Low voltage ride-through characteristics simulation system based on dynamic reactive power compensation device

Abstract

The present application provides a low voltage ride-through characteristic simulation system based on a dynamic reactive power compensation device, the system comprising: a low voltage ride-through trigger circuit receives a terminal voltage signal output by the dynamic reactive power compensation device, and generates a low voltage ride-through trigger signal according to the terminal voltage signal; a reactive current locking circuit receives the terminal voltage signal and the low voltage ride-through trigger signal, and generates a reactive current locking value at the low voltage ride-through moment according to the terminal voltage signal and the low voltage ride-through trigger signal; a reactive current output circuit receives the low voltage ride-through trigger signal and the reactive current locking value at the low voltage ride-through moment, and generates a reactive current command value according to the low voltage ride-through trigger signal and the reactive current locking value at the low voltage ride-through moment. The present application can simulate the electromagnetic transient characteristics of the dynamic reactive power compensation device under the low voltage ride-through situation.

Description

Technical Field

[0001] The present application relates to the field of power supply equipment characteristic simulation, and specifically to a low voltage ride-through characteristic simulation system based on a dynamic reactive power compensation device. Background Art

[0002] With the development of power systems, people's requirements for the grid connection of renewable energy power stations are increasing, and the requirements for equipping renewable energy power stations with dynamic reactive power compensation devices are also increasing. In this context, obtaining the electromagnetic transient model of the dynamic reactive power compensation device has become an important task in the field of power system simulation.

[0003] The low voltage ride-through capability of the dynamic VAR compensation device is of great significance to the voltage stability and frequency stability of the power system. Therefore, modeling the electromagnetic transient characteristics of the dynamic VAR compensation device under low voltage ride-through conditions is a very critical task.

[0004] In the prior art, when modeling the low voltage ride-through characteristics of a dynamic reactive power compensation device, it is generally achieved by collecting the input voltage and output current of the dynamic reactive power compensation device. Specifically, the external characteristics such as the input voltage and output current of the dynamic reactive power compensation device in the historical time period are first counted, and then the mathematical relationship between the input voltage and the output current is fitted based on these external characteristics, and finally the low voltage ride-through characteristics of the dynamic reactive power compensation device are simulated based on the mathematical relationship. However, the simulation accuracy of this method is poor, and it is still unable to simulate the electromagnetic transient characteristics of the dynamic reactive power compensation device under the low voltage ride-through situation. Summary of the invention

[0005] In response to the problems in the prior art, the present application provides a low voltage ride-through characteristic simulation system based on a dynamic reactive power compensation device, which can simulate the electromagnetic transient characteristics of the dynamic reactive power compensation device under low voltage ride-through conditions.

[0006] In order to solve the above technical problems, this application provides the following technical solutions:

[0007] The present application provides a low voltage ride-through characteristic simulation system based on a dynamic reactive power compensation device, comprising:

[0008] The low voltage ride through trigger circuit receives the terminal voltage signal output by the dynamic reactive power compensation device, and generates a low voltage ride through trigger signal according to the terminal voltage signal;

[0009] The reactive current locking circuit receives the terminal voltage signal and the low penetration trigger signal, and generates a reactive current locking value at the low penetration moment according to the terminal voltage signal and the low penetration trigger signal;

[0010] The reactive current output circuit receives the low-breakthrough trigger signal and the reactive current locking value at the low-breakthrough moment, and generates a reactive current command value according to the low-breakthrough trigger signal and the reactive current locking value at the low-breakthrough moment.

[0011] Furthermore, the low voltage ride through trigger circuit comprises:

[0012] a first hysteresis circuit, receiving the terminal voltage signal, and generating a first logic signal according to the terminal voltage signal and a preset hysteresis circuit threshold value;

[0013] a first sampling and holding circuit, receiving a first clock signal and the first logic signal, and generating a first sampling signal according to the first clock signal and the first logic signal;

[0014] a first adder, receiving a second clock signal and the first sampling signal, and generating a first addition signal according to the second clock signal and the first sampling signal;

[0015] a first signal selection circuit, receiving the first logic signal, and outputting a first selection signal according to the first logic signal; the first selection signal is a 0 signal or the first addition signal;

[0016] The second signal selection circuit receives the first selection signal and outputs the low-through trigger signal according to the first selection signal.

