JP7194139B2 - Power control method for three-phase or single-phase power converter - Google Patents

Description

The present invention relates to a method for controlling power supplied to a commercial power system to which power converters such as UPFC and self-commutated BTB are connected.

Conventionally, active power and reactive power are generated between the commercial power system by connecting an inverter to the commercial power system such as UPFC and self-commutated BTB and supplying a predetermined current from the inverter to the commercial power system. Flexible power converters are known. (See Non-Patent Document 1 below).

Verification research on new power network system Comprehensive research on new power network technology Progress report [Part 1] Progress report on verification research on power network technology March 2006 The Institute of Advanced Energy

FIG. 7 shows an example of a block diagram of these power converters. The power converter X is connected to a three-phase commercial power system, and the output current detector 101 detects the instantaneous values (iofu, iofv, iofw) of the three-phase output current of the power converter X using the current detection transformer 102. , a current instantaneous value vector <iof>uvw whose components are the instantaneous values (iofu, iofv, iofw), and is output to the αβ conversion unit 103 .

Further, the system voltage detection unit 104 detects the instantaneous values (vofu, vofv, vofw) of the voltage of the three-phase commercial power system to which the power converter X is connected by the voltage detection transformer 105, and detects the instantaneous values (vofu, vofv). , vofw) is output to the αβ conversion unit 106 .

The αβ transforming unit 103 coordinates the inputted current instantaneous value vector <iof>uvw to a vector <iof>ab of equivalent two-phase currents (α-phase current iofa, β-phase current iofb) (where the zero phase is 0) and outputs it to active power calculation section 107 and reactive power calculation section 108 .

Further, in the αβ conversion unit 106, the input voltage instantaneous value vector <vof>uvw is coordinate-converted into a vector <vof>ab of equivalent two-phase voltages (α-phase voltage vofa, β-phase voltage vofb) (where zero The phase is 0), and it is output to the active power calculator 107 and the reactive power calculator 108 .

Active power calculator 107 calculates instantaneous value p3f of active power from the inner product of output <iof>ab of αβ converter 103 and output <vof>ab of αβ converter 106 .

Further, reactive power calculation section 108 calculates instantaneous value q3f of reactive power from the outer product of output <iof>ab of αβ conversion section 103 and output <vof>ab of αβ conversion section 106 .

Alternatively, as shown in FIG. 8A, the active power calculation unit 107 calculates the active power from the inner product of the output vector <iof>uvw of the output current detection unit 101 and the output vector <vof>uvw of the system voltage detection unit 104. The instantaneous value p3f can also be calculated, and the reactive power calculation unit 108 calculates the instantaneous value of the reactive power from the outer product of the output vector <iof>uvw of the output current detection unit 101 and the output vector <vof>uvw of the system voltage detection unit 104. It is also possible to calculate the value q3f.

As another method, the output vector <iof>ab of the αβ converter 103 is converted by the γδ converter 109 into equivalent two-phase currents (γ-phase current iofg, δ-phase The output vector <vof>ab of the current iofd) is converted into a vector <iof>gd of the current iofd), and the output vector <vof>ab of the αβ conversion unit 106 is converted by the γδ conversion unit 110 into equivalent two-phase voltages (γ-phase voltage vofg, δ-phase voltage vofd). After the coordinate transformation to the vector <vof>gd of , each output is output to the active power calculation unit 107 and the reactive power calculation unit 108, and the active power calculation unit 107 converts the output vector <iof>gd of the γδ conversion unit 109 and the inner product of the output vector <vof>gd of the γδ conversion unit 110, the instantaneous value p3f of the active power is calculated. The instantaneous value q3f of the reactive power may be calculated from the cross product of the vector <vof>gd.

Regardless of which method is adopted, the instantaneous value p3f of the active power calculated by the active power calculator 107 and the instantaneous value q3f of the reactive power calculated by the reactive power calculator 108 are the same value. When the system voltage and the output current are three-phase symmetric sinusoidal waves, both the instantaneous value p3f of the active power and the instantaneous value q3f of the reactive power have only DC components (converted to DC). If it is not a three-phase symmetric sine wave, harmonic components will appear.

The instantaneous value p3f of the active power calculated by the active power calculator 107 is output to the summing point 111 . A target active power command value pr is input to the addition point 111 , and the difference is calculated and output to the low-pass filter 112 .

On the other hand, the reactive power instantaneous value q3f calculated by the reactive power calculator 108 is output to the summing point 113 . A target reactive power command value qr is input to the addition point 113 , and the difference is output to the low-pass filter 114 .

If the power system contains a reverse phase component or a harmonic component, ripples (harmonics) are generated in the active power p3f and the reactive power q3f. The outputs of low-pass filters 112 and 114 are output to active power (γ-phase) control system compensator 115 and reactive power (δ-phase) control system compensator 116 .

