CN103346586A - Switching control method for double-mode converter in three-phase microgrid - Google Patents

Abstract

The invention provides a switching control method for a double-mode converter in a three-phase microgrid. When the converter is converted from a networking mode to a grid-connected operation mode, a coordinated controller unit adjusts output voltage amplitude and frequency of the converter, and when grid-connected requirements are met, a static switch is connected, the converter is converted to current control, and then the converter enters the grid-connected operation mode; when abnormity of a grid state is detected or the converter needs to be switched to an autonomous operation mode, the coordinated controller unit adjusts the current set value of the converter, meanwhile, the static switch is disconnected, then the converter is converted to voltage control, and the converter enters the networking operation mode. The switching control method for the double-mode converter in the three-phase microgrid is simple in control and capable of improving stability and reliability of the double-mode converter.

Description

The method for handover control of double mode current transformer in the little electrical network of a kind of three-phase

Technical field

The present invention relates to the method for handover control of double mode current transformer in a kind of little electrical network.

Background technology

Little electrical network except be incorporated into the power networks and two kinds of steady state mode of operation of networking, also exist the transient process of changing between two kinds of patterns.The mode of pattern conversion is not restarting of power supply, but in the constant work of current transformer, by the continuous smooth transition that the adjustment of aspects such as its control method and network configuration guarantees to net interior voltage, namely realize taking over seamlessly, unaffected with the power supply of guaranteeing local load.At present, existing current transformer just adopts simple Current Control or voltage control mostly, realize being incorporated into the power networks or group net operation, and power is little, has suppressed the development of little electrical network.

Summary of the invention

For overcoming the shortcoming of prior art, the present invention proposes a kind of method for handover control to the double mode current transformer in the little electrical network of three-phase.The invention enables current transformer both can be incorporated into the power networks also can group net operation.The present invention also is applicable to high-power ruuning situation.

The method for handover control of the double mode current transformer of the present invention realizes being incorporated into the power networks taking over seamlessly between pattern and the group net operation pattern by the tuning controller unit.

The present invention adopts following technical scheme for achieving the above object:

Double mode converter system in the little electrical network of described three-phase comprises double mode current transformer, sample circuit, the cell controller that is incorporated into the power networks, networking cell controller and coordinates control unit.

Described double mode current transformer comprises dc bus power supply Vdc, three phase inverter bridge, three-phase filter inductance, three-phase filter capacitor and three-phase transformer.

Control method of the present invention realizes by being integrated in net-connected controller unit, networking controller unit and a coordination control unit in the dsp controller.

Sample circuit is with the voltage of gathering, and current signal is sent to net-connected controller unit, networking controller unit and tuning controller unit by holding wire.Connect by busbar between double mode current transformer, local load and the electrical network, be connected by serial communication between net-connected controller unit, networking controller unit and tuning controller unit and double mode current transformer, load and the electrical network.

The method for handover control of double mode current transformer is to be in when being incorporated into the power networks pattern at double mode current transformer in the little electrical network of three-phase of the present invention, electric current by net-connected controller unit controls filter inductance is controlled grid-connected current, when double mode current transformer is in the group net operation pattern, by networking controller unit control current transformer load voltage; When double mode current transformer is in the process of the pattern of being incorporated into the power networks and the conversion of group net operation pattern, realize being incorporated into the power networks taking over seamlessly between pattern and the group net operation pattern by coordinating control unit.

In the described net-connected controller unit, mainly control grid-connected current by the electric current of control filter inductance, realize being incorporated into the power networks requirement.In the process of being incorporated into the power networks, sample circuit sends to dsp chip with line voltage and the filtered circuit signal that collects, and produces pwm signal through the net-connected controller unit, directly drives three phase inverter bridge through drive circuit.

In the described networking cell controller, main load voltage and filter inductance electric current by the control current transformer guarantee the power supply quality of loading.When group net operation, sample circuit sends to dsp chip with current transformer load voltage and the filtered circuit signal that collects, and produces pwm signal through the networking controller unit, through drive circuit output, directly drives three phase inverter bridge.

Be converted to when being incorporated into the power networks pattern by the group net operation pattern at current transformer, the tuning controller unit detects the amplitude of the line voltage that obtains and amplitude and the frequency that frequency is constantly adjusted double mode current transformer load voltage by sample circuit, determine the change amount of given amplitude and frequency according to difference in magnitude and frequency extent, thereby change double mode current transformer output voltage amplitude and frequency, realize taking over seamlessly of double mode current transformer.

