JP2004147445A - Distributed power supply system and control method thereof - Google Patents

Abstract

In a distributed power supply system in which a power generation device (2) and a power storage device (1) connected to a commercial system (5) are combined, power fluctuation and power oscillation when the system is released from the commercial system (5) and shifts to independent operation are suppressed.
A control device (6) extracts a power fluctuation from an active power PL of a load detected by an active power detection unit (7), and extracts a frequency vibration ΔF from a frequency (F) detected by a frequency detection unit (8). A general command PB which is a sum of a first command value PB ^* 1 for suppressing power fluctuation and a second command value PB ^* 2 for suppressing power vibration, corresponding to these fluctuation and vibration components, respectively. ^{Based on *} , the power conversion unit 12 is controlled to control charging and discharging of the power storage unit 11.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a distributed power supply system including a power generation device and a power storage device in a premises system interconnected to a commercial system, and more particularly to a self-sustained operation control of a premises system.
[0002]
[Prior art]
Such a distributed power supply system includes a power generation device, such as a diesel or gas turbine, in which a power generator is directly connected to a system, and a power storage device that regulates power. Supply stable power to the load.
[0003]
As described in Patent Document 1, as a control method of the target system, a transient sudden change of a load, an excessive peak power consumption of a load, and a power shortage on a side of a private power generation system during interconnection with a commercial system. It is disclosed that power is supplied from a power storage device according to the following.
[0004]
Patent Literature 2 discloses that in a commercial system, charging and discharging of a power storage device is performed so as to suppress a change in frequency of a power system due to a change in demand load.
[0005]
Further, Patent Document 3 discloses that the charging power is increased (discharge power is reduced) while the power generated by the power generator is increasing, and the discharge power is increased (recharge power is reduced) while the power generated by the power generator is decreasing. A control of the power storage device to be activated is disclosed. Other than this, there are JP-A-2001-5543 and JP-A-2001-327080.
[0006]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 2000-69675 (abstract, etc.)
[Patent Document 2]
JP 2001-37085 A (Claim 1 and others)
[Patent Document 3]
JP 2000-175360 A (FIG. 1 and others)
[0007]
[Problems to be solved by the invention]
According to the distributed power system of the related art, load fluctuations and output fluctuations of a power generator using natural energy as a power source are supplemented by charge / discharge control of a power storage device at the time of commercial system interconnection.
[0008]
On the other hand, as a merit of introducing a distributed power supply system to a customer, it is conceivable that the distributed power supply system is used as an uninterruptible power supply even in the event of a commercial power failure. That is, a customer having a distributed power source can supply stable power to the premises system even when power supply from the commercial system is cut off.
[0009]
In order to continue the operation of the power generator as an uninterruptible power supply, the power in the premises system generated when the circuit breaker connected to the commercial system is opened from the state of the commercial system It is necessary to suppress fluctuation and power oscillation. In the above prior art, as described above, any of the above-described methods suppresses fluctuations in a state where the power storage device is synchronously connected to a commercial system, and is synchronized with a power generation device having a smaller capacity (inertia) than the commercial system. It is not possible to suppress the vibration in the self-sustaining operation state.
[0010]
SUMMARY OF THE INVENTION It is an object of the present invention to suppress power oscillation in a premises system when the system is separated from a commercial system and shifts to an independent operation in a premises distributed power system in which a power generation device and a power storage device are combined.
[0011]
Another object of the present invention is to suppress both power fluctuations and power oscillations in the premises system when the system is disconnected from the commercial system and shifts to independent operation.
[0012]
[Means for Solving the Problems]
A feature of the present invention is a premises system interconnected to a commercial system via a circuit breaker, a power generator connected to the premises system, and a power storage device connected to the premises system for charging and discharging power. In the distributed power supply system having: a means for detecting a vibration component of a frequency in a specific frequency band in the premises system; and a control means for controlling charging and discharging of the power storage device based on the vibration component.
[0013]
According to another feature of the present invention, a means for detecting a variation in the active power of the premises system, and controlling the charging and discharging of the power storage device based on the variation, as well as a specific frequency band in the premises system. It is provided with means for detecting a vibration component of a frequency, and control means for controlling charging and discharging of the power storage device based on the vibration component.
[0014]
Specifically, it detects the frequency of the premises system, extracts a vibration component in a specific frequency band of this frequency, operates the power storage device in the charging direction while the vibration component is rising, and reduces the vibration component. During the operation, the power storage device is operated so as to be directed in the discharging direction. This suppresses power oscillations when shifting to the self-sustaining operation.
