JPH0568343A - Inverter constant voltage control circuit for independent and interconnection operation - Google Patents

Abstract

(57) [Summary] [Purpose] To obtain a constant-voltage control circuit for an inverter for independent / interconnection operation that can perform parallel insertion and disconnection into the power system while maintaining a constant-voltage control state without causing instantaneous interruption. .. [Structure] An output voltage angular velocity calculation unit that is composed of an output end voltage detector, a three-phase to two-phase conversion circuit, and a vector analyzer that calculates the angular velocity of the output end voltage by separating it into a valid component and a reactive component, and the current of a single load A load current calculation unit that is composed of a detector, a three-phase / two-phase conversion circuit, and a vector rotator and calculates the active and reactive components of the load current, and the reactor voltage due to the load current that is arranged on the output side of the load current calculation unit. A current-voltage conversion circuit that calculates the effective and ineffective components of the drop, and a vector analyzer that calculates the absolute value of the output end voltage from the output of this current-voltage conversion circuit and the output voltage of the inverter,
The vector analyzer is provided with a proportional-plus-integral controller for controlling the inverter with a constant voltage by using the output voltage as a detection voltage and the absolute value of the power system voltage as a set voltage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an independent operation in which DC power from an independent power source such as a cogeneration system is converted into AC power by an inverter for interconnected operation and supplied to a single load, and an AC power system. The present invention relates to a constant voltage control circuit that maintains the voltage control state and performs non-interruptive operation, which is an interlocking operation of transmitting and receiving electric power in parallel.

[0002]

2. Description of the Related Art FIG. 8 shows a conventional independent / interconnection operation invertor.
FIG. 3 is a connection diagram showing a simplified constant voltage control circuit of the inverter, in which a DC output of an independent power source 2 is converted into an AC power having an output voltage V _I by a voltage type self-exciting inverter 1 (hereinafter abbreviated as an inverter). Then, the islanding operation in which the output end voltage V _{O and the} load current I _L are supplied to the independent load 5 through the reactor 3 and the transformer 4, and the switch 6 is turned on and the electric power is exchanged with the AC power system 7. The interconnection operation for performing the above is performed by controlling the inverter 1 at a constant voltage by the constant voltage control circuit 10.

The constant voltage control circuit 10 includes a proportional-plus-integral regulator 1.
1, the system voltage V _S is detected by the voltage detector 14, and the absolute value of the system voltage V _S obtained by rectifying by the rectifier circuit 15 is set as the set voltage V _SS, and the output voltage V _O of the transformer secondary side is set. Is detected by the voltage detector 12, and the absolute value of the output voltage obtained by rectifying by the rectifier circuit 13 is set as the detected voltage V _OD, and the difference between the two is added to the proportional-plus-integral adjuster 11, whereby the proportional-integral adjuster is input. Since the output voltage V _I of the inverter 1 is controlled so that the voltage becomes zero, the constant voltage control of the inverter 1 is performed so that the output end voltage V _O approaches the system voltage V _S. As a result, in the state where the switch 6 is opened, it is possible to perform an isolated operation in which the load current I _L is supplied by the constant voltage control in which the output voltage V _O is held in the isolated load 5. Further, since the constant voltage control is performed so that the magnitude of the output voltage V _O becomes equal to that of the system voltage V _S , it is possible to close the switch 6 and shift to the interconnection operation.

[0004]

However, the switch 6 is
When turned on, the output voltage V on the inverter side_OAnd system voltage V_S
Since and become equal, the setting of the proportional-plus-integral controller 11
Fixed value V_SSAnd detection value V _ODBecomes equal, and proportional-integral adjustment
And the control of the inverter 1 after that
Is in an uncontrolled state, and power transfer is
There is a problem of being left alone. So this
In order to avoid the situation like
-A control method was proposed in which the control of the
There is. However, with this method, parallel insertion into the grid and grid
When switching off from, switch 6 and control circuit are switched
Since there is a large timing deviation,
In the mode that is put in parallel to the system, or in the state of current control
There is a mode in which the power is disconnected from the system, and there is an instantaneous uncontrolled state.
Situation occurs, and when switching control
Inevitably there will be a momentary interruption in which the power supply to the individual load 5 will be momentarily stopped.
There is a problem that the individual load 5 has a momentary power interruption.
Not allowed, like a computer power supply
If so, that improvement is an important issue.