[0017] Furthermore, the low voltage ride through trigger circuit comprises:

[0018] a first hysteresis circuit, receiving the terminal voltage signal, and generating a first logic signal according to the terminal voltage signal and a preset hysteresis circuit threshold value;

[0019] a first sampling and holding circuit, receiving a first clock signal and the first logic signal, and generating a first sampling signal according to the first clock signal and the first logic signal;

[0020] a first adder, receiving a second clock signal and the first sampling signal, and generating a first addition signal according to the second clock signal and the first sampling signal;

[0021] a first signal selection circuit, receiving the first logic signal, and outputting a first selection signal according to the first logic signal; the first selection signal is a 0 signal or the first addition signal;

[0022] a second signal selection circuit, receiving the first selection signal and outputting a second selection signal according to the first selection signal;

[0023] The first multiplier receives the first logic signal and the second selection signal, and outputs the low-through trigger signal according to the first logic signal and the second selection signal.

[0024] Further, the first hysteresis circuit is used to compare the terminal voltage signal with the preset hysteresis circuit threshold value;

[0025] If the terminal voltage signal is less than the preset hysteresis circuit threshold value, output a 1 signal;

[0026] If the terminal voltage signal is greater than the preset hysteresis circuit threshold value, a 0 signal is output.

[0027] Further, when the first logic signal changes from a 0 signal to a 1 signal, the first sample and hold circuit is used to output the first clock signal as the first sampling signal.

[0028] Further, when the first logic signal is a 1 signal, the first signal selection circuit is used to output the first addition signal as the first selection signal; when the first logic signal is a 0 signal, the first signal selection circuit is used to output the 0 signal as the first selection signal.

[0029] Further, when the first selection signal is the first addition signal, the second signal selection circuit is used to output a 1 signal as the second selection signal; when the first selection signal is a 0 signal, the second signal selection circuit is used to output a 0 signal as the second selection signal.

[0030] Furthermore, the reactive current locking circuit comprises:

[0031] The second hysteresis circuit receives the terminal voltage signal and generates a second logic signal according to the terminal voltage signal and a preset hysteresis circuit threshold value;

[0032] The low-pass filter circuit receives a reactive current reference value of the dynamic reactive compensation device in a non-low voltage ride-through state, and generates a low-pass filter signal according to the reactive current reference value;

[0033] The second multiplier receives the low-pass filtered signal and generates a first multiplication signal according to the low-pass filtered signal;

[0034] The second sampling and holding circuit receives the second logic signal and the first multiplication signal, and generates the reactive current locking value at the low-breakthrough moment according to the second logic signal and the first multiplication signal.

[0035] Further, the second hysteresis circuit is used to compare the terminal voltage signal with the preset hysteresis circuit threshold value;

[0036] If the terminal voltage signal is less than the preset hysteresis circuit threshold value, output a 1 signal;

[0037] If the terminal voltage signal is greater than the preset hysteresis circuit threshold value, a 0 signal is output.

[0038] Further, when the second logic signal is a 1 signal, the second sampling and holding circuit is used to output the low-pass filtered signal as the reactive current locking value at the low-pass moment.

[0039] Furthermore, the reactive current output circuit comprises:

[0040] The second adder receives a preset reactive voltage calculation standard value and the terminal voltage signal, and generates a second addition signal according to the preset reactive voltage calculation standard value and the terminal voltage signal;

[0041] The third multiplier receives the preset reactive current calculation ratio and the second addition signal, and generates a second multiplication signal according to the preset reactive current calculation ratio and the second addition signal;

[0042] a fourth multiplier receiving the low-through trigger signal and the second multiplication signal, and generating a third multiplication signal according to the low-through trigger signal and the second multiplication signal;

[0043] A third adder receives the reactive current locking value at the low voltage break-through moment and the third multiplication signal, and generates a third addition signal according to the reactive current locking value at the low voltage break-through moment and the third multiplication signal;

[0044] The third signal selection circuit receives the low penetration trigger signal, the reactive current locking value at the low penetration moment and the third addition signal, and generates the reactive current command value according to the low penetration trigger signal, the reactive current locking value at the low penetration moment and the third addition signal.

[0045] Further, when the low-break trigger signal is a 1 signal, the third signal selection circuit is used to output the third addition signal as the reactive current command value; when the low-break trigger signal is a 0 signal, the third signal selection circuit is used to output the reactive current locking value at the low-break moment as the reactive current command value.

