Static VAR compensator and control method based on model prediction

Abstract

The present invention relates to a static VAR compensator and a control method based on model prediction. Based on the improved topology of the static VAR compensator, the control method based on model prediction predicts the switching coefficients of the two bridge arm switches of the H bridge in the power submodule according to the electrical parameters after obtaining the electrical parameters of the DC side and the AC side of any power submodule in the static VAR compensator, and controls the bridge arm switches of the H bridge according to the switching coefficients. Based on this, based on a circuit structure different from that of a traditional static VAR compensator, linear control is performed by a control method based on model prediction, thereby avoiding the overmodulation problem caused by the linear superposition of the AC side and the DC side in the static VAR compensator.

Description

Technical Field

[0001] The present invention relates to the technical field of high-voltage distribution network, and in particular to a static VAR compensator and a control method based on model prediction. Background Art

[0002] The emergence of more and more high-tech industries and high value-added industries has put forward higher requirements for power quality. High-quality power parks are an effective solution to the problem of regional high-quality power supply. Once short-circuit interruption and temporary drop occur on the feeder of the distribution network, it will cause significant economic losses.

[0003] Based on the topology of dual-circuit power supply and multiple power quality management devices, the solid-state switching switch needs to control the switching of two thyristors to achieve the switching of the main and standby power supplies, thereby solving the voltage drop and interruption problems. However, the thyristor switching time is relatively long, about 20ms. During this process, the load power supply will be interrupted for a short time, causing losses to sensitive users. The static VAR compensator based on the interconnection of distribution network feeders can avoid power supply interruptions caused by conventional switch switching operations, and can also alleviate voltage sags, harmonics and other phenomena, and improve the power quality during normal operation. However, traditional static VAR compensators require more switching tubes, which increases the cost of static VAR compensators. Changing the switch tube design of traditional static VAR compensators will change the signal modulation method of traditional static VAR compensators. The superimposed DC modulation signal will increase the peak value of the overall modulation signal, resulting in the linear control method used by traditional static VAR compensators being unable to meet their control requirements. Summary of the invention

[0004] Based on this, it is necessary to provide a static VAR compensator and a control method based on model prediction to address the shortcomings of the traditional static VAR compensator structure.

[0005] A static VAR compensator includes a plurality of cascaded power submodules:

[0006] The power submodule includes:

[0007] An H-bridge consisting of four bridge switches;

[0008] First inductor;

[0009] The second inductor;

[0010] A supercapacitor, one end of which is connected to the common end of the upper bridge arm of the H bridge through a first inductor, and the other end of which is connected to the common end of the lower bridge arm of the H bridge through a second inductor;

[0011] The common end of the lower bridge arm of a power submodule is connected to the common end of the upper bridge arm of the next power submodule to form a cascade structure.

[0012] The above-mentioned static VAR compensator includes a plurality of cascaded power submodules, each power submodule includes an H-bridge composed of four bridge switches, a first inductor, a second inductor and a supercapacitor. Among them, the common end of the lower bridge arm of a power submodule is connected to the common end of the upper bridge arm of the next power submodule to form a cascade structure; one end of the supercapacitor is connected to the common end of the upper bridge arm of the H-bridge through the first inductor, and the other end is connected to the common end of the lower bridge arm of the H-bridge through the second inductor. Based on this, a buck-boost converter is formed by the first inductor and the second inductor, saving the use of switches to reduce costs and improve reliability. At the same time, by controlling the H-bridge bridge switch, the charging and discharging of the supercapacitor can be realized, and the H-bridge can output an AC voltage square wave. The DC side can control the energy transmitted by the buck-boost converter by adjusting the duty cycle of the H-bridge; the voltage output by the static VAR compensator can also be controlled by controlling the phase shift angle of each power submodule, and harmonics can be eliminated to the greatest extent.

[0013] In one embodiment, the power submodule further includes:

[0014] A DC link capacitor has one end connected to the power supply voltage terminal of the H-bridge and the other end connected to the ground terminal of the H-bridge.

[0015] In one embodiment, the bridge switch includes an IGBT.

[0016] A voltage sag processing device, comprising:

[0017] Main power supply, connected to the first feeder;

[0018] Backup power supply, connected to the second feeder;

[0019] Static VAR compensator, one end of which is connected to the corresponding phase of the AC bus, and the other end is used for grounding;

[0020] A first controlled switch, one end of which is connected to a corresponding phase of the first feeder, and the other end of which is connected to a corresponding phase of the AC bus;

[0021] The second controlled switch has one end connected to the corresponding phase of the second feeder and the other end connected to the corresponding phase of the AC bus.