An object of the present invention is to provide a constant voltage control circuit for an inverter for independent / coupling operation, which can perform parallel insertion and disconnection into a power system while maintaining a constant voltage control state without causing instantaneous interruption. Especially.

[0006]

In order to solve the above problems, according to the present invention, a voltage type self-exciting inverter for converting a DC output of an independent power source into an AC is controlled to provide a reactor on its output side. And an independent operation that supplies power to a single load connected via a transformer, and an active system that controls active and reactive power to transfer power to and from a power system connected via a switch The operation is performed by controlling the voltage type self-exciting inverter with a constant voltage. The transformer comprises a detector of an output terminal voltage of the transformer, a three-phase / two-phase conversion circuit, and a vector analyzer. The output voltage angular velocity calculation unit that separates and outputs the angular velocity of the output terminal voltage into a valid component and a reactive component, the single load current detector, a three-phase two-phase conversion circuit, and a vector rotator Voltage angle The load current calculation unit that receives the output of the frequency calculation unit to the vector rotator and calculates and outputs the active and reactive components of the load current, and the voltage drop of the reactor due to the load current that is arranged on the output side of this load current calculation unit. Current-voltage conversion circuit for calculating and outputting the effective component and the ineffective component, and the absolute value of the output terminal voltage on the secondary side of the transformer is calculated and output from the output of the current-voltage conversion circuit and the output voltage of the inverter. And a proportional-plus-integral regulator that controls the voltage type self-exciting inverter with a constant voltage by using the output voltage of the vector analyzer as a detection voltage and the absolute value of the power system voltage as a set voltage.

The vector analyzer of the output voltage angular velocity calculation section has a pair of division circuits, a pair of multiplication circuits, each of which obtains an angular velocity from the effective component and the ineffective component of the output terminal voltage instantaneous value obtained by the three-phase / two-phase conversion circuit. And a circuit that is composed of an adder circuit and a proportional-plus-integral controller and that controls the operation of the pair of division circuits so that the sum of the squared values of the angular velocity obtained by the division circuit becomes 1.

The vector rotator of the load current calculation unit multiplies the active component of the output terminal voltage angular velocity and the reactive component of the load current, and the reactive component of the output terminal voltage angular velocity and the active component of the load current, respectively, in two pairs of multiplication circuits. And an addition circuit and a subtraction circuit for adding or subtracting the outputs of the pair of multiplication circuits to obtain the active component and the reactive component of the load current, respectively.

The current-voltage conversion circuit uses an effective component of the load current,
Four multiplication circuits for multiplying the reactive component and the resistance and inductance of the reactor to each other to convert into a voltage drop, and a pair of addition circuit and subtraction circuit arranged on the output side for obtaining the effective component and the reactive component of the voltage drop. Shall consist of

A vector analyzer arranged on the output side of the current-voltage conversion circuit calculates a multiplication circuit for each of the effective component, the ineffective component, and the inverter output voltage of the voltage drop and the multiplication value of the inverter output voltage. A subtraction circuit for subtracting the effective value multiplication value and the invalid value multiplication value of the voltage drop, a proportional-plus-integral controller arranged on the output side of the subtraction circuit and an input side of the voltage drop effective part multiplication circuit The output detection voltage of the proportional-plus-integral regulator is supplied to the addition circuit to control the output of the subtraction circuit to be zero, and the output voltage of the output terminal of the transformer is controlled according to the absolute value. It is assumed that it is formed so as to calculate a detection voltage to be applied.

A vector analyzer arranged on the output side of the current-voltage conversion circuit comprises a multiplication circuit for each of the effective and ineffective components of the voltage drop and a proportional-integral regulator for controlling the voltage type self-exciting inverter at a constant voltage. A gain-adjusted output voltage multiplication circuit, and a subtraction circuit that subtracts the effective value multiplication value and the invalid value multiplication value of the voltage drop from the multiplication value of the multiplication circuit,
A proportional-plus-integral controller arranged on the output side of the subtraction circuit and an adder circuit arranged on the input side of the multiplication circuit for the voltage drop effective component, and a proportional-plus-integral controller arranged on the output side of the subtraction circuit. An output detection voltage is supplied to the addition circuit so that the output of the subtraction circuit is controlled to be zero, and a detection voltage corresponding to the absolute value of the output end voltage on the transformer output side is calculated. To do.