[0046] In response to the problems in the prior art, the low voltage ride-through characteristic simulation system based on the dynamic reactive compensation device provided in the present application can simulate the electromagnetic transient characteristics of the dynamic reactive compensation device under low voltage ride-through conditions, and can be used to analyze the reactive characteristics of the dynamic reactive compensation device when a low voltage fault occurs in the power system, and guide the reactive current output of the dynamic reactive compensation device when a low voltage fault occurs in the power system, which has positive significance for ensuring the voltage stability and frequency stability of the power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0048] Figure 1 This is an application scenario diagram of a low voltage ride-through characteristic simulation system based on a dynamic reactive power compensation device in an embodiment of the present application;

[0049] Figure 2 This is a structural diagram of a low voltage ride-through characteristic simulation system based on a dynamic reactive power compensation device in an embodiment of the present application;

[0050] Figure 3 This is one of the structural diagrams of the low voltage ride through trigger circuit in the embodiment of the present application;

[0051] Figure 4 This is the second structural diagram of the low voltage ride through trigger circuit in the embodiment of the present application;

[0052] Figure 5 This is a structural diagram of a reactive current locking circuit in an embodiment of the present application;

[0053] Figure 6 This is a structural diagram of a reactive current output circuit in an embodiment of the present application;

[0054] Figure 7 It is a simulation schematic diagram in the embodiment of the present application. DETAILED DESCRIPTION

[0055] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0056] In one embodiment, in order to simulate the electromagnetic transient characteristics of a dynamic reactive power compensation device under a low voltage ride-through situation, the present application provides a low voltage ride-through characteristic simulation system based on a dynamic reactive power compensation device.

[0057] It is understandable that when a low voltage fault occurs in the power system, the generator set may suffer from voltage oscillation and frequency oscillation, affecting the normal operation of the generator set. In order to alleviate the above oscillation, it is usually necessary to equip the generator set with a dynamic reactive power compensation device. The dynamic reactive power compensation device can output dynamically changing reactive current to effectively improve the power factor and output of the generator set, improve the power quality, reduce line loss, and achieve the purpose of energy saving and consumption reduction.

[0058] However, in actual applications, the reactive current output by the dynamic reactive compensation device cannot completely offset the impact of voltage oscillation and frequency oscillation on the power factor and output of the generator set, because considering various environmental factors, the reactive current output by the dynamic reactive compensation device cannot change in real time following the voltage oscillation and frequency oscillation. Sometimes the reactive current output by the dynamic reactive compensation device is too large, and the compensation is excessive, resulting in a waste of electric energy; sometimes the reactive current output by the dynamic reactive compensation device is too small to offset the impact of the oscillation.

[0059] To this end, the present application intends to simulate the electromagnetic transient characteristics of the dynamic reactive compensation device under low voltage crossing conditions, so as to determine the size of the reactive current that the dynamic reactive compensation device needs to output when a low voltage fault occurs in the power generation system, and then guide the dynamic reactive compensation device to output a reactive current of appropriate size under the action of a controlled power supply.

[0060] It should be noted that the dynamic reactive power compensation device in the embodiment of the present application has a low voltage ride through capability. The so-called low voltage ride through capability refers to the ability of the power equipment to continue to operate without disconnecting from the power grid when its terminal voltage drops to a certain value, and even to provide a certain amount of reactive power to the power grid to help the power grid restore voltage.

[0061] Based on the above application scenario, see Figure 1 The input end of the low voltage ride-through characteristic simulation system based on the dynamic reactive compensation device provided in the present application can be connected to the voltage output end of the dynamic reactive compensation device to receive the terminal voltage signal output by the dynamic reactive compensation device; the output end of the system can be connected to the controlled power supply end of the dynamic reactive compensation device so that the reactive compensation device can output a reactive current of appropriate size under the action of the controlled power supply.

[0062] Specifically, see Figure 2The low voltage ride-through characteristic simulation system based on the dynamic reactive power compensation device provided in the present application includes: a low voltage ride-through trigger circuit, a reactive current locking circuit and a reactive current output circuit.

[0063] Among them, the low voltage ride-through trigger circuit receives the terminal voltage signal output by the dynamic reactive power compensation device, and generates a low voltage ride-through trigger signal according to the terminal voltage signal; the reactive current locking circuit receives the terminal voltage signal and the low voltage ride-through trigger signal, and generates a reactive current locking value at the low voltage ride-through moment according to the terminal voltage signal and the low voltage ride-through trigger signal; the reactive current output circuit receives the low voltage ride-through trigger signal and the reactive current locking value at the low voltage ride-through moment, and generates a reactive current command value according to the low voltage ride-through trigger signal and the reactive current locking value at the low voltage ride-through moment. Finally, the dynamic reactive power compensation device can output a reactive current equal to the reactive current command value according to the reactive current command value under the action of the controlled power supply.