[0022] The above-mentioned voltage sag processing device, based on the characteristics of the static VAR compensator, realizes the power switching of the AC bus through the on-off control of the first controlled switch and the second controlled switch, and uses the main power supply, the backup power supply or the static VAR compensator as the power supply of the AC bus to ensure the stability of the power supply of the AC bus to the load.

[0023] In one of the embodiments, the first controlled switch comprises a multi-phase first thyristor switch;

[0024] The first thyristor switch comprises:

[0025] A group of anti-parallel thyristors, one side of which is used to connect the corresponding phase of the first feeder, and the other side of which is used to connect the corresponding phase of the AC bus.

[0026] In one of the embodiments, the second controlled switch comprises a multi-phase second thyristor switch;

[0027] The second thyristor switch comprises:

[0028] A group of anti-parallel thyristors, one side of which is used to connect the corresponding phase of the second feeder, and the other side of which is used to connect the corresponding phase of the AC bus.

[0029] In one embodiment, the first thyristor switch or the second thyristor switch further includes:

[0030] Voltage equalizing circuit, connecting anti-parallel thyristors.

[0031] In one embodiment, it also includes:

[0032] Connect the reactor;

[0033] The static VAR compensator is connected to the corresponding phase of the AC bus through the connecting reactor.

[0034] A control method based on model prediction, applied to a static VAR compensator as in any of the above embodiments, comprises the steps of:

[0035] Obtaining electrical parameters of the DC side and AC side of any power submodule in the static VAR compensator;

[0036] Predict the switching coefficients of the two bridge arm switches of the H bridge in the power submodule based on the electrical parameters;

[0037] The bridge arm switches of the H bridge are controlled according to the switching coefficient.

[0038] The above control method based on model prediction, after obtaining the electrical parameters of the DC side and AC side of any power submodule in the static VAR compensator, predicts the switching coefficients of the two bridge arm switches of the H bridge in the power submodule according to the electrical parameters, and controls the bridge arm switches of the H bridge according to the switching coefficients. Based on this, based on a circuit structure different from that of the traditional static VAR compensator, linear control is performed through a control method based on model prediction, avoiding the overmodulation problem caused by the linear superposition of the AC side and the DC side in the static VAR compensator.

[0039] In one of the embodiments, the electrical parameters include active power, reactive power, DC side power, DC side resistance, DC side inductance, DC side current, DC side voltage, AC side power, AC side resistance, AC side current, AC side inductance, and AC side voltage of the power submodule;

[0040] The process of predicting the switching coefficients of the two bridge arm switches of the H bridge in the power submodule according to the electrical parameters includes the following steps:

[0041] Calculate the AC port current reference value and the supercapacitor port current reference value according to the active power, reactive power, DC side power, AC side power, AC side voltage and DC side voltage;

[0042] Substituting the DC side voltage, AC side current, DC side current, AC port current reference value and super capacitor port current reference value into a preset cost function to obtain converged DC link capacitor voltage, super capacitor current and AC port current;

[0043] The switching coefficient is calculated based on the DC link capacitor voltage, supercapacitor current, AC port current, DC side voltage, DC side resistance, DC side inductance, DC side current, AC side resistance, AC side inductance, AC side current and supercapacitor.

[0044] In one embodiment, the process of calculating the AC port current reference value and the supercapacitor port current reference value according to the active power, reactive power, DC side power, AC side power, AC side voltage and DC side voltage is as follows:

[0045]

[0046] in, Indicates active power, Represents reactive power, P dc1 Indicates the DC side power, Indicates the AC side power, v ac Indicates the AC side voltage, v dc2 Indicates the DC side voltage, Indicates the AC port current reference value, Indicates the supercapacitor port current reference value.

[0047] In one embodiment, the DC side voltage, AC side current, DC side current, AC port current reference value and super capacitor port current reference value are substituted into a preset cost function to obtain a converged DC link capacitor voltage, super capacitor current and AC port current process, as shown in the following formula:

[0048]

[0049] Among them, v dc1 Indicates the DC side voltage, i ac Indicates the AC side current, i dc2 Indicates the DC side current, Indicates the AC port current reference value, represents the supercapacitor port current reference value, and J represents the preset cost function.

