JP4030856B2 - Distributed power supply system and control method thereof - Google Patents

Description

[0001]
BACKGROUND 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 linked to a commercial system, and more particularly to a self-sustained operation control of the premises system.
[0002]
[Prior art]
Such a distributed power supply system includes a power generation device in which a generator is directly connected to the system, such as a diesel or gas turbine, and a power storage device that adjusts power, and the power storage device is charged and discharged to control Supply stable power to the load.
[0003]
As a control method of the target system, as described in Patent Document 1, when connecting to a commercial system, a transient sudden change of the load, an excessive peak power consumption of the load, and a power shortage on the private power generation system side Accordingly, it is disclosed that power is supplied from the power storage device.
[0004]
Patent Document 2 discloses that in a commercial system, the power storage device is charged and discharged so as to suppress fluctuations in the frequency of the power system due to demand load fluctuations.
[0005]
Furthermore, in Patent Document 3, charging power is increased (discharging power is decreased) while the generated power of the power generating apparatus is increasing, and discharging power is increased (decreasing charging power) while the generated power of the power generating apparatus is decreasing. Control of a power storage device is disclosed. In addition to this, there are JP-A-2001-5543, JP-A-2001-327080, and the like.
[0006]
[Patent Document 1]
Japanese Unexamined Patent Publication No. 2000-69675 (summary, 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 supply system of the prior art, during fluctuations in commercial grid connection, load fluctuations and output fluctuations of the power generator using natural energy as a power source are compensated by charge / discharge control of the power storage apparatus.
[0008]
On the other hand, as a merit for a customer to introduce a distributed power supply system, it is conceivable to use the distributed power supply system as an uninterruptible power supply device even in the event of a commercial power failure. That is, a consumer having a distributed power source can supply stable power to the local system even if the power supply from the commercial system is cut off.
[0009]
In order to continue the operation of the power generation device as an uninterruptible power supply, the power of the on-site system generated when the circuit breaker connected to the commercial system is opened and the operation is shifted to the independent operation from the state of the commercial system interconnection operation. It is necessary to suppress fluctuations and power oscillations. In the above prior arts, as described above, each of the power storage devices suppresses fluctuations in a state where the power storage device is synchronously linked to the commercial system, and is synchronized with a power generation device having a smaller capacity (inertia) than that of the commercial system. It is not possible to suppress vibration in the self-sustaining operation state.
[0010]
An object of the present invention is to suppress power oscillations in a local system when the system is separated from a commercial system and shifts to a self-sustained operation in a distributed power supply system on the premises combining a power generation device and a power storage device.
[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 the independent operation.
[0012]
[Means for Solving the Problems]
A feature of the present invention is that a premise system linked to a commercial system via a circuit breaker, a power generation device connected to the premise system, and a power storage device connected to the premise system to charge and discharge power. Is provided with means for detecting a vibration component of a frequency in a specific frequency band in the premises system, and control means for charge / discharge control of the power storage device based on the vibration component.
[0013]
Another feature of the present invention is that the means for detecting the fluctuation of the active power of the campus system, the charge storage and discharge control of the power storage device based on the fluctuation, and the specific frequency band in the campus system There are provided means for detecting a vibration component of frequency and control means for charge / discharge control of the power storage device based on the vibration component.
[0014]
Specifically, the frequency of the local system is detected, the vibration component in a specific frequency band of this frequency is extracted, the power storage device is operated in the charging direction while the vibration component is rising, and the vibration component is reduced. The power storage device is operated in the discharge direction. As a result, power oscillations when shifting to independent operation are suppressed.
[0015]
The same vibration suppression effect can be obtained by using the voltage of the local system, the effective power of the local load, the effective power of the power generator, or the angular velocity of the power generator instead of the frequency of the local system.
[0016]
In addition, the fluctuation of the active power in the campus system is detected, and when the active power decreases, the power storage device is charged, and conversely, when the active power increases, the power storage device is set to discharge. Suppresses power fluctuations immediately after the transition.