[0064] From the above description, it can be seen that the low voltage ride-through characteristic simulation system based on the dynamic reactive compensation device provided by the present application can simulate the electromagnetic transient characteristics of the dynamic reactive compensation device under low voltage ride-through conditions, and can be used to analyze the reactive characteristics of the dynamic reactive compensation device when a low voltage fault occurs in the power system, and guide the reactive current output of the dynamic reactive compensation device when a low voltage fault occurs in the power system, which has positive significance for ensuring the voltage stability and frequency stability of the power system.

[0065] In one embodiment, see Figure 3 The low voltage ride-through trigger circuit includes: a hysteresis circuit 1, a clock 2, a sample and hold circuit 3, a clock 4, an adder 5, a signal selection circuit 6 and a signal selection circuit 7.

[0066] Among them, the hysteresis circuit 1 receives the terminal voltage signal Vabc_Bstatcom_Mag of the dynamic reactive power compensation device, and generates a first logic signal according to the terminal voltage signal Vabc_Bstatcom_Mag and the preset hysteresis circuit threshold value Venter; the sampling and holding circuit 3 receives the first logic signal and the first clock signal generated by the clock 2, and generates a first sampling signal according to the first clock signal and the first logic signal; the adder 5 receives the first sampling signal and the second clock signal generated by the clock 4, and generates a first addition signal according to the second clock signal and the first sampling signal; the signal selection circuit 6 receives the first logic signal, and outputs a first selection signal (0 signal or first addition signal) according to the first logic signal; the signal selection circuit 7 receives the first selection signal, and outputs a low-wear trigger signal HVRT_dur according to the first selection signal.

[0067] Specifically, the working principle of the low voltage ride-through trigger circuit is as follows:

[0068] First, the terminal voltage signal Vabc_Bstatcom_Mag of the dynamic reactive power compensation device is input into the hysteresis circuit 1. By comparing the magnitude relationship between the terminal voltage signal Vabc_Bstatcom_Mag and the preset hysteresis circuit threshold value Venter, the hysteresis circuit 1 can set the output value of the hysteresis circuit 1 to 1 when the terminal voltage is lower than Venter; and set the output value of the hysteresis circuit 1 to 0 when the terminal voltage is higher than Venter. In practical applications, a low voltage crossing exit threshold value Vout can be set separately. By comparing the magnitude relationship between the terminal voltage signal Vabc_Bstatcom_Mag and Vout, the hysteresis circuit 1 sets the output value of the hysteresis circuit 1 to 0 only when the terminal voltage is higher than Vout. Usually, the value of Vout can be higher than the value of Venter.

[0069] Then, through the sampling and holding circuit 3, the adder 5, the signal selection circuit 6 and the signal selection circuit 7, the signal selection circuit 7 sets the low-through trigger signal to 1 when the output value of the hysteresis circuit 1 is 1 and the output value of the adder 5 is greater than or equal to the threshold value of the signal selection circuit 7. In the embodiment of the present application, the threshold value of the signal selection circuit 7 is set to 0.02 seconds, but the present application is not limited thereto.

[0070] The above process can also be understood as, when the low voltage is stable for more than 0.02s, it can be considered that it has entered the low voltage ride-through state, and the low voltage ride-through trigger signal HVRT_dur is set to 1 at this time.

[0071] It can be seen from the above description that the low voltage ride-through characteristic simulation system based on the dynamic reactive power compensation device provided in the present application can generate a low voltage ride-through trigger signal by using a low voltage ride-through trigger circuit.

[0072] In one embodiment, see Figure 4, the low voltage ride-through trigger circuit may also include a multiplier 8. At this time, the hysteresis circuit 1 receives the terminal voltage signal Vabc_Bstatcom_Mag, and generates a first logic signal according to the terminal voltage signal Vabc_Bstatcom_Mag and the preset hysteresis circuit threshold value Venter; the sampling and holding circuit 3 receives the first clock signal and the first logic signal generated by the clock 2, and generates a first sampling signal according to the first clock signal and the first logic signal; the adder 5 receives the second clock signal and the first sampling signal generated by the clock 4, and generates a first addition signal according to the second clock signal and the first sampling signal; the signal selection circuit 6 receives the first logic signal, and outputs a first selection signal (0 signal or first addition signal) according to the first logic signal; the signal selection circuit 7 receives the first selection signal, and outputs a second selection signal according to the first selection signal; the multiplier 8 receives the first logic signal and the second selection signal, and outputs a low voltage ride-through trigger signal HVRT_dur according to the first logic signal and the second selection signal.