[0050] In one embodiment, the process of calculating the switching coefficient according to the supercapacitor current, the AC port current, the DC side voltage, the DC side resistance, the DC side inductance, the DC side current, the AC side resistance, the AC side inductance, the AC side current and the supercapacitor is as follows:

[0051]

[0052] Among them, v dc2 Indicates the DC link capacitor voltage, represents the supercapacitor current, Indicates the AC port current, v dc1 represents the DC side voltage, r dc Indicates the DC side resistance, L dc represents the DC side inductance, i dc2 represents the DC side current, r ac Indicates the AC side resistance, L ac Indicates the AC side inductance, i ac represents the AC side current, C represents the supercapacitor, S a , S b Indicates the switching coefficient.

[0053] A control device based on model prediction, comprising:

[0054] A parameter acquisition module, used to acquire electrical parameters of the DC side and AC side of any power submodule in the static VAR compensator;

[0055] A coefficient calculation module, used for predicting the switching coefficients of the two bridge arm switches of the H bridge in the power submodule according to the electrical parameters;

[0056] The switch control module is used to control the bridge arm switches of the H bridge according to the switch coefficient.

[0057] The above-mentioned control device based on model prediction, after obtaining the electrical parameters of the DC side and the AC side of any power submodule in the static VAR compensator, predicts the switching coefficients of the two bridge arm switches of the H bridge in the power submodule according to the electrical parameters, and controls the bridge arm switches of the H bridge according to the switching coefficients. Based on this, based on a circuit structure different from that of the traditional static VAR compensator, linear control is performed through a control method based on model prediction, thereby avoiding the overmodulation problem caused by the linear superposition of the AC side and the DC side in the static VAR compensator.

[0058] A computer storage medium stores computer instructions, which, when executed by a processor, implement the control method based on model prediction of any of the above embodiments.

[0059] After obtaining the electrical parameters of the DC side and the AC side of any power submodule in the static VAR compensator, the computer storage medium predicts the switching coefficients of the two bridge arm switches of the H bridge in the power submodule according to the electrical parameters, and controls the bridge arm switches of the H bridge according to the switching coefficients. Based on this, based on a circuit structure different from that of a traditional static VAR compensator, linear control is performed by a control method based on model prediction, thereby avoiding the overmodulation problem caused by the linear superposition of the AC side and the DC side in the static VAR compensator.

[0060] A computer device includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, the control method based on model prediction of any of the above embodiments is implemented.

[0061] After obtaining the electrical parameters of the DC side and the AC side of any power submodule in the static VAR compensator, the above-mentioned computer device predicts the switching coefficients of the two bridge arm switches of the H bridge in the power submodule according to the electrical parameters, and controls the bridge arm switches of the H bridge according to the switching coefficients. Based on this, based on a circuit structure different from that of the traditional static VAR compensator, linear control is performed through a control method based on model prediction, thereby avoiding the overmodulation problem caused by the linear superposition of the AC side and the DC side in the static VAR compensator. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 It is a schematic diagram of the circuit structure of a traditional static VAR compensator;

[0063] Figure 2 A schematic diagram of a static VAR compensator circuit according to an embodiment;

[0064] Figure 3 It is a working schematic diagram of a static VAR compensator of a specific application example;

[0065] Figure 4 It is a schematic structural diagram of a voltage sag processing device according to one embodiment;

[0066] Figure 5 A flow chart of a control method based on model prediction according to an embodiment;

[0067] Figure 6 A schematic diagram of model prediction in one implementation mode;

[0068] Figure 7 A module structure diagram of a control device based on model prediction according to an embodiment;

[0069] Figure 8 A schematic diagram of the internal structure of a computer according to an embodiment. DETAILED DESCRIPTION

[0070] In order to better understand the purpose, technical solution and technical effect of the present invention, the present invention is further explained below in conjunction with the accompanying drawings and embodiments. At the same time, it is stated that the embodiments described below are only used to explain the present invention and are not used to limit the present invention.

[0071] An embodiment of the present invention provides a static VAR compensator.

[0072] Figure 2 FIG. 1 is a schematic diagram of a static VAR compensator circuit according to an embodiment of the present invention. Figure 2 As shown, a static VAR compensator according to an embodiment includes a plurality of cascaded power submodules 1000:

[0073] The power submodule 1000 includes:

[0074] H-bridge consisting of four bridge switches (1 / 2 / 3 / 4);

[0075] A first inductor L1;

[0076] The second inductor L2;

[0077] A supercapacitor Cs, one end of which is connected to the common terminal R1 of the upper bridge arm of the H bridge through the first inductor L1, and the other end of which is connected to the common terminal R2 of the lower bridge arm of the H bridge through the second inductor L2;

[0078] The lower bridge arm common terminal R2 of a power sub-module 1000 is connected to the upper bridge arm common terminal R1 of the next power sub-module 1000 to form a cascade structure.