Active power (γ-phase) control system compensator 115 and reactive power (δ-phase) control system compensator 116 are PI controllers, and output current command values iorg and iord to limit processor 117 . In the limit processing unit 117, as shown in FIG. 9, ior'g (=k·iorg) which is equal to or less than the output current command value limit Iorl and ior'd (=k·iord) which is equal to or less than the output current command value limit Iorl ).

When the limit processing unit 117 limits the output current command values iorg and iord of the compensators 115 and 116, anti-reset windup processing is performed to properly adjust the output of each unit constituting the compensators 115 and 116. to improve the response of the compensator (make the output of the compensator change immediately).

ior'g and ior'd calculated by the limit processing unit 117 are output to the decoupling unit 118 . The non-interfering section 118 performs processing for preventing interference with a current output section, which will be described later, due to the conversion performed by the inverse γδ converting section 119 shown in FIG. 7 . The output of non-interference unit 118 is subjected to inverse γδ conversion and inverse αβ conversion in inverse γδ conversion unit 119 and inverse αβ conversion unit 120, and current It is output to the output unit 121 .

The current output unit 121 operates the output current of the power converter X according to the output current command values ioru and iorv. Active power p and reactive power q are controlled by the above.

According to the power control method for the three-phase power converter described above, the power system can be controlled by directly feedback-controlling the active power p and the reactive power q.

However, the active power p and the reactive power q are expressed as p=w·cos φ and q=w·sin φ using the apparent power w and the power factor angle φ. If only the power p is to be changed, it is necessary to control both the apparent power w and the power factor angle φ. That is, since the active power p and the reactive power q are not independent variables, there is a problem of interference between the active power control system and the reactive power control system.

Therefore, the present invention provides a power control method for a three-phase or single-phase power converter that can avoid the problem of interference between the active power control system and the reactive power control system by using essentially independent parameters.

The power control method for a three-phase or single-phase power converter according to claim 1 has the following features. Active power p and reactive power q are measured from the voltage of the commercial power system to which the power converter is connected and the output current of the power converter. A power feedback vector having p and q as xy coordinate components is formed, and the vector is reversely rotated (-φr rotated) by the power factor angle target value φr (rotational coordinate conversion). Feedback control is performed using the xy coordinate components of the vector obtained by reverse rotation. The apparent power is feedback-controlled with the apparent power target value wr and the x-coordinate component of the vector obtained by the reverse rotation. The power factor angle is feedback-controlled with a command value of 0 and a value obtained by dividing the y-coordinate component of the vector obtained by the reverse rotation by the length of the vector. The apparent power target value wr and the power factor angle target value φr are obtained from the active power target value pr and the reactive power target value qr by the following equation (1). It is characterized by controlling p and q by these.
formula (1)
wr = ( ^pr2 + ^qr2 ) ^1/2
φr = tan ^-1 (qr/pr), where φr is -π to π[rad]

The power control method for a three-phase power converter according to claim 2 has the following features. 2. The power control method according to claim 1 , wherein when controlling the active power p and the reactive power q using a power converter connected to a three-phase commercial power system, the instantaneous voltage of the system voltage at the connection point of the power converter A voltage instantaneous value vector <vof>uvw whose components are the values vofu, vofv, and vofw, and a current instantaneous value vector <iof>uvw whose components are the instantaneous values iofu, iofv, and iofw of the three-phase output current of the power converter are Configure. An instantaneous value p3f of the active power is obtained from the inner product of the two instantaneous value vectors, and an instantaneous value q3f of the reactive power is obtained from the outer product of the two instantaneous value vectors. The power feedback vector according to claim 1 is configured with these p3f and q3f as xy coordinate components. Furthermore, after limiting the output of the two feedback control system compensators according to claim 1 , the command value vector in the γδ space of the output current of the power converter or the output voltage of the inverter constituting the power converter Let it be magnitude and phase. After decoupling the xy coordinate components of this command value vector, each component of the vector obtained by inverse γδ conversion and inverse αβ conversion is converted to the U-phase, V-phase, and W-phase output current command values of the power converter or An output voltage command value for the inverter. It is characterized by controlling p and q by manipulating the output current of the power converter or the output voltage of the inverter according to the three-phase command values.

A power control method for a three-phase power converter according to claim 3 has the following features. In the power control method according to claim 2 , the voltage instantaneous value vector <vof>uvw and the current instantaneous value vector <iof>uvw are subjected to αβ conversion. The instantaneous value p3f of the active power is obtained from the inner product of the vector <vof>ab obtained by αβ-transforming <vof>uvw and the vector <iof>ab obtained by αβ-transforming <iof>uvw, and <vof>ab and <iof>ab, the instantaneous value q3f of the reactive power is obtained. It is characterized by constructing a power feedback vector using these p3f and q3f as xy coordinate components.