[0015]
The same vibration suppression effect can be obtained by using the voltage of the local system, the active power of the local load, the active power of the power generator, or the angular velocity of the power generator instead of the frequency of the local system.
[0016]
In addition, it detects the fluctuation of the active power of the premises system, sets the power storage device to perform the charging operation when the active power decreases, and sets the power storage device to perform the discharging operation when the active power increases. Suppress power fluctuations immediately after the transition.
[0017]
Other objects and features of the present invention will become apparent from the following description of the embodiments.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described below with reference to the drawings.
[0019]
FIG. 1 is a configuration diagram of a distributed power supply system according to an embodiment of the present invention. The distributed power supply system according to the present embodiment includes a power storage device 1 and a power generation device 2. The power storage device 1 includes a power storage unit 11 that stores power, and a power conversion unit 12 that adjusts power, such as an AC / DC converter. Examples of the power storage unit 11 include a secondary battery such as a lead storage battery, a sodium-sulfur battery, a nickel-cadmium battery, or a lithium-sulfur battery, an electric double-layer capacitor, a flywheel, and a superconducting coil. The power generation device 2 is configured by at least one power generator such as a diesel or gas turbine connected to the grid. These are both connected to the on-premise load 3 and are connected to the commercial system 5 via the circuit breaker 4. Here, the active power of the power storage device 1 is PB, the active power of the power generation device 2 is PG, the active power of the local load is PL, and the direction of the arrow is defined as positive (plus).
[0020]
The control device (control means) 6 takes in the active power PL and the frequency F of the load via the active power detection unit 7 and the frequency detection unit 8 and outputs a control signal to the power conversion unit 12. The relationship between the active power PL of the load, the active power PB of the power storage device 1, and the active power PG of the power generation device 2 is expressed by equation (1).
[0021]
PL = PG + PB ……………………………………… (1)
Therefore, when it is difficult to detect the active power PL of the load 3, a value obtained by detecting and adding the active power PG of the power generation device 2 and the active power PB of the power storage device 1 may be used.
[0022]
FIG. 2 is an operation explanatory diagram when power fluctuation and power vibration occur during the self-sustaining operation. The self-sustaining operation refers to a state in which an abnormality occurs in the commercial system 5 in FIG. 1, the circuit breaker 4 is opened, and power is supplied to the load 3 connected to the local system only by the distributed power system. The waveforms represent the voltage VS, the frequency F, the active power PL of the local load, the active power PG of the power generation device 2 and the active power PB of the power storage device 1 from the upper stage. At time t1, the distributed power supply system is disconnected from the commercial power system 5 and shifts to independent operation. At this time, when a large power fluctuation occurs due to the power generation amount of the distributed power source and the load amount in the premises, the capacity (inertia) of the power generation device 2 is small, so that the vibration of the frequency F0 as shown in FIG. Power cannot be supplied. In the worst case, the situation is such that the vibrations diverge and the self-sustaining operation cannot be performed.
[0023]
FIG. 3 is a functional block diagram of the control device 6 according to one embodiment of the present invention for solving this. The control device 6 includes two systems, that is, a power fluctuation suppressing unit 61 and a power vibration suppressing unit 62, and includes a converter control unit 63 that controls the power converting unit 12 based on the sum PB ^* of the outputs PB ^* 1 and PB ^* 2. Have.
[0024]
First, the power fluctuation suppressing unit 61 subtracts the output of the primary delay circuit 611, which also has PL as input, from the active power PL of the local load taken in through the active power detecting unit 7 by the subtracting unit 612, and The variation of the active power PL is extracted. The first active power command value PB ^* 1 for suppressing the power fluctuation immediately after the transition to the self-sustained operation is determined according to the variation of the active power of the load. Since the discharge direction of the active power PB of the power storage device 1 is defined as positive (plus), when the active power PL of the local load decreases, the power storage device 1 performs a charging operation to suppress the acceleration of the power generation device 2. Thus, the output sign of the subtraction unit 612 becomes negative (minus). Conversely, when the active power PL increases, the output sign of the subtraction unit 612 may be set to be positive (plus) as shown in the drawing so that the discharging operation is performed to suppress the deceleration of the power generation device 2. Note that the transfer function L1 (S) of the first-order delay circuit 611 is expressed by equation (2).
