Hybrid dc energy dissipation device sinusoidal modulation compensation method and system

Abstract

The application belongs to the field of direct current transmission and relates to a sine modulation compensation method and system for a hybrid direct current energy consumption device, which comprises the following steps: obtaining an energy consumption valve sine modulation voltage according to surplus power of the hybrid direct current energy consumption device; if the energy consumption valve sine modulation voltage is negative, analyzing the cause of power imbalance of the energy consumption valve based on voltage non-negativity of a half-bridge energy consumption unit; and according to the cause of power imbalance of the device, expanding a compensation factor y through an alternating current component and reducing a compensation factor x through a direct current component, so as to ensure that the discharge energy and the charging energy of the energy consumption valve in a unit period are equivalent, and the average power of the energy consumption resistor in a unit period is equivalent to the surplus power. The method can effectively reduce the number of power devices of the hybrid direct current energy consumption device, greatly reduce the volume and cost of the hybrid direct current energy consumption device, and has great practical value and broad application prospect in the field of offshore wind power transmission through flexible direct current.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of hybrid DC energy consumption device sine modulation compensation method and system, belong to DC power transmission field, especially to hybrid DC energy consumption technical field. BACKGROUND

[0002] Flexible DC power transmission is the optimal technical scheme of large capacity, long distance and offshore wind power grid connection. In order to solve the problem of power surplus of offshore wind power flexible DC system after the fault of receiving end AC power grid, it is necessary to introduce DC energy consumption device with flexible and controllable power consumption to realize fault ride-through. DC energy consumption device includes centralized, distributed and hybrid three technical routes. The power device of centralized energy consumption device shows "switching type" action characteristic, and the energy consumption resistor is arranged centrally, which has low cost but large switching impact; The power device of distributed energy consumption device shows "voltage source type" action characteristic, and the energy consumption resistor is arranged distributedly, which has smooth switching performance but needs to configure water cooling system, and has high cost; The power device of hybrid energy consumption device shows "voltage source type" action characteristic and the energy consumption resistor is arranged centrally, which theoretically has the advantages of both centralized and distributed technical routes, and usually uses sine modulation strategy to generate modulation voltage of energy consumption valve. However, when the system surplus power is large, the sine modulation voltage will be negative. At this time, only full-bridge MMC energy consumption unit can be used, and the half-bridge MMC energy consumption unit with less device and better economy is no longer applicable due to the limitation of capacitor voltage direction. SUMMARY

[0003] In view of the above problems, the purpose of the present application is to provide a kind of hybrid DC energy consumption device sine modulation compensation method and system, which can effectively reduce the number of power devices of hybrid DC energy consumption device, greatly reduce the volume and cost of hybrid DC energy consumption device, and has great practical value and broad application prospect in the field of offshore wind power through flexible DC transmission.

[0004] To achieve the above purpose, the present application provides the following technical scheme: a kind of hybrid DC energy consumption device sine modulation compensation method, comprising: obtaining energy consumption valve sine modulation voltage according to the surplus power of hybrid DC energy consumption device;If energy consumption valve sine modulation voltage is negative, analyze the reason of device power imbalance based on the voltage non-negativity of energy consumption valve of half-bridge energy consumption unit;According to the reason of device power imbalance, through the expansion compensation factor y of alternating component and the reduction compensation factor x of direct current component, ensure that the discharge energy and charging energy of energy consumption valve in unit period are equivalent, and the average power of energy consumption resistor in unit period is equivalent to surplus power.

[0005] Further, the compensation method meets the following modulation principle: the sum of direct current average power and alternating current average power of energy consumption valve in unit modulation period is 0;The sum of direct current average power and alternating current average power of energy consumption resistor in unit modulation period is equal to device surplus power.

[0006] Further, the energy-consuming valve sinusoidal modulation voltage u sm is:

[0007]

[0008] where a is the modulation coefficient, w is the angular frequency, t is the time, U dc is the device rated DC voltage, and duty is the surplus power coefficient.

[0009] Further, the causes of the device power imbalance are: the first cause: when u sm <0 and u R >U dc , the energy-consuming valve voltage is reversed, the capacitor of the energy-consuming unit discharges through the energy-consuming resistor, so that the discharge energy of the energy-consuming valve in a unit period is less than the charging energy; the second cause: when u sm <0 and u R >U dc , the average power of the energy-consuming resistor R is less than the surplus power.

[0010] Further, the compensation method for the first cause is: by adjusting the AC component to expand the compensation factor y, the peak value of the reverse current of the energy-consuming branch in a unit period is increased, the peak value of the energy-consuming valve modulation voltage corresponding thereto is increased, and the discharge power of the capacitor of the energy-consuming unit to the outside is increased.

[0011] Further, the compensation method for the second cause is: by adjusting the DC component to reduce the compensation factor x, the energy-consuming resistor bears the entire inter-electrode DC voltage U dc in a unit period, and the time of consuming the maximum energy-consuming power P max is prolonged.