[0073] It should be noted that see Figure 4 Compared with the previous embodiment of the low voltage ride-through trigger circuit, this embodiment adds a multiplier 8 after the signal selection circuit 7. The purpose of this is to improve the stability of the output of the low voltage ride-through trigger signal HVRT_dur. That is, only when the first logic signal output by the hysteresis circuit 1 is a 1 signal and the second selection signal output by the signal selection circuit 7 is a 1 signal, the low voltage ride-through trigger signal HVRT_dur is set to 1.

[0074] It can be seen from the above description that the low voltage ride-through characteristic simulation system based on the dynamic reactive power compensation device provided in the present application can generate a low voltage ride-through trigger signal by using a low voltage ride-through trigger circuit.

[0075] Specifically, in one embodiment, when the first logic signal changes from a 0 signal to a 1 signal, the sampling and holding circuit 3 is used to output the first clock signal generated by the clock 2 as the first sampling signal. The first clock signal represents the time point of entering the low voltage ride-through state; the second clock signal represents the time point in the real world under the natural state. The duration of the low voltage state can be obtained by subtracting the first clock signal from the second clock signal.

[0076] In one embodiment, when the first logic signal is a 1 signal, the signal selection circuit 6 is used to output the first addition signal as the first selection signal; when the first logic signal is a 0 signal, the signal selection circuit 6 is used to output the 0 signal as the first selection signal.

[0077] In one embodiment, when the first selection signal is a first addition signal, and the first addition signal is greater than or equal to a threshold value of the signal selection circuit 7 (in the embodiment of the present application, the threshold value can be set to 0.02 seconds, for example, but not limited to this), the signal selection circuit 7 is used to output a 1 signal as the second selection signal; when the first selection signal is a 0 signal, the signal selection circuit 7 is used to output a 0 signal as the second selection signal.

[0078] In one embodiment, see Figure 5 The reactive current locking circuit includes: a hysteresis circuit 9, a low-pass filter circuit 10, a multiplier 11 and a sample-and-hold circuit 12.

[0079] Among them, the hysteresis circuit 9 receives the terminal voltage signal Vabc_Bstatcom_Mag, and generates a second logic signal according to the terminal voltage signal Vabc_Bstatcom_Mag and a preset hysteresis circuit threshold value Venter; the low-pass filter circuit 10 receives the reactive current reference value IqrefSVG of the dynamic reactive compensation device in a normal state, and generates a low-pass filter signal according to the reactive current reference value IqrefSVG; the multiplier 11 receives the low-pass filter signal, and generates a first multiplication signal according to the low-pass filter signal; the sampling and holding circuit 12 receives the second logic signal and the first multiplication signal, and generates a reactive current locking value IqSVGLVRT at the low-breakthrough moment according to the second logic signal and the first multiplication signal.

[0080] Specifically, the working principle of the reactive current locking circuit is as follows:

[0081] First, the terminal voltage signal Vabc_Bstatcom_Mag of the dynamic reactive power compensation device is input to the hysteresis circuit 9. By comparing the magnitude relationship between the terminal voltage signal Vabc_Bstatcom_Mag and the preset threshold value Venter of the hysteresis circuit, the hysteresis circuit 9 can set the output value of the hysteresis circuit 9 to 1 when the terminal voltage is lower than Venter; and set the output value of the hysteresis circuit 9 to 0 when the terminal voltage is higher than Venter. In practical applications, a low voltage crossing exit threshold value Vout can be set separately. By comparing the magnitude relationship between the terminal voltage signal Vabc_Bstatcom_Mag and Vout, the hysteresis circuit 9 sets the output value of the hysteresis circuit 9 to 0 when the terminal voltage is higher than Vout.

[0082] Then, the output value of the hysteresis circuit 9 is used as a trigger pulse of the sampling and holding circuit 12, so that the sampling and holding circuit 12 records the reactive current reference value IqrefSVG of the dynamic reactive compensation device at the moment when it enters the low voltage ride-through state. Specifically, when the output value of the hysteresis circuit 9, that is, the second logic signal is a 1 signal, the sampling and holding circuit 12 is used to output the first multiplication signal as the reactive current locking value IqSVGLVRT at the low voltage ride-through moment.

[0083] In other words, the reactive current locking value IqSVGLVRT at the low-breakthrough moment is the result of filtering the reactive current reference value IqrefSVG of the dynamic reactive compensation device in the normal state through the low-pass filter circuit 10 and calculating through the multiplier 11. Finally, the reactive current locking circuit outputs the reactive current locking value IqSVGLVRT at the low-breakthrough moment.

