Voltage support coordinated control method and system for high-inertia energy storage type synchronous condenser

Abstract

This invention relates to the field of power system protection and control technology, specifically disclosing a voltage support coordination control method and system for high-inertia energy storage synchronous condensers. Addressing the problem of drastic fluctuations in the junction temperature of power devices caused by large-scale changes in rotor current amplitude and frequency during voltage support in high-inertia energy storage synchronous condensers using power electronic converters, the invention considers the interaction between the synchronous condenser's motor electrical quantities, converter losses, thermal impedance, and device junction temperature. A converter thermal network model is established, and a junction temperature safety domain is constructed with the synchronous condenser's active and reactive power as state variables. Under the constraints of the junction temperature safety domain, the active and reactive power outputs of the synchronous condenser are coordinated in real time to achieve voltage support control. This invention can fully exploit the short-time overload capability of high-inertia energy storage synchronous condensers while avoiding junction temperature exceedances of power devices, thus improving voltage support effectiveness.

Description

Technical Field

[0001] This invention relates to the field of power system protection and control technology, specifically to a voltage support coordination control method and system for a high-inertia energy storage type synchronous condenser. Background Technology

[0002] With the widespread application of new energy sources, power systems face increasingly severe voltage stability challenges under large disturbance conditions, leading to a growing demand for dynamic reactive power compensation. Synchronous synchronous condensers, with their continuous reactive power output, strong short-term overload capacity, and high control reliability, have attracted attention for providing dynamic voltage support and improving system transient stability. However, in medium- and low-voltage power grids and new energy integration systems, the coordinated use of active power not only helps improve system power balance but can also reduce the equipment capacity and control costs required for dynamic reactive power compensation to some extent. Existing synchronous condensers, due to mechanical limitations, cannot directly participate in active power support, and their adjustment flexibility remains insufficient in the context of high-proportion new energy grid integration.

[0003] In recent years, researchers have developed a novel high-inertia energy storage synchronous condenser. This high-inertia energy storage synchronous condenser employs a doubly-fed motor structure, utilizing back-to-back converters to provide AC excitation. The converter adopts an active neutral-point clamped three-level topology and uses integrated gate-commutated thyristors as power devices. The high-inertia energy storage synchronous condenser achieves variable-speed operation and bidirectional active power regulation through the rotor-side converter, thus retaining the strong reactive power support capability of traditional synchronous condensers while achieving short-term active power support. However, when outputting active power, the high-inertia energy storage synchronous condenser often operates at variable speeds with a large slip, causing large-scale and rapid changes in the rotor current amplitude and frequency. Changes in rotor current frequency significantly affect the switching and conduction losses of the power devices, leading to dynamic fluctuations in the device junction temperature. Simultaneously, the increase in current amplitude exacerbates the accumulation of transient thermal stress. Since the junction temperature of the power devices directly determines their reliability and lifespan, the thermal safety of the high-inertia energy storage synchronous condenser converter during active power support is particularly prominent.

[0004] Currently, research on thermal management of high-inertia energy storage synchronous condensers mainly focuses on the thermal constraints of the motor windings, with little consideration given to thermal constraints from the perspective of the converter. Some literature studies the temperature fields of the stator and rotor of the synchronous condenser under different inertia support conditions to determine current limits; others indirectly establish upper limits for current amplitude by combining factors such as stator-side capacity limitations, rotor winding capacity limitations, and junction temperature margin. Extensive research has been conducted on thermal management of power electronic equipment such as new energy sources and flexible DC converters, but all methods indirectly constrain temperature rise by setting current limits. Some studies set current limits for grid commutation converters based on different fault scenarios; others indirectly constrain reference values ​​by introducing dynamic margins into reactive power reference values, thereby suppressing rotor current and temperature rise. However, for high-inertia energy storage synchronous condensers with more drastic rotor current frequency changes, it is difficult to achieve a balance between thermal safety and control performance with current limits. If the current limit is set too high, it can easily lead to junction temperature exceeding the limit; if the current limit is set too low, it will significantly weaken the support capability.

[0005] Therefore, it is urgent to explore the impact of thermal constraints on the power control of synchronous condensers and to achieve coordinated voltage support control of high-inertia energy storage synchronous condensers. Summary of the Invention

[0006] To address the shortcomings of the prior art, this invention provides a voltage support coordination control method for a high-inertia energy storage synchronous condenser, which can fully exploit the voltage support control potential of the high-inertia energy storage synchronous condenser without exceeding the limit of the converter junction temperature, thereby overcoming the limitations of traditional static thermal constraints and fixed margins.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a voltage support coordination control method for a high-inertia energy storage type synchronous condenser, comprising the following steps:

[0009] S1. Collect the operating parameters of the high-inertia energy storage synchronous condenser and the grid connection point voltage of the high-inertia energy storage synchronous condenser; when the grid connection point voltage of the high-inertia energy storage synchronous condenser drops to outside the normal allowable range, start the voltage support coordination control and execute S2.

[0010] S2. Based on the junction temperature constraints of power devices, construct a junction temperature safety domain constraint model for a high-inertia energy storage synchronous condenser converter with the active power and reactive power of the stator as state variables.

[0011] S3. Based on the junction temperature safety domain constraint model, construct a voltage support control model for a high-inertia energy storage synchronous condenser.

[0012] S4. The rotor-side converter adopts constant active power and reactive power control, solves the voltage support control model of the high inertia energy storage synchronous condenser, and uses the optimal active power and reactive power solutions obtained from the solution as the control reference values ​​of the rotor-side converter.

[0013] S5. Check whether the rotational speed of the high-inertia energy storage synchronous condenser has reached or exceeded the minimum allowable rotational speed; if yes, continue to execute S6; otherwise, return to execute S4.

[0014] S6. Switch the constant active power control of the rotor-side converter to constant speed control, set the control reference value to the minimum allowable speed, and set the constant reactive power control reference value of the rotor-side converter to the stator maximum reactive power under the rotor allowable current limit.

[0015] S7. Determine whether the grid connection point voltage has returned to the normal allowable range; if it has, proceed to S8; otherwise, return to S4.

[0016] S8. The high-inertia energy storage synchronous condenser is controlled by constant speed control and constant reactive power control. The reference value for constant speed control is set to the normal operating speed determined by the design, and the reference value for constant reactive power control is set to zero.

[0017] In the aforementioned voltage support coordination control method for high-inertia energy storage synchronous condensers, specifically, in step S2, the junction temperature safety domain constraint model for the high-inertia energy storage synchronous condenser converter, with the stator's active power and reactive power as state variables, is as follows:

[0018] ;

[0019] in, , , These are respectively the stator active power of high inertia energy storage type synchronous condenser. and reactive power Junction temperature of the switching device, freewheeling diode, and clamping diode, which are variables; , , These are the maximum operating temperatures of the switching device, freewheeling diode, and clamping diode, respectively.

[0020] The junction temperature of the switching device, freewheeling diode, and clamping diode , , This was determined by solving the following heat network model:

[0021] ;

[0022] in, This refers to the radiator temperature. For the device losses of the converter switching devices, The thermal impedance of the converter switching devices; For the device losses of the freewheeling diode in the converter, The thermal resistance of the freewheeling diode in the converter; For the device losses of the converter clamping diode, This is the thermal resistance of the converter clamping diode.