[0025]
L1 (S) = 1 / (1 + TS) .................................................. (2)
The time constant T is a delay time until the active power command value PB ^* 1 is reset (zero), and is set with respect to a response time constant (inertia constant) of the power generation device 2 so as not to cause a large fluctuation in the power generation device 2. And a sufficiently long value, for example, 30 seconds. The response time constant of the power generation device 2 is usually about several seconds, and the time constant is set to several to several tens of seconds.
[0026]
On the other hand, the power vibration suppression unit 62 extracts a vibration component ΔF of a frequency in a specific frequency band via the band-pass filter 621A from the frequency F of the local system taken in through the frequency detection unit 8. This specific frequency band is a band including the natural vibration frequency F0 of the power generation device 2. For example, in a diesel engine generator of 60 [kW], the natural vibration frequency F0 is about F0 = 6 [Hz], and the specific frequency band is usually several [Hz] less than 10 [Hz].
[0027]
The second active power command value PB for adjusting the gain by the gain adjusting section 622A and further adjusting the phase by the phase adjusting section (phase adjusting means) 623A to suppress the power oscillation after the transition to the autonomous operation. ^* Determine 2.
[0028]
Further, when a plurality of power generation devices 2 are installed to suppress different power vibrations, it is necessary to provide vibration suppression systems by the number thereof. That is, the band-pass filter 621B, the gain adjustment unit 622B, the phase adjustment unit 623B, and the addition unit 624 are used, for example, when there are two power generation devices A and B.
[0029]
Now, the converter control unit 63, the effective by adding the active power command value PB * ² of the active power command value PB * ¹ and the power vibration suppressing portion 62 of the power fluctuation suppressing unit 61 by an adder (adding means) 64 power Command value PB ^* is input. Based on the total power command value PB ^* , a signal for controlling the power conversion unit 12 is generated by the converter control unit 63, and the power is supplied so that the power supplied to the local load 3 is stabilized even during the self-sustaining operation. The charge / discharge active power PB of the storage device 1 is controlled.
[0030]
FIG. 4 is an explanatory diagram of a method for setting the gain and phase of the band-pass filter 621 (621A, 621B) according to one embodiment of the present invention. The transfer function BPF (S) of the band-pass filter 621 for extracting the vibration component ΔF of the frequency F is represented by Expression (3).
[0031]
BPF (S) = ((ω0 / QB) · S) / (S 2 + (ω0 / QB) · S + ω0 2) ...... (3)
As for ω0, the vibration frequency F0 is set as a cutoff frequency as in the equation (4).
[0032]
ω0 = 2π × F0 …………………………………… (4)
QB is a value for setting the sharpness of the gain characteristic. When this value is increased, the gain around the cutoff frequency F0 decreases, and the extraction accuracy increases. However, on the other hand, extraction accuracy when the vibration frequency changes is reduced. Since the so-called robustness is lost, it is necessary to set a value that can cope with a certain change in the vibration frequency. For example, it is desirable to set the value around QB = 0.5.
[0033]
FIG. 5 is a diagram illustrating the relationship between the phase of the frequency detection signal and damping according to one embodiment of the present invention. In order to suppress the vibration of the power generation device 2, while the frequency vibration component ΔF is increasing, the power storage device 1 is operated to move in the direction of charging to suppress the acceleration of the power generation device. Conversely, while the frequency vibration component ΔF is decreasing, the power generation device may be operated in the direction of discharge to suppress the deceleration of the power generation device. Accordingly, assuming that the discharge direction of the active power PB of the power storage device 1 is positive (plus), the active power command value PB ^* 2 of the power oscillation suppressing unit 62 is 180 ° with respect to the phase of ΔF as shown in the figure. Most preferably, the values are out of phase. To obtain this 180 ° phase shifted value, it is only necessary to set the sign of the gain adjustment unit 622 (622A, 622B) to negative (minus).
[0034]
The phase adjuster 623 (623A, 623B) adjusts a phase delay due to, for example, a detection delay so as to maintain the above-described phase relationship. The transfer function LL (S) of the phase adjustment unit 623 is expressed by Expression (5), and the phase ∠LL (jω) is obtained from Expression (6).
[0035]
LL (S) = (1 + T1 · S) / (1 + T2 · S) (5)
∠LL (jω) = tan ⁻¹ (ω · T1) −tan ⁻¹ (ω · T2) (6)
That is, if T1> T2, the phase can be adjusted in the leading direction, and if T1 <T2, the phase can be adjusted in the lagging direction.