[0079] like Figure 2 As shown, four bridge switches form an H bridge, the AC side of the H bridge structure is cascaded output, and the DC side H bridge switch is connected to the inductor and the super capacitor Cs.

[0080] In the connection between the H bridge and the super capacitor Cs, a buck-boost converter composed of the first inductor L1 and the second inductor L2 is driven by the super capacitor Cs according to the buck-boost converter.

[0081] In one embodiment, the bridge switch includes a semiconductor switch, such as a MOS tube, a triode or an IGBT. As a preferred implementation, the bridge switch uses an IGBT. Figure 2 As shown, an H bridge is formed by four IGBTs, as well as an upper bridge arm common terminal R1 and a lower bridge arm common terminal R2.

[0082] In one embodiment, the power submodule 1000 further includes:

[0083] A DC link capacitor Cl has one end connected to the power supply voltage terminal VCC of the H-bridge, and the other end connected to the ground terminal GND of the H-bridge.

[0084] The DC link capacitor Cl is used to form a bidirectional flow of energy for the DC side H-bridge switch.

[0085] In order to better explain a static VAR compensator according to an embodiment, a specific application example is used for explanation. Figure 3 FIG. 1 is a schematic diagram of a static VAR compensator operation in a specific application example. Figure 3 As shown, it includes bridge switches 1, 2, 3, and 4. When bridge switches 1 and 3 are turned on, the super capacitor Cs is in a working state through the second inductor L2, and the DC link capacitor Cl is in a working state; when bridge switches 2 and 4 are turned on, the super capacitor Cs is in a working state through the first inductor L1, and the DC link capacitor Cl is in a working state; when all bridge switches are turned on, the DC link capacitor Cl is in a working state.

[0086] The static VAR compensator of any of the above embodiments includes a plurality of cascaded power submodules 1000, each power submodule 1000 includes an H-bridge composed of four bridge switches, a first inductor L1, a second inductor L2 and a supercapacitor Cs. Among them, the lower bridge arm common terminal R2 of a power submodule 1000 is connected to the upper bridge arm common terminal R1 of the next power submodule 1000 to form a cascade structure; one end of the supercapacitor Cs is connected to the upper bridge arm common terminal R1 of the H-bridge through the first inductor L1, and the other end is connected to the lower bridge arm common terminal R2 of the H-bridge through the second inductor L2. Based on this, a buck-boost converter is formed by the first inductor L1 and the second inductor L2, saving the use of switches to reduce costs and improve reliability. At the same time, by controlling the H-bridge bridge switch, the charging and discharging of the supercapacitor Cs can be realized, and the H-bridge can output an AC voltage square wave. The DC side can control the energy transmitted by the buck-boost converter by adjusting the duty cycle of the H-bridge; the voltage output by the static VAR compensator can also be controlled by controlling the phase shift angle of each power sub-module 1000, and harmonics can be eliminated to the greatest extent.

[0087] The embodiment of the present invention further provides a voltage sag processing device.

[0088] Figure 4 FIG. 1 is a schematic diagram of a voltage sag processing device according to an embodiment of the present invention. Figure 4 As shown, a voltage sag processing device according to one embodiment includes:

[0089] Main power supply S1, connected to the first feeder Line1;

[0090] A backup power supply S2 is connected to the second feeder Line2;

[0091] Static VAR compensator Y1, one end of which is connected to the corresponding phase of AC bus Line3, and the other end is used for grounding;

[0092] A first controlled switch K1, one end of which is connected to a corresponding phase of the first feeder Line1, and the other end of which is connected to a corresponding phase of the AC bus Line3;

[0093] The second controlled switch K2 has one end connected to the corresponding phase of the second feeder Line2, and the other end connected to the corresponding phase of the AC bus Line3.

[0094] The main power supply S1 is used to provide AC power to the first feeder Line1, and the backup power supply S2 is used to provide AC power to the second feeder Line2. For the convenience of explaining this embodiment, the first feeder Line1, the second feeder Line2, and the AC bus Line3 are all three-phase electricity. It should be noted that the three-phase electricity is related to the static VAR compensator Y1 or the number of corresponding switches. The three-phase electricity does not represent the only limitation on the number of phases, but is only for the convenience of explanation.