The tuning controller unit is converted to when being incorporated into the power networks pattern by the group net operation pattern at current transformer, detects the amplitude U of the line voltage that obtains in real time by sample circuit _gAnd frequency f _gConstantly adjust the amplitude U (k-1) of the given voltage of double mode current transformer ^*And frequency f (k-1) ^*, according to difference in magnitude Δ U(U _g-U (k-1) ^*) and difference on the frequency Δ f(f _g-f (k-1) ^*) size, determine given voltage magnitude U (k-1) ^*And frequency f (k-1) ^*The change amount, with the current transformer voltage magnitude U (k) after adjusting ^*And frequency f (k) ^*As the set-point of bimodulus current transformer, thereby amplitude and the frequency of change current transformer load voltage are adjusted back networking controller unit voltage magnitude U (k) ^*And frequency f (k) ^*Value be shown below:

$\left\{\begin{array}{c}f{\left(k\right)}^{*}=\frac{f_g-f{(k-1)}^{*}}{n}+f{(k-1)}^{*}=\frac{\mathrm{\Δf}}{n}+f{(k-1)}^{*}\\ U{\left(k\right)}^{*}=\frac{U_g-U{(k-1)}^{*}}{n}+U{(k-1)}^{*}=\frac{\mathrm{\ΔU}}{n}+U{(k-1)}^{*}\end{array}\right.$

In the formula: n represents integer, and k represents that k constantly, (k-1) represents (k-1) constantly, f (k) ^*Expression k given electric voltage frequency constantly, f (k-1) ^*Expression (k-1) given electric voltage frequency constantly, U (k) ^*Expression k given voltage magnitude constantly, U (k-1) ^*Expression (k-1) given voltage magnitude constantly.

After satisfying the requirement of being incorporated into the power networks, with the voltage magnitude U (k) that obtains after adjusting ^*And frequency f (k) ^*As the set-point of bimodulus current transformer, guarantee that with this current transformer load voltage and electric current do not undergo mutation, realize taking over seamlessly.After treating current transformer stable operation, be Current Control by the net-connected controller cell translation, realize being incorporated into the power networks.

Electrical network breaks down or when initiatively requiring current transformer to be converted to group net operation by being incorporated into the power networks, the tuning controller unit is adjusted the given current i of current transformer rapidly _d ^*, i _q ^*, work as i _d ^*, i _q ^*After being complementary with load current, current transformer is converted to group net operation, treat current transformer stable operation after, be converted to voltage control by the networking controller unit, guarantee the output of current transformer, realize taking over seamlessly.

The present invention can make double mode current transformer realize taking over seamlessly in group net operation and the transient process of switching mutually that is incorporated into the power networks, and can improve stability and the reliability of electric power system.

Description of drawings

The double mode converter system structured flowchart of Fig. 1;

The double mode converter structure figure of Fig. 2.

Embodiment

Further specify the present invention below in conjunction with the drawings and the specific embodiments.

As shown in Figure 1, double mode converter system comprises double mode current transformer 1, the cell controller 3 that is incorporated into the power networks, networking cell controller 2, coordinates control unit 4, sample circuit 5.

As shown in Figure 2, double mode current transformer 1 comprises dc bus power supply Vdc, three phase inverter bridge 101, three-phase filter inductance 102, three-phase filter capacitor 103 and three-phase transformer 104, in addition current transformer for the load 105 the power supply, by static switch 106 to the electrical network conveying capacity.

Sample circuit 5 is with the voltage of gathering, and current signal is sent to net-connected controller unit, networking controller unit and tuning controller unit by holding wire.Connect the control unit that is incorporated into the power networks, networking control unit and coordinate to be connected by serial communication between control unit and double mode current transformer, load and the electrical network between double mode current transformer, load and the electrical network by busbar.

The control method of double mode current transformer is as follows in the little electrical network of three-phase of the present invention:

In the described net-connected controller unit, mainly control grid-connected current by the electric current of control filter inductance, realize being incorporated into the power networks requirement.In the process of being incorporated into the power networks, sample circuit sends to dsp chip with line voltage and the filtered circuit signal that collects, and produces pwm signal through the net-connected controller unit, directly drives three phase inverter bridge through drive circuit.

In the described networking cell controller, main load voltage and filter inductance electric current by the control current transformer guarantee the power supply quality of loading.When group net operation, sample circuit sends to dsp chip with current transformer load voltage and the filtered circuit signal that collects, and produces pwm signal through the networking controller unit, directly drives three phase inverter bridge through drive circuit.

Described tuning controller unit detects amplitude and the frequency of the line voltage that obtains in real time by sample circuit, constantly adjust output voltage amplitude and the frequency of current transformer, according to difference in magnitude and frequency extent, determine the change amount of given amplitude and frequency, thereby change amplitude and the frequency of current transformer load voltage, realize taking over seamlessly of double mode current transformer.