[0023] In the aforementioned voltage support coordination control method for high-inertia energy storage synchronous condensers, specifically, the device losses of the switching devices, freewheeling diodes, and clamping diodes are expressed as follows:

[0024] ;

[0025] ;

[0026] ;

[0027] in, , These are the conduction loss and switching loss of the switching device, respectively. , These are the conduction loss and switching loss of the freewheeling diode, respectively. , These represent the conduction loss and switching loss of the clamping diode, respectively.

[0028] In the voltage support coordination control method for the high-inertia energy storage synchronous condenser described above, specifically, the conduction losses of the switching devices, freewheeling diodes, and clamping diodes are determined as follows:

[0029] ;

[0030] ;

[0031] ;

[0032] in, The initial phase angle corresponding to the inverter output current; This refers to the rotor current amplitude. The rotor current angular frequency; , , The switching device, freewheeling diode, and clamping diode are respectively located at time [time]. The on-state voltage drop; , , The switching device, freewheeling diode, and clamping diode are respectively located at time [time]. The duty cycle of the switching transistor during one corresponding switching cycle;

[0033] The switching losses of the switching device, freewheeling diode, and clamping diode are determined as follows:

[0034] ;

[0035] ;

[0036] ;

[0037] in, The switching frequency; , These are the turn-on loss and turn-off loss of the switching device under rated conditions, respectively. This refers to the bridge arm voltage; , These are the reference current and the reference voltage, respectively. The reference current and reference voltage The junction temperature corresponding to the test conditions; , , These are the rotor current amplitudes. Bridge arm voltage and junction temperature of switching devices The influence coefficient on the switching loss of switching devices; , These are the switching losses of the freewheeling diode and the clamping diode under rated conditions, respectively. , , These are the rotor current amplitudes. Bridge arm voltage and the junction temperature of the freewheeling diode The influence coefficient on the switching loss of the freewheeling diode; , , These are the rotor current amplitudes. Bridge arm voltage and clamping diode junction temperature The influence coefficient on the switching loss of the clamping diode.

[0038] In the aforementioned voltage support coordination control method for high-inertia energy storage synchronous condensers, specifically, the rotor current amplitude... With rotor current angular frequency It is a function of the active and reactive power of a high-inertia synchronous condenser, and is determined as follows:

[0039] ;

[0040] ;

[0041] in, The stator equivalent inductance; For magnetizing inductance; This refers to the stator voltage amplitude. , These are the active power and reactive power of the stator, respectively. Synchronous speed; This indicates the time at which the rotor current angular frequency is determined; The inertial constant of a high-inertia energy storage synchronous condenser; For time integration variables; The initial rotational speed before the voltage drops.

[0042] In the above-mentioned voltage support coordination control method for high-inertia energy storage synchronous condensers, specifically, in step S3, the voltage support control model for the high-inertia energy storage synchronous condenser is constructed as follows:

[0043] ;

[0044] in, This refers to the voltage at the grid connection point. , These are the active power and reactive power of the stator, respectively. This is the equivalent electromotive force of the power grid; , These are the equivalent resistance and equivalent reactance of the power grid, respectively. , , These are respectively the stator active power of high inertia energy storage type synchronous condenser. and reactive power Junction temperature of the switching device, freewheeling diode, and clamping diode, which are variables; , , These are the maximum operating temperatures of the switching device, freewheeling diode, and clamping diode, respectively. This refers to the rotor current amplitude. This is the maximum allowable current under the constraints of converter capacity and motor winding limitations.

[0045] In the above-mentioned voltage support coordination control method for high-inertia energy storage synchronous condensers, specifically, in step S4, the voltage support control model is solved in the following manner:

[0046] S401. All constraints of the voltage support control model are made dimensionless, and a total constraint violation quantity is introduced. Measuring infeasible solutions and total constraint violations. The calculation method is as follows:

[0047] ;

[0048] in, For the search space, a solution that simultaneously covers both the constraints and the constraints of the high-inertia energy storage synchronous condenser is required. To solve The corresponding number The value of a constraint violation is the solution. In the The difference between the parameter value corresponding to each constraint and its maximum value; For the first The comparison weight parameters of each constraint, and , For the first The maximum amount of violation of a constraint; The number of constraints;

[0049] S402. Randomly generate N pairs of solutions for active power and reactive power in the search space. Each pair of solutions is used as a vector element to form the initial population; where N is an even number.

[0050] S403. Substitute each pair of solutions in the current population into the grid connection point voltage respectively. The calculation formula uses the calculated maximum grid connection point voltage as the optimal target value. The pair of solutions corresponding to the maximum voltage at the grid connection point is denoted as the optimal solution. The normalized teaching factor is obtained by normalizing the other solutions in the initial population:

[0051] ;

[0052] in, In the initial population, besides the optimal solution The other Solution Normalized teaching factors; According to the first Solution The calculated target value of the grid connection point voltage;

[0053] S404. During the teaching phase, the current population is updated through evolution to obtain an evolved population containing N vector elements. The evolution update method is to first evolve the population elements according to the following formula:

[0054] ;

[0055] in, , These are the first and second stages of the teaching process, before and after its evolution. Solution; A random value between [0,1]; This is the average value of all pairs of solutions in the population before the evolution update;

[0056] After evolution, if Superior This would cause the first [element] in the evolved population to [become the first]. Solution = Otherwise, the first in the evolved population will be... Solution = Thus, the evolved population after evolutionary renewal is obtained;

[0057] S405. During the learning phase, based on the evolutionary population obtained at the current teaching phase, randomly select two pairs of solutions that have not been previously selected. , Compare the merits of the two solutions and move the weaker solution pair closer to the stronger one:

[0058] ;

[0059] in, , This is a new solution after adjustments during the learning phase;

[0060] S406. Repeat step S405 until all solutions in the evolutionary population have been selected, then execute step S407.

[0061] S407. Determine whether the number of iterations in the current teaching-learning stage has reached the preset maximum number of iterations; if yes, proceed to step S408; if no, further determine whether the absolute value deviation between the optimal target value of the current teaching-learning stage and the previous teaching-learning stage is less than the preset precision threshold. If yes, proceed to step S408; otherwise, increment the number of iterations in the teaching-learning phase by 1 and return to step S403.

[0062] S408. Output the optimal target value obtained in the current teaching-learning phase. and its corresponding optimal solution With the optimal solution The active and reactive power are used as control reference values ​​for the rotor-side converter.

[0063] In the above-mentioned voltage support coordination control method for high-inertia energy storage synchronous condensers, specifically, in step S404, the determination is made... and When determining the merits of two options, the following criteria are used: If one is located in the feasible region and the other in the infeasible region, the one located in the feasible region is considered superior; if both are located in the feasible region, then the two options are compared. and Corresponding target value and The one with the larger objective value is better; if both are located in the infeasible region, then compare... and Corresponding total constraint violation and The one with a smaller total constraint violation is better;

[0064] In step S405, determine and When determining the merits of two options, the following criteria are used: If one is located in the feasible region and the other in the infeasible region, the one located in the feasible region is considered superior; if both are located in the feasible region, then the two options are compared. and Corresponding target value and The one with the larger objective value is better; if both are located in the infeasible region, then compare... and Corresponding total constraint violation and The one with a smaller total number of constraint violations is better.