[0012]

The structure of the present invention is equivalent to the output end voltage by subtracting the potential drop caused by the load current flowing through the reactor arranged on the output side from the output voltage of the voltage type self-exciting inverter. It is configured by focusing on the fact that the detection voltage of the proportional-plus-integral regulator can be obtained. Specifically, the output voltage angular velocity calculator calculates the detected value of the output end voltage and its angular velocity by dividing them into valid and ineffective components,
The load current calculator calculates the effective and ineffective components of the load current from the detected value of the load current and the angular velocity calculated by the output voltage angular velocity calculator, and the current-voltage conversion circuit calculates the effective and ineffective components of the reactor voltage drop due to the load current. It is possible to obtain the voltage equivalent to the absolute value of the target output end voltage by calculating the minutes and subtracting the voltage drop of the reactor from the output voltage of the inverter by the vector analyzer arranged on the output side. .. Therefore, if a constant voltage control circuit is configured to control the voltage type self-exciting inverter with a constant voltage using this voltage as the detection voltage of the proportional-plus-integral regulator and the absolute value of the power system voltage as the set voltage, the output terminal voltage The system can be operated independently while maintaining the system voltage and supplying electric power to a single load, and proportional to the voltage detected by the constant voltage control circuit that detects the system voltage change as a change in load current even after the system is connected in parallel. Since the constant voltage control of the inverter can be maintained without saturation of the integral regulator, the function of performing parallel insertion and disconnection into the system while maintaining the constant voltage control state without interruption is obtained.

In addition, the vector analyzer of the output voltage angular velocity calculation unit is provided with a pair of division circuits for obtaining the angular velocity from the effective component and the ineffective component of the output terminal voltage instantaneous value obtained by the three-phase / two-phase conversion circuit, respectively, and a pair of multiplication circuits. Circuit, an adder circuit, and a circuit that controls the operation of the pair of division circuits so that the sum of the squared values of the angular velocity obtained by the division circuit becomes 1 The function of extracting only the phase information necessary for the constant voltage control from the output terminal voltage can be obtained.

Further, the vector rotator of the load current calculation unit is provided with two pairs of a multiplier for the active component of the output end voltage angular velocity and a reactive component of the load current, and a product for multiplying the reactive component of the output end voltage angular velocity and the active component of the load current, respectively. By including a multiplication circuit and an addition circuit and a subtraction circuit for obtaining the active component and the reactive component of the load current by adding or subtracting the outputs of the pair of multiplication circuits respectively, the calculation result of the output voltage angular velocity calculation unit can be obtained. It is possible to obtain the function of separately calculating the load current flowing through the single load into its effective component and reactive component.

Next, the current-voltage conversion circuit is arranged on the output side of four multiplication circuits for converting the effective and ineffective components of the load current and the resistance and inductance of the reactor into each other and converting them into a voltage drop. It consists of a pair of adder circuit and subtractor circuit to obtain the effective and ineffective components of the voltage drop, so that the voltage drop caused by the load current flowing through the reactor placed on the output side of the inverter It is possible to obtain a function that separates and obtains the effective component in the same phase and the ineffective component orthogonal to this.

Further, the vector analyzer arranged on the output side of the current-voltage conversion circuit is provided with a multiplication circuit for each of the effective component, the ineffective component of the voltage drop and the inverter output voltage,
A subtraction circuit for subtracting the product value of the effective part of the voltage drop and the product value of the ineffective part from the product value of the inverter output voltage, the proportional-plus-integral controller and the effective part of the voltage drop arranged on the output side of the subtraction circuit. It consists of an adding circuit arranged on the input side of the multiplying circuit.The output detection voltage of this proportional-plus-integral regulator is supplied to the adding circuit to control the output of the subtracting circuit to zero, and to obtain the absolute value of the output terminal voltage. If it is configured to calculate the corresponding detection voltage, the voltage equivalent to the absolute value of the output terminal voltage can be obtained by calculation, so the obtained voltage is the absolute value of the detection voltage of the proportional-plus-integral regulator and the power system voltage. By performing constant voltage control of the voltage type self-exciting inverter using as a set voltage, it is possible to obtain a function of maintaining the constant voltage control state regardless of whether the load switch is ON or OFF and performing the isolated operation and the interconnection operation.

