the phase regulator can generate is calculated based on the minimum value of the maximum adjustable reactive power in the stator power domain and the maximum adjustable reactive power in the rotor power domain;

[0086] According to the ordinate, abscissa and radius of the center of the stator side power domain circle, the minimum adjustable reactive power of the stator side power domain is calculated;

[0087] According to the ordinate, abscissa and radius of the center of the rotor side power domain circle, the minimum adjustable reactive power of the rotor side power domain is calculated;

[0088] The maximum reactive power that the phase regulator can absorb is calculated based on the maximum value of the minimum adjustable reactive power in the stator side power domain and the minimum adjustable reactive power in the rotor side power domain.

[0089] Among them, by taking the minimum value, it is ensured that the calculated maximum reactive power that the phase regulator can generate is the maximum reactive power that the phase regulator can generate under the comprehensive restrictions of the stator and rotor sides. By taking the maximum value, it is determined that under the comprehensive restrictions of the stator and rotor sides, it is ensured that the calculated maximum reactive power that the phase regulator can absorb is the maximum reactive power that the phase regulator can absorb under the comprehensive restrictions of the stator and rotor sides.

[0090] Specifically, the calculation formula for the maximum adjustable reactive power of the high inertia energy storage synchronous condenser is expressed as:

[0091]

[0092] In the formula, Q sf Q is the maximum reactive power that the phase regulator can generate. sx is the maximum reactive power that the phase regulator can absorb, are the maximum adjustable reactive power in the stator side power domain and the rotor side power domain, They 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, it is determined whether the grid connection point voltage can be restored by outputting active and reactive power using a high inertia energy storage type synchronous condenser according to the following method:

[0094] Compare whether the output power function of the high-inertia energy storage type synchronous condenser capable of restoring the grid-connected point voltage has an intersection with the power range of the high-inertia energy storage type synchronous condenser under the real-time speed and the grid-connected point voltage. If there is an intersection, it is judged that the grid-connected point voltage can be restored by outputting active and reactive power of the high-inertia energy storage type synchronous condenser; otherwise, it is judged that the grid-connected point voltage cannot be restored by outputting active and reactive power of the high-inertia energy storage type synchronous condenser.

[0095] Among them, the output power function of the high inertia energy storage type synchronous phase condenser capable of restoring the grid connection point voltage is determined as follows:

[0096]

[0097] This function reflects the relationship between the active power and reactive power output by the phase regulator and the rated voltage at the grid connection point, the grid voltage, and the line reactance. Its purpose is to clarify the mathematical relationship between various electrical quantities in the process of the phase regulator restoring the grid connection point voltage, so as to facilitate the analysis and control of the output power of the phase regulator.

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

[0099] Combine the output power function of the high-inertia energy storage synchronous condenser with the power control range, calculate the intersection point and take the point with the minimum active power among the two intersection points. The active and reactive powers at this point are the active and reactive powers required to restore the grid connection point voltage to the rated voltage.

[0100] In specific implementation, in step S108, the active and reactive power that makes the grid connection point voltage as large as possible is solved by combining the power control range with the power demand curve normal function. The power demand curve normal function is calculated as follows:

[0101]

[0102] Among them, Q sr It represents the active and reactive power that makes the grid connection point voltage as large as possible. It is the target value calculated by this formula. Its size works together with other parameters to meet the requirement of making the grid connection point voltage as large as possible. s0 With Qs0 They are respectively the horizontal and vertical coordinates of the point on the power demand curve that is closest to the power control range.

[0103] The embodiment of the present invention can adjust reactive power first, and adjust active power when necessary, and can reduce the deviation of the terminal voltage as much as possible. Give full play to the control ability of high-inertia energy storage synchronous condenser and reduce the voltage change of the terminal voltage. The active and reactive power output of the synchronous condenser can be flexibly adjusted by adopting different strategies, which can adapt to various disturbance conditions and effectively support the grid voltage. No communication and complex calculation are required, the principle is simple, and the reliability is high.

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

[0105] Acquisition module, used to collect the grid connection point voltage and rotor speed of high inertia energy storage synchronous condenser;

[0106] The first calculation module is used to calculate the controllable range of active and reactive power of the high inertia energy storage type synchronous condenser taking into account the speed change;

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

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

[0110] The second judgment module is used to judge whether the grid connection point voltage can be restored by outputting active and reactive power using the high inertia energy storage type synchronous condenser. If the determination is satisfied, 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 type synchronous condenser to active and reactive power that can restore the grid connection point voltage to the rated voltage, and implement control;

[0113] A fourth calculation module is used to calculate active and reactive power target values ​​that can make the grid connection point voltage as large as possible;

[0114] The third control module is used to set the active and reactive power control reference values ​​of the high-inertia energy storage type synchronous phase condenser to the active and reactive power that can make the grid connection point voltage as large as possible, and implement control.