A power control method for a three-phase power converter according to claim 4 has the following features. In the power control method according to claim 3 , the voltage instantaneous value vector <vof>ab and the current instantaneous value vector <iof>ab in the αβ space are γδ-converted. The instantaneous value p3f of the active power is obtained from the inner product of the vector <vof>gd obtained by γδ-converting <vof>ab and the vector <iof>gd obtained by γδ-converting <iof>ab, and <vof>gd and <iof>gd, the instantaneous value q3f of the reactive power is obtained. It is characterized by constructing a power feedback vector using these p3f and q3f as xy coordinate components.

A power control method for a single-phase power converter according to claim 5 has the following features. 2. The power control method according to claim 1, wherein when controlling the active power p and the reactive power q using a power converter connected to a single-phase commercial power system, the instantaneous voltage of the system voltage at the connection point of the power converter The product of the value and the instantaneous value of the output current (first product) is input to the first LPF (low pass filter). Alternatively, the first product is moving averaged (first moving average). Let the output of the first LPF or the value of the first moving average be active power p1f. Also, the product (second product) of the instantaneous value of the system voltage one-fourth cycle before and the instantaneous value of the output current is input to the second LPF. Alternatively, the second product is moving averaged (second moving average). Let the output of the second LPF or the value of the second moving average be reactive power q1f. The power feedback vector according to claim 1 is configured with these p1f and q1f as xy coordinate components. Furthermore, after limiting the output of the two feedback control system compensators according to claim 1 , the command value vector in the γδ space of the output current of the power converter or the output voltage of the inverter constituting the power converter Let it be magnitude and phase. After decoupling the xy coordinate components of the command value vector, the x coordinate component of the vector obtained by inverse γδ transformation is used as the output current command value of the power converter or the output voltage command value of the inverter. It is characterized by controlling p and q by manipulating the output current of the power converter or the output voltage of the inverter according to this command value.

A power control method for a three-phase or single-phase power converter according to claim 6 has the following features. In the power control method according to any one of claims 1 to 5 , the output limit processing of the compensator (γ-phase compensator) of the apparent power feedback control system (γ-phase control system) is limited by upper and lower limits. by doing. The output limit processing of the compensator (δ-phase compensator) of the power factor angle feedback control system (δ-phase control system) is such that when the output exceeds the range of ±π [rad], the output is adjusted to ±2π [rad ] (-2π [rad] is added when the output exceeds π [rad], and 2π [rad] is added when the output falls below -π [rad]). Furthermore, it is characterized in that, when the compensator output is limited, anti-reset windup processing is performed on the compensator that has been limited.

According to the invention of claims 1 and 2 , it is possible to perform power control using the apparent power and the power factor angle that are essentially independent, thereby avoiding the problem of interference between the active power control system and the reactive power control system. Power control becomes possible.

Furthermore, complicated limit processing combining the outputs of the γ-phase and δ-phase compensators becomes unnecessary, and the limit processing can be independent and simplified.

According to the inventions of claims 3 and 4 , the three-phase active and reactive powers can be obtained even by using the voltages and currents after the αβ conversion and the γδ conversion. can.

According to the inventions of claims 1 and 5 , it is possible to control power using essentially independent apparent power and power factor angle, and a single-phase power control system that avoids the problem of interference between the active power control system and the reactive power control system. Power control becomes possible. Furthermore, complicated limit processing combining the outputs of the γ-phase and δ-phase compensators becomes unnecessary, and the limit processing can be independent and simplified.

According to the sixth aspect of the present invention, limit processing of the γ-phase control system compensator prevents the magnitude of the current command value vector and the voltage command value vector from becoming excessively large, and problems due to overcurrent and overvoltage occur. You can definitely prevent it from happening. Also, by limiting the output of the δ-phase control system compensator, the phases of the current command value vector and the voltage command value vector are always within the range of ±π [rad], preventing the phase from becoming an excessive value. Furthermore, by performing anti-reset windup processing on each compensator, when the output of the compensator is limited, the output of each part that composes the compensator can be appropriately changed, and the output of the compensator can be immediately restored. It can be made to change, improving the response of the control system.

It is a control block diagram of the three-phase power converter of the present invention. FIG. 4 is a diagram illustrating a method of obtaining the magnitude of the feedback vector (apparent power wf) and the phase difference (deviation Δφ of the power factor angle) between the feedback vector and the target vector from the power feedback vector and the target vector in the three-phase power converter of the present invention; . FIG. 10 is an explanatory diagram of limit processing of an output voltage command value or an output current command value in the three-phase power converter of the present invention; FIG. 4 is a control block diagram of a three-phase power converter according to another embodiment of the present invention; It is a control block diagram of the single-phase power converter of the present invention. FIG. 5 is a control block diagram of a single-phase power converter according to another embodiment of the present invention; FIG. 3 is a control block diagram of a conventional three-phase power converter; FIG. 4 is a control block diagram illustrating a method of calculating active power and reactive power in a conventional three-phase power converter; FIG. 10 is an explanatory diagram of limit processing of an output current command value in a conventional three-phase power converter;

An embodiment of the present invention will be described below with reference to FIGS. 1 to 6. FIG. FIG. 1 is a power control block diagram of a three-phase power converter A according to the present invention.