[0012] Further, the energy-consuming valve modulation voltage u′ sm after compensation is as follows:

[0013]

[0014] where a is the modulation coefficient, w is the angular frequency, t is the time, U dc is the device rated DC voltage.

[0015] Further, the solving equation of the AC component expansion compensation factor y and the DC component reduction compensation factor x is:

[0016]

[0017] where, is the difference between the phase corresponding to the first zero crossing point of the energy-consuming valve modulation voltage after compensation and π.

[0018] Further, if the voltage of the energy consumption valve is a non-negative value, the direct current component reduction compensation factor x is zero, and the alternating current component expansion compensation factor y is 1; if the voltage of the energy consumption valve is a negative value, a plurality of different modulation coefficients a are set, the direct current component reduction compensation factor x and the alternating current component expansion compensation factor y are solved, when the value of a is in the interval of 0-2 / 3, x and y monotonically and continuously change with the modulation coefficient a, the modulation coefficient a under a certain specific surplus power is obtained, the values of x and y are solved according to the monotonically changing function, and the compensated modulation voltage of the energy consumption valve is obtained according to the values of x and y.

[0019] The application further discloses a hybrid direct current energy consumption device sinusoidal modulation compensation system, which comprises a modulation voltage obtaining module, a loss of balance reason judging module and a compensation module.

[0020] Further, the compensation method satisfies the following modulation principle: the sum of the direct current average power and the alternating current average power of the energy consumption valve in a unit modulation period is 0; and the sum of the direct current average power and the alternating current average power of the energy consumption resistor in a unit modulation period is equal to the surplus power of the device.

[0021] Further, the sinusoidal modulation voltage u of the energy consumption valve is: sm

[0022]

[0023] Wherein, a is a modulation coefficient, w is an angular frequency, t is time, U is a device rated direct current voltage, and duty is a surplus power coefficient. dc

[0024] Further, the reasons for the device power imbalance are as follows: a first reason: when u sm <0 and u R >U dc , the voltage of the energy consumption valve is reversed, the capacitor of the energy consumption unit is discharged through the energy consumption resistor, so that the discharge energy of the energy consumption valve in a unit period is less than the charging energy; a second reason: when u sm <0 and u R >U dc , the average power of the energy consumption resistor R is less than the surplus power.

[0025] ​​Further, the compensation method for the first reason is: by adjusting the AC component to expand the compensation factor y, the peak value of the reverse current of the energy consumption branch in a unit period is increased, the peak value of the modulation voltage of the energy consumption valve corresponding to the peak value is increased, and the discharge power of the capacitor of the energy consumption unit to the outside is increased.

[0026] Further, the compensation method for the second reason is: by adjusting the DC component to reduce the compensation factor x, the energy consumption resistor bears the whole inter-electrode DC voltage U dc in a unit period. max , and the time of consuming the maximum energy consumption power P

[0027] Further, the modulation voltage u′ sm of the energy consumption valve after compensation is as follows:

[0028]

[0029] Wherein, a is a modulation coefficient, w is an angular frequency, t is time, U dc is the rated DC voltage of the device.

[0030] Further, the solving equation of the AC component expansion compensation factor y and the DC component reduction compensation factor x is:

[0031]

[0032] Wherein, is the difference between the phase corresponding to the first zero crossing point of the modulation voltage of the energy consumption valve after compensation and π.

[0033] Further, if the voltage of the energy consumption valve is a non-negative value, the DC component reduction compensation factor x is zero, and the AC component expansion compensation factor y is 1; if the voltage of the energy consumption valve is a negative value, a plurality of different modulation coefficients a are set, the DC component reduction compensation factor x and the AC component expansion compensation factor y are solved, when the value of a is in the interval of 0-2 / 3, x and y change monotonously and continuously with the modulation coefficient a, the modulation coefficient a under a certain specific surplus power is obtained, the values of x and y are solved according to the monotonous change function, and the modulation voltage of the energy consumption valve after compensation is obtained according to the values of x and y.

[0034] The application further discloses a computer readable storage medium, and the computer readable storage medium stores a computer program.

[0035] The application has the following advantages: under the premise of ensuring non-negativity of the modulation voltage, the application meets the balance of the charging and discharging power of the energy consumption valve in a unit period and the balance of the average power and surplus power of the energy consumption resistor by increasing the discharging power of the energy consumption unit capacitor to the outside and prolonging the maximum power time of the energy consumption resistor, thereby realizing the effectiveness of the hybrid DC energy consumption device based on the half-bridge energy consumption unit under the full-series surplus power working condition, effectively reducing the number of power devices of the hybrid DC energy consumption device, greatly reducing the volume and cost of the hybrid DC energy consumption device, and having great practical value and broad application prospect in the field of offshore wind power transmission through flexible DC. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 is a topological structure diagram of the hybrid DC energy consumption device in an embodiment of the application;