The tuning controller unit is converted to when being incorporated into the power networks by group net operation at current transformer, and the given voltage of current transformer and frequency are respectively U (k-1) ^*And f (k-1) ^*, by the amplitude U of sample circuit 5 real-time detection of grid voltages _gAnd frequency f _gConstantly adjust U (k) ^*And f (k) ^*, according to difference in magnitude Δ U(U _g-U (k-1) ^*) and difference on the frequency Δ f(f _g-f (k-1) ^*) size, determine given amplitude U (k-1) ^*And frequency f (k-1) ^*The change amount, with the current transformer voltage magnitude U (k) after adjusting ^*And frequency f (k) ^*As the set-point of bimodulus current transformer, change current transformer output voltage amplitude and frequency, thereby change amplitude and the frequency of current transformer load voltage, adjust back networking controller unit voltage magnitude U (k) ^*And frequency f (k) ^*Value be shown below:

$\left\{\begin{array}{c}f{\left(k\right)}^{*}=\frac{f_g-f{(k-1)}^{*}}{n}+f{(k-1)}^{*}=\frac{\mathrm{\Δf}}{n}+f{(k-1)}^{*}\\ U{\left(k\right)}^{*}=\frac{U_g-U{(k-1)}^{*}}{n}+U{(k-1)}^{*}=\frac{\mathrm{\ΔU}}{n}+U{(k-1)}^{*}\end{array}\right.$

N represents integer, and k represents that k constantly, (k-1) represents (k-1) constantly, f (k) ^*Expression k given frequency constantly, f (k-1) ^*Expression (k-1) given frequency constantly, U (k) ^*Expression k given voltage magnitude constantly, U (k-1) ^*Expression (k-1) given voltage magnitude constantly.

After satisfying the requirement of being incorporated into the power networks, with the voltage magnitude U (k) that obtains after adjusting ^*And frequency f (k) ^*As the set-point of current transformer, realize taking over seamlessly.After treating current transformer stable operation, be changed to Current Control by the net-connected controller unit, realize being incorporated into the power networks.

When electrical network broke down or initiatively require current transformer to be converted to group net operation by being incorporated into the power networks, the tuning controller unit was adjusted the given current i of current transformer rapidly _d ^*, i _q ^*, work as i _d ^*, i _q ^*After being complementary with load current, current transformer is converted to group net operation, treat current transformer stable operation after, be changed to voltage control by the networking controller unit, guarantee the output of current transformer, realize taking over seamlessly.

Claims (4)

1. the method for handover control of double mode current transformer in the little electrical network of three-phase, it is characterized in that, the method for handover control of double mode current transformer is in the little electrical network of described three-phase, be in when being incorporated into the power networks pattern at double mode current transformer, control grid-connected current by the electric current of net-connected controller unit controls filter inductance; When double mode current transformer is in the group net operation pattern, by networking controller unit control current transformer load voltage; When double mode current transformer is in the process of the pattern of being incorporated into the power networks and the conversion of group net operation pattern, realize being incorporated into the power networks taking over seamlessly between pattern and the group net operation pattern by the tuning controller unit.

2. the method for handover control of double mode current transformer in the little electrical network of three-phase according to claim 1, it is characterized in that: described double mode current transformer is converted to when being incorporated into the power networks pattern by the group net operation pattern, and the unit adjustment of described tuning controller detects the amplitude U of the line voltage that obtains in real time by sample circuit _gAnd frequency f _gConstantly adjust the amplitude U (k-1) of the given voltage of double mode current transformer ^*And frequency f (k-1) ^*, k represents that k constantly, (k-1) represents (k-1) constantly, according to difference in magnitude Δ U(U _g-U (k-1) ^*) and difference on the frequency Δ f(f _g-f (k-1) ^*) size, determine given voltage magnitude U (k-1) ^*And frequency f (k-1) ^*The change amount, with the current transformer voltage magnitude U (k) after adjusting ^*And frequency f (k) ^*As the set-point of bimodulus current transformer, change amplitude and the frequency of double mode current transformer load voltage, realize taking over seamlessly; After treating the stable operation of bimodulus current transformer, be Current Control by the net-connected controller cell translation, realize being incorporated into the power networks.

3. the method for handover control of double mode current transformer in the little electrical network of three-phase according to claim 1 is characterized in that: described adjustment back networking controller unit voltage magnitude U (k) ^*And frequency f (k) ^*Value be shown below:

$\left\{\begin{array}{c}f{\left(k\right)}^{*}=\frac{f_g-f{(k-1)}^{*}}{n}+f{(k-1)}^{*}=\frac{\mathrm{\Δf}}{n}+f{(k-1)}^{*}\\ U{\left(k\right)}^{*}=\frac{U_g-U{(k-1)}^{*}}{n}+U{(k-1)}^{*}=\frac{\mathrm{\ΔU}}{n}+U{(k-1)}^{*}\end{array}\right.$

In the formula: n represents integer, and k represents that k constantly, (k-1) represents (k-1) constantly, f (k) ^*Expression k given electric voltage frequency constantly, f (k-1) ^*Expression (k-1) given electric voltage frequency constantly, U (k) ^*Expression k given voltage magnitude constantly, U (k-1) ^*Expression (k-1) given voltage magnitude constantly.

4. the method for handover control of double mode current transformer in the little electrical network of three-phase according to claim 1, it is characterized in that: when electrical network broke down or initiatively require described bimodulus current transformer to be converted to group net operation by being incorporated into the power networks, described tuning controller unit was adjusted the given current i of current transformer rapidly _d ^*, i _q ^*, when given current i _d ^*, i _q ^*After being complementary with load current, the bimodulus current transformer is converted to group net operation, treat the stable operation of bimodulus current transformer after, be converted to voltage control by the networking controller unit.