[0095] The main power source S1 transmits power to the AC bus Line 3 by switching the first controlled switch K1 on and off, and provides power to the load of the AC bus Line 3. The sensitive load type in the load is sensitive to power quality events such as power outage or voltage sag.

[0096] The backup power supply S2 transmits power to the AC bus Line 3 by switching the second controlled switch K2 on and off, and provides power to the load of the AC bus Line 3. The sensitive load type in the load is sensitive to power quality events such as power outage or voltage sag.

[0097] Among them, the static VAR compensator Y1 corresponds to the AC bus Line3 one by one. When the main power source S1 or the backup power source S2 is connected to the AC bus Line3, the AC bus Line3 charges the supercapacitor of the static VAR compensator Y1. When no power source is connected to the AC bus Line3, the supercapacitor of the static VAR compensator Y1 is discharged to supply power to the load carried by the AC bus Line3.

[0098] In one embodiment, if Figure 4 As shown, a three-phase static VAR compensator Y1 is included, which is connected to the phases of the AC bus Line3 one by one, so that the AC bus Line3 phase A, phase B and phase C are all connected with the corresponding static VAR compensator Y1.

[0099] The first controlled switch K1 and the second controlled switch K2 can be turned on or off according to an external switch control signal to control the corresponding main power source S1 or backup power source S2 to be connected to the AC bus Line3.

[0100] In one embodiment, the first controlled switch K1 and the second controlled switch K2 include controllable switch devices or controllable switch modules such as electronic switches, relays or semiconductor switches.

[0101] As a preferred implementation method, Figure 4 As shown, the first controlled switch K1 includes a multi-phase first thyristor switch D1;

[0102] The first thyristor switch D1 comprises:

[0103] A group of anti-parallel thyristors Z1, one side of which is used to connect the corresponding phase of the first feeder Line1, and the other side of which is used to connect the corresponding phase of the AC bus Line3.

[0104] The external switch control signal is input to the gate of each thyristor in the anti-parallel thyristor Z1 to realize the on-off control of the thyristor.

[0105] Similarly, in one embodiment, if Figure 4 As shown, the second controlled switch K2 includes a multi-phase second thyristor switch D2;

[0106] The second thyristor switch D2 comprises:

[0107] A group of anti-parallel thyristors Z1, one side of which is used to connect the corresponding phase of the second feeder Line2, and the other side of which is used to connect the corresponding phase of the AC bus Line3.

[0108] In one embodiment, if Figure 4 As shown, the first thyristor switch D1 or the second thyristor switch D2 further includes:

[0109] The voltage equalizing circuit J1 is connected to the anti-parallel thyristor Z1.

[0110] The control logic of the external switch control signal is realized through the resistor voltage division of the voltage equalizing circuit J1 in cooperation with the anti-parallel thyristor Z1, and the on-off logic is kept stable.

[0111] In one embodiment, if Figure 4 As shown, the voltage sag processing device of one embodiment further includes:

[0112] Connect the reactor P1;

[0113] The static VAR compensator Y1 is connected to the corresponding phase of the AC bus Line3 via the connecting reactor P1.

[0114] By connecting the reactor P1, a path is provided between the AC bus Line3 and the static VAR compensator Y1.

[0115] In one embodiment, if Figure 4 As shown, the voltage sag processing device of one embodiment further includes:

[0116] Compensator switch H1;

[0117] The static VAR compensator Y1 is connected to the corresponding phase of the AC bus Line3 through the compensator switch H1.

[0118] By turning on or off the compensator switch H1, the static VAR compensator Y1 is managed to be connected to the AC bus Line 3. In one embodiment, the compensator switch H1 includes a controllable switch device or a controllable switch module such as an electronic switch, a relay or a semiconductor switch.

[0119] The voltage sag processing device of any of the above embodiments, based on the characteristics of the static VAR compensator Y1, realizes the power switching of the AC bus Line3 by controlling the on-off of the first controlled switch K1 and the second controlled switch K2, and uses the main power supply S1, the backup power supply S2 or the static VAR compensator Y1 as the power supply of the AC bus Line3 to ensure the stable power supply of the AC bus Line3 to the load.

[0120] The embodiment of the present invention also provides a control method based on model prediction.