[0037] Figure 2 is a schematic diagram of the relationship between the modulation voltage u of the energy consumption valve and the surplus power coefficient duty before implementation of the sinusoidal modulation compensation strategy in an embodiment of the application; sm

[0038] Figure 3 is a change curve of the modulation voltage of the energy consumption valve in a unit period before and after implementation of the sinusoidal modulation compensation strategy in an embodiment of the application;

[0039] Figure 4 is a change curve of the terminal voltage of the energy consumption resistor in a unit period before and after implementation of the sinusoidal modulation compensation strategy in an embodiment of the application;

[0040] Figure 5 is a trend graph of the compensation coefficients x and y in the sinusoidal modulation compensation strategy varying with the modulation coefficient a in an embodiment of the application, Figure 5 (a) is a curve of x varying with the modulation coefficient a, Figure 5 (b) is a curve of y varying with the modulation coefficient a;

[0041] Figure 6 is a schematic diagram of the relationship between the modulation voltage u of the energy consumption valve and the surplus power coefficient duty after implementation of the sinusoidal modulation compensation strategy in an embodiment of the application; sm

[0042] Figure 7 is a circuit diagram of the surplus power simulation device in an embodiment of the application;

[0043] Figure 8 is a simulation waveform of the sinusoidal modulation compensation strategy when the surplus power coefficient is 0.1 in an embodiment of the application, Figure 8 (a) is a diagram of the modulation voltage of the energy consumption valve; Figure 8 (b) is a diagram of the average and instantaneous power of the energy consumption valve; Figure 8 ​​(c) is the average and instantaneous power of the energy-consuming resistor; Figure 8 (d) is the voltage graph of the energy-consuming module;

[0044] Figure 9 is the simulation waveform of the sine modulation compensation strategy when the surplus power coefficient is 0.5 in an embodiment of the present application, Figure 9 (a) is the voltage graph of the energy-consuming valve modulation; Figure 9 (b) is the average and instantaneous power graph of the energy-consuming valve; Figure 9 (c) is the average and instantaneous power graph of the energy-consuming resistor; Figure 9 (d) is the voltage graph of the energy-consuming module;

[0045] Figure 10 is the simulation waveform of the sine modulation compensation strategy when the surplus power coefficient is 0.1 in an embodiment of the present application, Figure 10 (a) is the voltage graph of the energy-consuming valve modulation; Figure 10 (b) is the average and instantaneous power graph of the energy-consuming valve; Figure 10 (c) is the average and instantaneous power graph of the energy-consuming resistor; Figure 10 (d) is the voltage graph of the energy-consuming module. DETAILED DESCRIPTION

[0046] In order for those skilled in the art to better understand the technical solutions of the present application, the present application will be described in detail through specific embodiments. However, it should be understood that the specific embodiments are provided only for better understanding of the present application, and they should not be understood as limiting the present application. In the description of the present application, it should be understood that the terms used are only for the purpose of description, and should not be understood as indicating or implying relative importance.

[0047] For a direct current energy-consuming device, when the surplus power of the device is large, the sine modulation voltage will be negative, and only a full-bridge type MMC energy-consuming unit can be used, and a half-bridge type MMC energy-consuming unit with fewer devices and better economy cannot be used. In order to solve the problems in the prior art, the present application proposes a sine modulation compensation method and device for a hybrid direct current energy-consuming device, which, under the premise of ensuring that the modulation voltage is non-negative, meets the balance of the charging and discharging power of the energy-consuming valve within a unit period and the balance of the average power of the energy-consuming resistor and the surplus power by increasing the discharging power of the energy-consuming unit capacitor to the outside and prolonging the maximum power time of the energy-consuming resistor, thereby realizing the effectiveness of the hybrid direct current energy-consuming device based on the half-bridge energy-consuming unit under the full series of surplus power conditions, effectively reducing the number of power devices of the hybrid direct current energy-consuming device, and greatly reducing the volume and cost of the hybrid direct current energy-consuming device. The scheme of the present application will be described in detail through embodiments in combination with the drawings.

[0048] Embodiment one

[0049] Figure 1is a topological structure diagram of a hybrid DC energy dissipation device in an embodiment of the present application. As shown in Figure 1 , the energy dissipation device includes a plurality of energy dissipation arms, each of which includes a plurality of energy dissipation units (SM), an energy dissipation valve, and an energy dissipation resistor, wherein the plurality of energy dissipation units are connected in series, and all of the energy dissipation units are connected in series with the energy dissipation resistor and in parallel with the energy dissipation valve. SM1-SMn are n cascaded half-bridge energy dissipation units. The voltage between the positive electrode and the negative electrode, i.e., the rated DC voltage, is denoted by U dc , the sinusoidal modulation voltage of the energy dissipation valve is denoted by u sm , and the terminal voltage of the energy dissipation resistor is denoted by u R .