[0017]
Other objects and features of the present invention will become apparent from the following description of embodiments.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments 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. The power storage unit 11 may be 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, a superconducting coil, or the like. The power generation device 2 is composed of at least one generator such as a diesel turbine or a gas turbine that is connected to the grid. These are both connected to the premises load 3 and connected to the commercial system 5 via the circuit breaker 4. Here, the description will proceed by defining the active power of the power storage device 1 as PB, the active power of the power generation device 2 as PG, the active power of the local load as PL, and the direction of the arrow 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 fluctuations and power vibrations occur during the self-sustaining operation. Self-sustained operation refers to a state in which some abnormality occurs in the commercial system 5 of 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. From the top, the waveform represents the voltage VS, frequency F, the active power PL of the local load, the active power PG of the power generator 2 and the active power PB of the power storage device 1 from the upper stage. The distributed power supply system is disconnected from the commercial system 5 at time t1 and shifts to the independent operation. At this time, if a large power fluctuation occurs due to the power generation amount of the distributed power source and the load amount on the premises, the capacity (inertia) of the power generation device 2 is small, so that the vibration of the frequency F0 as shown in the figure occurs and the load is stabilized The power cannot be supplied. In the worst case, vibrations diverge and the vehicle cannot be operated independently.
[0023]
FIG. 3 is a functional block diagram of the control device 6 according to an embodiment of the present invention for solving this. The control device 6 includes two systems of a power fluctuation suppression unit 61 and a power vibration suppression unit 62, and includes a converter control unit 63 that controls the power conversion unit 12 by the sum PB ^* of these outputs PB ^* 1 and PB ^* 2. I have.
[0024]
First, the power fluctuation suppression unit 61 subtracts the output of the first-order lag circuit 611 that also receives PL from the active power PL of the local load taken in via the active power detection unit 7 by the subtraction 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 independent operation is determined according to the fluctuation 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 acceleration of the power generation device 2. Thus, the output sign of the subtraction unit 612 becomes negative (minus). On the contrary, when the active power PL increases, the output sign of the subtractor 612 may be set as shown in the figure so that the discharge operation is performed in order to suppress the deceleration of the power generation device 2 so as to be positive (plus). Note that the transfer function L1 (S) of the first-order lag circuit 611 is expressed by equation (2).
[0025]
L1 (S) = 1 / (1 + T · S) ……………………………………… (2)
The time constant T is a delay time until the active power command value PB ^* 1 is reset (zero), and the response time constant (inertia constant) of the power generator 2 is set so as not to give a large fluctuation to the power generator 2. And a sufficiently long value, for example, 30 seconds is set. The response time constant of the power generation device 2 is normally 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 the vibration component ΔF of the frequency in the specific frequency band through the bandpass filter 621A from the frequency F of the local system taken in through the frequency detection unit 8. The 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 a few [Hz] less than 10 [Hz].
[0027]
Further, the second active power command value PB for adjusting the gain by the gain adjusting unit 622A and further adjusting the phase by the phase adjusting unit (phase adjusting unit) 623A to suppress the power oscillation after shifting to the independent operation. ^* 2 is determined.
[0028]
Further, when a plurality of power generation devices 2 are installed to suppress different power vibrations, it is necessary to provide the same number of vibration suppression systems. That is, the bandpass filter 621B, the gain adjustment unit 622B, the phase adjustment unit 623B, and the addition unit 624 are used when, for example, two power generation devices A and B exist.
[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 ^* , the converter control unit 63 generates a signal for controlling the power conversion unit 12 so that the power supplied to the premises load 3 is stable during the independent operation. The charge / discharge effective 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 bandpass filter 621 (621A, 621B) according to one embodiment of the present invention. A transfer function BPF (S) of the bandpass filter 621 for extracting the vibration component ΔF of the frequency F is expressed by the following equation (3).
[0031]
BPF (S) = ((ω0 / QB) · S) / (S ² + (ω0 / QB) · S + ω0 ² ) (3)
For ω0, the vibration frequency F0 is set as a cutoff frequency as shown 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 is decreased, and the extraction accuracy is increased. However, on the other hand, the extraction accuracy when the vibration frequency changes is lowered. Since the so-called robustness is lost, it is necessary to set a value that can cope with a certain change in vibration frequency. For example, it is desirable to set the value around QB = 0.5.
