Energy control circuit and control method

Abstract

An energy control circuit and control method, comprising: a main resistor, multiple main switches, and multiple voltage source modules; the main switch and the voltage source module are connected in parallel; the main resistor and the multiple voltage source modules are connected in series; the voltage source modules are used for circuit voltage division; in this method, the input amount of the voltage source module is determined according to energy consumption requirements; based on the input amount, the main switch is controlled to be disconnected, and the voltage source module that needs to be put into operation is adjusted to a voltage division state and the voltage division is kept stable, and the main resistor consumes energy according to the energy consumption requirements; the remaining voltage source modules are adjusted to a short-circuited state by controlling the main switch to be closed; within a set working cycle, the voltage source modules are controlled to be alternately put into and out of operation based on the input amount. In this method, by controlling the voltage source modules to be alternately put into and out of operation within the set working cycle, the voltage source modules in the energy control circuit are alternately cooled, thereby reducing the loss rate of the hardware.

Description

Technical Field

[0001] The present invention relates to the field of direct current transmission energy transfer, and in particular to an energy control circuit and a control method. Background Art

[0002] DC transmission lines can efficiently and conveniently transmit large amounts of electricity from energy bases to load centers. The structural diagram of DC transmission lines is shown in the figure below. Figure 2 As shown, for an operating DC transmission project, the power consumed by the receiving end is balanced with the power generated by the sending end, and the voltage and operating frequency of the sending-end grid remain constant. When a disturbance or fault occurs in the receiving-end power system and makes it unable to absorb the power sent by the sending end, the voltage and frequency of the sending-end grid will be disturbed. This disturbance can be reduced by quickly adjusting the generator output. If the sending-end power source is a thermal or hydroelectric generator, the generator output can be adjusted, but the adjustment process requires a certain delay and cannot achieve an instant response, so the voltage and frequency of the grid will still be disturbed. If the sending-end power source is a wind turbine, due to the uncontrollable natural wind force, the wind turbine output cannot be adjusted according to operational needs, resulting in severe disturbances in the voltage and frequency of the sending-end grid. In severe cases, the generator set may rupture, causing serious grid accidents.

[0003] The development of ultra-high voltage direct current (UHVDC) transmission technology has increased the transmission capacity of direct current to 8,000-12,000 MW. Consequently, the installed capacity of traditional thermal and hydropower generators in the sending grid has increased, making rapid regulation of generator output increasingly difficult. Bundling wind, solar, hydro, and thermal power for external transmission has exacerbated this difficulty. The development of flexible direct current (VFD) transmission technology has led to an increasing scale of wind power grid connection, increasing the risk of wind turbine failure caused by power mismatch between the sending and receiving ends due to grid faults in the receiving grid.

[0004] In order to solve the above problems and improve the operational reliability of DC transmission, it is necessary to design an energy control circuit to maintain the power balance between the sending and receiving ends of the entire DC transmission system.

[0005] There are currently three types of energy control circuits. Among them, circuit 1 uses a switch and a resistor in series, such as Figure 3 As shown in Figure 1, the switch is a valve composed of power electronic devices connected in series. The on-off control of the valve is achieved by pulse width modulation (PWM) to adjust the power consumption of the resistor. This circuit has the characteristics of simple structure and easy control. However, when the DC voltage rises to a certain level, the increase in the number of power electronic devices will make it difficult to balance the voltage of the devices. Due to the use of pulse width modulation, the consistency of the operation of all power electronic devices cannot be guaranteed. Therefore, this control circuit is suitable for low voltage fields. Circuit 2 is modularized based on circuit 1. Figure 4As shown in Figure 1, the control method is to disperse switches and resistors within each module. The module voltage is balanced by the module capacitors, and the power consumption of the circuit is controlled by controlling the number of module switches that are turned on. This circuit has the advantages of simple control and is not limited by DC voltage. However, its disadvantage is that the energy-consuming resistors are placed within the module, which increases the module size and the valve hall area, and places high demands on the cooling system. Compared with Circuit 1, Circuit 3 improves on Circuit 1 in that the switch valves use modular multilevel converter (MMC) modules in series, as shown in Figure 1. Figure 5 As shown, the modular multilevel converter module can adopt a full-bridge or half-bridge structure. Its control method can achieve module voltage equalization by charging and discharging the capacitors of the modular multilevel converter module. When the control circuit is in operation, the modular multilevel converter modules do not need to be switched on and off simultaneously. Therefore, the circuit is not limited by DC voltage and can be applied to high-voltage projects. However, the control method of this circuit has the disadvantages of complex control mode and high equipment cost. Summary of the Invention

[0006] In order to solve the problem in the prior art of lacking an energy control method applicable to high-voltage DC lines, the present invention provides an energy control circuit and a control method.