[0050] The modulation principle of the hybrid DC energy dissipation device in the embodiment includes the following two requirements:

[0051] 1. The sum of the DC average power and the AC average power of the energy dissipation valve in a unit modulation period is 0, so that the charge / discharge energy of all energy dissipation unit capacitors in a unit modulation period is balanced, to ensure the stability of the energy dissipation unit capacitor voltage in the energy dissipation valve.

[0052] 2. The sum of the DC average power and the AC average power of the energy dissipation resistor in a unit modulation period is equal to the system surplus power, so that the energy absorbed by the energy dissipation resistor and the system energy fed in are balanced in a unit modulation period, to ensure the stability of the system DC voltage.

[0053] The embodiment discloses a sinusoidal modulation compensation method for a hybrid DC energy dissipation device, which comprises the following steps:

[0054] S1. Obtaining the sinusoidal modulation voltage of the energy dissipation valve according to the surplus power of the hybrid DC energy dissipation device. The sinusoidal modulation voltage of the energy dissipation valve u sm is:

[0055]

[0056] wherein a is a modulation coefficient, w is an angular frequency, t is time, U dc is the rated DC voltage of the device, and duty is a surplus power coefficient.

[0057] Figure 2 is a schematic diagram of the relationship between the modulation voltage u sm of the energy dissipation valve and the surplus power coefficient duty before the compensation strategy is implemented, as shown in Figure 2 , when the surplus power coefficient duty is less than 1 / 3, the sinusoidal modulation voltage u sm of the energy dissipation valve is a non-negative value, i.e., a positive value or zero; and when the surplus power coefficient duty is greater than 1 / 3, the sinusoidal modulation voltage u smIf the value is negative, the DC power consumption device needs to be compensated. The non-negativity of the voltage of the power consumption valve of the half-bridge power consumption unit will cause the power imbalance of the device, and compensation should be made according to the cause of the power imbalance.

[0058] S2 If the sinusoidal modulation voltage of the energy dissipation valve is negative, analyze the power imbalance of the device based on the non-negativity of the voltage of the energy dissipation valve of the half-bridge energy dissipation unit.

[0059] The reason for the power imbalance of the device is:

[0060] The first reason: Figure 3 As shown, the discharge time of the capacitor in the energy-consuming unit of the original energy-consuming valve should consist of two parts: ① when u before compensation sm >U dc When the current in the energy-consuming branch reverses, the capacitor in the energy-consuming unit discharges to the outside; ② When the current before compensation is u sm When the voltage is less than 0, the voltage of the energy dissipation valve reverses, and the energy dissipation unit capacitor discharges through the energy dissipation resistor. However, due to the unidirectional nature of the voltage of the half-bridge energy dissipation unit capacitor, the discharge of the energy dissipation resistor cannot actually be achieved, thus making the discharge energy of the energy dissipation valve less than the charging energy per unit cycle.

[0061] The second reason: such as Figure 4 As shown, when u sm <0andu R >U dc At that time, the instantaneous power of the energy-consuming resistor will be greater than:

[0062]

[0063] However, due to the unidirectional nature of the capacitor voltage in the half-bridge energy dissipation unit, the voltage of the energy dissipation valve can only drop to zero at its lowest point, and the maximum value of the inter-terminal voltage of the energy dissipation resistor can only reach the rated DC voltage U. dc The maximum instantaneous power of the energy-consuming resistor is equal to P. max This results in the average power of the energy-consuming resistor being less than the surplus power.

[0064] Based on the cause of the device power imbalance, S3 increases the compensation factor y by increasing the AC component and decreases the compensation factor x by decreasing the DC component, ensuring that the discharge energy of the energy-consuming valve is equivalent to the charging energy per unit cycle, and that the average power of the energy-consuming resistor is equivalent to the surplus power per unit cycle.

[0065] like Figure 3 As shown, the compensation method for the first cause is as follows: by adjusting the AC component to increase the compensation factor y, the peak value of the reverse current of the energy-consuming branch within a unit cycle is increased, the peak value of the corresponding energy-consuming valve modulation voltage is increased, and the discharge power of the capacitor of the energy-consuming unit is increased, so as to make up for the lack of the capacitor reverse voltage discharge process of the energy-consuming unit and ensure that the discharge energy of the energy-consuming valve within a unit cycle is still comparable to the charging energy.

[0066] As Figure 4 shown, the compensation method for the second reason is to reduce the compensation factor x by adjusting the DC component, so that the energy consumption resistance bears the entire inter-electrode DC voltage U dc in a unit period, prolongs the time of consuming the maximum energy consumption power P max , and thus ensures that the average power of the energy consumption resistance in a unit period is still comparable to the surplus power.

[0067] On the basis of the sinusoidal modulation voltage u sm of the energy consumption valve, the DC component reduction compensation factor x and the AC component expansion compensation factor y are introduced, and the modulation voltage u′ sm of the compensated energy consumption valve is as follows:

[0068]

[0069] where a is the modulation coefficient, w is the angular frequency, t is the time, U dc is the rated DC voltage of the device.