[0084] It should be noted that the reason for using the low-pass filter circuit 10 for filtering is that there is a large amount of high-frequency noise in the actual reactive current signal of the dynamic reactive compensation device, which will cause serious interference to the subsequent signal processing process. That is to say, the low-pass filter circuit 10 is used to generate a low-pass filter signal after performing low-pass filtering on the reactive current reference value IqrefSVG. In actual operation, the frequency threshold of the low-pass filter circuit 10 can be set to a larger value, such as 100rad / s. After low-pass filtering, the multiplier 11 can adjust the coefficient of the low-pass filter signal output by the low-pass filter circuit 10 to obtain a first multiplication signal, which is then output through the sampling and holding circuit 12, thereby locking the reactive current reference value IqrefSVG of the normal state of the wind turbine before the low voltage ride-through moment occurs. In an embodiment of the present application, the coefficient of the multiplier 11 can be set to 0.95, but the present application is not limited thereto.

[0085] From the above description, it can be seen that the low voltage ride-through characteristic simulation system based on the dynamic reactive power compensation device provided in the present application can generate a reactive current locking value at the low voltage ride-through moment by using a reactive current locking circuit.

[0086] In one embodiment, see Figure 6 The reactive current output circuit includes: an adder 13, a multiplier 14, a multiplier 15, an adder 16 and a signal selection circuit 17.

[0087] Among them, the adder 13 receives the preset reactive voltage calculation standard value LVRT_u0 and the terminal voltage signal Vabc_Bstatcom_Mag, and generates a second addition signal according to the preset reactive voltage calculation standard value LVRT_u0 and the terminal voltage signal Vabc_Bstatcom_Mag; the multiplier 14 receives the preset reactive current calculation ratio LVRT_iq_cof and the second addition signal, and generates a second multiplication signal according to the preset reactive current calculation ratio LVRT_iq_cof and the second addition signal; the multiplier 15 receives the low wear trigger signal HVRT_dur and the second multiplication signal, and generates a second multiplication signal according to the preset reactive current calculation ratio LVRT_iq_cof and the second addition signal. The low penetration trigger signal HVRT_dur and the second multiplication signal generate a third multiplication signal; the adder 16 receives the reactive current locking value IqSVGLVRT at the low penetration moment and the third multiplication signal, and generates a third addition signal according to the reactive current locking value IqSVGLVRT at the low penetration moment and the third multiplication signal; the signal selection circuit 17 receives the low penetration trigger signal HVRT_dur, the reactive current locking value IqSVGLVRT at the low penetration moment and the third addition signal, and generates a reactive current command value Iq_ref according to the low penetration trigger signal HVRT_dur, the reactive current locking value IqSVGLVRT at the low penetration moment and the third addition signal.

[0088] Specifically, the working principle of the reactive current output circuit is as follows:

[0089] First, the adder 13 subtracts the terminal voltage Vabc_Bstatcom_Mag of the dynamic reactive compensation device from the reactive voltage calculation standard value LVRT_u0 to obtain a voltage difference, that is, a second addition signal; the multiplier 14 then multiplies the second addition signal by a preset reactive current calculation ratio LVRT_iq_cof (generally not less than 1.5) to obtain a second multiplication signal; the multiplier 15 then multiplies the second multiplication signal by a low voltage ride-through trigger signal LVRT_dur (1 after entering the low voltage ride-through state and 0 for the rest of the time) to obtain a third multiplication signal; the adder 16 adds the reactive current locking value IqSVGLVRT at the low voltage ride-through moment to the third multiplication signal to obtain a third addition signal.

[0090] In the embodiment of the present application, the reactive voltage calculation standard value LVRT_u0 can be calculated according to the relevant standard formula I q ≥1.5×(U T -0.9)I n To determine, where I q is the reactive current output by the dynamic reactive power compensation device, U T is the terminal voltage of the dynamic reactive power compensation device, I n is the rated current of the dynamic reactive power compensation device; for example, LVRT_u0 may be 0.9, but the present application is not limited thereto.

[0091] Then, when the low wear trigger signal HVRT_dur is greater than or equal to 1, the signal selection circuit 17 outputs the third addition signal as the reactive current command value Iq_ref; when the low wear trigger signal HVRT_dur is 0 (or less than 1), the reactive current reference value IqrefSVG is output as the reactive current command value Iq_ref.

[0092] In order to illustrate the usability of the system provided by the present application, the output reactive current command value Iq_ref given by the system provided by the present application is input into the electromagnetic transient simulation system of the infinite power grid (which can be a simulation system built using the Simulink visual simulation tool), and at the same time, a visual simulation tool such as Simulink is used to construct a simulation model of the dynamic reactive compensation device. The simulation model of the dynamic reactive compensation device is constructed according to Figure 1 The connection relationship shown is connected to the electromagnetic transient simulation system.