[0007] The technical solution provided by the present invention is:

[0008] An energy control circuit, comprising:

[0009] a main resistor, a plurality of main switches, and a plurality of voltage source modules;

[0010] The main switch is connected in parallel with the voltage source module;

[0011] The main resistor and the multiple voltage source modules are connected in series in sequence;

[0012] The voltage source module is used for circuit voltage division;

[0013] The power consumed by the main resistor is greater than the power consumed by the multiple voltage source modules.

[0014] Preferably, the circuit is asymmetrical or symmetrical and connected to a DC transmission line.

[0015] Preferably, the voltage source module includes:

[0016] Voltage source, auxiliary switch, auxiliary resistor and control submodule;

[0017] The auxiliary switch and the auxiliary resistor are connected in series to form an auxiliary circuit;

[0018] The voltage source and the auxiliary circuit are connected in parallel;

[0019] The control submodule is connected to the voltage source and the auxiliary switch, and is used to control the closing and opening of the auxiliary switch according to the voltage across the voltage source;

[0020] The voltage source is a capacitor or a battery.

[0021] Preferably, the circuit further includes:

[0022] Three diodes;

[0023] a diode connected in antiparallel with the main switch;

[0024] A diode is connected in series with the voltage source module;

[0025] Another diode is connected in antiparallel with the auxiliary switch.

[0026] Preferably, the voltage source module includes:

[0027] Two voltage sources, two auxiliary switches, auxiliary resistors and control submodule;

[0028] The two voltage sources are connected in series to form a first series circuit;

[0029] The two auxiliary switches are connected in series to form a second series circuit;

[0030] The center point of the first series circuit and the center point of the second series circuit are connected via the auxiliary resistor;

[0031] The control submodule is connected to the voltage source and the auxiliary switch, and is used to control the closing and opening of the auxiliary switch according to the voltage across the voltage source;

[0032] Shorten the voltage source to a capacitor.

[0033] Preferably, the voltage source module further includes:

[0034] Four diodes;

[0035] a diode connected in antiparallel with the main switch;

[0036] A diode is connected in series with the voltage source module;

[0037] The other two diodes are connected in antiparallel with the two auxiliary switches.

[0038] Preferably, the voltage source module includes:

[0039] voltage source, four auxiliary switches, auxiliary resistors, and control submodule;

[0040] The auxiliary switches are connected in series in pairs to obtain two series circuits, and the two series circuits are connected in parallel with the voltage source;

[0041] The center points of the two series circuits are connected via the auxiliary resistor;

[0042] The control submodule is connected to the voltage source and the auxiliary switch, and is used to control the closing and opening of the auxiliary switch according to the voltage across the voltage source;

[0043] The voltage source is a capacitor.

[0044] Preferably, the voltage source module further includes:

[0045] six diodes;

[0046] a diode connected in antiparallel with the main switch;

[0047] A diode is connected in series with the voltage source module;

[0048] Another four diodes are connected in antiparallel with the four auxiliary switches.

[0049] Preferably, the resistance of the main resistor is determined by the preset maximum power consumption value of the circuit and the voltage of the DC transmission line. The resistance of the main resistor is calculated as follows:

[0050]

[0051] Among them, R m_usy The resistance of the main resistor, P max is the preset maximum power consumption value of the circuit, U dc is the voltage of the DC transmission line.

[0052] Preferably, the minimum number of voltage source modules arranged in the circuit is determined by the withstand voltage capability of the main switch and the voltage of the DC transmission line, and is calculated as follows:

[0053]

[0054] Among them, N m_min_usy When the arrangement is asymmetric, the minimum number of voltage source modules, N m_min_sy When the arrangement is symmetrical, the minimum number of voltage source modules, U dc is the voltage of the DC transmission line, U m_e is the withstand voltage capability of the main switch.

[0055] The circuit control method includes:

[0056] Determining the input amount of the voltage source module according to energy consumption requirements;

[0057] According to the input amount, by controlling the main switch to be disconnected, the voltage source module that needs to be put into operation is adjusted to a voltage-dividing state and the voltage division is kept stable, and the main resistor consumes energy according to the energy consumption demand; by controlling the main switch to be closed, the remaining voltage source modules are adjusted to a short-circuited state;

[0058] In a set working cycle, the voltage source modules are controlled to be alternately switched on and off based on the input amount.

[0059] Preferably, the step of controlling the main switch to be disconnected according to the input amount to adjust the voltage source module to be input into a voltage-dividing state includes:

[0060] The main switch and the auxiliary switch in the voltage source module that needs to be put into operation are disconnected, and the voltage source in the voltage source module is connected in series with the circuit for voltage division.