Further, the vector analyzer arranged on the output side of the current-voltage conversion circuit is provided with a proportional-integral control for controlling the voltage-dependent self-exciting inverter by a constant voltage, and a multiplication circuit for each of the effective and ineffective parts of the voltage drop. A multiplier circuit for the gain-adjusted output voltage of the converter, a subtracter circuit that subtracts the effective value and the ineffective value of the voltage drop from the product value of this multiplier circuit, and the subtractor circuit that is placed on the output side of this subtractor circuit. It is composed of a proportional-plus-integral controller and an adder circuit arranged on the input side of the multiplication circuit for the effective voltage drop, and supplies the output detection voltage of the proportional-plus-integral controller arranged on the output side of the subtraction circuit to the adder circuit. If the output of the subtraction circuit is controlled to zero and the detection voltage corresponding to the absolute value of the output end voltage on the transformer output side is configured to be calculated, the voltage is used instead of the output voltage of the voltage-type self-exciting inverter. Self-excited inverter control Since the voltage equivalent to the absolute value of the output terminal voltage can be calculated by using the input, the obtained voltage is used as the voltage detected by the proportional-plus-integral regulator and the absolute value of the power system voltage as the set voltage. By controlling the inverter with a constant voltage, it is possible to maintain the constant voltage control state regardless of whether the load switch is turned on or off, and perform the isolated operation and the interconnection operation.

[0018]

EXAMPLES The present invention will be described below based on examples. FIG. 1 is a block diagram showing the entire constant voltage control circuit of an inverter for independent / interconnection operation according to an embodiment of the present invention, and FIG. 2 is a detailed view showing a vector analyzer of an output voltage angular velocity calculation unit in the embodiment. 3 is a detailed view showing a vector rotator in the embodiment, FIG. 4 is a detailed view showing a current-voltage conversion circuit in the embodiment, FIG. 5 is a detailed view showing a vector analyzer in the embodiment, and FIG. 6 is a vector in the embodiment. In the drawings, the same components as those of the conventional technique are designated by the same reference numerals, and duplicate description will be omitted.

As shown in FIG. 1, the constant voltage control circuit comprises a detector 12 for the output voltage V _O on the secondary side of the transformer 4, a three-phase / two-phase conversion circuit 22, and a vector analyzer-23. From the output voltage angular velocity calculation unit 21 that separately calculates and outputs the angular velocity of the end voltage into the active component and the reactive component, the load current detector 32 of the individual load 5, the three-phase / two-phase conversion circuit 33, and the vector rotator 34. The load current calculation unit 3 receives the output of the output voltage angular velocity calculation unit 21 in the vector rotator and calculates and outputs the effective component and the invalid component of the load current I _L.
1 and the load current I which is arranged on the output side of the load current calculation unit.
The voltage drop of the reactor 3 due to _L is divided into an effective component and an ineffective component, and is calculated and output, and the output of this current-voltage conversion circuit and the voltage detector 16 and the rectification circuit 17 Output voltage V _I of the inverted inverter 1
A vector analyzer -51 to calculates the absolute value equivalent to voltage V _OD of output voltage V _O output from the vector analyzer - the detected voltage a voltage V _OD of, via the voltage detector 14 and the rectifier circuit 15 to obtain Voltage type self-exciting inverter 1 using the absolute value of the system voltage V _S of the power system 7 to be set as the set voltage.
And a proportional-plus-integral adjuster 11 for controlling the constant voltage of.

In the constant voltage control circuit according to the embodiment configured as described above, the detection voltage V of the proportional-plus-integral controller 11 is detected.
_Since the arithmetic circuit is configured to obtain the voltage drop that occurs in the reactor 3 due to the load current I _L by subtracting it from the absolute value of the output voltage V _I of the inverter 1, the absolute value of the output end voltage is proportional. was a problem in the conventional constant voltage control circuit to detect the voltage of the integral controller, a problem that the proportional integral controller is saturated by lines parallel input is eliminated, variations and communicating the output voltage V _O in the islanding operation The fluctuation of the system voltage V _S in the system operation is detected by the change of the phase information thereof, the change of the active component and the reactive component of the load current I _L of the individual load 5, the constant voltage control state is maintained, and the power interruption occurs. It is possible to obtain a constant voltage control circuit for an inverter for independent / coupling operation that can perform parallel insertion and parallel disconnection into the system without any operation.