[0093] A low voltage test is carried out in the electromagnetic transient simulation system, and the reactive current command value Iq_ref generated by the system provided by the present application is input into the simulation model of the dynamic reactive compensation device in the electromagnetic transient simulation system. The simulation model of the dynamic reactive compensation device can output a reactive current of appropriate magnitude under the control of the reactive current command value Iq_ref.

[0094] The reactive current output by the simulation model of the dynamic reactive compensation device under the control of the reactive current command value Iq_ref is compared with the actual test results obtained by the RT-Lab test based on the actual controller (see the comparison results for details). Figure 7 As shown), it can be seen that the low voltage ride-through characteristic simulation system based on the dynamic reactive power compensation device provided by the present application can reproduce the characteristics of the RT-Lab physical controller, and then reproduce the active power characteristics of the actual dynamic reactive power compensation device controller during the low voltage ride-through process. The system provided by the present application is available.

[0095] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the embodiment of the device implementation method, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0096] The above is a description of a specific embodiment of the specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recorded in the claims can be performed in an order different from that in the embodiments and still achieve the desired results. In addition, the processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0097] Although the present specification embodiment provides the method operation steps as described in the embodiment or flow chart, more or less operation steps may be included based on conventional or non-creative means. The order of steps listed in the embodiment is only one way in the order of execution of many steps, and does not represent a unique execution order. The term "include", "comprise" or any other variant thereof is intended to cover non-exclusive inclusion, so that the process, method, product or equipment including a series of elements not only includes those elements, but also includes other elements not clearly listed, or also includes elements inherent to such process, method, product or equipment. In the absence of more restrictions, it is not excluded that there are other identical or equivalent elements in the process, method, product or equipment including the elements.

[0098] Each embodiment in this specification is described in a progressive manner, and the same and similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment. In the description of this specification, the description of the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiment of this specification. In this specification, the schematic representation of the above terms does not necessarily target the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, in the absence of contradiction, a person skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0099] The above is only an example of the embodiment of the present specification and is not intended to limit the embodiment of the present specification. For those skilled in the art, the embodiment of the present specification may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the embodiment of the present specification shall be included in the scope of the claims of the embodiment of the present specification.

Claims

1. A low voltage ride-through characteristics simulation system based on a dynamic reactive power compensation device, characterized in that: include: The low voltage ride through trigger circuit receives the terminal voltage signal output by the dynamic reactive power compensation device, and generates a low voltage ride through trigger signal according to the terminal voltage signal; The reactive current locking circuit receives the terminal voltage signal and the low penetration trigger signal, and generates a reactive current locking value at the low penetration moment according to the terminal voltage signal and the low penetration trigger signal; The reactive current output circuit receives the low penetration trigger signal and the reactive current locking value at the low penetration moment, and generates a reactive current command value according to the low penetration trigger signal and the reactive current locking value at the low penetration moment; Wherein, the low voltage ride through trigger circuit comprises: a first hysteresis circuit, receiving the terminal voltage signal, and generating a first logic signal according to the terminal voltage signal and a preset hysteresis circuit threshold value; a first sampling and holding circuit, receiving a first clock signal and the first logic signal, and generating a first sampling signal according to the first clock signal and the first logic signal; a first adder, receiving a second clock signal and the first sampling signal, and generating a first addition signal according to the second clock signal and the first sampling signal; a first signal selection circuit, receiving the first logic signal, and outputting a first selection signal according to the first logic signal; the first selection signal is a 0 signal or the first addition signal; The second signal selection circuit receives the first selection signal and outputs the low-through trigger signal according to the first selection signal.

2. The low voltage ride-through characteristics simulation system based on a dynamic reactive power compensation device according to claim 1 is characterized in that: The low voltage ride through trigger circuit comprises: a first hysteresis circuit, receiving the terminal voltage signal, and generating a first logic signal according to the terminal voltage signal and a preset hysteresis circuit threshold value; a first sampling and holding circuit, receiving a first clock signal and the first logic signal, and generating a first sampling signal according to the first clock signal and the first logic signal; a first adder, receiving a second clock signal and the first sampling signal, and generating a first addition signal according to the second clock signal and the first sampling signal; a first signal selection circuit, receiving the first logic signal, and outputting a first selection signal according to the first logic signal; the first selection signal is a 0 signal or the first addition signal; a second signal selection circuit, receiving the first selection signal and outputting a second selection signal according to the first selection signal; The first multiplier receives the first logic signal and the second selection signal, and outputs the low-through trigger signal according to the first logic signal and the second selection signal.