[0115] Through the cooperation of the acquisition module, various calculation modules, various judgment modules and various control modules of the embodiment of the present invention, the active and reactive power of the high-inertia energy storage type synchronous condenser can be adjusted to support the grid voltage, and the reactive power is adjusted first. When necessary, the active power is adjusted, and the deviation of the machine-end voltage can be reduced as much as possible. Considering the influence of the machine-end voltage and rotor speed changes on the power control ability of the condenser, the control ability of the high-inertia energy storage type synchronous condenser can be fully exerted to reduce the voltage change of the machine-end voltage. According to the degree of change of the voltage at the grid connection point of the high-inertia energy storage type synchronous condenser, different strategies can be used to flexibly adjust the active and reactive power output of the synchronous condenser, which can adapt to various disturbance situations and effectively support the grid voltage. The voltage control of the high-inertia energy storage type synchronous condenser is realized by constant power control, without the need for communication and complex calculations, with a simple principle and high reliability.

[0116] In MATLAB / Simulink, create Figure 3 The simulation model of the high inertia energy storage type high inertia energy storage type synchronous phase condenser has a rated capacity of 11.11MVA, an inertia time constant of 20.3s, a pole pair number of 1, a stator rated voltage of 10.5kV, a rotor rated voltage of 3.3kV, stator and rotor resistances of 0.074Ω and 0.0275Ω respectively, stator and rotor total leakage inductances of 6.11mH and 6.4mH respectively, excitation inductance of 234.93mH, stator / rotor turns ratio of 0.6, DC bus voltage of 7000V, and DC bus capacitance of 30mF. The high inertia double-fed phase condenser and each new energy station are connected to the common connection point B through their respective busbars. 1 , and then connected to the grid through the high voltage AC transmission line via the step-up substation, B 2 is the low voltage side busbar, PCC is the grid connection point between the double-fed phase regulator and the new energy station, B 3 The effectiveness of the method of the present invention is verified by comparing the control method of the conventional synchronous condenser that only provides reactive power under transient conditions with the method of the present invention.

[0117] The simulation results are as follows Figure 4As shown, method 1 is a control method for traditional synchronous condensers to provide reactive current according to reactive demand, and method 2 is the method of the present invention. In the case of grid fault and grid point fluctuation, the grid point voltage drops to 0.75pu under method 1, and the grid point voltage drops to 0.78pu under method 2, which is 2% higher than that of method 1. The comparison results show that the adaptive voltage support control method of high inertia energy storage synchronous condensers provides greater voltage support than traditional synchronous condensers.

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

Claims

1. An adaptive voltage support control method for a high inertia energy storage type synchronous condenser, characterized in that: The steps include: S101, collecting 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 during normal operation of the power grid, start the adaptive voltage support control to support the grid voltage, and execute step 102; S102, calculating the controllable range of active and reactive power of a high-inertia energy storage type synchronous condenser taking into account speed changes according to the grid connection point voltage; S103, calculating the reactive power required to restore the grid connection point voltage to the rated value according to the grid connection point rated voltage, the grid voltage and the line reactance; S104, determining whether the high inertia energy storage synchronous condenser can restore the grid connection point voltage by only outputting reactive power, if satisfied, executing step S105, otherwise executing step S106; S105, setting the active power control reference value of the high inertia energy storage type synchronous condenser to zero, and setting 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; S106, judging whether the grid connection point voltage can be restored by outputting active and reactive power using the high inertia energy storage type synchronous condenser, if satisfied, executing step S107, otherwise executing step S108; S107, according to the real-time voltage and real-time speed of the high-inertia energy storage type synchronous condenser, calculate the active and reactive power required to restore the grid connection point voltage to the rated voltage, set them as the active and reactive power control reference values ​​of the high-inertia energy storage type synchronous condenser, and implement control; S108. According to the real-time voltage and real-time speed of the high-inertia energy storage type synchronous condenser, the active and reactive power that can make the grid connection point voltage as large as possible is calculated, and set as the active and reactive power control reference values ​​of the high-inertia energy storage type synchronous condenser to implement control.

2. The adaptive voltage support control method for a high inertia energy storage type synchronous condenser according to claim 1 is characterized in that: 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: The controllable range of active and reactive power of the high inertia energy storage type synchronous phase condenser 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 connection point voltage, and the rotor side power domain is determined by the grid connection point voltage and the rotation speed.