In FIG. 1, reference numeral 1 denotes an output current detector, which detects instantaneous values (iofu, iofv, iofw) of the three-phase output current of the power converter A from the current detection transformer 2, and detects the instantaneous values (iofu, iofv, iofw) as a component, and outputs the current instantaneous value vector <iof>uvw to the αβ conversion unit 3 .

Reference numeral 4 denotes a system voltage detection unit that detects instantaneous values (vofu, vofv, vofw) of the voltage of the three-phase commercial power system to which the power converter A is connected from the voltage detection transformer 5, and detects the instantaneous values (vofu, vofv, vofw) as components, and outputs the voltage instantaneous value vector <vof>uvw to the αβ conversion unit 6 .

In the αβ conversion unit 3, the input instantaneous value vector <iof>uvw of the three-phase output current is coordinate-converted into a vector <iof>ab of equivalent two-phase currents (α-phase current iofa, β-phase current iofb) (where , the zero phase is 0), and it is output to the active power calculator 7 and the reactive power calculator 8 .

In the αβ conversion unit 6, the input instantaneous value vector <vof>uvw of the three-phase system voltage is coordinate-converted into a vector <vof>ab of equivalent two-phase voltages (α-phase voltage vofa, β-phase voltage vofb) (where , the zero phase is 0), and it is output to the active power calculator 7 and the reactive power calculator 8 .

The active power calculator 7 calculates an instantaneous value p3f of active power by the vector inner product of the output <iof>ab of the αβ converter 3 and the output <vof>ab of the αβ converter 6 .

Reactive power calculator 8 calculates an instantaneous value q3f of reactive power from the vector product of the output <iof>ab of αβ converter 3 and the output <vof>ab of αβ converter 6 .

Alternatively, as in the case of FIG. 8A described above, the active power calculation unit 7 calculates from the inner product of the vector of the output <iof>uvw of the output current detection unit 1 and the output <vof>uvw of the system voltage detection unit 4 An instantaneous value p3f of active power may be calculated. Further, the reactive power calculator 8 may calculate the instantaneous value q3f of the reactive power from the vector product of the output <iof>uvw of the output current detector 1 and the output <vof>uvw of the system voltage detector 4 .

As another method, as described with reference to FIG. Phase current iofd) is coordinate-transformed into a vector <iof>gd, and the output <vof>ab of the αβ converter 6 is converted by the γδ converter 110 into equivalent two-phase voltages (γ-phase voltage vofg, δ-phase voltage vofd). , and the respective outputs are output to the active power calculator 7 and the reactive power calculator 8, and the active power calculator 7 converts the output <iof>gd of the γδ converter 109 and The instantaneous value p3f of the active power is calculated from the vector inner product of the output <vof>gd of the γδ conversion unit 110, and the reactive power calculation unit 8 calculates the output <iof>gd of the γδ conversion unit 109 and the output < The instantaneous value q3f of the reactive power can also be calculated from the outer product of vectors with vof>gd.

Regardless of which method is adopted, the instantaneous value p3f of the active power calculated by the active power calculation unit 7 and the instantaneous value q3f of the reactive power calculated by the reactive power calculation unit 8 are the same value. When the output current is a three-phase symmetric sine wave, both the instantaneous value p3f of the active power and the instantaneous value q3f of the reactive power are DC components.

The instantaneous value p3f of active power calculated by the active power calculator 7 and the instantaneous value q3f of reactive power calculated by the reactive power calculator 8 are output to the coordinate rotator 11 . In other words, a power feedback vector is configured with the input instantaneous value p3f of the active power and the input instantaneous value q3f of the reactive power as xy coordinate components (γδ coordinate components in FIG. 2).

The coordinate rotation unit 11 reversely rotates (-φr rotation) the power feedback vector by the power factor angle φr of the target power vector. That is, the γ phase component (γ phase feedback value) pf′ and the δ phase component qf′ shown in FIG. 1 are calculated. Here, coordinate rotation will be described. First, the relationship between the polar coordinate component (wf, φf) and the xy coordinate component (p3f, q3f) of the power feedback vector is described as [Formula 1].

The relationship between the polar coordinate components (wr, φr) and the xy coordinate components (pr, qr) of the target power vector is described as [Formula 2]. Here, wr is the magnitude of the target power vector (target value of apparent power), and φr is the phase of the target vector (target value of power factor angle). Also, pr is an active power target value, and qr is a reactive power target value.

The xy coordinate components (pf', qf') of the vector obtained by coordinate-rotating the feedback vector by -φr can be calculated by [Equation 3].

Near the operating point, Δφ≈0, so cos Δφ≈1, sin Δφ≈Δφ, and pf′ and qf′ are approximately obtained as in [Equation 4].