[0065] In the aforementioned voltage support coordination control method for high-inertia energy storage synchronous condensers, specifically in step S6, the maximum reactive power of the stator under the rotor allowable current limit is... Determine as follows:

[0066] ;

[0067] in, The stator equivalent inductance; For magnetizing inductance; This refers to the stator voltage amplitude. Synchronous speed; This is the maximum allowable current under the constraints of converter capacity and motor winding limitations.

[0068] Secondly, the present invention also provides a voltage support coordination control system for a high-inertia energy storage type synchronous condenser, used to implement the above-mentioned method, comprising:

[0069] The acquisition module is used to acquire the operating parameters of the high-inertia energy storage synchronous condenser and the grid connection point voltage of the high-inertia energy storage synchronous condenser.

[0070] The first judgment module is used to determine whether the grid connection point voltage of the high-inertia energy storage synchronous condenser has dropped to outside the normal allowable range, and then to start the voltage support coordination control and call the constraint module.

[0071] The constraint module is used to construct a voltage support control model for a high-inertia energy storage synchronous condenser based on the junction temperature safety domain constraint model.

[0072] The first calculation module is used to enable the rotor-side converter to adopt constant active power and reactive power control, solve the voltage support control model of the high-inertia energy storage synchronous condenser, and use the optimal active power and reactive power solutions obtained from the solution as the control reference values ​​of the rotor-side converter; then the second judgment module is called.

[0073] The second judgment module is used to detect whether the rotational speed of the high-inertia energy storage type synchronous condenser has reached or exceeded the minimum allowable rotational speed; if so, the first control module is called; otherwise, the first calculation module is called.

[0074] The first control module is used to switch the constant active power control of the rotor-side converter to constant speed control, set the control reference value to the minimum allowable speed, and set the constant reactive power control reference value of the rotor-side converter to the stator maximum reactive power under the rotor allowable current limit; then it calls the third judgment module.

[0075] The third judgment module determines whether the grid connection point voltage has returned to the normal allowable range; if it has, it calls the second control module; otherwise, it calls the first calculation module.

[0076] The second control module is used to control the high-inertia energy storage synchronous condenser to adopt constant speed control and constant reactive power control. The constant speed control reference value is set to the normal operating speed determined by the design, and the constant reactive power control reference value is set to zero.

[0077] Compared with the prior art, the present invention has the following beneficial effects:

[0078] 1. The present invention relates to a voltage support coordination control method and system for a high-inertia energy storage synchronous condenser. It considers the characteristic that the junction temperature of the device changes in real time with the operating conditions, and constructs a dynamic junction temperature safety domain for the converter of the high-inertia energy storage synchronous condenser with active and reactive power as state variables. The boundary of the safety domain can be adjusted according to the real-time temperature status, which can accurately quantify the adjustable range of active and reactive power of the condenser at different operating times. This provides a clear feasible domain boundary for upper-level coordination control, and realizes the quantitative characterization of the active and reactive power control capability of the high-inertia energy storage synchronous condenser under junction temperature safety constraints, so as to better support the optimization of coordination control decisions.

[0079] 2. The present invention breaks through the conservatism of traditional static current limiting. Under the premise of ensuring the thermal safety of the device, it allows the converter to output higher power in a short time, maximizes the short-time overload capacity and voltage recovery potential of the high-inertia energy storage synchronous condenser, accelerates the voltage recovery process, improves the grid support efficiency of the high-inertia energy storage synchronous condenser, and achieves the optimal balance between thermal safety and control performance.

[0080] 3. The implementation method of the present invention is clear. It only requires the collection of real-time operating data of the current high-inertia energy storage synchronous condenser and the processing of the data in real time through the voltage support control system. It can be seamlessly integrated with the original control architecture of the synchronous condenser without large-scale hardware modification or system reconstruction. It is easy to implement, has strong economy and practicality, and has broad engineering application prospects. Attached Figure Description

[0081] 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:

[0082] Figure 1 This is a flowchart of the voltage support coordination control method for the high-inertia energy storage synchronous condenser of the present invention.

[0083] Figure 2 This is a schematic diagram of the architecture of the simulation system in the embodiment;

[0084] Figure 3 This is a characteristic curve of a high-inertia energy storage synchronous condenser with a smaller current limiting in the embodiment.

[0085] Figure 4 This is a characteristic curve of a high-inertia energy storage synchronous condenser when the current limit is large in the embodiment. Detailed Implementation

[0086] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but only to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0087] 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.

[0088] First, the relevant parameters involved in this invention will be explained as follows:

[0089] High-inertia energy storage synchronous condenser: It is an induction generator without a prime mover, which uses a back-to-back converter composed of a generator-side converter and a grid-side converter to provide AC excitation for the rotor winding. The active and reactive power of the high-inertia energy storage synchronous condenser is regulated by the generator-side converter; the DC voltage of the back-to-back converter is stabilized by the grid-side converter, thereby implementing the support control of the grid voltage by the high-inertia energy storage synchronous condenser.

[0090] Grid connection point: The electrical node where the high-inertia energy storage synchronous condenser connects to the power grid.

[0091] Grid connection point voltage: The voltage at the connection point between the high-inertia energy storage synchronous condenser and the power grid.

[0092] Ambient temperature: The temperature of the working environment of the high-inertia energy storage synchronous condenser.

[0093] Firstly, in response to the shortcomings of existing technologies, this invention constructs a dynamic junction temperature safety domain for a high-inertia energy storage synchronous condenser converter with active and reactive power as state variables. It realizes a quantitative characterization of the active and reactive power control capability of the high-inertia energy storage synchronous condenser under junction temperature safety constraints, and proposes a voltage support control method for a high-inertia energy storage synchronous condenser that takes into account direct temperature rise constraints, so as to overcome the limitations of traditional static thermal constraints and fixed margins.

[0094] The high-inertia energy storage type synchronous condenser voltage support coordination control method proposed in this invention specifically includes the following steps:

[0095] S1. Collect the operating parameters of the high-inertia energy storage synchronous condenser and the grid connection point voltage of the high-inertia energy storage synchronous condenser; when the grid connection point voltage of the high-inertia energy storage synchronous condenser drops to outside the normal allowable range, start the voltage support coordination control and execute S2.

[0096] S2. Based on the junction temperature constraints of power devices, construct a junction temperature safety domain constraint model for a high-inertia energy storage synchronous condenser converter with the active power and reactive power of the stator as state variables.

[0097] S3. Based on the junction temperature safety domain constraint model, construct a voltage support control model for a high-inertia energy storage synchronous condenser.

[0098] S4. The rotor-side converter adopts constant active power and reactive power control, solves the voltage support control model of the high inertia energy storage synchronous condenser, and uses the optimal active power and reactive power solutions obtained from the solution as the control reference values ​​of the rotor-side converter.