3. The adaptive voltage support control method for a high inertia energy storage type synchronous condenser according to claim 2, characterized in that: In step S102, the stator side power domain is calculated according to the following method: According to the stator voltage amplitude, the stator resistance and the impedance on the stator side, the abscissa of the center of the stator side power domain circle is calculated; According to the stator voltage amplitude, the stator resistance and the impedance on the stator side, the ordinate of the center of the stator side power domain is calculated; The radius of the stator side power domain is calculated based on the stator voltage amplitude, stator resistance, stator side impedance and rotor current allowable value; According to the abscissa and ordinate of the center of the stator side power domain, the inner area of ​​the circle is constructed as the stator side power domain with the radius of the stator side power domain.

4. The adaptive voltage support control method for a high inertia energy storage type synchronous condenser according to claim 2, characterized in that: In step S102, the rotor side power domain is calculated according to the following method: The horizontal coordinate of the center of the power domain of the rotor side is calculated according to the first power domain coefficient, the second power domain coefficient and the stator voltage amplitude of the rotor side; The ordinate of the center of the power domain of the rotor side is calculated according to the first power domain coefficient, the third power domain coefficient and the stator voltage amplitude of the rotor side; The radius of the rotor side power domain is calculated according to the first power domain coefficient, the second power domain coefficient, the third power domain coefficient, the stator voltage amplitude, and the rotor current allowable value on the rotor side; According to the abscissa and ordinate of the rotor side power domain and the radius of the rotor side power domain, the inner area of ​​the circle is constructed as the rotor side power domain.

5. The adaptive voltage support control method for a high inertia energy storage type synchronous condenser according to claim 1, characterized in that: In step S105, it is determined whether the high inertia energy storage type synchronous condenser can restore the grid connection point voltage by only outputting reactive power according to the following method: Compare the maximum adjustable reactive power of the high inertia energy storage type synchronous condenser with the reactive power required to restore the grid connection 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 connection point voltage to the rated value, then it is judged that the high inertia energy storage type synchronous condenser can restore the grid connection point voltage by only outputting reactive power; otherwise, it is judged that the high inertia energy storage type synchronous condenser cannot restore the grid connection point voltage by only outputting reactive power.

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

7. The adaptive voltage support control method for a high inertia energy storage type synchronous condenser according to claim 1, characterized in that: In step S106, it is determined whether the grid connection point voltage can be restored by outputting active and reactive power using the high inertia energy storage type synchronous condenser according to the following method: Compare whether the output power function of the high-inertia energy storage type synchronous condenser capable of restoring the grid-connected point voltage has an intersection with the power range of the high-inertia energy storage type synchronous condenser under the real-time speed and the grid-connected point voltage. If there is an intersection, it is judged that the grid-connected point voltage can be restored by outputting active and reactive power of the high-inertia energy storage type synchronous condenser; otherwise, it is judged that the grid-connected point voltage cannot be restored by outputting active and reactive power of the high-inertia energy storage type synchronous condenser.

8. The adaptive voltage support control method for a high inertia energy storage type synchronous condenser according to claim 1, characterized in that: In step S107, the active and reactive powers required to restore the grid connection point voltage to the rated voltage are determined in the following manner: Combine the output power function of the high-inertia energy storage synchronous condenser with the power control range, calculate the intersection point and take the point with the minimum active power among the intersection points. The active and reactive powers at this point are the active and reactive powers required to restore the grid connection point voltage to the rated voltage.

9. The adaptive voltage support control method for a high inertia energy storage type synchronous condenser according to claim 1, characterized in that: In step S108, the active and reactive powers that make the grid connection point voltage as large as possible are solved by combining the power control range with the normal function of the power demand curve.

10. An adaptive voltage support control device for a high inertia energy storage type synchronous condenser, characterized in that: The control device comprises: Acquisition module, used to collect the grid connection point voltage and rotor speed of high inertia energy storage synchronous condenser; The first calculation module is used to calculate the controllable range of active and reactive power of the high inertia energy storage type synchronous condenser taking into account the speed change; The second calculation module is used to calculate the reactive power required to restore the grid connection point voltage to the rated value; The first judgment module is used to judge whether the high-inertia energy storage type synchronous condenser can restore the grid connection point voltage by only outputting reactive power. If the high-inertia energy storage type 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; The first control module is used to set the active power control reference value of the high inertia energy storage type 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 implement control; The second judgment module is used to judge whether the grid connection point voltage can be restored by outputting active and reactive power using the high inertia energy storage type synchronous condenser. If the determination is satisfied, the third calculation module is called, otherwise the fourth calculation module is called; 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; The second control module is used to set the active and reactive power control reference values ​​of the high-inertia energy storage type synchronous condenser to active and reactive power that can restore the grid connection point voltage to the rated voltage, and implement control; A fourth calculation module is used to calculate active and reactive power target values ​​that can make the grid connection point voltage as large as possible; The third control module is used to set the active and reactive power control reference values ​​of the high-inertia energy storage type synchronous phase condenser to the active and reactive power that can make the grid connection point voltage as large as possible, and implement control.

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