[0061] Preferably, maintaining the voltage division of the voltage source module stable includes:

[0062] When the divided voltage of the voltage source module reaches a first threshold, the main switch is kept in an off state and the voltage source module is adjusted to a protection state to reduce the voltage;

[0063] When the divided voltage of the voltage source module drops to a second threshold, the main switch is kept in an off state and the voltage source module is adjusted to a divided voltage state to perform voltage division;

[0064] The second threshold is lower than the first threshold by a set amplitude.

[0065] Preferably, when the voltage divided by the voltage source module reaches a first threshold, keeping the main switch in an off state and adjusting the voltage source module to a protection state to reduce the voltage includes:

[0066] The voltage across the voltage source through the control submodule;

[0067] When the voltage across the voltage source reaches a first threshold, the main switch remains in an open state, the control submodule controls the auxiliary switch to close, and the voltage source discharges and reduces the voltage.

[0068] Preferably, when the voltage divided by the voltage source module drops to a second threshold, maintaining the main switch in an off state and adjusting the voltage source module to a voltage divided state to perform voltage division includes:

[0069] The voltage across the voltage source through the control submodule;

[0070] When the voltage across the voltage source drops to a second threshold, the main switch remains in an off state, the control submodule controls the auxiliary switch to be off, and the voltage source is connected in series with the circuit for voltage division.

[0071] Preferably, adjusting the remaining voltage source modules to a short-circuited state includes:

[0072] By closing the main switch, the voltage source module is short-circuited.

[0073] Preferably, the step of controlling the voltage source modules to alternately switch on and off based on the input amount within the set working cycle includes:

[0074] Determining the input duration of the voltage source module according to the energy consumption demand and input amount;

[0075] Based on the input duration, the main switch is controlled to be turned on and off once, thereby controlling the alternating input and output of the voltage source module.

[0076] Preferably, the input duration is determined by the following formula:

[0077]

[0078] Among them, duty is the energy demand, T arr is the investment time, N on N is the number of voltage source modules put into operation. T is the total number of voltage source modules, T ch The set working cycle duration.

[0079] Preferably, determining the input amount of the voltage source module according to the energy consumption demand includes:

[0080] Based on the energy consumption requirement and the voltage division amount of the capacitor, the input amount of the voltage source module is determined as shown in the following formula:

[0081]

[0082] Among them, N on_usy For asymmetric setting, the input amount of voltage source module, N on_sy For symmetrical setting, the input amount of voltage source module, U dc is the DC line voltage, U mo is the voltage division of the capacitor, duty is the energy consumption requirement, 0≤duty≤1.

[0083] Preferably, the step of controlling the voltage source modules to be alternately switched on and off based on the input amount within a set working cycle further includes:

[0084] By changing the charging time and discharging time of the voltage source in the voltage source module, the auxiliary switch in the voltage source module is switched once within a set working cycle.

[0085] Preferably, the auxiliary switch in the voltage source module is switched once within a set working cycle, and the charging time and discharging time of the voltage source should satisfy the following formula:

[0086] t ch +t dis >(1-duty)×T ch

[0087] Among them, t ch is the charging time of the voltage source, t dis is the discharge time of the voltage source, duty is the energy consumption demand, T ch For the set working cycle.

[0088] Compared with the prior art, the present invention has the following beneficial effects:

[0089] The technical solution provided by the present invention includes: a main resistor, multiple main switches, and multiple voltage source modules; the main switches are connected in parallel with the voltage source modules; the main resistor and the multiple voltage source modules are connected in series; the voltage source modules are used to divide the circuit voltage. This solution controls the circuit voltage by controlling the multiple voltage source modules, thereby smoothing the current in the energy control circuit and dissipating energy through the main resistors. The modularization of the voltage source in this solution simplifies the circuit structure and occupies a small footprint.

[0090] The amount of voltage source modules to be put into operation is determined based on energy consumption requirements. Based on the amount of voltage source modules put into operation, the main switch is controlled to be disconnected, adjusting the required voltage source modules to a voltage-dividing state and maintaining the voltage division stable. The main resistor consumes energy based on the energy consumption requirements. The main switch is controlled to be closed, adjusting the remaining voltage source modules to a short-circuited state. Within a set operating cycle, the voltage source modules are alternately switched on and off based on the amount of voltage source modules put into operation. In this solution, by controlling the voltage source modules to alternately switch on and off within the set operating cycle, the voltage source modules in the energy control circuit are alternately cooled, reducing hardware loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0091] Figure 1 This is a structural diagram of an energy control circuit based on a resistor and capacitor device of the present invention;