That is, the x-coordinate component (γ-coordinate component) after coordinate rotation is approximately the apparent power wf, and the y-coordinate component (δ-coordinate component) is approximately wf·Δφ=wf(φf−φr). Therefore, the γ-coordinate component pf′ after coordinate rotation is used as the γ-phase feedback value wf as it is.

Further, by dividing this δ-coordinate component by wf in the dividing unit 12, the deviation Δφ of the power factor angle is obtained. By the way, when wf≈0, qf′≈0, so in this case, the value is used as the feedback value Δφ of the δ-phase without being divided by wf.

The γ-phase feedback value wf is output to the summing point 13 . A target value wr of the apparent power is input to the summation point 13 , and the difference is output to the low-pass filter 14 .

The low-pass filter 14 removes ripples (harmonics) that occur in the γ-phase feedback value wf when the three-phase commercial power system includes an anti-phase component and a harmonic component. The output of the low-pass filter 14 is output to the γ-phase control system compensator 15 .

The γ-phase control system compensator 15 is a PI controller and outputs the magnitude vinvr of the output voltage command value vector to the limit processor 16 .

On the other hand, the δ-phase feedback value Δφ (=φf−φr) is output to the summing point 17 . The δ-phase feedback value Δφ and the δ-phase command value 0 are input to the addition point 17 , and the difference between them is output to the low-pass filter 18 . Here, since the δ-phase command value is 0, control is performed so that Δφ=0 (φf=φr).

In the low-pass filter 18, if the power system contains a reverse phase component or a harmonic component, a ripple (harmonic) is generated in the δ-phase feedback value Δφ, and this ripple is removed. The output of the low-pass filter 18 is output to the δ-phase control system compensator 19 .

The δ-phase control system compensator 19 is a PI adjuster and outputs the phase φinvr of the output voltage command value vector to the limit processor 16 .

As shown in FIG. 3, the limit processor 16 limits the output vinvr of the γ-phase control system compensator 15 to upper and lower limits and outputs it to the inverter output voltage command value generator 20 as vinvr'. In this limit processing, when vinvr is excessive (exceeds the limit value), the output voltage of the voltage output unit (inverter) described later becomes excessive and an overvoltage relay (OVR) (not shown) operates, or the overvoltage causes the LC filter or This is done to prevent overheating and damage to transformers. The output vinvr' after the limit processing is output to the inverter output voltage command value generator 20. FIG.

Also, the limit processing unit 16 limits the output φinvr of the δ-phase control system compensator 19 within the range of upper and lower limits. Since φinvr is the phase of the output voltage command value vector, it may be theoretically unlimited, but if the value is too large, the finite data length will be exceeded, so it is limited. Specifically, when the phase φinvr exceeds ±π [rad], ±2π [rad] is added to φinvr (when the phase φinvr exceeds π [rad], -2π [rad], - If it falls below π [rad], 2π [rad] is added).

Theoretically, the range for limiting the phase φinvr may be -π to π as described above, but in FIG. .

The output φinvr′ after the limit processing is output to the inverter output voltage command value generator 20 .

When the outputs vinvr and φinvr of the compensators 15 and 19 are limited by the limit processing section 16, the outputs of the sections constituting the compensators 15 and 19 are appropriately changed by performing anti-reset windup processing. to improve the response of the compensator (make the compensator output change immediately).

The inverter output voltage command value generation unit 20 converts the polar coordinate components of the output voltage command value vector into xy coordinate components (γδ coordinate components), and output to the non-interfering unit 21 as inverter output voltage command values vinvrg and vinvrd. Here, vinvrg and vinvrd are the γ-phase component vinvrg and the δ-phase component vinvrd of the output voltage command value vector in the γδ space of the voltage output section (inverter) described later.

The non-interfering unit 21 performs processing to prevent the three-phase output voltages of the voltage output unit (inverter) from interfering with each other due to the conversion performed by the inverse γδ converting unit 22 . The output of the non-interfering unit 21 is subjected to inverse γδ conversion in the inverse γδ conversion unit 22, and then inverse αβ conversion in the inverse αβ conversion unit 23, and the voltage output unit ( output to the inverter) 24 .

Voltage output unit 24 controls active power p and reactive power q by manipulating the output voltage of the inverter that constitutes power converter A according to output voltage command values vinvru and vinvrv.

As described above, according to the power control method by the three-phase power converter A shown in FIGS. 1 to 3, in controlling the active power p and the reactive power q, the apparent power w and the power factor angle φ (the apparent power w and the power factor angle φ are feedback-controlled), essentially independent power control becomes possible.

In addition, regarding the limit processing of the output voltage command value, the compensator output of the γ phase and the compensator output of the δ phase can be performed separately. Limit processing becomes unnecessary.

Another embodiment of the present invention will now be described with reference to FIG. FIG. 4 is a control block diagram showing another embodiment of the power control method by the three-phase power converter B of the present invention. In FIG. 4, the same means as those in FIG. 1 are given the same reference numerals, and the description thereof will be omitted as much as possible.