[0036]
In addition, as the detection signal of the power vibration suppression unit 62, instead of the frequency F of the local system, the voltage VS of the local system, the active power PL of the local load, the active power PG of the power generator 2 or the angular velocity ω of the power generator 2 are used. May be used. Since the vibration frequency F0 and the phase of each signal are the same as the frequency F of the premises system, except for the magnitude of the gain of the gain adjustment unit 622 depending on each signal, the configuration of the power vibration suppression unit 62 and You can follow the settings as they are. That is, in order to suppress the vibration of the power generation device 2, the power storage is performed while the voltage VS of the premises system, the active power PL of the premises load, the active power PG of the power generation device 2, or the angular velocity ω of the power generation device 2 increases (increases). The device 1 is operated to move in the direction of charging to suppress the acceleration of the power generation device. Conversely, while these signals are decreasing (decreasing), the operation may be performed in the direction of discharge to suppress the deceleration of the power generation device.
[0037]
Preferably, the signals are detected collectively at one place as much as possible. However, when there are a plurality of power generation devices, the angular velocity ω needs to be individually detected from each power generation device. However, when the fluctuation frequency of each power generation device is the same or close, only one detection may be performed. Further, when there is a difference in the capacity (inertia) of the power generation devices, the vibration may be suppressed for the largest power generation device.
[0038]
FIG. 6 is a waveform diagram of each part for explaining the operation and effect of the embodiment of the present invention. From the upper stage, the in-plant system voltage VS, frequency F, load active power PL, power generator active power PG, power storage device active power PB, power fluctuation suppression command value PB ^* 1, power vibration suppression command value PB ^* 2, and overall command value PB ^* is shown. Similarly to FIG. 2, at time t1, the distributed power supply system is disconnected from the commercial power system 5 and shifts to the self-sustaining operation, and the fluctuation of the active power occurs. Here, the variation of the active power PL of the load is reduced. At the same time, vibration occurs in which each time width from time t1 to t4 is a half cycle.
[0039]
First, the power fluctuation suppressing unit 61 obtains a first active power command value PB ^* 1 having a negative (negative) polarity corresponding to a fluctuation amount of the active power PL of the load, here, a decrease amount. It is a signal to be performed. Thereby, it works in the direction of suppressing the power fluctuation immediately after shifting to the self-sustaining operation.
[0040]
On the other hand, the power vibration suppression unit 62 suppresses the vibration based on the vibration component in the specific frequency F0 band of the system frequency F. Therefore, based on the vibration component ΔF and second active power command value PB * ² relationship between the frequency F described in FIG. 5, the second to obtain active power command value PB * ² that changes polarity in opposite phase It acts in a direction to suppress the vibration of the power generator 2.
[0041]
Therefore, the distributed power supply system suppresses power fluctuations and power oscillations even during self-sustained operation by the total active power command PB ^* (= first active power command value PB ^{* 1} + second active power command value PB ^* 2). Meanwhile, power can be stably supplied to the local load 3.
[0042]
This embodiment is a control method for a distributed power system including the following steps. That is, first, when the active power of the in-house system is detected, the fluctuation of the active power is detected. Next, the power storage device is charged according to the decrease in the active power, and the power storage device is discharged according to the increase in the active power. In addition, a vibration component of a frequency, voltage or active power in a specific frequency band in the premises system is detected, and the phase of the vibration component is adjusted. Then, based on the phase-adjusted vibration component, while the frequency is increasing, the power storage device is controlled to move in the direction of charging. On the other hand, there is provided a control method of a distributed power supply system for controlling the power storage device to be directed in a discharging direction while the frequency is decreasing.
[0043]
According to the above embodiment, in a distributed power supply system combining a private power generation device and a power storage device connected to a commercial system, both power fluctuation and power vibration during transition to independent operation are suppressed, and even during transition to independent operation. Stable power can be supplied to the premises system.
[0044]
【The invention's effect】
According to the present invention, in a distributed power supply system combining a private power generation device and a power storage device linked to a commercial system, power oscillation during transition to independent operation is suppressed, and stable power is transferred to the private system even during transition to independent operation. Can supply.
[Brief description of the drawings]
FIG. 1 is an overall configuration block diagram of a distributed power supply system according to an embodiment of the present invention.
FIG. 2 is an operation explanatory diagram in a case where power fluctuation and power vibration occur during self-sustaining operation.
FIG. 3 is a functional block diagram of a control device 6 according to one embodiment of the present invention.
FIG. 4 is a view for explaining a method of setting the characteristics of a bandpass filter according to one embodiment of the present invention.