[0070] Through the compensated energy consumption valve modulation voltage u′ sm , the expression of the compensated energy consumption resistance terminal voltage u′ R is as follows:

[0071]

[0072] The zero-crossing point of the compensated energy consumption valve modulation voltage is and , and the following relationship is obtained:

[0073]

[0074] In order to satisfy the average power of the energy consumption valve in a unit period after compensation, the following relationship is obtained:

[0075]

[0076] In order to satisfy the average power of the energy consumption resistance in a unit period after compensation, the following relationship is obtained:

[0077]

[0078] Combining the above relationships, the solving equation of the AC component expansion compensation factor y and the DC component reduction compensation factor x is:

[0079]

[0080] where is the difference between the phase corresponding to the first zero-crossing point of the compensated energy consumption valve modulation voltage and π, as shown in Figure 3 .

[0081] Based on the set modulation coefficient a, the compensation factor y for amplifying the AC component and the compensation factor x for reducing the DC component can be solved.

[0082] When the voltage of the energy-consuming valve is non-negative, the DC component reduction compensation factor x is zero, and the AC component expansion compensation factor y is 1. When the voltage of the energy-consuming valve is negative, several different modulation coefficients a are set, and their specific values ​​are shown in Table 1. The DC component reduction compensation factor x and the AC component expansion compensation factor y are then solved. When the value of a is in the range of 0-2 / 3, x and y change monotonically and continuously with the modulation coefficient a, as shown in Table 1. Figure 5 As shown, the modulation coefficient 'a' under a specific surplus power is obtained, and the values ​​of x and y are solved according to a monotonically changing function. Based on the values ​​of x and y, the compensated modulation voltage of the energy dissipation valve is obtained, as shown below. Figure 6 As shown, the compensated energy-consuming valve modulation voltage exhibits obvious non-negativity, thereby ensuring that the hybrid DC energy-consuming device based on the half-bridge energy-consuming unit can achieve power balance control under all surplus power conditions.

[0083] Table 1 shows the x and y values ​​obtained under several different modulation coefficients 'a'.

[0084] a x v U smmax / pu]] 0.05 69.3405 228.8646 1.2503 0.1 16.6191 41.8851 1.2513 0.15 6.8966 15.8413 1.2529 0.2 3.5262 8.0989 1.2552 0.25 1.9931 4.9012 1.2582 0.3 1.1832 3.3103 1.2621 0.35 0.7148 2.4189 1.2668 0.4 0.4285 1.8779 1.2726 0.45 0.2481 1.5316 1.2795 0.5 0.1336 1.3030 1.2878 0.55 0.0624 1.1517 1.2979 0.6 0.0211 1.0557 1.3103 0.65 0.0019 1.0056 1.3264

[0085] Example 2

[0086] To further verify the effectiveness and feasibility of the present invention, the following embodiments are provided for further illustration:

[0087] In this embodiment, the surplus power simulation device, such as Figure 7 As shown, the circuit includes a DC voltage source, a controlled current source, a capacitor, an energy-consuming device, and switches K1 and K2. The capacitor is connected in parallel with the DC voltage source, and switch K1 is installed in the circuit between the capacitor and the DC voltage source. The energy-consuming device consists of an energy-consuming valve and an energy-consuming resistor connected in series, and is connected in parallel with the DC voltage source. The energy-consuming valve is illustrated by a circuit diagram of a field-effect transistor and a reverse diode connected in parallel. Switch K2 is installed between the energy-consuming device and the controlled current source. PN is the rated power of the system, u(t) is the voltage between the terminals of the energy-consuming device, and the diamond with arrows represents the controlled current source. This circuit places the energy-consuming device in a power surplus system, simulates various different system surplus power conditions through the controlled current source, and verifies the effectiveness of the energy-consuming device modulation strategy proposed in this patent under various system surplus power conditions (which can be verified by...). Figures 8-10 see, Figures 8-10 yes Figure 7 (Simulation results of the circuit shown). First, K1 is closed and K2 is opened, and the DC power-consuming device is charged to the rated voltage; then K1 is opened and K2 is closed, and the constant surplus power delivered to the DC power-consuming device is simulated using a controlled current source.