[0033]
FIG. 5 is a diagram for explaining the relationship between the phase of the frequency detection signal and damping according to an embodiment of the present invention. In order to suppress the vibration of the power generation device 2, while the vibration component ΔF of the frequency is increasing, the power storage device 1 is operated so as to go in the charging direction to suppress the acceleration of the power generation device. On the contrary, while the vibration component ΔF of the frequency is decreasing, it is only necessary to operate in the direction of discharge to suppress the deceleration of the power generator. Therefore, the active power command value PB ^* 2 of the power vibration suppression unit 62 is 180 ° with respect to the phase of ΔF as shown in the figure, when the discharge direction of the active power PB of the power storage device 1 is positive (plus). Most preferably, the values are out of phase. In order to obtain a value that is 180 degrees out of phase, it is only necessary to set the sign of the gain adjustment unit 622 (622A, 622B) to negative.
[0034]
In the phase adjustment unit 623 (623A, 623B), for example, a phase delay due to a detection delay or the like is adjusted so as to maintain the above phase relationship. The transfer function LL (S) of the phase adjustment unit 623 is expressed by equation (5), and the phase ∠LL (jω) is obtained from equation (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 advance direction, and conversely if T1 <T2, the phase can be adjusted in the delay direction.
[0036]
In addition, as a 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 effective power PL of the local load, the effective power PG of the power generation device 2, or the angular velocity ω of the power generation device 2 are used. It may be used. Since any signal has the same vibration frequency F0 and its phase as the frequency F of the local system, the configuration of the power vibration suppression unit 62 and the above are different except that the magnitude of the gain of the gain adjustment unit 622 differs depending on each signal. 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 local system, the effective power PL of the local load, the active power PG of the power generation device 2 or the angular velocity ω of the power generation device 2 is increasing (increasing). The device 1 is operated so as to go in the charging direction to suppress the acceleration of the power generation device. Conversely, while these signals are decreasing (decreasing), it is only necessary to operate in the direction of discharge to suppress deceleration of the power generation device.
[0037]
Although it is preferable to detect each signal collectively as much as possible at one place, the angular velocity ω needs to be detected individually from each power generator when there are a plurality of power generators. However, when the fluctuating frequency of each power generator is the same or close, it may be detected at one location. In addition, when there is a difference in capacity (inertia) of the power generation device, vibration may be suppressed for the largest power generation device.
[0038]
FIG. 6 is a waveform diagram of each part for explaining the function and effect of the embodiment of the present invention. From the top, the on-site 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 general command value PB ^* is represented. As in FIG. 2, the distributed power supply system is disconnected from the commercial system 5 at time t <b> 1 and shifts to the self-sustaining operation, and the fluctuation of the active power occurs. Here, the fluctuation amount of the active power PL of the load is reduced. At the same time, a vibration having a half period of each time width from time t1 to t4 is generated.
[0039]
First, in the power fluctuation suppressing unit 61, the first active power command value PB ^* 1 having a negative (minus) polarity corresponding to the fluctuation of the active power PL of the load, here, the reduction is obtained, and the power storage device 1 is charged. It is a signal to be performed. Thereby, it works in the direction which suppresses the electric power fluctuation immediately after shifting to independent operation.
[0040]
On the other hand, the power vibration suppression unit 62 suppresses this 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 And acts in a direction to suppress vibration of the power generation device 2.
[0041]
Therefore, the distributed power supply system suppresses power fluctuations and power oscillations even during independent operation by the total active power command PB ^* (= first active power command value PB ^{* 1} + second active power command value PB ^* 2). However, power can be stably supplied to the premises load 3.
[0042]
In this embodiment, the distributed power supply system control method includes the following steps. That is, when the active power of the on-premise system is first detected, the variation of this active power is detected. Next, the power storage device is charged according to the decrease in the effective power, and the power storage device is discharged according to the increase in the effective power. Further, the vibration component of the frequency, voltage or active power in the specific frequency band in the campus system is detected, and the phase of this vibration component is adjusted. Then, based on the phase-adjusted vibration component, the power storage device is controlled to go in the charging direction while the frequency is increasing. On the other hand, it is a control method of the distributed power supply system that controls the power storage device so as to go in the direction of discharge while the frequency is decreasing.