[0092] Figure 2 This is a structural diagram of a DC transmission line in the prior art;

[0093] Figure 3 It is a structural diagram of circuit 1 in the prior art;

[0094] Figure 4 It is a structural diagram of circuit 2 in the prior art;

[0095] Figure 5 It is a structural diagram of circuit 3 in the prior art;

[0096] Figure 6 It is a symmetrical connection diagram of the energy control circuit of the present invention;

[0097] Figure 7 This is a first topological structure diagram of the voltage source module of the present invention;

[0098] Figure 8 A second topological structure diagram of the voltage source module of the present invention;

[0099] Figure 9 This is a third topological structure diagram of the voltage source module of the present invention;

[0100] Figure 10 This is a fourth topological structure diagram of the voltage source module of the present invention;

[0101] Figure 11 is a flow chart of a control method of an energy control circuit of the present invention;

[0102] Among them, 1-converter transformer; 2-converter; 3-AC filter; 4-smoothing reactor; 5-DC filter; 6-external cooling system of converter station. DETAILED DESCRIPTION

[0103] In order to better understand the present invention, the present invention is further described below with reference to the accompanying drawings and examples.

[0104] Example 1:

[0105] This embodiment provides an energy control circuit based on resistor and capacitor devices, the circuit structure is as follows Figure 1 As shown, the circuit includes: a main resistor R m , energy control submodule and inductor L m .

[0106] Among them, the topology of the voltage source module is as follows Figure 7 and Figure 8 As shown, the principle is as follows: a topological circuit consisting of a DC / DC step-down conversion circuit and a resistor or a battery, specifically including: a voltage source, an auxiliary switch, an auxiliary resistor and a control submodule; the auxiliary switch and the auxiliary resistor are connected in series to form an auxiliary loop; the voltage source and the auxiliary loop are connected in parallel; the control submodule is connected to the voltage source and the auxiliary switch, and is used to control the closing and opening of the auxiliary switch according to the voltage across the voltage source; the voltage source is a capacitor or a battery.

[0107] against Figure 7 or Figure 8 The topology structure of the circuit further includes: three diodes; one diode is connected in reverse parallel to the main switch; one diode is connected in series with the voltage source module; and another diode is connected in reverse parallel to the auxiliary switch.

[0108] The topology of the voltage source module can also be Figure 9 As shown, the principle is a topological circuit composed of a DC / AC half-bridge conversion circuit and a voltage source, specifically including: two voltage sources, two auxiliary switches, an auxiliary resistor, and a control submodule; the two voltage sources are connected in series to form a first series circuit; the two auxiliary switches are connected in series to form a second series circuit; the center point of the first series circuit is connected to the center point of the second series circuit via the auxiliary resistor; the control submodule is connected to the voltage sources and the auxiliary switches, and is used to control the closing and opening of the auxiliary switches according to the voltage across the voltage sources;

[0109] Shorten the voltage source to a capacitor.

[0110] against Figure 9 The topology structure of the circuit further includes: four diodes; one diode is connected in reverse parallel to the main switch; one diode is connected in series with the voltage source module; and the other two diodes are connected in reverse parallel to the two auxiliary switches.

[0111] The topology of the voltage source module can also be Figure 10 As shown, the principle is a topological circuit composed of a DC / AC full-bridge conversion circuit and a voltage source, specifically including: a voltage source, four auxiliary switches, an auxiliary resistor and a control submodule;

[0112] The auxiliary switches are connected in series in pairs to form two series circuits, and the two series circuits are connected in parallel with the voltage source; the center points of the two series circuits are connected via the auxiliary resistor; the control submodule is connected to the voltage source and the auxiliary switches, and is used to control the closing and opening of the auxiliary switches according to the voltage across the voltage source;

[0113] The voltage source is a capacitor.

[0114] against Figure 9 The topology structure of the circuit further includes: six diodes; one diode is connected in reverse parallel to the main switch; one diode is connected in series with the voltage source module; and the other four diodes are connected in reverse parallel to the four auxiliary switches.

[0115] When the energy control circuit is in hot standby state, the voltage U dc Evenly distributed on each submodule, the voltage U mo =U dc / N T .

[0116] When all main switches K m When closed, the power consumed by the energy control circuit is equal to the rated power of the DC system, so:

[0117]

[0118] Let the power instruction of the energy control circuit be duty (0≤duty≤1), and the number of submodules required to be invested is N on for:

[0119] N on =N T ×(1-duty)

[0120] When 0.5<duty≤1, the input N on The duration of each submodule is T arr for:

[0121]

[0122] When 0≤duty≤0.5, the input N on The duration T of k submodules arr for:

[0123]

[0124] When the submodule is put into operation, the submodule voltage source is charged and the voltage increases, and the control submodule voltage source is discharged and the voltage decreases. The voltage of each submodule voltage source will be monitored in real time, and a hysteresis control link will be set. The control logic is as follows:

[0125] When U ca >U ca_c When the submodule voltage source discharges, C a The voltage drops;

[0126] When U ca_f ≤U ca ≤U ca_c When the submodule voltage source continues to discharge, C a The voltage continues to drop;

[0127] When U ca <U ca_f When , the submodule voltage source stops discharging and starts the next cycle.