The configuration and operation of the arithmetic circuit of the main part of the constant voltage control circuit according to the embodiment will be described below. Vector analyzer of output voltage angular velocity calculator 21
As shown in FIG. 2, the reference numeral 23 designates a reactive component V _O sin ωt and an effective component V _O cos ωt of the instantaneous value of the output end voltage V _O obtained by the three-phase / two-phase conversion circuit 22 as a voltage V equivalent to V _{O. A} pair of division circuits 24 and 25 that obtain phase information of angular velocities sin ωt and cos ωt by division by _oB , multiplication circuits 26 and 27 that square the phase information, an addition circuit 28 of the multiplication result, and a set value It is composed of the proportional-plus-integral controller 29 set to 1, and si
n ² ωt + cos ² ωt = 1 is used to output a voltage V _OB equivalent to V _O toward a divider circuit, and only phase information of the output end voltage V _O is used. As a result, it is possible to obtain a function of separating the constant voltage control circuit from the output end voltage V _O and performing the calculation.

Vector rotator 34 of load current calculator 31
3, as shown in FIG. 3, a pair of multiplication circuits 35A and 35B provided corresponding to the phase information sin ωt and cos ωt obtained by the vector analyzer-23, and an addition circuit 37 for adding the calculation results of both, The reactive component I _L sin (ωt− of the instantaneous value of the load current I _L obtained by the three-phase / two-phase conversion circuit 33.
θ), a pair of multiplication circuits 36A and 36B provided corresponding to the effective component I _L cos (ωt −θ), and a subtraction circuit 38 for subtracting the calculation results of both, and the effective output voltage angular velocity By multiplying each of the minute and the load current instantaneous value reactive component, and the output terminal voltage angular velocity reactive component and the load current instantaneous value active component by the multiplication circuit, respectively, and then adding or subtracting the outputs of the pair of multiplication circuits, respectively. A function of obtaining the effective component I _L cos θ and the reactive component I _L sin θ of the load current I _L can be obtained.

The current-voltage conversion circuit 41 includes a pair of multiplication circuits 42R, 42R, which calculate the product of the effective component I _L cos θ = I α of the load current calculated by the vector rotator 34 and the resistance R and the inductance L of the reactor 3. and 42L, the reactive component I _L sin θ = Iβ and R, a pair of multiplying circuit for calculating the product of the L 43R load current, 43L and the effective amount V of a voltage drop
Subtraction circuit 44 for obtaining α, and reactive component Vβ of voltage drop
Is composed of an adding circuit 45 for obtaining the load current I _L voltage drop its active component a generated in the reactor by flowing through the reactor 3 _V.alpha, the function of obtaining by separating the reactive component Vβ obtained.

The vector analyzer 51 provided at the final stage of the arithmetic circuit has a circuit configuration shown in FIG. 5 and an output voltage V _I of the voltage type self-exciting inverter 1 and a potential as shown in the vector diagram of FIG. Multiplying circuits (square circuits) 52, 53, 54 for the effective component Vα and the ineffective component Vβ of the descent, and the multiplying circuit 52, respectively.
Of the subtraction circuit 55 for subtracting the multiplication values of the multiplication circuits 53 and 54 from the multiplication value of, and the output voltage V _OD arranged on the output side of the subtraction circuit 55 as a detection signal to the proportional-plus-integral regulator 11 in FIG. , And a proportional-plus-integral regulator 56 which sends the sum to the adder circuit 57 arranged on the input side of the multiplier circuit 54 and adds it to the effective component Vα of the voltage drop. In the vector analyzer-51 configured as described above, the multiplication circuit and the subtraction circuit perform an operation of V _I ² −Vβ ² − (Vα + V _OD ) ² , and the proportional-plus-integral regulator 56 calculates the result of the above equation. There by controlling the output voltage V _OD to be zero, as is clear from the vector diagram shown in FIG. 6, the output terminal voltage V _O of the transformer 4 to the output side in FIG. 1 of the proportional integral controller 56 A voltage V _OD corresponding to the absolute value of is output. Therefore, the obtained voltage V _{OD is set} to the proportional-integral regulator 1
The voltage-type self-exciting inverter 1 is subjected to constant voltage control with a voltage corresponding to the detected voltage of No. 1 and the absolute value V _S of the power system voltage as the set voltage V _SS , thereby controlling the constant voltage regardless of whether the load switch is turned on or off. It is possible to carry out independent operation and interconnection operation while maintaining the state.