[0099] S5. Check whether the rotational speed of the high-inertia energy storage synchronous condenser has reached or exceeded the minimum allowable rotational speed; if yes, continue to execute S6; otherwise, return to execute S4.

[0100] S6. Switch the constant active power control of the rotor-side converter to constant speed control, set the control reference value to the minimum allowable speed, and set the constant reactive power control reference value of the rotor-side converter to the stator maximum reactive power under the rotor allowable current limit.

[0101] S7. Determine whether the grid connection point voltage has returned to the normal allowable range; if it has, proceed to S8; otherwise, return to S4.

[0102] S8. The high-inertia energy storage synchronous condenser is controlled by constant speed control and constant reactive power control. The reference value for constant speed control is set to the normal operating speed determined by the design, and the reference value for constant reactive power control is set to zero.

[0103] The proposed method for coordinated voltage support control of high-inertia energy storage synchronous condensers, which takes into account direct temperature rise constraints, is designed for high-inertia energy storage synchronous condensers with active and reactive power support capabilities. It considers the impact of large changes in rotor current amplitude and frequency caused by the output of active and reactive power on the junction temperature of converter power devices, constructs a junction temperature safety domain for the converter, and uses the junction temperature safety domain as a direct constraint to coordinate the active and reactive power output of the synchronous condenser in real time to achieve grid voltage support.

[0104] In practical applications, the operating parameters that need to be collected for the high-inertia energy storage synchronous condenser mainly include the ambient temperature, rotor speed, stator active power and reactive power, and other relevant operating parameters, which will be shown in the subsequent calculations. In addition, it is also necessary to collect the grid connection point voltage of the high-inertia energy storage synchronous condenser to determine whether the grid connection point voltage has dropped to outside the normal allowable range, and then decide whether to start voltage support coordination control.

[0105] In specific implementation, in step S2, the junction temperature safety domain constraint model of the high-inertia energy storage synchronous condenser converter, with the active and reactive power of the stator as state variables, characterizes the feasible range of the active and reactive power of the stator of the high-inertia energy storage synchronous condenser under the junction temperature constraints of the converter switching devices, freewheeling diodes, and clamping diodes. This junction temperature safety domain constraint model can be specifically expressed as follows:

[0106] ;

[0107] in, , , These are respectively the stator active power of high inertia energy storage type synchronous condenser. and reactive power Junction temperature of the switching device, freewheeling diode, and clamping diode, which are variables; , , These are the maximum operating temperatures of the switching device, freewheeling diode, and clamping diode, respectively.

[0108] In specific implementation, the junction temperature of the switching device, freewheeling diode, and clamping diode... , , This was determined by solving the following heat network model:

[0109] ;

[0110] in, This refers to the radiator temperature. For the device losses of the converter switching devices, The thermal impedance of the converter switching devices; For the device losses of the freewheeling diode in the converter, The thermal resistance of the freewheeling diode in the converter; For the device losses of the converter clamping diode, This is the thermal resistance of the converter clamping diode.

[0111] In practical implementation, the device losses of the switching device, freewheeling diode, and clamping diode are expressed as follows:

[0112] ;

[0113] ;

[0114] ;

[0115] in, , These are the conduction loss and switching loss of the switching device, respectively. , These are the conduction loss and switching loss of the freewheeling diode, respectively. , These represent the conduction loss and switching loss of the clamping diode, respectively.

[0116] Specifically, the conduction losses of the switching device, freewheeling diode, and clamping diode are determined as follows:

[0117] ;

[0118] ;

[0119] ;

[0120] in, The initial phase angle corresponding to the inverter output current; This refers to the rotor current amplitude. The rotor current angular frequency; , , The switching device, freewheeling diode, and clamping diode are respectively located at time [time]. The on-state voltage drop; , , The switching device, freewheeling diode, and clamping diode are respectively located at time [time]. The duty cycle of the switching transistor during one switching cycle.

[0121] The switching losses of the switching device, freewheeling diode, and clamping diode are determined as follows:

[0122] ;

[0123] ;

[0124] ;

[0125] in, The switching frequency; , These are the turn-on loss and turn-off loss of the switching device under rated conditions, respectively. This refers to the bridge arm voltage; , These are the reference current and the reference voltage, respectively. The reference current and reference voltage The junction temperature corresponding to the test conditions; , , These are the rotor current amplitudes. Bridge arm voltage and junction temperature of switching devices The influence coefficient on the switching loss of switching devices; , These are the switching losses of the freewheeling diode and the clamping diode under rated conditions, respectively. , , These are the rotor current amplitudes. Bridge arm voltage and the junction temperature of the freewheeling diode The influence coefficient on the switching loss of the freewheeling diode; , , These are the rotor current amplitudes. Bridge arm voltage and clamping diode junction temperature The influence coefficient on the switching loss of the clamping diode.

[0126] In practical implementation, the rotor current amplitude and angular frequency are functions of the active and reactive power of the high-inertia synchronous condenser, and are determined as follows:

[0127] ;

[0128] ;

[0129] in, The stator equivalent inductance; For magnetizing inductance; This refers to the stator voltage amplitude. Synchronous speed; This indicates the time at which the rotor current angular frequency is determined; The inertial constant of a high-inertia energy storage synchronous condenser; For time integration variables; The initial rotational speed before the voltage drops.

[0130] In specific implementation, the voltage support control model for the high-inertia energy storage synchronous condenser constructed in step S3 is as follows:

[0131] ;

[0132] in, This refers to the voltage at the grid connection point. This is the equivalent electromotive force of the power grid; , These are the equivalent resistance and equivalent reactance of the power grid, respectively. This is the maximum allowable current under the constraints of converter capacity and motor winding limitations.

[0133] In practice, in step S4, the voltage support control model is solved in the following way:

[0134] S401. All constraints of the voltage support control model are made dimensionless, and a total constraint violation quantity is introduced. Measuring infeasible solutions and total constraint violations. The calculation method is as follows:

[0135] ;

[0136] in, It is a solution in the search space that simultaneously covers both the constraints and the constraints of the high-inertia energy storage synchronous condenser. To solve The corresponding number The value of a constraint violation is the solution. In the The difference between the parameter values ​​corresponding to each constraint and their maximum values; specifically, the violation amounts of the four constraints included in the voltage support control model can be expressed as follows: , , and The values ​​of the violation amounts of the four constraints are respectively , , , , , , solutions respectively The corresponding junction temperatures of the switching devices, freewheeling diodes, and clamping diodes. Representing the solution The corresponding rotor current amplitude; The comparison weights change continuously during the iteration process, and , To constrain Maximum violation; The number of constraints;

[0137] S402. Randomly generate N pairs of solutions for active power and reactive power in the search space. Each pair of solutions is used as a vector element to form the initial population; where N is an even number.