[0128] Submodule capacitor charging time t ch and discharge time t dis The sum should be greater than the submodule investment time and must satisfy the following relationship:

[0129] t ch +t dis >(1-duty)×T ch

[0130] When the power command takes different values, the main resistance R m Power P Rmfor:

[0131]

[0132] The total power consumed by the submodule resistors P Ra_T for:

[0133] P Ra_T =P N duty-P N duty 2

[0134] =P N duty(1-duty)

[0135] The power consumed by each submodule resistor P Ra for:

[0136] P Ra =P N duty(1-duty) / N t .

[0137] Example 2:

[0138] This embodiment provides a method for controlling an energy control circuit. The method flow chart is as follows: Figure 11 As shown, it is characterized by comprising:

[0139] Determining the input amount of the voltage source module according to energy consumption requirements;

[0140] According to the input amount, by controlling the main switch to be disconnected, the voltage source module that needs to be put into operation is adjusted to a voltage-dividing state and the voltage division is kept stable, and the main resistor consumes energy according to the energy consumption demand; by controlling the main switch to be closed, the remaining voltage source modules are adjusted to a short-circuited state;

[0141] In a set working cycle, the voltage source modules are controlled to be alternately switched on and off based on the input amount.

[0142] The step of controlling the main switch to be disconnected according to the input amount to adjust the voltage source module to be input into a voltage-dividing state includes:

[0143] The main switch and the auxiliary switch in the voltage source module that needs to be put into operation are disconnected, and the voltage source in the voltage source module is connected in series with the circuit for voltage division.

[0144] Maintaining the voltage division of the voltage source module stable, comprising:

[0145] When the divided voltage of the voltage source module reaches a first threshold, the main switch is kept in an off state and the voltage source module is adjusted to a protection state to reduce the voltage;

[0146] When the divided voltage of the voltage source module drops to a second threshold, the main switch is kept in an off state and the voltage source module is adjusted to a divided voltage state to perform voltage division;

[0147] The second threshold is lower than the first threshold by a set amplitude.

[0148] When the voltage divided by the voltage source module reaches a first threshold, the main switch is kept in an off state and the voltage source module is adjusted to a protection state to reduce the voltage, including:

[0149] The voltage across the voltage source through the control submodule;

[0150] When the voltage across the voltage source reaches a first threshold, the main switch remains in an open state, the control submodule controls the auxiliary switch to close, and the voltage source discharges and reduces the voltage.

[0151] When the divided voltage of the voltage source module drops to a second threshold, maintaining the main switch in an off state and adjusting the voltage source module to a divided voltage state to perform voltage division includes:

[0152] The voltage across the voltage source through the control submodule;

[0153] When the voltage across the voltage source drops to a second threshold, the main switch remains in an off state, the control submodule controls the auxiliary switch to be off, and the voltage source is connected in series with the circuit for voltage division.

[0154] The step of adjusting the remaining voltage source modules to a short-circuited state includes:

[0155] By closing the main switch, the voltage source module is short-circuited.

[0156] The step of controlling the voltage source modules to alternately switch on and off based on the input amount within the set working cycle includes:

[0157] Determining the input duration of the voltage source module according to the energy consumption demand and input amount;

[0158] Based on the input duration, the main switch is controlled to be turned on and off once, thereby controlling the alternating input and output of the voltage source module.

[0159] The input duration is determined by the following formula:

[0160]

[0161] Among them, duty is the energy demand, T arr is the investment time, N on N is the number of voltage source modules put into operation. Tis the total number of voltage source modules, T ch The set working cycle duration.

[0162] The step of determining the input amount of the voltage source module according to the energy consumption requirement includes:

[0163] Based on the energy consumption requirement and the voltage division amount of the capacitor, the input amount of the voltage source module is determined as shown in the following formula:

[0164]

[0165] Among them, N on_usy For asymmetric setting, the input amount of voltage source module, N on_sy For symmetrical setting, the input amount of voltage source module, U dc is the DC line voltage, U mo is the voltage division of the capacitor, duty is the energy consumption requirement, 0≤duty≤1.