[0121] Figure 5 is a flow chart of a control method based on model prediction according to an embodiment of the present invention, Figure 5 As shown, a control method based on model prediction in one embodiment includes steps S100 to S102:

[0122] S100, obtaining electrical parameters of the DC side and AC side of any power submodule in the static VAR compensator;

[0123] S101, predicting the switching coefficients of two bridge arm switches of the H bridge in the power submodule according to the electrical parameters;

[0124] S102, controlling the switches of the bridge arms of the H bridge according to the switching coefficient.

[0125] like Figure 3 As shown in the figure, the static VAR compensator is divided into a DC side and an AC side. Among them, since the control target of the DC side buck-boost circuit in the static VAR compensator is to stabilize the voltage of the DC link capacitor, it is necessary to add a DC modulation signal to the modulation signal. However, the superimposed DC modulation signal will increase the peak value of the overall modulation signal, resulting in overmodulation of the control.

[0126] Therefore, this embodiment controls the static VAR compensator based on model prediction. To facilitate the explanation of the method flow of this embodiment, the model of the switching coefficient and the bridge arm switch control is presented below. Figure 6 A schematic diagram of model prediction according to an implementation method is shown in FIG. Figure 6As shown, the electrical parameters include the active power, reactive power, DC side power, DC side resistance, DC side inductance, DC side current, DC side voltage, AC side power, AC side resistance, AC side current, AC side inductance and AC side voltage of the power submodule.

[0127] based on Figure 6 The prediction model of the present invention comprises the following steps:

[0128] Calculate the AC port current reference value and the supercapacitor port current reference value according to the active power, reactive power, DC side power, AC side power, AC side voltage and DC side voltage;

[0129] Substituting the DC side voltage, AC side current, DC side current, AC port current reference value and super capacitor port current reference value into a preset cost function to obtain converged DC link capacitor voltage, super capacitor current and AC port current;

[0130] The switching coefficient is calculated based on the DC link capacitor voltage, supercapacitor current, AC port current, DC side voltage, DC side resistance, DC side inductance, DC side current, AC side resistance, AC side inductance, AC side current and supercapacitor.

[0131] In one embodiment, the process of calculating the AC port current reference value and the supercapacitor port current reference value according to the active power, reactive power, DC side power, AC side power, AC side voltage and DC side voltage is as follows:

[0132]

[0133] in, Indicates active power, Represents reactive power, P dc1 Indicates the DC side power, Indicates the AC side power, v ac Indicates the AC side voltage, v dc2 Indicates the DC side voltage, Indicates the AC port current reference value, Indicates the supercapacitor port current reference value.

[0134] In one embodiment, the DC side voltage, AC side current, DC side current, AC port current reference value and super capacitor port current reference value are substituted into a preset cost function to obtain a converged DC link capacitor voltage, super capacitor current and AC port current process, as shown in the following formula:

[0135]

[0136] Among them, v dc1 Indicates the DC side voltage, i ac Indicates the AC side current, i dc2 Indicates the DC side current, Indicates the AC port current reference value, represents the supercapacitor port current reference value, and J represents the preset cost function.

[0137] The DC link capacitor voltage, super capacitor current and AC port current are converged by minimizing the solution value of the preset cost function to obtain the DC link capacitor voltage, super capacitor current and AC port current when the solution value of the preset cost function is the smallest.

[0138] In one embodiment, the process of calculating the switching coefficient according to the supercapacitor current, the AC port current, the DC side voltage, the DC side resistance, the DC side inductance, the DC side current, the AC side resistance, the AC side inductance, the AC side current and the supercapacitor is as follows:

[0139]

[0140] Among them, v dc2 Indicates the DC link capacitor voltage, represents the supercapacitor current, Indicates the AC port current, v dc1 represents the DC side voltage, r dc Indicates the DC side resistance, L dc represents the DC side inductance, i dc2 represents the DC side current, r ac Indicates the AC side resistance, L ac Indicates the AC side inductance, i ac represents the AC side current, C represents the supercapacitor, S a , S b Indicates the switching coefficient.

[0141] The switching coefficient is related to the switching of the bridge arm. In one embodiment, a corresponding relationship is established between the switching coefficient and the operation of the bridge arm, and the on-off of the bridge switch in the static VAR compensator is controlled according to the corresponding relationship.