FIG. 7 is a block diagram showing another embodiment of the vector analyzer provided at the final stage of the arithmetic circuit,
The output voltage V _I of the voltage type self-exciting inverter 1 is applied to the multiplication circuit 62.
5 is different from that of the embodiment shown in FIG. 5 in that the output control signal V _IC of the proportional-plus-integral controller 11 is adjusted in gain by the amplifier circuit 63 and input. Proportional integral controller 1
Since the output control signal V _IC of No. 1 is proportional to the output voltage V _I of the voltage type self-exciting inverter 1, the same operation and effect as already described with reference to FIG. 5 can be obtained.

[0026]

As described above, according to the present invention, the output voltage angular velocity calculation unit calculates the angular velocity of the output terminal voltage into the effective component and the invalid component, and the load current calculation unit calculates the load current detected value and the output voltage angular velocity. The active and reactive components of the load current are calculated from the angular velocity obtained by the computing unit, and the active and reactive components of the reactor voltage drop due to the load current are calculated by the current-voltage conversion circuit, and the vector analyzer placed on the output side −
By subtracting the voltage drop of the reactor from the output voltage of the inverter, the detection voltage equivalent to the absolute value of the target output end voltage is obtained. As a result, it becomes possible to control the voltage type self-exciting inverter with a constant voltage by using the obtained voltage as the detection voltage of the proportional-plus-integral regulator and the absolute value of the power system voltage as the set voltage, and the output terminal voltage as the power system voltage. It is possible to perform independent operation to supply power to a single load by holding the power supply at the same time, and proportionally-integral adjustment based on the detected voltage of the constant voltage control circuit that captures the change in system voltage as a change in load current even after the system is connected in parallel. Since the constant voltage control of the inverter is maintained without saturation of the voltage regulator, there was a problem in the conventional technique of controlling the voltage type self-exciting inverter with constant voltage by using the output terminal voltage as the detection voltage of the proportional-plus-integral regulator. , The problem that the proportional-plus-integral regulator is saturated when the system is connected in parallel is eliminated, and the system is equipped with a constant voltage control circuit that can continuously supply power while maintaining a constant voltage control state for system interconnection operation. Inverter for driving It is possible to provide a. Further, since the constant current control circuit and its switching device are not required, the device can be simplified, and instantaneous interruption of the power supply that occurs at the time of switching can be eliminated, so that the power supply can be stabilized.

In addition, the vector analyzer of the output voltage angular velocity calculation unit is provided with a pair of division circuits for obtaining the angular velocity from the effective component and the ineffective component of the output terminal voltage instantaneous value obtained by the three-phase / two-phase conversion circuit, respectively, and a pair of multiplication circuits. Circuit, an adder circuit, and a circuit that controls the operation of the pair of division circuits so that the sum of the squared values of the angular velocity obtained by the division circuit becomes 1 It is possible to provide a constant voltage control circuit provided with a vector analyzer having a function of extracting only phase information necessary for the constant voltage control from the output terminal voltage.

Further, the vector rotator of the load current calculation unit is provided with two pairs of a product that multiplies the active component of the output end voltage angular velocity and the reactive component of the load current, and the reactive component of the output end voltage angular velocity and the active component of the load current, respectively. By including a multiplication circuit and an addition circuit and a subtraction circuit for obtaining the active component and the reactive component of the load current by adding or subtracting the outputs of the pair of multiplication circuits respectively, the calculation result of the output voltage angular velocity calculation unit can be obtained. It is possible to provide a constant voltage control circuit provided with a vector rotator having a function of separately utilizing the load current flowing in a single load into its effective component and its ineffective component.

Next, the current-voltage conversion circuit is arranged on the output side of four multiplication circuits for converting the effective and ineffective components of the load current and the resistance and inductance of the reactor into each other to convert them into a voltage drop. It consists of a pair of adder circuit and subtractor circuit to obtain the effective and ineffective components of the voltage drop, so that the voltage drop caused by the load current flowing through the reactor placed on the output side of the inverter It is possible to provide a constant voltage control circuit provided with a current-voltage conversion circuit having a function of separately obtaining an effective component having the same phase and an ineffective component orthogonal thereto.