[0043]
According to the above embodiment, in the distributed power supply system that combines the on-site power generation device and the power storage device linked to the commercial system, both the power fluctuation and the power vibration during the transition to the independent operation are suppressed, and the Stable power can be supplied to the campus system.
[0044]
【The invention's effect】
According to the present invention, it is possible to suppress power oscillation at the time of transition to independent operation in a distributed power supply system that combines a power generation device and a power generation device linked to a commercial system, and to supply stable power to the campus system even at the time of 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 when power fluctuation and power vibration occur during self-sustained operation.
FIG. 3 is a functional block diagram of a control device 6 according to an embodiment of the present invention.
FIG. 4 is a diagram for explaining a method for setting the characteristics of a bandpass filter according to an embodiment of the present invention.
FIG. 5 is a relationship diagram 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 function and effect of one embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Electric power storage apparatus, 11 ... Electric power storage part, 12 ... Electric power conversion part, 2 ... Electric power generation apparatus, 3 ... Load of premises system, 4 ... Circuit breaker, 5 ... Commercial system, 6 ... Control apparatus (control means), 7 ... Active power detection unit, 8 ... Frequency detection unit, PG ... Active power of power generation device, PB ... Active power of power storage device, PL ... Active power of local load, 61 ... Power fluctuation suppression unit, 611 ... Primary delay circuit , PB ^* 1... (First) active power command value of the power fluctuation suppression unit, F... Frequency of the local system, 62... Power vibration suppression unit, 621, 621A, 621B. 622, 622A, 622B, gain adjustment unit, 623, 623A, 623B, phase adjustment unit, PB ^* 2, ... (second) active power command value of power vibration suppression unit, PB ^*, converter control unit (overall) ) Active power command value, 63 ... Converter system Part, (the natural vibration frequency of the generator) F0 ... band-pass filter cut-off frequency, voltage of VS ... campus system, ω ... angular velocity of the power plant.

Claims (3)

A premises system linked to the commercial system via a circuit breaker that is opened in the event of an abnormality in the commercial system,
A power generator that is connected to the local system, is operated after the circuit breaker is turned on , the internal system is connected to the commercial system, the circuit breaker is opened, and the local system is shifted to independent operation ;
In a distributed power supply system comprising a power storage device connected to the on-premises system and charging and discharging power,
Means for detecting a change in active power of the on-site load immediately after the circuit breaker is opened and the on-site system shifts to a self-sustaining operation;
Means for detecting a vibration component of a frequency in a specific frequency band including a natural vibration frequency of the power generation device in a campus system;
Control means for charge / discharge control of the power storage device based on the detected fluctuation of the active power and the vibration component of the frequency ,
The control means causes the power storage device to perform a charging operation according to a decrease in the active power of the local system, and discharges the power storage device according to an increase in the active power of the local system, and A distributed power supply system , wherein the power storage device is operated in a charging direction while rising, and the power storage device is operated in a discharging direction while the vibration component is decreasing .   2. The control device according to claim 1, wherein the control unit includes a unit that adds a variation of the active power and a vibration component of the frequency, and performs charge / discharge control of the power storage device according to an output of the addition unit. And distributed power system. A premises system linked to the commercial system via a circuit breaker that is opened in the event of an abnormality in the commercial system,
A power generator that is connected to the on- premises system, is operated after the circuit breaker is turned on and the on-site system is connected to the commercial system after the circuit breaker is opened and the on-site system shifts to a self-sustaining operation ;
A control method of a distributed power supply system comprising a power storage device connected to the local system and charging and discharging power,
Detecting the amount of change in active power of the on-site load immediately after the circuit breaker is opened and the on-site system shifts to the autonomous operation;
Charging and discharging the power storage device according to the variation of the active power; and
Detecting a vibration component of the frequency at a particular frequency band including the natural frequency of the power generator in the premises system,
Adjusting the phase of the vibration component;
Based on the phase-adjusted vibration component, controlling the power storage device in a charging direction during the increase in the frequency; and
A control method for a distributed power supply system, comprising the step of controlling the power storage device in a direction of discharge while the frequency is decreasing.

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