The output current detection unit 1 shown in FIG. 4 detects the instantaneous values (iofu, iofv, iofw) of the three-phase output current of the power converter B by the current detection transformer 2, and the instantaneous values (iofu, iofv, iofw) After forming the current instantaneous value vector <iof>uvw having the The instantaneous voltage values (vofu, vofv, vofw) of the phase commercial power system are detected, and the voltage instantaneous value vector <vof>uvw having the components of the instantaneous values (vofu, vofv, vofw) is formed, and the αβ conversion unit 6 , to input the γ-phase feedback value wf (=pf′) to the summing point 13, and to the summing point 17 to the δ-phase feedback value Δφ (=φf−φr=qf′/wf ) is input, and then the low-pass filters 14 and 18 remove the ripples (harmonics) generated in the γ-phase and δ-phase feedback values wf and Δφ, and the γ-phase control system compensator 15b and the δ-phase control Since the operation up to the output to the system compensator 19b is the same as in the case of FIG. 1, the explanation is omitted.

The γ-phase control system compensator 15b is a PI controller, and outputs the magnitude ior of the output current command value vector to the limit processor 16b. The δ-phase control system compensator 19b is a PI adjuster and outputs the phase φor of the output current command value vector to the limit processor 16b.

As shown in FIG. 3, the limit processor 16b limits the output ior of the γ-phase control system compensator 15b to upper and lower limits and outputs ior' to the output current command value generator 20b.

In this limit processing, when ior is excessive (exceeds the limit value), the output current of a current output unit (inverter), which will be described later, becomes excessive and an overcurrent relay (OCR) (not shown) operates, or the overcurrent causes the inverter to malfunction. This is to prevent overheating and damage to components such as transformers and transformers. The output ior' after the limit processing is output to the output current command value generator 20b.

Also, the limit processing unit 16b limits the output φor of the δ-phase control system compensator 19b within the upper and lower limits. Since φor is the phase of the output current command value vector, it may be theoretically unlimited. Specifically, when the phase φor exceeds ±π [rad], add ±2π [rad] to φor (if the phase φor exceeds π [rad], add -2π [rad], - If it falls below π [rad], 2π [rad] is added).

Theoretically, the range for limiting the phase φor may be -π to π as described above, but in FIG. . The output φor' after the limit processing is output to the output current command value generating section 20b.

When the outputs ior and φor of the compensators 15b and 19b are subjected to limit processing by the limit processing section 16b, the outputs of the sections constituting the compensators 15b and 19b are appropriately changed by performing anti-reset windup processing. to make the compensator respond better (immediately change the compensator output).

The output current command value generation unit 20b converts the polar coordinate components of the output current command value vector into xy coordinate components (γδ coordinates component), and output to the non-interfering unit 21b as the output current command values iorg and iord.

The non-interfering unit 21b performs processing to prevent three-phase output currents of a current output unit (inverter), which will be described later, from interfering with each other due to the conversion performed by the inverse γδ converting unit 22b. The output of the non-interfering unit 21b is subjected to inverse γδ conversion in the inverse γδ conversion unit 22b, then inverse αβ conversion in the inverse αβ conversion unit 23b, and the current output unit ( output to the inverter) 25 .

The current output unit 25 controls the active power p and the reactive power q by manipulating the output current of the power converter B according to the output current command values ioru and iorv.

In the power control method of the three-phase power converter B shown in FIG. 4, as in the case of FIG. 1, the apparent power w and the power factor angle φ can control the active power p and the reactive power q. essentially independent (non-interfering) control becomes possible.

In addition, regarding the limit processing of the output current command value, the compensator output of the γ-phase and the compensator output of the δ-phase can be performed separately, and complicated limit processing becomes unnecessary.

FIG. 5 is a control block diagram showing a power control method by the single-phase power converter C of the present invention. In FIG. 5, the same means as in FIG. 1 are given the same reference numerals, and the description thereof will be omitted as much as possible.

In FIG. 5, 1c is an output current detector, which detects the instantaneous value iof of the single-phase output current of the power converter C from the current detection transformer 2c and sends it to the active power calculator 7c and the reactive power calculator 8c. Output.

Reference numeral 4c denotes a system voltage detection unit which detects the instantaneous value vof of the voltage of the single-phase commercial power system to which the power converter C is connected from the voltage detection transformer 5c, and outputs it to the active power calculation unit 7c and the reactive power calculation unit 7c. 8c.

The active power calculator 7c multiplies the input instantaneous value iof of the single-phase output current by the instantaneous value vof of the single-phase system voltage in the first multiplier 7c1, and obtains the product (first product) as the first or a moving average calculator (first moving average) 7c2. The output of the first low-pass filter or the first moving average value is output to the coordinate rotation section 11c as the active power p1f.