[0166] The step of controlling the voltage source modules to alternately switch on and off based on the input amount within a set working cycle further includes:

[0167] By changing the charging time and discharging time of the voltage source in the voltage source module, the auxiliary switch in the voltage source module is switched once within a set working cycle.

[0168] The auxiliary switch in the voltage source module is switched once within a set working cycle, and the charging time and discharging time of the voltage source should satisfy the following formula:

[0169] t ch +t dis >(1-duty)×T ch

[0170] Among them, t ch is the charging time of the voltage source, t dis is the discharge time of the voltage source, duty is the energy consumption demand, T ch For the set working cycle.

[0171] Example 3:

[0172] This embodiment provides an energy control method, the steps of which are as follows:

[0173] (1) When the energy control circuit is in hot standby mode, the voltage of the DC line is used to charge the voltage source of each submodule;

[0174] (2) The voltage of each submodule voltage source will be monitored in real time, and hysteresis control logic will be designed to make the submodule voltage source voltage fluctuate around a certain value;

[0175] (3) Determine the number of submodules to be put into operation according to the power instruction of the energy absorption circuit;

[0176] (4) In one working cycle, the submodules are switched on and off alternately to ensure that the power of the energy control circuit is evenly distributed among the submodules and the main switch K of the submodule is m Only switch once;

[0177] (5) If the submodule voltage source uses capacitors, the selection of the submodule capacitor value can ensure that when the duty takes different values, the auxiliary switch k a Only switch once, or flexibly control the auxiliary switch k according to actual needs a Switching frequency;

[0178] (6) Main resistor R m The maximum power is equal to the rated power P of the DC system N , the maximum power of all submodule resistors is equal to the DC system rated power P N 25% of.

[0179] Furthermore, the energy control circuit includes: a main resistor R m , energy control submodule and inductor L m Each energy control submodule consists of a main switch K m , submodule voltage source, the submodule voltage source is composed of auxiliary switch K a and auxiliary resistor R a composition.

[0180] Furthermore, in step (1), when the energy control circuit is in the hot standby state, the voltage U dc Evenly distributed on each submodule, so the voltage U mo =U dc / N T .

[0181] Furthermore, in step (2), when the submodule is put into operation, the submodule voltage source is charged, the voltage increases, and the control submodule voltage source is discharged, the voltage decreases; the voltage of each submodule voltage source will be monitored in real time, and a hysteresis control link is set. The control logic is as follows:

[0182] When U ca >U ca_c When the submodule voltage source discharges, C a The voltage drops;

[0183] When U ca_f ≤U ca ≤U ca_c When the submodule voltage source continues to discharge, C a The voltage continues to drop;

[0184] When U ca <U ca_f When , the submodule voltage source stops discharging and starts the next cycle.

[0185] The above control logic can ensure that the submodule capacitor voltage is within the range of U mo_h Fluctuates nearby.

[0186] Furthermore, in step (3), when all main switches K m When closed, the power consumed by the energy control circuit is equal to the rated power of the DC system, so:

[0187]

[0188] When the power instruction of the energy control circuit is duty (0≤duty≤1), the number of submodules N required to be put into operation is on for:

[0189] N on =N T ×(1-duty)

[0190] The number of submodule voltage sources N that need to be put into operation can be determined based on the power instruction duty on .

[0191] Furthermore, in step (4), when duty takes different values, in order to ensure that the power of the energy control circuit is evenly distributed among the submodules in each working cycle of the energy control circuit, the main switch K of each submodule m Only switch once, the following control logic is designed:

[0192] When 0.5<duty≤1, the input N on The duration of each submodule is T arr for:

[0193]

[0194] When 0≤duty≤0.5, the input N on The duration T of k submodules arr for:

[0195]

[0196] Furthermore, in step (5), if the submodule voltage source adopts a capacitor, in order to reduce the switching loss of the IGBT, when duty takes different values, k is designed. a It is also switched only once, and the submodule capacitor charging time t ch and discharge time t dis The sum should be greater than the submodule investment time and must satisfy the following relationship:

[0197] t ch +t dis >(1-duty)×T ch

[0198] You can also reduce the submodule capacitance charging time t by reducing the submodule capacitance value according to actual needs. ch and discharge time t dis The sum of the auxiliary switches k a Switching frequency.

[0199] Furthermore, in step (6), when the power instruction is duty, the current I ch for:

[0200] I ch =I N ×duty

[0201] Then the main resistance R m Power P Rm for:

[0202]

[0203] When duty = 1, the main resistor power is equal to the rated power of the DC system. The main resistor power is proportional to the square of duty. The main resistor power will decrease rapidly as duty decreases.