[0088] Figure 8 is the simulation waveform of the sinusoidal modulation compensation strategy when the surplus power coefficient is 0.1 in this embodiment, Figure 8 (a) is the energy-consuming valve modulation voltage graph; Figure 8 (b) is the energy-consuming valve average and instantaneous power graph; Figure 8 (c) is the energy-consuming resistor average and instantaneous power graph; Figure 8 (d) is the energy-consuming module voltage graph; Figure 9 is the simulation waveform of the sinusoidal modulation compensation strategy when the surplus power coefficient is 0.5 in this embodiment, Figure 9 (a) is the energy-consuming valve modulation voltage graph; Figure 9 (b) is the energy-consuming valve average and instantaneous power graph; Figure 9 (c) is the energy-consuming resistor average and instantaneous power graph; Figure 9 (d) is the energy-consuming module voltage graph; Figure 10 is the simulation waveform of the sinusoidal modulation compensation strategy when the surplus power coefficient is 0.1 in this embodiment, Figure 10 (a) is the energy-consuming valve modulation voltage graph; Figure 10 (b) is the energy-consuming valve average and instantaneous power graph; Figure 10 (c) is the energy-consuming resistor average and instantaneous power graph; Figure 10 (d) is the energy-consuming module voltage graph; Figures 8-10 It can be seen from the above that after the sinusoidal modulation compensation strategy, the hybrid DC energy-consuming device can meet the condition that the average power of the energy-consuming valve in a unit cycle is always 0, and the average power of the energy-consuming resistor is always equal to the surplus power, that is, the energy-consuming valve energy-consuming unit voltage and the device DC voltage can be kept stable under the premise that the energy-consuming valve modulation voltage is in a non-negative state.

[0089] Embodiment three

[0090] Based on the same inventive concept, the embodiment discloses a sinusoidal modulation compensation system of a hybrid DC energy-consuming device. The modulation principle of the hybrid DC energy-consuming device in the embodiment includes the following two requirements:

[0091] 1. The sum of the DC average power and the AC average power of the energy-consuming valve in a unit modulation period is 0, so that the charge / discharge energy of all energy-consuming unit capacitors in a unit modulation period is balanced, so as to ensure the stability of the energy-consuming unit capacitor voltage in the energy-consuming valve.

[0092] It includes:

[0093] The modulation voltage obtaining module is used for obtaining the sinusoidal modulation voltage of the energy-consuming valve according to the surplus power of the hybrid DC energy-consuming device.

[0094] The sinusoidal modulation voltage of the energy-consuming valve u sm is:

[0095]

[0096] wherein a is a modulation coefficient, w is an angular frequency, t is time, U dc is a rated DC voltage of the device, and duty is a surplus power coefficient.

[0097] Figure 2 is a sinusoidal modulation voltage of the energy consumption valve before the compensation strategy is implemented in the embodiment sm and the surplus power coefficient duty, as shown in Figure 2 , when the surplus power coefficient duty < 1 / 3, the sinusoidal modulation voltage u sm of the energy consumption valve is a non-negative value, that is, a positive value or zero; when the surplus power coefficient duty > 1 / 3, the sinusoidal modulation voltage u sm of the energy consumption valve is a negative value, at which time the DC energy consumption device needs to be compensated, and the reason for the power imbalance of the device based on the non-negativity of the voltage of the energy consumption valve of the half-bridge energy consumption unit needs to be compensated according to the reason for the power imbalance.

[0098] The imbalance reason judgment module is configured to, if the sinusoidal modulation voltage of the energy consumption valve is a negative value, analyze the reason for the power imbalance of the device based on the non-negativity of the voltage of the energy consumption valve of the half-bridge energy consumption unit.

[0099] The reason for the power imbalance of the device is:

[0100] The first reason is that, as shown in Figure 3 , the energy consumption unit capacitor discharge time of the energy consumption valve should be composed of two parts: ① when u sm > U dc before compensation, the energy consumption branch current is reversed, and the energy consumption unit capacitor discharges externally; ② when u sm < 0 before compensation, the energy consumption valve voltage is reversed, and the energy consumption unit capacitor discharges through the energy consumption resistor. However, due to the unidirectionality of the half-bridge energy consumption unit capacitor voltage, the energy consumption resistor discharge cannot actually be implemented, so that the energy consumption valve discharge energy in a unit period is less than the charging energy.

[0101] The second reason is that, as shown in Figure 4 , when u sm < 0 and u R > U dc , the instantaneous power of the energy consumption resistor will be greater than:

[0102]

[0103] However, due to the unidirectionality of the half-bridge energy consumption unit capacitor voltage, the energy consumption valve voltage can only be reduced to zero at the lowest, and the maximum voltage across the energy consumption resistor can only reach the rated DC voltage U dc , and the maximum instantaneous power of the energy consumption resistor is equal to P max , so that the average power of the energy consumption resistor is less than the surplus power.

[0104] The compensation module is used to compensate the power imbalance of the device by expanding the AC component compensation factor y and reducing the DC component compensation factor x according to the reasons of the power imbalance, so as to ensure that the discharge energy of the energy consumption valve in a unit period is equal to the charging energy, and the average power of the energy consumption resistor in a unit period is equal to the surplus power.