3. The low voltage ride-through characteristics simulation system based on a dynamic reactive power compensation device according to claim 2 is characterized in that: The first hysteresis circuit is specifically used to compare the terminal voltage signal with the preset hysteresis circuit threshold value; If the terminal voltage signal is less than the preset hysteresis circuit threshold value, output a 1 signal; If the terminal voltage signal is greater than the preset hysteresis circuit threshold value, a 0 signal is output.

4. The low voltage ride-through characteristics simulation system based on a dynamic reactive power compensation device according to claim 2 is characterized in that: When the first logic signal changes from a 0 signal to a 1 signal, the first sample-and-hold circuit outputs the first clock signal as the first sampling signal.

5. The low voltage ride-through characteristics simulation system based on a dynamic reactive power compensation device according to claim 2 is characterized in that: When the first logic signal is a 1 signal, the first signal selection circuit outputs the first addition signal as the first selection signal; when the first logic signal is a 0 signal, the first signal selection circuit outputs a 0 signal as the first selection signal.

6. The low voltage ride-through characteristics simulation system based on a dynamic reactive power compensation device according to claim 2 is characterized in that: When the first selection signal is the first addition signal and the first addition signal is greater than or equal to the threshold value of the second signal selection circuit, the second signal selection circuit outputs a 1 signal as the second selection signal; when the first selection signal is a 0 signal, the second signal selection circuit outputs a 0 signal as the second selection signal.

7. The low voltage ride-through characteristics simulation system based on a dynamic reactive power compensation device according to claim 2 is characterized in that: The reactive current locking circuit comprises: a second hysteresis circuit, receiving the terminal voltage signal, and generating a second logic signal according to the terminal voltage signal and a preset hysteresis circuit threshold value; A low-pass filter circuit receives a reactive current reference value of the dynamic reactive compensation device in a non-low voltage ride-through state, and generates a low-pass filter signal according to the reactive current reference value; a second multiplier, receiving the low-pass filtered signal and generating a first multiplication signal according to the low-pass filtered signal; The second sampling and holding circuit receives the second logic signal and the first multiplication signal, and generates the reactive current locking value at the low-breakthrough moment according to the second logic signal and the first multiplication signal.

8. The low voltage ride-through characteristics simulation system based on a dynamic reactive power compensation device according to claim 7 is characterized in that: The second hysteresis circuit is specifically used to compare the terminal voltage signal with the preset hysteresis circuit threshold value; If the terminal voltage signal is less than the preset hysteresis circuit threshold value, output a 1 signal; If the terminal voltage signal is greater than the preset hysteresis circuit threshold value, a 0 signal is output.

9. The low voltage ride-through characteristics simulation system based on a dynamic reactive power compensation device according to claim 7, characterized in that: When the second logic signal is a 1 signal, the second sampling and holding circuit outputs the low-pass filtered signal as the reactive current locking value at the low-pass moment.

10. The low voltage ride-through characteristics simulation system based on a dynamic reactive power compensation device according to claim 1, characterized in that: The reactive current output circuit comprises: a second adder, receiving a preset reactive voltage calculation standard value and the terminal voltage signal, and generating a second addition signal according to the preset reactive voltage calculation standard value and the terminal voltage signal; a third multiplier, receiving a preset reactive current calculation ratio and the second addition signal, and generating a second multiplication signal according to the preset reactive current calculation ratio and the second addition signal; a fourth multiplier, receiving the low-through trigger signal and the second multiplication signal, and generating a third multiplication signal according to the low-through trigger signal and the second multiplication signal; a third adder, receiving the reactive current locking value at the low-voltage breakthrough moment and the third multiplication signal, and generating a third addition signal according to the reactive current locking value at the low-voltage breakthrough moment and the third multiplication signal; The third signal selection circuit receives the low-breakthrough trigger signal, the reactive current locking value at the low-breakthrough moment and the third addition signal, and generates the reactive current command value according to the low-breakthrough trigger signal, the reactive current locking value at the low-breakthrough moment and the third addition signal.

11. The low voltage ride-through characteristic simulation system based on a dynamic reactive power compensation device according to claim 10, characterized in that: When the low-break trigger signal is a 1 signal, the third signal selection circuit outputs the third addition signal as the reactive current command value; when the low-break trigger signal is a 0 signal, the third signal selection circuit outputs the reactive current locking value at the low-break moment as the reactive current command value.

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