Further, a vector analyzer arranged on the output side of the current-voltage conversion circuit is provided with a multiplication circuit for each of the effective component, the ineffective component of the voltage drop and the inverter output voltage,
A subtraction circuit for subtracting the product value of the effective part of the voltage drop and the product value of the ineffective part from the product value of the inverter output voltage, the proportional-plus-integral controller and the effective part of the voltage drop arranged on the output side of the subtraction circuit. It consists of an adder circuit arranged on the input side of the multiplier circuit, supplies the output detection voltage of the proportional-plus-integral controller to the adder circuit, and controls so that the output of the subtractor circuit becomes zero. Since the detection voltage corresponding to the absolute value of is calculated, a voltage equivalent to the absolute value of the output voltage can be obtained by calculation. By controlling the voltage type self-exciting inverter with a constant voltage using the absolute value of the system voltage as a set voltage, a function to maintain a constant voltage control state regardless of whether the load switch is turned on or off and to perform independent operation and interconnection operation is provided. Having a constant current It is possible to provide a control circuit.

Further, a vector analyzer arranged on the output side of the current-voltage conversion circuit is provided with a multiplication circuit for each of effective and ineffective portions of the voltage drop and a proportional-plus-integral adjustment for constant voltage control of the voltage type self-exciting inverter. A gain-adjusted output voltage multiplication circuit, a subtraction circuit that subtracts the effective value multiplication value and the invalid value multiplication value of the voltage drop from the multiplication value of the multiplication circuit, and the subtraction circuit that is provided at the output side of the subtraction circuit. And an adder circuit arranged on the input side of the multiplication circuit for the effective portion of the voltage drop, and supplies the output detection voltage of the proportional-plus-integral controller arranged on the output side of the subtraction circuit to the adder circuit. If the output voltage of the subtraction circuit is controlled to zero and the detection voltage corresponding to the absolute value of the output end voltage is calculated, the voltage type self-excited inverter is used instead of the output voltage of the voltage type self-excited inverter. −
Since the voltage equivalent to the absolute value of the output end voltage can be calculated by using the control input of the controller, the obtained voltage is used as the detected voltage of the proportional-plus-integral regulator and the absolute value of the power system voltage as the set voltage. It is possible to provide a constant voltage control circuit having a function of maintaining a constant voltage control state regardless of whether the load switch is turned on or off and performing an isolated operation and an interconnected operation by controlling the constant voltage of the self-exciting inverter of the type. it can.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing a constant voltage control circuit for an independent / interconnection operation inverter according to an embodiment of the present invention.

FIG. 2 is a detailed diagram showing a vector analyzer of an output voltage angular velocity calculation unit in the embodiment.

FIG. 3 is a detailed view showing a vector rotator in the embodiment.

FIG. 4 is a detailed diagram showing a current-voltage conversion circuit according to an embodiment.

FIG. 5 is a detailed diagram showing the vector analyzer at the final stage of the arithmetic circuit in the embodiment.

FIG. 6 is a vector diagram in an example.

FIG. 7 is a configuration diagram showing a different embodiment of a vector analyzer provided at the final stage of an arithmetic circuit.

FIG. 8 is a connection diagram showing a constant voltage control circuit of a conventional independent / interconnection operation inverter.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Voltage type self-exciting inverter 2 Single power source 3 Reactor 4 Transformer 5 Single load 6 Load switch 7 AC power system 11 Proportional integral regulator 12 Detector of output end voltage V _O 14 Detector of system voltage V _S 15 Rectifier circuit 16 Detector of output voltage V _I of voltage type self-exciting inverter 17 Rectifier circuit 21 Output voltage angular velocity calculation unit 22 3-phase 2-phase conversion circuit 23 Vector analyzer-31 Load current calculation unit 32 3-phase 2-phase conversion circuit 33 vector rotation unit 41 current-voltage conversion circuit 51 vector analyzer - V _OD detection voltage V _SS set voltage V _IC voltage type self-excited inverter (final stage of the operation circuit) - the active component of the other control input I _F load current Vα voltage drop Vβ voltage drop invalid component

Claims (6)