[0105] As shown in Figure 3 , the compensation method for the first reason is to expand the AC component compensation factor y by adjusting the AC component, so as to increase the peak value of the reverse current of the energy consumption branch in a unit period, increase the modulation voltage peak value of the energy consumption valve corresponding to the peak value, increase the discharge power of the capacitor of the energy consumption unit to the outside, compensate for the loss of the capacitor reverse pressure discharge process, and ensure that the discharge energy of the energy consumption valve in a unit period is still equal to the charging energy.

[0106] As shown in Figure 4 , the compensation method for the second reason is to reduce the DC component compensation factor x by adjusting the DC component, so as to make the energy consumption resistor bear the entire inter-electrode DC voltage U dc in a unit period, prolong the time of consuming the maximum energy consumption power P max , and thus ensure that the average power of the energy consumption resistor in a unit period is still equal to the surplus power.

[0107] On the basis of the sinusoidal modulation voltage u sm of the energy consumption valve, the DC component reduction compensation factor x and the AC component expansion compensation factor y are introduced, and the modulation voltage u′ sm of the energy consumption valve after compensation is as follows:

[0108]

[0109] Wherein, a is the modulation coefficient, w is the angular frequency, t is the time, U dc is the rated DC voltage of the device.

[0110] Through the modulation voltage u′ sm of the energy consumption valve after compensation, the terminal voltage u′ R of the energy consumption resistor after compensation can be obtained, and the expression is as follows:

[0111]

[0112] The zero-crossing point of the modulation voltage of the energy consumption valve after compensation is and , and the following relationship can be obtained:

[0113]

[0114] In order to meet the average power of the energy consumption valve in a unit period after compensation, the following relationship can be obtained:

[0115]

[0116] In order to meet the average power of the energy consumption resistor in the unit period after compensation still equal to the surplus power, the following relationship can be obtained:

[0117]

[0118] According to the above relationship, the solving equation of the AC component expansion compensation factor y and the DC component reduction compensation factor x is:

[0119]

[0120] Wherein, is the difference between the phase corresponding to the first zero crossing point of the modulation voltage of the energy consumption valve after compensation and π, as shown in Figure 3

[0121] According to the set modulation coefficient a, the AC component expansion compensation factor y and the DC component reduction compensation factor x can be solved.

[0122] If the voltage of the energy consumption valve is non-negative, the DC component reduction compensation factor x is zero, and the AC component expansion compensation factor y is 1; if the voltage of the energy consumption valve is negative, set a plurality of different modulation coefficients a, and the specific values are shown in Table 1, solve the DC component reduction compensation factor x and the AC component expansion compensation factor y. When the value of a is in the interval of 0-2 / 3, x and y change monotonously and continuously with the modulation coefficient a, as shown in Figure 5 , obtain the modulation coefficient a under a certain specific surplus power, and solve the values of x and y according to the monotonous change function, and obtain the modulation voltage of the energy consumption valve after compensation according to the values of x and y, as shown in Figure 6 , the modulation voltage of the energy consumption valve after compensation is obviously non-negative, so as to ensure that the hybrid DC energy consumption device based on the half-bridge energy consumption unit can realize power balance control under the whole series of surplus power working conditions.

[0123] Embodiment four

[0124] Based on the same inventive concept, the embodiment discloses a computer readable storage medium, and the computer readable storage medium stores a computer program. The computer program is executed by a processor to implement the sinusoidal modulation compensation method of the hybrid DC energy consumption device in any one of the above embodiments.

[0125] ​It should be pointed out finally that the above embodiments are only used to illustrate the technical solutions of the present application but not to limit it. Although the present application has been described in detail with reference to the above embodiments, it should be understood by those skilled in the art that the specific embodiments of the present application can be modified or replaced equivalently without departing from the spirit and scope of the present application, and any modification or equivalent replacement should be covered in the protection scope of the claims of the present application. The above content is only a specific embodiment of the present application, but the protection scope of the present application is not limited to this. Any person skilled in the art can easily think of changes or replacements within the technical scope disclosed by the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A sinusoidal modulation compensation method for a hybrid DC energy-consuming device, characterized in that, include: The sinusoidal modulation voltage of the energy dissipation valve is obtained based on the surplus power of the hybrid DC energy dissipation device; If the sinusoidal modulation voltage of the energy dissipation valve is negative, analyze the power imbalance of the energy dissipation valve based on the voltage non-negativity of the half-bridge energy dissipation unit. The reason for the power imbalance of the device is: The first reason: the energy-consuming unit of the energy-consuming valve when u sm <0andu sm >U dc When the voltage of the energy-consuming valve reverses, the capacitor of the energy-consuming unit discharges through the energy-consuming resistor, making the discharge energy of the energy-consuming valve less than the charging energy per unit cycle. sm It is the sinusoidal modulation voltage of the energy dissipation valve, u R This is the voltage between the terminals of the energy-consuming resistor; The second reason: when u sm <0andu R >U dc At that time, the average power of the energy-consuming resistor R is less than the surplus power, U dc The rated DC voltage of the device; Based on the cause of the power imbalance in the device, the compensation factor y is increased by the AC component and the compensation factor x is decreased by the DC component to ensure that the discharge energy of the energy-consuming valve is equivalent to the charging energy per unit cycle, and the average power of the energy-consuming resistor is equivalent to the surplus power per unit cycle. The compensation method for the first cause is as follows: by adjusting the AC component to increase the compensation factor y, the peak value of the reverse current of the energy-consuming branch within a unit cycle is increased, the peak value of the corresponding energy-consuming valve modulation voltage is increased, and the external discharge power of the capacitor of the energy-consuming unit is increased. The compensation method for the second reason is as follows: by adjusting the DC component to reduce the compensation factor x, the energy-consuming resistor bears the full inter-electrode DC voltage within a unit cycle, thereby extending the period of maximum energy consumption. P max The time.