[0138] S403. Substitute each pair of solutions in the current population into the grid connection point voltage respectively. The calculation formula uses the calculated maximum grid connection point voltage as the optimal target value. The pair of solutions corresponding to the maximum voltage at the grid connection point is denoted as the optimal solution. The normalized teaching factor is obtained by normalizing the other solutions in the initial population:

[0139] ;

[0140] in, In the initial population, besides the optimal solution The other Solution The normalized teaching factor is used to reflect the degree of learning of each solution from the optimal solution. When the target value is poor, the learning ability should be enhanced. According to the first Solution The calculated target value of the grid connection point voltage;

[0141] S404. During the teaching phase, the current population is updated through evolution to obtain an evolved population containing N vector elements. The evolution update method is to first evolve the population elements according to the following formula:

[0142] ;

[0143] in, , These are the first and second stages of the teaching process, before and after its evolution. Solution; A random value between [0,1]; This is the average value of all pairs of solutions in the population before the evolution update;

[0144] After evolution, if Superior This would cause the first [element] in the evolved population to [become the first]. Solution = Otherwise, the first in the evolved population will be... Solution = Thus, the evolved population after evolutionary renewal is obtained;

[0145] S405. During the learning phase, based on the evolutionary population obtained at the current teaching phase, randomly select two pairs of solutions that have not been previously selected. , Compare the merits of the two solutions and move the weaker solution pair closer to the stronger one:

[0146] ;

[0147] in, , This is a new solution after adjustments during the learning phase;

[0148] S406. Repeat step S405 until all solutions in the evolutionary population have been selected, then execute step S407.

[0149] S407. Determine whether the number of iterations in the current teaching-learning stage has reached the preset maximum number of iterations; if yes, proceed to step S408; if no, further determine whether the absolute value deviation between the optimal target value of the current teaching-learning stage and the previous teaching-learning stage is less than the preset precision threshold. If yes, proceed to step S408; otherwise, increment the number of iterations in the teaching-learning phase by 1 and return to step S403.

[0150] S408. Output the optimal target value obtained in the current teaching-learning phase. and its corresponding optimal solution With the optimal solution The active and reactive power are used as control reference values ​​for the rotor-side converter.

[0151] Specifically, in step S404, the determination is made. and When determining the merits of two options, the following criteria are used: If one is located in the feasible region and the other in the infeasible region, the one located in the feasible region is considered superior; if both are located in the feasible region, then the two options are compared. and Corresponding target value and The one with the larger objective value is better; if both are located in the infeasible region, then compare... and Corresponding total constraint violation and The one with a smaller total constraint violation is better;

[0152] In step S405, determine and When determining the merits of two options, the following criteria are used: If one is located in the feasible region and the other in the infeasible region, the one located in the feasible region is considered superior; if both are located in the feasible region, then the two options are compared. and Corresponding target value and The one with the larger objective value is better; if both are located in the infeasible region, then compare... and Corresponding total constraint violation and The one with a smaller total number of constraint violations is better.

[0153] Through the above solution process of the voltage support control model of the high-inertia energy storage synchronous condenser, it can be seen that the present invention adopts a teaching-learning stage iterative evolution mechanism, which cyclically evolves and optimizes the population constructed by the solutions of active power and reactive power in the search space. The optimal solution is used as the control reference value of the rotor-side converter to coordinate the active power and reactive power output of the synchronous condenser in real time. Moreover, in the process of evolution and iterative optimization, the solutions of active power and reactive power are always within the thermal constraints and are always optimized towards a better solution. In this process, under the premise of ensuring the thermal safety of the device, the converter may be allowed to output higher power in a short time. However, this can also more effectively tap the short-term overload capacity and voltage recovery potential of the high-inertia energy storage synchronous condenser, accelerate the voltage recovery process, and improve the grid support efficiency of the high-inertia energy storage synchronous condenser.

[0154] In specific implementation, in step S6, the maximum reactive power of the stator under the rotor allowable current limit is... Determine as follows:

[0155] ;

[0156] in, The stator equivalent inductance; For magnetizing inductance; This refers to the stator voltage amplitude. Synchronous speed; This is the maximum allowable current under the constraints of converter capacity and motor winding limitations.

[0157] Secondly, this invention also proposes a high-inertia energy storage synchronous condenser voltage support coordination control system based on a dynamic junction temperature safety domain, used to implement a high-inertia energy storage synchronous condenser voltage support coordination control method based on a dynamic junction temperature safety domain; the system includes:

[0158] The acquisition module is used to acquire the operating parameters of the high-inertia energy storage synchronous condenser and the grid connection point voltage of the high-inertia energy storage synchronous condenser.

[0159] The first judgment module is used to determine whether the grid connection point voltage of the high-inertia energy storage synchronous condenser has dropped to outside the normal allowable range, and then to start the voltage support coordination control and call the constraint module.

[0160] The constraint module is used to construct a voltage support control model for a high-inertia energy storage synchronous condenser based on the junction temperature safety domain constraint model.

[0161] The first calculation module is used to enable the rotor-side converter to adopt constant active power and reactive power control, solve the voltage support control model of the high-inertia energy storage synchronous condenser, and use the optimal active power and reactive power solutions obtained from the solution as the control reference values ​​of the rotor-side converter; then the second judgment module is called.

[0162] The second judgment module is used to detect whether the rotational speed of the high-inertia energy storage type synchronous condenser has reached or exceeded the minimum allowable rotational speed; if so, the first control module is called; otherwise, the first calculation module is called.

[0163] The first control module is used to switch the constant active power control of the rotor-side converter to constant speed control, set the control reference value to the minimum allowable speed, and set the constant reactive power control reference value of the rotor-side converter to the stator maximum reactive power under the rotor allowable current limit; then it calls the third judgment module.

[0164] The third judgment module determines whether the grid connection point voltage has returned to the normal allowable range; if it has, it calls the second control module; otherwise, it calls the first calculation module.

[0165] The second control module is used to control the high-inertia energy storage synchronous condenser to adopt constant speed control and constant reactive power control. The constant speed control reference value is set to the normal operating speed determined by the design, and the constant reactive power control reference value is set to zero.

[0166] The high-inertia energy storage type synchronous condenser voltage support coordination control system is designed to implement the aforementioned high-inertia energy storage type synchronous condenser voltage support coordination control method, and has the corresponding technical advantages of the aforementioned method of this invention.

[0167] Example:

[0168] To verify the effectiveness of the method of the present invention, the present invention solution is analyzed and verified through the following embodiments.

[0169] Taking a certain type of high-inertia energy storage synchronous condenser as an example, the voltage support control effect was verified, and the simulation system constructed is as follows: Figure 2As shown, the parameters are as follows: The new energy power station includes 20 1.5 MW doubly-fed wind turbines. The HI-ES-SC is connected to bus A via a 10.5kV / 35kV step-up transformer. Among them, the rated capacity of the high-inertia energy storage synchronous condenser is 11.11 MVA, the stator rated voltage is 10.5 kV, the rotor rated voltage is 3.3 kV, the number of pole pairs is 1, the no-load rated speed is 3150 r / min, the inertia time constant is 20.3s, the maximum permissible slip is ±0.2 pu, the maximum rotor slip voltage is 3.5 kV, the stator resistance is 0.074Ω, the total stator leakage inductance is 6.11mH, the excitation inductance is 234.93mH, the rotor resistance is 0.0275Ω, the total rotor leakage inductance is 6.4mH, the stator / rotor turns ratio is 0.6, the DC bus voltage is 7000 V, and the DC bus capacitance is 30mF. The parameters of the IGCT converter, according to the ABB 5SHX 26L4503 chip datasheet, indicate a maximum operating temperature of 110℃, a maximum permissible rotor current of 1345A, and an ambient temperature of 25℃. To simulate a typical weak grid scenario in a region with abundant renewable energy, the equivalent grid resistance is set to 1.84Ω, the equivalent reactance to 44.1Ω, and the short-circuit ratio to approximately 2.5.