The reactive power calculator 8c delays the instantaneous value vof of the single-phase system voltage input by the delay unit 8c0 by 1/4 period, and then inputs the delayed value to the second multiplier 8c1. The second multiplier 8c1 multiplies the input instantaneous value iof of the single-phase output current by the instantaneous value vof of the single-phase system voltage delayed by 1/4 cycle, and converts the product (second product) to the second Input to a low-pass filter or a moving average calculator (second moving average) 8c2. The output of the second low-pass filter or the second moving average value is output to the coordinate rotating section 11c as the reactive power q1f.

Then, a power feedback vector having xy-coordinate components of the active power p1f and the reactive power q1f is constructed, and this is input to the coordinate rotation section 11c. Since the operations from the coordinate rotation unit 11c to the inverse γδ conversion unit 22 are the same as in the case of FIG. 1, description thereof will be omitted.

In addition, although there are low-pass filters 14 and 18 in FIG. 1, these are for removing the ripple component of the feedback value, and in FIG. Alternatively, since the ripple component of the feedback value is removed by the moving averages 7c2 and 8c2, it is unnecessary in FIG.

The output of the non-interference unit 21 is subjected to inverse γδ conversion in the inverse γδ conversion unit 22, and its x-coordinate component (=α phase component=U phase component) vinvra (single-phase inverter output voltage command value) is converted to the voltage output unit ( inverter) 24c.

The voltage output unit 24c controls the active power p and the reactive power q by manipulating the output voltage of the inverter constituting the power converter C according to the inverter output voltage command value vinvra.

According to the power control method of the power converter C shown in FIG. (The apparent power w and the power factor angle φ are feedback-controlled), so independent power control is possible.

FIG. 6 is a control block diagram showing a power control method by the single-phase power converter D of the present invention. In FIG. 6, the same means as those in FIGS. 3 and 5 are denoted by the same reference numerals, and the description thereof will be omitted as much as possible.

In FIG. 6, the output current detection unit 1c detects the instantaneous value iof of the single-phase output current of the power converter D, outputs the instantaneous value iof to the active power calculation unit 7c and the reactive power calculation unit 8c, and detects the system voltage. The instantaneous value vof of the voltage of the single-phase commercial power system to which the power converter D is connected is detected by the unit 4c, and the instantaneous value vof is output to the active power calculation unit 7c and the reactive power calculation unit 8c. 13 is output to the .gamma.-phase control system compensator 15b, and the operation until the output of the summing point 17 is output to the .delta.-phase control system compensator 19b is the same as in FIG.

Further, subsequent operations from the γ-phase control system compensator 15b and the δ-phase control system compensator 19b to the inverse γδ conversion unit 22b are the same as in the case of FIG. The x-coordinate component (=α-phase component=U-phase component) iora (single-phase output current command value) of the output of the inverse γδ conversion unit 22b is output to the current output unit (inverter) 25d.

The current output unit 25d controls the active power p and the reactive power q by manipulating the output current of the power converter D according to the output current command value iora.

According to the power control method of the power converter D shown in FIG. 6, as in the case shown in FIG. Since the power factor angle φ is used (the apparent power w and the power factor angle φ are feedback-controlled), independent power control is possible.

INDUSTRIAL APPLICABILITY The present invention is applicable to equipment with a three-phase or single-phase power converter installed in a power system.

1, 1c, 101 output current detection unit 2, 2c, 102 current detection transformer 3, 6, 103, 106 αβ conversion unit 4, 4c, 104 system voltage detection unit 5, 5c, 105 voltage detection transformer 7, 7c, 107 active power calculation unit 7c1 first multiplication unit 7c2 first low-pass filter or first moving average calculation unit 8, 8c, 108 reactive power calculation unit 8c0 delay unit 8c1 second multiplication unit 8c2 second low-pass filter or Second moving average calculation unit 109, 110 γδ conversion unit 11, 11c Coordinate rotation unit 12 Division unit 13, 17, 111, 113 Addition points 14, 18, 112, 114 Low pass filter 15, 15b γ phase control system compensator 16, 16b limit processing unit 19, 19b δ-phase control system compensator 20 inverter output voltage command value generation unit 20b output current command value generation unit 21, 21b, 118 non-interfering unit 22, 22b, 119 reverse γδ conversion unit 23, 23b, 120 inverse αβ conversion unit 24, 24c voltage output unit 25, 25d, 121 current output unit 115 active power control system compensator 116 reactive power control system compensator 117 limit processing unit A, B, X three-phase power converter C , D single-phase power converter

Claims (6)