[0204] The total power consumed by the submodule resistors P Ra_T for:

[0205] P Ra_T =P N duty-P N duty 2

[0206] =P N duty(1-duty)

[0207] The power consumed by each submodule resistor P Ra for:

[0208] P Ra =P N duty(1-duty) / N t

[0209] When duty = 0.5, P Ra_T Reaching a maximum value of 0.25P N The maximum power consumed by each submodule resistor is 0.25P N / N t .

[0210] Example 4:

[0211] Taking a DC project as an example, the rated DC voltage of the project is U dc = ±320kV, the energy control circuit adopts a symmetrical arrangement, and the maximum power consumed by the energy control circuit is P max =900MW, the single-pole power is P max_s =P N =450MW, the main resistance value R m =227.5Ω; Number of energy submodules N T =128, main switch K m The withstand voltage is U m_e =2.5kV, submodule resistance R a =1.56Ω, the operating frequency of the energy control circuit is f ch =200Hz, duty cycle T ch =0.005s; the submodule voltage source uses a capacitor, capacitor C a Voltage fluctuation lower limit U Ca_f =2.2kV, submodule capacitance C a Voltage fluctuation upper limit U Ca_c =2.7kV, we can get the submodule capacitance C a >2.4mF.

[0212] Let duty = 0.7, the number of submodules required is N on =128×(1-0.7)=38.4, take the integer value 38; the duration T of the 38 sub-modules arr =0.005×38 / 128=0.0015s, after 0.0015s, it switches to the next 38 sub-modules, and so on; the main resistance R m Power P Rm =P N ×0.7 2 =220.5MW, the total power consumed by the submodule resistors P Ra_T =P N × 0.7 × (1-0.7) = 94.5MW, the power consumed by each submodule resistor P Ra =P Ra_T / 128=0.7383MW.

[0213] Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0214] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0215] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the steps in the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0216] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0217] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 The steps for the function specified in one or more boxes.

[0218] The above are merely embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are included in the scope of the claims of the present invention to be approved.

Claims

1. An energy control circuit, characterized in that: The circuit includes: a main resistor, a plurality of main switches and a plurality of voltage source modules; The main switch is connected in parallel with the voltage source module; The main resistor and the multiple voltage source modules are connected in series in sequence; The voltage source module divides the voltage of the circuit when charging; The power consumed by the main resistor is >> the power consumed by the multiple voltage source modules; The voltage source module includes: a voltage source, an auxiliary switch, an auxiliary resistor and a control submodule; The auxiliary switch and the auxiliary resistor are connected in series to form an auxiliary circuit; The voltage source and the auxiliary circuit are connected in parallel; The control submodule is connected to the voltage source and the auxiliary switch, and is used to control the closing and opening of the auxiliary switch according to the voltage across the voltage source; The voltage source is a capacitor or a battery.

2. The circuit according to claim 1, wherein The circuit is asymmetrical or symmetrical and is connected to a DC transmission line.

3. The circuit according to claim 1, wherein The circuit further includes: three diodes; a diode connected in antiparallel with the main switch; A diode is connected in series with the voltage source module; Another diode is connected in antiparallel with the auxiliary switch.

4. The circuit according to claim 1, wherein The voltage source module includes: two voltage sources, two auxiliary switches, an auxiliary resistor and a control submodule; The two voltage sources are connected in series to form a first series circuit; The two auxiliary switches are connected in series to form a second series circuit; The center point of the first series circuit and the center point of the second series circuit are connected via the auxiliary resistor; The control submodule is connected to the voltage source and the auxiliary switch, and is used to control the closing and opening of the auxiliary switch according to the voltage across the voltage source; The voltage source is a capacitor.

5. The circuit according to claim 4, wherein The voltage source module further includes: Four diodes; a diode connected in antiparallel with the main switch; A diode is connected in series with the voltage source module; The other two diodes are connected in antiparallel with the two auxiliary switches.

6. The circuit according to claim 1, wherein The voltage source module includes: a voltage source, four auxiliary switches, an auxiliary resistor and a control submodule; The auxiliary switches are connected in series in pairs to obtain two series circuits, and the two series circuits are connected in parallel with the voltage source; The center points of the two series circuits are connected via the auxiliary resistor; The control submodule is connected to the voltage source and the auxiliary switch, and is used to control the closing and opening of the auxiliary switch according to the voltage across the voltage source; The voltage source is a capacitor.

7. The circuit according to claim 6, wherein: The voltage source module further includes: six diodes; a diode connected in antiparallel with the main switch; A diode is connected in series with the voltage source module; Another four diodes are connected in antiparallel with the four auxiliary switches.