[0170] To verify the voltage support control effect of the proposed method, it was compared with control methods under different current limiting conditions: Method 1 controls the high-inertia energy storage synchronous condenser to provide reactive power based on the voltage drop, with a reactive current control reference value of 1.5(0.9-U). T )I N In the formula, U T For terminal voltage, I N For the rated current, the active power reference value is taken as the maximum power under the rotor current limit, until the speed reaches the lower limit. The reactive power reference value is taken as the maximum reactive power under the rotor current limit. Method 2 aims to maximize the grid connection point voltage and solves for the reference value based on the current amplitude constraint until the speed reaches the lower limit. The reactive power reference value for the high-inertia energy storage synchronous condenser is taken as the maximum reactive power under the rotor current limit. Method 3 is the method proposed in this paper. This paper verifies the support effect by simulating voltage drop by adding active load to bus A. To highlight the difference between the different methods, no capacitor is added after the high-inertia energy storage synchronous condenser withdraws from active support.

[0171] For methods 1 and 2, the rotor current amplitude limit is set to 1.1 times the rated current. When the speed does not reach the lower limit, the active and reactive power reference values ​​for methods 1 and 2 are constrained by the rotor current amplitude limit. For method 3, when neither the speed nor the current exceeds the limit, the active and reactive power are constrained by the junction temperature safety domain. After reaching the lower speed limit, due to speed constraints, the high-inertia energy storage synchronous condenser cannot continue to support active power; all three methods can only provide reactive power support. The bus A voltage, rotor current, power, speed, and junction temperature for the three methods are as follows: Figure 3 As shown. At 40s, a 120MW active load is applied to bus A to simulate a voltage drop to 0.8pu. For Method 1, the reactive current reference value is 0.15pu, the reactive power reference value is 0.12pu, and the active power reference value is 1.09pu. At 48.5s, when the speed reaches 0.8pu, only 1.1pu of reactive power is generated. For Method 2, the reactive power reference value is 0.62pu, and the active power reference value is 0.91pu. At 49.5s, when the speed reaches 0.8pu, only 1.1pu of reactive power is generated. For Method 3, the reactive power reference value is 0.67pu, and the active power reference value is 1.23pu. At 47.5s, when the speed reaches 0.8pu, only 1.54pu of reactive power is generated.

[0172] Figure 3 In the diagram, the blue line represents Method 1, the green line represents Method 2, and the red line represents Method 3. Figure 3The dashed line in (a) represents the voltage drop when the high-inertia energy storage synchronous condenser is not involved in voltage support control. Regarding the voltage support effect when the high-inertia energy storage synchronous condenser's speed is below 0.8 pu, Method 2, compared to Method 1, increases the bus A voltage from 0.8 pu to 0.845 pu by appropriately reducing active power and increasing reactive power, provided the current does not exceed the amplitude limit. Method 3, compared to Method 1, increases both active and reactive power, causing the rotor current amplitude to reach 1.41 times the rated current, thus increasing the bus A voltage from 0.8 pu to 0.859 pu. The proposed method improves the voltage support effect by 55.2% compared to Method 1 (from 0.8 pu to 0.838 pu) and by 31.1% compared to Method 2, provided the junction temperature does not exceed the limit. Regarding the voltage support effect of the high-inertia energy storage synchronous condenser after reaching a speed of 0.8 pu, the bus A voltage of Method 1 and Method 2 is 0.822 pu, while that of Method 3 is 0.840 pu. In terms of thermal safety performance, the peak junction temperature of Method 1 is 90.3℃, that of Method 2 is 98.1℃, and that of Method 3 is 108.1℃. None of the three methods experienced junction temperature exceeding the limit, but the junction temperature of Method 3 is closest to the maximum operating temperature of the device, indicating that Method 3 maximizes the utilization of the device's safety margin. Furthermore, the speed of the high-inertia energy storage synchronous condenser under all three methods remains within the safe operating range.

[0173] With the load unchanged, the rotor current amplitude limit for methods 1 and 2 is set to 1.5 times the rated current. For method 1, the reactive current reference value is 0.15 pu, the reactive power reference value is 0.12 pu, and the active power reference value is 1.49 pu. At 46 seconds, when the speed reaches 0.8 pu, the high-inertia energy storage synchronous condenser only generates 1.5 pu of reactive power. For method 2, the reactive power reference value is 1.18 pu, and the active power reference value is 0.92 pu. At 50 seconds, when the speed reaches 0.8 pu, the high-inertia energy storage synchronous condenser only generates 1.5 pu of reactive power. The active and reactive power reference values ​​for method 3 are set as follows... Figure 3 The corresponding calculation examples are consistent. The grid connection point voltage, rotor current, power, speed, and junction temperature for the three methods are as follows: Figure 4 As shown.

[0174] Figure 4 In the diagram, the blue line represents Method 1, the green line represents Method 2, and the red line represents Method 3. Figure 4The dashed line in (a) represents the voltage drop when the high-inertia energy storage synchronous condenser is not involved in voltage support control. Regarding the voltage support effect when the high-inertia energy storage synchronous condenser's speed is below 0.8 pu, Method 3, by reducing active power generation and increasing reactive power generation, further increased the bus A voltage without significantly increasing the junction temperature. Comparing Method 2 and Method 3, Method 2 has lower active power, causing the converter's rotor current to operate at low frequencies for a longer period. The larger reactive current also causes a significant rise in junction temperature, exceeding the limit, but the support effect is not significantly improved compared to the proposed method. Figure 3 and Figure 4 As can be seen, compared with the control effect of traditional methods under different current limits, the proposed method can significantly improve the voltage support effect while avoiding temperature rise exceeding the limit, thus verifying the effectiveness of the proposed method. Regarding thermal safety performance, the peak junction temperature of Method 1 is 104.7℃, that of Method 2 is 115.8℃, and that of Method 3 is 108.1℃. The peak junction temperature of Method 2 exceeds the maximum operating temperature, while Methods 1 and 3 do not experience temperature rise exceeding the limit. Furthermore, the rotational speed of the high-inertia energy storage synchronous condenser remains within the safe operating range under all three methods.

[0175] The rotor current amplitude limit for methods 1 and 2 is set to 1.5 times the rated current. The electrical quantities of the high-inertia energy storage synchronous condenser for the three methods under different voltage drop depths are shown in Table 1. Among them, The voltage of bus A when the high-inertia energy storage synchronous condenser is not involved in voltage support control; The voltage of bus A when the high-inertia energy storage synchronous condenser has not reached the lower speed limit; This represents the voltage of bus A when a high-inertia energy storage synchronous condenser is generating only reactive power after reaching its speed limit. Under all three methods, the junction temperature slightly increases with increasing voltage sag depth. Method 1 did not experience junction temperature exceeding the limit under any of the three different voltage sag levels, but its voltage support effect was weaker than Methods 2 and 3. Method 2 had better voltage support, but junction temperature exceeding the limit occurred. The current limiting of Method 3 decreased slightly with increasing voltage sag depth, and its voltage support effect was similar to Method 2, but it effectively suppressed temperature rise exceeding the limit, verifying the effectiveness of the proposed method in suppressing temperature rise and supporting voltage under different voltage sag levels.