Active power p and reactive power q are measured from the voltage of the commercial power system to which the power converter is connected and the output current of the power converter. A power feedback vector having p and q as xy coordinate components is formed, and the vector is reversely rotated (-φr rotated) by the power factor angle target value φr (rotational coordinate conversion). Feedback control is performed using the xy coordinate components of the vector obtained by reverse rotation. The apparent power is feedback-controlled with the apparent power target value wr and the x-coordinate component of the vector obtained by the reverse rotation. The power factor angle is feedback-controlled with a command value of 0 and a value obtained by dividing the y-coordinate component of the vector obtained by the reverse rotation by the length of the vector. The apparent power target value wr and the power factor angle target value φr are obtained from the active power target value pr and the reactive power target value qr by the following equation (1). A power control method for a three-phase or single-phase power converter, wherein p and q are controlled by these.
formula (1)
wr = ( ^pr2 + ^qr2 ) ^1/2
φr = tan ^-1 (qr/pr), where φr is -π to π [rad] 2. The power control method according to claim 1, wherein when controlling the active power p and the reactive power q using a power converter connected to a three-phase commercial power system, the instantaneous voltage of the system voltage at the connection point of the power converter A voltage instantaneous value vector <vof>uvw whose components are the values vofu, vofv, and vofw, and a current instantaneous value vector <iof>uvw whose components are the instantaneous values iofu, iofv, and iofw of the three-phase output current of the power converter are Configure. An instantaneous value p3f of the active power is obtained from the inner product of the two instantaneous value vectors, and an instantaneous value q3f of the reactive power is obtained from the outer product of the two instantaneous value vectors. The power feedback vector according to claim 1 is configured with these p3f and q3f as xy coordinate components. Furthermore, after limiting the output of the two feedback control system compensators according to claim 1 , the command value vector in the γδ space of the output current of the power converter or the output voltage of the inverter constituting the power converter Let it be magnitude and phase. After decoupling the xy coordinate components of this command value vector, each component of the vector obtained by inverse γδ conversion and inverse αβ conversion is converted to the U-phase, V-phase, and W-phase output current command values of the power converter or An output voltage command value for the inverter. A power control method for a three-phase power converter, wherein p and q are controlled by manipulating the output current of the power converter or the output voltage of the inverter according to the three-phase command values. In the power control method according to claim 2, the voltage instantaneous value vector <vof>uvw and the current instantaneous value vector <iof>uvw are subjected to αβ conversion. The instantaneous value p3f of the active power is obtained from the inner product of the vector <vof>ab obtained by αβ-transforming <vof>uvw and the vector <iof>ab obtained by αβ-transforming <iof>uvw, and <vof>ab and <iof>ab, the instantaneous value q3f of the reactive power is obtained. A power control method for a three-phase power converter, comprising forming a power feedback vector using these p3f and q3f as xy coordinate components. In the power control method according to claim 3, the voltage instantaneous value vector <vof>ab and the current instantaneous value vector <iof>ab in the αβ space are γδ-converted. The instantaneous value p3f of the active power is obtained from the inner product of the vector <vof>gd obtained by γδ-converting <vof>ab and the vector <iof>gd obtained by γδ-converting <iof>ab, and <vof>gd and <iof>gd, the instantaneous value q3f of the reactive power is obtained. A power control method for a three-phase power converter, comprising forming a power feedback vector using these p3f and q3f as xy coordinate components. 2. The power control method according to claim 1, wherein when controlling the active power p and the reactive power q using a power converter connected to a single-phase commercial power system, the instantaneous voltage of the system voltage at the connection point of the power converter The product of the value and the instantaneous value of the output current (first product) is input to the first LPF (low pass filter). Alternatively, the first product is moving averaged (first moving average). Let the output of the first LPF or the value of the first moving average be active power p1f. Also, the product (second product) of the instantaneous value of the system voltage one-fourth cycle before and the instantaneous value of the output current is input to the second LPF. Alternatively, the second product is moving averaged (second moving average). Let the output of the second LPF or the value of the second moving average be reactive power q1f. The power feedback vector according to claim 1 is configured with these p1f and q1f as xy coordinate components. Furthermore, after limiting the output of the two feedback control system compensators according to claim 1 , the command value vector in the γδ space of the output current of the power converter or the output voltage of the inverter constituting the power converter Let it be magnitude and phase. After decoupling the xy coordinate components of the command value vector, the x coordinate component of the vector obtained by inverse γδ transformation is used as the output current command value of the power converter or the output voltage command value of the inverter. A power control method for a single-phase power converter, wherein p and q are controlled by manipulating the output current of the power converter or the output voltage of the inverter according to the command value. In the power control method according to any one of claims 1 to 5, the output limit processing of the compensator (γ-phase compensator) of the apparent power feedback control system (γ-phase control system) is limited by upper and lower limits. by doing. The output limit processing of the compensator (δ-phase compensator) of the power factor angle feedback control system (δ-phase control system) is such that when the output exceeds the range of ±π [rad], the output is adjusted to ±2π [rad ] (add −2π [rad] if the output exceeds π [rad], and add 2π [rad] if the output falls below −π [rad]). A power control method for a three-phase or single-phase power converter, further comprising performing anti-reset windup processing on the limited compensator when the output of the compensator is limited.

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