8. The circuit according to claim 2, wherein: The resistance of the main resistor is determined by the preset maximum power consumption value of the circuit and the voltage of the DC transmission line. The resistance of the main resistor is calculated as follows: Among them, R m_usy The resistance of the main resistor, P max is the preset maximum power consumption value of the circuit, U dc is the voltage of the DC transmission line.

9. The circuit according to claim 2, wherein: The minimum number of voltage source modules arranged in the circuit is determined by the withstand voltage capability of the main switch and the voltage of the DC transmission line, and is calculated as follows: Among them, N m_min_usy When the arrangement is asymmetric, the minimum number of voltage source modules, N m_min_sy When the arrangement is symmetrical, the minimum number of voltage source modules, U dc is the voltage of the DC transmission line, U m_e is the withstand voltage capability of the main switch.

10. The circuit control method according to any one of claims 1 to 9, characterized in that: include: Determining the input amount of the voltage source module according to energy consumption requirements; According to the input amount, by controlling the main switch to be disconnected, the voltage source module that needs to be put into operation is adjusted to a voltage-dividing state and the voltage division is kept stable, and the main resistor consumes energy according to the energy consumption demand; by controlling the main switch to be closed, the remaining voltage source modules are adjusted to a short-circuited state; In a set working cycle, the voltage source modules are controlled to be alternately switched on and off based on the input amount.

11. The method according to claim 10, wherein The step of controlling the main switch to be disconnected according to the input amount to adjust the voltage source module to be input into a voltage-dividing state includes: The main switch and the auxiliary switch in the voltage source module that needs to be put into operation are disconnected, and the voltage source in the voltage source module is connected in series with the circuit for voltage division.

12. The method according to claim 10, wherein Maintaining the voltage division of the voltage source module stable, comprising: When the divided voltage of the voltage source module reaches a first threshold, the main switch is kept in an off state and the voltage source module is adjusted to a protection state to reduce the voltage; When the divided voltage of the voltage source module drops to a second threshold, the main switch is kept in an off state and the voltage source module is adjusted to a divided voltage state to perform voltage division; The second threshold is lower than the first threshold by a set amplitude.

13. The method according to claim 12, wherein: When the voltage divided by the voltage source module reaches a first threshold, keeping the main switch in an off state and adjusting the voltage source module to a protection state to reduce the voltage includes: By controlling the voltage across the voltage source of the submodule; When the voltage across the voltage source reaches a first threshold, the main switch remains in an open state, the control submodule controls the auxiliary switch to close, and the voltage source discharges and reduces the voltage.

14. The method according to claim 12, wherein When the divided voltage of the voltage source module drops to a second threshold, maintaining the main switch in an off state and adjusting the voltage source module to a divided voltage state to perform voltage division includes: By controlling the voltage across the voltage source of the submodule; When the voltage across the voltage source drops to a second threshold, the main switch remains in an off state, the control submodule controls the auxiliary switch to be off, and the voltage source is connected in series with the circuit for voltage division.

15. The method according to claim 10, wherein The step of adjusting the remaining voltage source modules to a short-circuited state includes: By closing the main switch, the voltage source module is short-circuited.

16. The method according to claim 10, wherein The step of controlling the voltage source modules to alternately switch on and off based on the input amount within the set working cycle includes: Determining the input duration of the voltage source module according to the energy consumption demand and input amount; Based on the input duration, the main switch is controlled to be turned on and off once, thereby controlling the alternating input and output of the voltage source module.

17. The method according to claim 16, wherein The input duration is determined by the following formula: Among them, duty is the energy demand, T arr is the investment time, N on N is the number of voltage source modules put into operation. T is the total number of voltage source modules, T ch The set working cycle duration.

18. The method according to claim 10, wherein The step of determining the input amount of the voltage source module according to the energy consumption requirement includes: Based on the energy consumption requirement and the voltage division amount of the capacitor, the input amount of the voltage source module is determined as shown in the following formula: Among them, N on_usy For asymmetric setting, the input amount of voltage source module, N on_sy For symmetrical setting, the input amount of voltage source module, U dc is the DC line voltage, U mo is the voltage division of the capacitor, duty is the energy consumption requirement, 0≤duty≤1.

19. The method according to claim 10, wherein The step of controlling the voltage source modules to alternately switch on and off based on the input amount within a set working cycle further includes: By changing the charging time and discharging time of the voltage source in the voltage source module, the auxiliary switch in the voltage source module is switched once within a set working cycle.

20. The method of claim 19, wherein The auxiliary switch in the voltage source module is switched once within a set working cycle, and the charging time and discharging time of the voltage source should satisfy the following formula: t ch +t dis >(1-duty)×T ch Among them, t ch is the charging time of the voltage source, t dis is the discharge time of the voltage source, duty is the energy consumption demand, T ch For the set working cycle.

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