[0142] In any of the above-mentioned embodiments, after obtaining the electrical parameters of the DC side and the AC side of any power submodule in the static VAR compensator, the control method based on model prediction predicts the switching coefficients of the two bridge arm switches of the H bridge in the power submodule according to the electrical parameters, and controls the bridge arm switches of the H bridge according to the switching coefficients. Based on this, based on a circuit structure different from that of a traditional static VAR compensator, linear control is performed by a control method based on model prediction, thereby avoiding the overmodulation problem caused by the linear superposition of the AC side and the DC side in the static VAR compensator.

[0143] An embodiment of the present invention also provides a control device based on model prediction.

[0144] Figure 7 is a module structure diagram of a control device based on model prediction according to an embodiment of the present invention, as shown in FIG. Figure 7 As shown, a control device based on model prediction in one embodiment includes a parameter acquisition module 100, a coefficient calculation module 101 and a switch control module 102:

[0145] The parameter acquisition module 100 is used to acquire the electrical parameters of the DC side and the AC side of any power submodule in the static VAR compensator;

[0146] A coefficient calculation module 101 is used to predict the switching coefficients of the two bridge arm switches of the H bridge in the power submodule according to the electrical parameters;

[0147] The switch control module 102 is used to control the switches of the bridge arms of the H bridge according to the switch coefficient.

[0148] The above-mentioned control device based on model prediction, after obtaining the electrical parameters of the DC side and the AC side of any power submodule in the static VAR compensator, predicts the switching coefficients of the two bridge arm switches of the H bridge in the power submodule according to the electrical parameters, and controls the bridge arm switches of the H bridge according to the switching coefficients. Based on this, based on a circuit structure different from that of the traditional static VAR compensator, linear control is performed through a control method based on model prediction, thereby avoiding the overmodulation problem caused by the linear superposition of the AC side and the DC side in the static VAR compensator.

[0149] An embodiment of the present invention further provides a computer storage medium on which computer instructions are stored. When the instructions are executed by a processor, the control method based on model prediction of any of the above embodiments is implemented.

[0150] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM is available in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

[0151] Alternatively, if the above-mentioned integrated unit of the present invention is implemented in the form of a software function module and sold or used as an independent product, it can also be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the embodiment of the present invention can be essentially or partly reflected in the form of a software product that contributes to the relevant technology. The computer software product is stored in a storage medium, including a number of instructions for a computer device (which can be a personal computer, terminal, or network device, etc.) to execute all or part of the methods of each embodiment of the present invention. The aforementioned storage medium includes: various media that can store program codes, such as mobile storage devices, RAM, ROM, magnetic disks or optical disks.

[0152] Corresponding to the above-mentioned computer storage medium, in one embodiment, a computer device is also provided, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, it implements any one of the model prediction-based control methods in the above-mentioned embodiments.

[0153] The computer device may be a terminal, and its internal structure diagram may be as follows: Figure 8As shown. The computer device includes a processor, a memory, a network interface, a display screen and an input device connected through a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The network interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, a control method based on model prediction is implemented. The display screen of the computer device can be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device can be a touch layer covering the display screen, or a button, trackball or touchpad set on the computer device housing, or an external keyboard, touchpad or mouse, etc.

[0154] After obtaining the electrical parameters of the DC side and the AC side of any power submodule in the static VAR compensator, the above-mentioned computer device predicts the switching coefficients of the two bridge arm switches of the H bridge in the power submodule according to the electrical parameters, and controls the bridge arm switches of the H bridge according to the switching coefficients. Based on this, based on a circuit structure different from that of the traditional static VAR compensator, linear control is performed through a control method based on model prediction, thereby avoiding the overmodulation problem caused by the linear superposition of the AC side and the DC side in the static VAR compensator.