FIG. 5 is a diagram illustrating a relationship between a phase of a frequency detection signal and damping according to an embodiment of the present invention.
FIG. 6 is a waveform diagram of each part for explaining the operation and effect of the embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Electric power storage device, 11 ... Electric power storage part, 12 ... Electric power conversion part, 2 ... Power generation device, 3 ... Local system load, 4 ... Circuit breaker, 5 ... Commercial system, 6 ... Control device (control means), 7 .. Active power detector, 8 frequency detector, PG active power of power generator, PB active power of power storage device, PL active power of local load, 61 power fluctuation suppressor, 611 primary delay circuit , PB ^* 1 ... (first) active power command value of the power fluctuation suppressing unit, F ... frequency of the local system, 62 ... power vibration suppressing unit, 621, 621A, 621B ... band-pass filter, ΔF ... frequency vibration component , 622A, 622B: gain adjuster, 623, 623A, 623B: phase adjuster, PB ^* 2: (second) active power command value of power vibration suppressor, PB ^* : converter controller ) Active power command value, 63 conversion Controller, F0 ... (natural vibration frequency of the generator), VS ... voltage premises system band pass filter cut-off frequency, omega ... angular velocity of the generator.

Claims (10)

In a distributed power supply system including a premises system interconnected to a commercial system via a circuit breaker, a power generation device connected to the premises system, and a power storage device connected to the premises system for charging and discharging power, A distributed power supply system comprising: means for detecting a vibration component of a frequency in a specific frequency band in a system; and control means for controlling charging and discharging of the power storage device based on the vibration component. 2. The distributed power supply system according to claim 1, further comprising means for adjusting a phase of the vibration component, wherein the control means controls charging and discharging of the power storage device in accordance with an output of the phase adjusting means. 3. The control device according to claim 1, wherein the control unit causes the power storage device to operate in a charging direction while the vibration component is rising, and moves the power storage device in a discharging direction while the vibration component is decreasing. 4. A distributed power supply system characterized by operating as described above. In any one of claims 1 to 3, instead of the vibration component of the frequency, a voltage of the premises system, active power of a premises load, active power of the power generator, or a vibration component of an angular velocity of the power generator is detected. A distributed power supply system comprising means. The distributed power supply system according to any one of claims 1 to 4, wherein the specific frequency band is a frequency band of several [Hz]. In a distributed power supply system including a premises system interconnected to a commercial system via a circuit breaker, a power generation device connected to the premises system, and a power storage device connected to the premises system for charging and discharging power, Means for detecting a change in the active power of the system, means for controlling charging and discharging of the power storage device based on the change, and means for detecting a vibration component of a frequency in a specific frequency band in the premises system; A distributed power supply system comprising control means for controlling charging and discharging of the power storage device based on components. 7. The control device according to claim 6, wherein the control unit causes the power storage device to perform a charging operation in accordance with a decrease in the active power of the premises system, and causes the power storage device to perform a discharging operation in accordance with an increase in the active power of the premises system. Operating the power storage device in a charging direction while the vibration component is rising, and operating the power storage device in a discharging direction while the vibration component is falling. . 7. The control device according to claim 6, wherein the control unit includes a unit that adds the fluctuation amount of the active power and the vibration component of the frequency, and controls charging and discharging of the power storage device according to an output of the adding unit. And a distributed power system. A control method for a distributed power supply system comprising: a premises system interconnected to a commercial system via a circuit breaker; a power generator connected to the premises system; and a power storage device connected to the premises system for charging and discharging power. Detecting a vibration component of a frequency, a voltage, an active power, or an angular velocity of a power generator in a specific frequency band in the premises system, adjusting a phase of the vibration component, and adjusting the phase-adjusted vibration component. Controlling the charge and discharge of the power storage device based on the control method. A control method for a distributed power supply system comprising: a premises system interconnected to a commercial system via a circuit breaker; a power generator connected to the premises system; and a power storage device connected to the premises system for charging and discharging power. Detecting the active power of the premises system, detecting the variation of the active power, and performing a charge / discharge operation of the power storage device according to the variation of the active power; Detecting a vibration component of a frequency, voltage or active power in a specific frequency band in the step of adjusting the phase of the vibration component, and, based on the phase-adjusted vibration component, Controlling the power storage device to be in the direction of charging; and controlling the power storage device to be in the direction of discharging during the reduction of the frequency. The method of the distributed power supply system according to claim.

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