[Claims] 1. An independent operation in which a voltage type self-exciting inverter for converting DC output of an independent power source into AC is controlled to supply electric power to an isolated load connected to the output side through a reactor and a transformer. And the interconnection operation for controlling the active power and the reactive power to transfer the power to and from the power system connected via the switch, the constant voltage control of the voltage type self-exciting inverter. According to the method described above, the output terminal voltage detector of the transformer, a three-phase to two-phase conversion circuit, and a vector analyzer are used to separate the angular velocity of the output terminal voltage of the transformer into an effective component and a reactive component. The output voltage angular velocity calculation unit, a current detector for the single load, a three-phase to two-phase conversion circuit, and a vector rotator are provided, and the output of the output voltage angular velocity calculation unit is received by the vector rotator to obtain an effective load current component. And A load current calculation unit that calculates and outputs the reactive component, a current-voltage conversion circuit that is arranged on the output side of the load current calculation unit and that calculates and outputs the effective component and the reactive component of the voltage drop of the reactor due to the load current, and A vector analyzer that calculates and outputs the absolute value of the output terminal voltage of the transformer from the output of the current-voltage conversion circuit and the output voltage of the inverter, and the output voltage of this vector analyzer is the detection voltage, the power system voltage. And a proportional-plus-integral controller for controlling the voltage type self-exciting inverter with a constant voltage by using the absolute value of the voltage as a set voltage.
Constant voltage control circuit. 2. A pair of division circuits, and a pair of multiplication circuits, in which the vector analyzer of the output voltage phase calculation unit respectively obtains the angular velocity from the effective component and the ineffective component of the output end voltage instantaneous value obtained by the three-phase / two-phase conversion circuit. Of the angular velocity obtained by the division circuit, which is composed of a circuit, an addition circuit, and a proportional-plus-integral controller.
2. A constant voltage control circuit for an inverter for independent / interconnection operation according to claim 1, further comprising a circuit for controlling the operation of the pair of division circuits so that the sum of power values becomes 1. 3. A pair of vector rotators of the load current calculation unit multiply the active component phase of the output end voltage and the reactive component of the load current, and the reactive component phase of the output end voltage and the active component of the load current, respectively. The isolated / interconnected operation according to claim 1, further comprising: a multiplication circuit; and an addition circuit and a subtraction circuit that add or subtract outputs of a pair of multiplication circuits to obtain an active component and a reactive component of the load current. Constant voltage control circuit for inverter. 4. The current-voltage conversion circuit comprises an effective component of load current,
Four multiplication circuits for multiplying the reactive component and the resistance and inductance of the reactor with each other to convert into a potential drop, and a pair of adder and subtraction circuits arranged on the output side thereof to obtain the effective component and the reactive component of the potential drop. The invertor for independent / interconnection operation according to claim 1, characterized in that
Constant voltage control circuit. 5. A vector analyzer arranged on the output side of the current-voltage conversion circuit comprises a multiplication circuit for each of the effective component, the ineffective component, and the inverter output voltage of the potential drop, and the multiplication of the inverter output voltage. A subtraction circuit for subtracting the effective value multiplication value and the invalid value multiplication value of the potential drop from the value, and a proportional-plus-integral controller arranged at the output side of this subtraction circuit and an input side of the potential drop effective part multiplication circuit. And the output detection voltage of the proportional-plus-integral regulator is supplied to the addition circuit to control the output of the subtraction circuit to zero, and the absolute value of the output end voltage of the transformer output side. 2. The constant voltage control circuit for an inverter for independent / interconnection operation according to claim 1, wherein the constant voltage control circuit is formed so as to calculate a detection voltage corresponding to. 6. A proportional-integral control in which a vector analyzer arranged on the output side of the current-voltage conversion circuit controls the voltage drop self-exciting inverter by a constant voltage, and a multiplication circuit for each of the effective and ineffective parts of the potential drop. A gain-adjusted output voltage multiplier circuit, and a subtraction circuit for subtracting the effective value multiplication value and the invalid value multiplication value of the potential drop from the multiplication value of the multiplication circuit,
A proportional-plus-integral controller arranged on the output side of the subtraction circuit and an adder circuit arranged on the input side of the multiplication circuit for the potential drop effective component, and a proportional-plus-integral controller arranged on the output side of the subtraction circuit. An output detection voltage is supplied to the addition circuit to control the output of the subtraction circuit to zero, and a detection voltage corresponding to the absolute value of the output end voltage of the transformer output side is calculated. The constant voltage control circuit of the inverter for independent / interconnection operation according to claim 1.