[0155] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0156] The above embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for those of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A control method based on model prediction, characterized in that: Applied to static VAR compensator, including the steps of: Obtaining electrical parameters of the DC side and AC side of any power submodule in the static VAR compensator; Predicting the switching coefficients of the two bridge arm switches of the H bridge in the power submodule according to the electrical parameters; Controlling the arm switches of the H-bridge according to the switching coefficient; The electrical parameters include active power, reactive power, DC side power, DC side resistance, DC side inductance, DC side current, DC side voltage, AC side power, AC side resistance, AC side current, AC side inductance and AC side voltage of the power submodule; The process of predicting the switching coefficients of the two bridge arm switches of the H bridge in the power submodule according to the electrical parameters comprises the steps of: Calculate an AC port current reference value and a supercapacitor port current reference value according to the active power, the reactive power, the DC side power, the AC side power, the AC side voltage, and the DC side voltage; Substituting the DC side voltage, the AC side current, the DC side current, the AC port current reference value and the super capacitor port current reference value into a preset cost function to obtain converged DC link capacitor voltage, super capacitor current and AC port current; the process is as follows: Among them, v dc1 represents the DC side voltage, i ac represents the AC side current, i dc2 represents the DC side current, represents the AC port current reference value, represents the supercapacitor port current reference value, and J represents the preset cost function; The switching coefficient is calculated according to the DC link capacitor voltage, the super capacitor current, the AC port current, the DC side voltage, the DC side resistance, the DC side inductance, the DC side current, the AC side resistance, the AC side inductance, the AC side current and the super capacitor; the process is as follows: Among them, v dc2 represents the DC link capacitor voltage, represents the supercapacitor current, represents the AC port current, v dc1 represents the DC side voltage, r dc Represents the DC side resistance, L dc represents the DC side inductance, i dc2 represents the DC side current, r ac Represents the AC side resistance, L ac represents the AC side inductance, i ac represents the AC side current, C represents the supercapacitor, S a , S b represents the switching coefficient.

2. The control method based on model prediction according to claim 1, characterized in that: The process of calculating the AC port current reference value and the supercapacitor port current reference value according to the active power, the reactive power, the DC side power, the AC side power, the AC side voltage and the DC side voltage is as follows: in, represents the active power, Represents the reactive power, P dc1 represents the DC side power, represents the AC side power, v ac represents the AC side voltage, v dc2 represents the DC side voltage, represents the AC port current reference value, Indicates the current reference value of the supercapacitor port.

3. The control method based on model prediction according to claim 1, characterized in that: in: The static VAR compensator comprises a plurality of cascaded power submodules: The power submodule comprises: An H-bridge consisting of four bridge switches; First inductor; The second inductor; A supercapacitor, one end of which is connected to the common end of the upper bridge arm of the H bridge through the first inductor, and the other end of which is connected to the common end of the lower bridge arm of the H bridge through the second inductor; A DC link capacitor, one end of which is connected to the power supply voltage terminal of the H-bridge, and the other end of which is connected to the ground terminal of the H-bridge; The common end of the lower bridge arm of a power submodule is connected to the common end of the upper bridge arm of the next power submodule to form a cascade structure.

4. A control device based on model prediction, characterized in that: The method for executing the control method based on model prediction as claimed in claim 1 comprises: A parameter acquisition module, used to acquire electrical parameters of the DC side and AC side of any power submodule in the static VAR compensator; the electrical parameters include active power, reactive power, DC side power, DC side resistance, DC side inductance, DC side current, DC side voltage, AC side power, AC side resistance, AC side current, AC side inductance and AC side voltage of the power submodule; A coefficient calculation module is used to predict the switching coefficients of the two bridge arm switches of the H bridge in the power submodule according to the electrical parameters; it is also used to calculate the AC port current reference value and the supercapacitor port current reference value according to the active power, the reactive power, the DC side power, the AC side power, the AC side voltage and the DC side voltage; the DC side voltage, the AC side current, the DC side current, the AC port current reference value and the supercapacitor port current reference value are substituted into a preset cost function to obtain a converged DC link capacitor voltage, supercapacitor current and AC port current; the process is as follows: Among them, v dc1 represents the DC side voltage, i ac represents the AC side current, i dc2 represents the DC side current, represents the AC port current reference value, represents the supercapacitor port current reference value, and J represents the preset cost function; The coefficient calculation module is further used to calculate the switching coefficient according to the DC link capacitor voltage, the super capacitor current, the AC port current, the DC side voltage, the DC side resistance, the DC side inductance, the DC side current, the AC side resistance, the AC side inductance, the AC side current and the super capacitor; the process is as follows: Among them, v dc2 represents the DC link capacitor voltage, represents the supercapacitor current, represents the AC port current, v dc1 represents the DC side voltage, r dc Represents the DC side resistance, L dc represents the DC side inductance, i dc2 represents the DC side current, r ac Represents the AC side resistance, L ac represents the AC side inductance, i ac represents the AC side current, C represents the supercapacitor, S a , S b represents the switching coefficient; A switch control module is used to control the bridge arm switches of the H bridge according to the switch coefficient.

5. A computer storage medium having computer instructions stored thereon, characterized in that: When the computer instructions are executed by a processor, the model prediction-based control method according to any one of claims 1 to 3 is implemented.

6. A computer device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, the control method based on model prediction as described in any one of claims 1 to 3 is implemented.

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