[0176] Table 1. Voltage support effect under different voltage drop levels

[0177]

[0178] Overview:

[0179] The voltage support coordination control scheme for high-inertia energy storage synchronous condensers proposed in this invention considers the real-time variation of device junction temperature with operating conditions. It constructs a dynamic junction temperature safety domain for the high-inertia energy storage synchronous condenser converter, with active and reactive power as state variables. The boundary of this safety domain can be adjusted according to real-time temperature conditions, accurately quantifying the adjustable range of active and reactive power of the condenser at different operating times. This provides a clear feasible domain boundary for upper-level coordination control, achieving a quantitative characterization of the active and reactive power control capabilities of the high-inertia energy storage synchronous condenser under junction temperature safety constraints, thus better supporting the optimization of coordination control decisions. Simultaneously, it overcomes the conservatism of traditional static current limiting, allowing the converter to output higher power in short periods while ensuring device thermal safety. This maximizes the short-term overload capability and voltage recovery potential of the high-inertia energy storage synchronous condenser, accelerates the voltage recovery process, improves the grid support efficiency of the high-inertia energy storage synchronous condenser, and achieves the optimal balance between thermal safety and control performance. Furthermore, the implementation method of the present invention is clear. It only requires the collection of real-time operating data of the current high-inertia energy storage synchronous condenser and the processing of the data in real time through the voltage support control system. It can be seamlessly integrated with the original control architecture of the synchronous condenser without large-scale hardware modification or system reconstruction. It is easy to implement, has strong economic efficiency and practicality, and has broad engineering application prospects.

[0180] In summary, the voltage support coordination control scheme for high-inertia energy storage synchronous condensers of this invention achieves a technical leap from indirect current limiting to direct power domain constraint by constructing a dynamic junction temperature safety domain. It solves the coordination problem between thermal safety and voltage support control of high-inertia energy storage synchronous condensers, demonstrating significant advantages in both theoretical innovation and engineering practicality. It provides effective technical support for the optimized operation of high-inertia energy storage synchronous condensers in new power systems.

[0181] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit the technical solutions. Those skilled in the art should understand that any modifications or equivalent substitutions to the technical solutions of the present invention without departing from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.

Claims

1. A voltage support coordination control method for high-inertia energy storage type synchronous condensers, characterized in that, Includes the following steps: S1. Collect the operating parameters of the high-inertia energy storage synchronous condenser and the grid connection point voltage of the high-inertia energy storage synchronous condenser; when the grid connection point voltage of the high-inertia energy storage synchronous condenser drops to outside the normal allowable range, start the voltage support coordination control and execute S2. S2. Based on the junction temperature constraints of power devices, construct a junction temperature safety domain constraint model for a high-inertia energy storage synchronous condenser converter with the active power and reactive power of the stator as state variables. S3. Based on the junction temperature safety domain constraint model, construct a voltage support control model for a high-inertia energy storage synchronous condenser. S4. The rotor-side converter adopts constant active power and reactive power control, solves the voltage support control model of the high inertia energy storage synchronous condenser, and uses the optimal active power and reactive power solutions obtained from the solution as the control reference values ​​of the rotor-side converter. S5. Check whether the rotational speed of the high-inertia energy storage synchronous condenser has reached or exceeded the minimum allowable rotational speed; if yes, continue to execute S6; otherwise, return to execute S4. S6. Switch the constant active power control of the rotor-side converter to constant speed control, set the control reference value to the minimum allowable speed, and set the constant reactive power control reference value of the rotor-side converter to the stator maximum reactive power under the rotor allowable current limit. S7. Determine whether the grid connection point voltage has returned to the normal allowable range; if it has, proceed to S8; otherwise, return to S4. S8. The high-inertia energy storage synchronous condenser is controlled by constant speed control and constant reactive power control. The reference value for constant speed control is set to the normal operating speed determined by the design, and the reference value for constant reactive power control is set to zero.

2. The voltage support coordination control method for high-inertia energy storage synchronous condensers according to claim 1, characterized in that, In step S2, the junction temperature safety domain constraint model for the high-inertia energy storage synchronous condenser converter, with the active and reactive power of the stator as state variables, is as follows: ； in, , , These are respectively the stator active power of high inertia energy storage type synchronous condenser. and reactive power Junction temperature of the switching device, freewheeling diode, and clamping diode, which are variables; , , These are the maximum operating temperatures of the switching device, freewheeling diode, and clamping diode, respectively. The junction temperature of the switching device, freewheeling diode, and clamping diode , , This was determined by solving the following heat network model: ； in, This refers to the radiator temperature. For the device losses of the converter switching devices, The thermal impedance of the converter switching devices; For the device losses of the freewheeling diode in the converter, The thermal resistance of the freewheeling diode in the converter; For the device losses of the converter clamping diode, This is the thermal resistance of the converter clamping diode.

3. The voltage support coordination control method for high-inertia energy storage synchronous condensers according to claim 2, characterized in that, The device losses of the switching device, freewheeling diode, and clamping diode are expressed as follows: ； ； ； in, , These are the conduction loss and switching loss of the switching device, respectively. , These are the conduction loss and switching loss of the freewheeling diode, respectively. , These represent the conduction loss and switching loss of the clamping diode, respectively.

4. The voltage support coordination control method for high-inertia energy storage synchronous condensers according to claim 3, characterized in that, The conduction losses of the switching device, freewheeling diode, and clamping diode are determined as follows: ； ； ； in, The initial phase angle corresponding to the inverter output current; This refers to the rotor current amplitude. The rotor current angular frequency; , , The switching device, freewheeling diode, and clamping diode are respectively located at time [time]. The on-state voltage drop; , , The switching device, freewheeling diode, and clamping diode are respectively located at time [time]. The duty cycle of the switching transistor during one corresponding switching cycle; The switching losses of the switching device, freewheeling diode, and clamping diode are determined as follows: ； ； ； in, The switching frequency; , These are the turn-on loss and turn-off loss of the switching device under rated conditions, respectively. This refers to the bridge arm voltage; , These are the reference current and the reference voltage, respectively. The reference current and reference voltage The junction temperature corresponding to the test conditions; , , These are the rotor current amplitudes. Bridge arm voltage and junction temperature of switching devices The influence coefficient on the switching loss of switching devices; , These are the switching losses of the freewheeling diode and the clamping diode under rated conditions, respectively. , , These are the rotor current amplitudes. Bridge arm voltage and the junction temperature of the freewheeling diode The influence coefficient on the switching loss of the freewheeling diode; , , These are the rotor current amplitudes. Bridge arm voltage and clamping diode junction temperature The influence coefficient on the switching loss of the clamping diode.