2. The sinusoidal modulation compensation method for hybrid DC energy-consuming devices as described in claim 1, characterized in that, The compensation method satisfies the following modulation principle: the sum of the average DC power and the average AC power of the energy-consuming valve within a unit modulation period is 0; the sum of the average DC power and the average AC power of the energy-consuming resistor within a unit modulation period is equal to the surplus power of the device.

3. The sinusoidal modulation compensation method for hybrid DC energy-consuming devices as described in claim 1, characterized in that, The sinusoidal modulation voltage u of the energy-consuming valve sm for: in, a The modulation coefficient, w Angular frequency, t For time, duty is the surplus power coefficient.

4. The sinusoidal modulation compensation method for hybrid DC energy-consuming devices as described in claim 1, characterized in that, Compensated energy dissipation valve modulation voltage as follows: in, a The modulation coefficient, w Angular frequency, t For time, U dc This is the rated DC voltage of the device.

5. The sinusoidal modulation compensation method for hybrid DC energy-consuming devices as described in claim 4, characterized in that, The equations for solving the AC component amplification compensation factor y and the DC component reduction compensation factor x are: in, It is the difference between the phase corresponding to the first zero-crossing point of the compensated energy dissipation valve modulation voltage and π.

6. The sinusoidal modulation compensation method for hybrid DC energy-consuming devices as described in claim 5, characterized in that, If the voltage of the energy dissipation valve is non-negative, the DC component reduction compensation factor x is zero, and the AC component expansion compensation factor y is 1. If the voltage of the energy dissipation valve is negative, several different modulation coefficients a are set, and the DC component reduction compensation factor x and the AC component expansion compensation factor y are solved. When the value of a is in the range of 0-2 / 3, x and y change monotonically and continuously with the modulation coefficient a, and the modulation coefficient a under a specific surplus power is obtained. The values ​​of x and y are solved according to the monotonically changing function, and the compensated energy dissipation valve modulation voltage is obtained according to the values ​​of x and y.

7. A sinusoidal modulation compensation system for a hybrid DC energy-consuming device, characterized in that, include: The modulation voltage acquisition module is used to obtain the sinusoidal modulation voltage of the energy dissipation valve based on the surplus power of the hybrid DC energy dissipation device; The imbalance cause judgment module is used to analyze the cause of power imbalance in the device based on the non-negativity of the voltage of the energy-consuming valve of the half-bridge energy-consuming unit if the sinusoidal modulation voltage of the energy-consuming valve is negative. The reason for the power imbalance of the device is: The first reason: the energy-consuming unit of the energy-consuming valve when u sm <0andu sm >U dc When the voltage of the energy-consuming valve reverses, the capacitor of the energy-consuming unit discharges through the energy-consuming resistor, making the discharge energy of the energy-consuming valve less than the charging energy per unit cycle. sm It is the sinusoidal modulation voltage of the energy dissipation valve, u R This is the voltage between the terminals of the energy-consuming resistor; The second reason: when u sm <0andu R >U dc At that time, the average power of the energy-consuming resistor R is less than the surplus power, U dc The rated DC voltage of the device; The compensation module is used to increase the compensation factor y by AC component and decrease the compensation factor x by DC component according to the cause of the power imbalance of the device, so as to ensure that the discharge energy of the energy-consuming valve is equivalent to the charging energy per unit cycle, and the average power of the energy-consuming resistor is equivalent to the surplus power per unit cycle. The compensation method for the first cause is as follows: by adjusting the AC component to increase the compensation factor y, the peak value of the reverse current of the energy-consuming branch within a unit cycle is increased, the peak value of the corresponding energy-consuming valve modulation voltage is increased, and the external discharge power of the capacitor of the energy-consuming unit is increased. The compensation method for the second reason is as follows: by adjusting the DC component to reduce the compensation factor x, the energy-consuming resistor bears the full inter-electrode DC voltage within a unit cycle, thereby extending the period of maximum energy consumption. P max The time.

8. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that is executed by a processor to implement the sinusoidal modulation compensation method for a hybrid DC power consumption device as described in any one of claims 1-6.

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