5. The voltage support coordination control method for a high-inertia energy storage type synchronous condenser according to claim 4, characterized in that, Rotor current amplitude With rotor current angular frequency It is a function of the active and reactive power of a high-inertia synchronous condenser, and is determined as follows: ； ； in, The stator equivalent inductance; For magnetizing inductance; This refers to the stator voltage amplitude. , These are the active power and reactive power of the stator, respectively. Synchronous speed; This indicates the time at which the rotor current angular frequency is determined; The inertial constant of a high-inertia energy storage synchronous condenser; For time integration variables; The initial rotational speed before the voltage drops.

6. The voltage support coordination control method for high-inertia energy storage synchronous condensers according to claim 1, characterized in that, In step S3, the voltage support control model for the high-inertia energy storage synchronous condenser is constructed as follows: ； in, This refers to the voltage at the grid connection point. , These are the active power and reactive power of the stator, respectively. This is the equivalent electromotive force of the power grid; , These are the equivalent resistance and equivalent reactance of the power grid, respectively. , , These are respectively the stator active power of high inertia energy storage type synchronous condenser. and reactive power Junction temperature of the switching device, freewheeling diode, and clamping diode, which are variables; , , These are the maximum operating temperatures of the switching device, freewheeling diode, and clamping diode, respectively. This refers to the rotor current amplitude. This is the maximum allowable current under the constraints of converter capacity and motor winding limitations.

7. The voltage support coordination control method for high-inertia energy storage synchronous condensers according to claim 6, characterized in that, In step S4, the voltage support control model is solved as follows: S401. All constraints of the voltage support control model are made dimensionless, and a total constraint violation quantity is introduced. Measuring infeasible solutions and total constraint violations. The calculation method is as follows: ； in, For the search space, a solution that simultaneously covers both the constraints and the constraints of the high-inertia energy storage synchronous condenser is required. To solve The corresponding number The value of a constraint violation is the solution. In the The difference between the parameter value corresponding to each constraint and its maximum value; For the first The comparison weight parameters of each constraint, and , For the first The maximum amount of violation of a constraint; The number of constraints; S402. Randomly generate N pairs of solutions for active power and reactive power in the search space. Each pair of solutions is used as a vector element to form the initial population; where N is an even number. S403. Substitute each pair of solutions in the current population into the grid connection point voltage respectively. The calculation formula uses the calculated maximum grid connection point voltage as the optimal target value. The pair of solutions corresponding to the maximum voltage at the grid connection point is denoted as the optimal solution. The normalized teaching factor is obtained by normalizing the other solutions in the initial population: ； in, In the initial population, besides the optimal solution The other Solution Normalized teaching factors; According to the first Solution The calculated target value of the grid connection point voltage; S404. During the teaching phase, the current population is updated through evolution to obtain an evolved population containing N vector elements. The evolution update method is to first evolve the population elements according to the following formula: ； in, , These are the first and second stages of the teaching process, before and after its evolution. Solution; A random value between [0,1]; This is the average value of all pairs of solutions in the population before the evolution update; After evolution, if Superior This would cause the first [element] in the evolved population to [become the first]. Solution = Otherwise, the first in the evolved population will be... Solution = Thus, the evolved population after evolutionary renewal is obtained; S405. During the learning phase, based on the evolutionary population obtained at the current teaching phase, randomly select two pairs of solutions that have not been previously selected. , Compare the merits of the two solutions and move the weaker solution pair closer to the stronger one: ； in, , This is a new solution after adjustments during the learning phase; S406. Repeat step S405 until all solutions in the evolutionary population have been selected, then execute step S407. S407. Determine whether the number of iterations in the current teaching-learning stage has reached the preset maximum number of iterations; if yes, proceed to step S408; if no, further determine whether the absolute value deviation between the optimal target value of the current teaching-learning stage and the previous teaching-learning stage is less than the preset precision threshold. If yes, proceed to step S408; otherwise, increment the number of iterations in the teaching-learning phase by 1 and return to step S403. S408. Output the optimal target value obtained in the current teaching-learning phase. and its corresponding optimal solution With the optimal solution The active and reactive power are used as control reference values ​​for the rotor-side converter.

8. The voltage support coordination control method for high-inertia energy storage synchronous condensers according to claim 7, characterized in that, In step S404, determine and When determining the merits of two options, the following criteria are used: If one is located in the feasible region and the other in the infeasible region, the one located in the feasible region is considered superior; if both are located in the feasible region, then the two options are compared. and Corresponding target value and The one with the larger objective value is better; if both are located in the infeasible region, then compare... and Corresponding total constraint violation and The one with a smaller total constraint violation is better; In step S405, determine and When determining the merits of two options, the following criteria are used: If one is located in the feasible region and the other in the infeasible region, the one located in the feasible region is considered superior; if both are located in the feasible region, then the two options are compared. and Corresponding target value and The one with the larger objective value is better; if both are located in the infeasible region, then compare... and Corresponding total constraint violation and The one with a smaller total number of constraint violations is better.

9. The voltage support coordination control method for high-inertia energy storage synchronous condensers according to claim 1, characterized in that, In step S6, the maximum reactive power of the stator under the rotor allowable current limit is determined. Determine as follows: ； in, The stator equivalent inductance; For magnetizing inductance; This refers to the stator voltage amplitude. Synchronous speed; This is the maximum allowable current under the constraints of converter capacity and motor winding limitations.

10. A voltage support coordination control system for a high-inertia energy storage type synchronous condenser, characterized in that, To implement the method according to any one of claims 1 to 9, comprising: The acquisition module is used to acquire the operating parameters of the high-inertia energy storage synchronous condenser and the grid connection point voltage of the high-inertia energy storage synchronous condenser. The first judgment module is used to determine whether the grid connection point voltage of the high-inertia energy storage synchronous condenser has dropped to outside the normal allowable range, and then to start the voltage support coordination control and call the constraint module. The constraint module is used to construct a voltage support control model for a high-inertia energy storage synchronous condenser based on the junction temperature safety domain constraint model. The first calculation module is used to enable the rotor-side converter to adopt constant active power and reactive power control, solve the voltage support control model of the high-inertia energy storage synchronous condenser, and use the optimal active power and reactive power solutions obtained from the solution as the control reference values ​​of the rotor-side converter; then the second judgment module is called. The second judgment module is used to detect whether the rotational speed of the high-inertia energy storage type synchronous condenser has reached or exceeded the minimum allowable rotational speed; if so, the first control module is called; otherwise, the first calculation module is called. The first control module is used to switch the constant active power control of the rotor-side converter to constant speed control, set the control reference value to the minimum allowable speed, and set the constant reactive power control reference value of the rotor-side converter to the stator maximum reactive power under the rotor allowable current limit; then it calls the third judgment module. The third judgment module determines whether the grid connection point voltage has returned to the normal allowable range; if it has, it calls the second control module; otherwise, it calls the first calculation module. The second control module is used to control the high-inertia energy storage synchronous condenser to adopt constant speed control and constant reactive power control. The constant speed control reference value is set to the normal operating speed determined by the design, and the constant reactive power control reference value is set to zero.

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