JP2012130146A - Self-supporting power supply system adjustment device and adjustment method for self-supporting power supply system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve problems related to a proposed technique requiring a complex measurement system that takes time for measurement, causing delay in the control and possibly failing to achieve stable control, the technique for compensating for output variation and the like, of a generator and the like, trying to maintain power quality of a self-supporting power supply system having a natural-energy generator and a large power load, the power quality that is difficult to maintain because the self-supporting power supply system has a small power capacity, making it susceptible to variation in the load and the like.SOLUTION: Power storage equipment, comprising a secondary battery and a power converter, is provided with a power adjustment device to control active power and reactive power, thereby realizing simple, quick-response control. This enables adjustment of the power and frequency of a power supply system at predetermined values, thereby maintaining the stability and quality of the self-supporting power supply system.

Description

  The present invention relates to a stand-alone power supply system that is independent of a commercial power supply system, and more particularly, to a power quality adjusting device and method.

  Currently, an ordinary general power system is a commercial power system supplied by an electric power company. In the commercial power system, maintenance of power source quality is mainly performed by the electric power company. The power system is operated so that the quality of the power supply satisfies the standards defined by laws and regulations.

  Except for special cases, general consumers do not need to maintain power supply quality and consume power supplied from the power company.

  However, in an independent power system that is not connected to a commercial power system, it is necessary for the power source quality to be maintained and managed by itself. Examples of such a self-sustained power supply system include a power supply system in a place away from a commercial power distribution line and a power supply system in a ship. Also, in a large-scale factory having a private power generation facility, a self-sustained power system is also established when not connected to the system.

  In a self-sustained power supply system, where reliability and quality are problems, reliability is evaluated by obtaining necessary power when necessary, and it refers to reliability for power supply. In general, a power source that does not cause a power failure is a highly reliable power source. On the other hand, quality is evaluated mainly by fluctuations in voltage and frequency falling within a predetermined range. Furthermore, the harmonics contained in the power supply also bear part of the power supply quality.

  The voltage and frequency of the power supply fluctuate due to changes in power supply and demand, and adjust the prime mover governor and the AVR of the generator to compensate for the fluctuations, as well as stop the power generation equipment and adjust the reactive power compensation device. Sometimes. When power generation equipment using natural energy such as solar power generation or wind power generation is connected to the power supply system, it is necessary to maintain the power supply quality to compensate for voltage and frequency fluctuations accompanying fluctuations in the output of the power generation equipment. .

  FIG. 11 is a diagram illustrating an example of a power supply system in a ship made of a conventional technique (for example, Patent Document 1). The power system in the ship is an independent power system that is independent of the commercial power system, except in special cases such as mooring on the quay. In recent years, ships may be equipped with power generation equipment using natural energy, and a solar cell unit (103) is connected to an inboard power supply system (101) via a power converter (104). And in order to utilize natural energy effectively, the power storage equipment which consists of a secondary battery (105) and a power converter device (106) is provided.

  In the example of FIG. 11, two diesel generators (107) provide power necessary for ship operation. A necessary number of these two diesel generators (107) are operated according to the power demand in the ship. The inboard power system (101) is connected to an inboard power load (102) such as inboard lighting and air conditioning equipment, and is also connected to a bow thruster (108) used at the time of detachment and berthing of the ship. Since the bow thruster (108) is driven by a motor and consumes a large amount of power, the power supply system in the ship is subject to great fluctuations due to its operation.

  As a power system adjusting device, a power system stabilizing device and a method therefor when a wind power generator is connected to a system power source (for example, Patent Document 2 and Patent Document 3), output fluctuation of a solar power generator Is disclosed without using a secondary battery (for example, Patent Document 4), or a power system control apparatus (for example, Patent Document 5) having a generator and a combined heat and power facility using natural energy. However, these Patent Documents 2 to 5 are all linked to a commercial power system and are not related to a self-supporting power system.

JP 2010-116071 A JP 2001-286062 A JP 2001-101557 A Japanese Patent Laying-Open No. 2005-312163 JP 2005-151746 A

  Since the power capacity (suppliable power) of a self-sustained power generation system is not large as in a commercial power system, it is easily affected by power supply quality due to load fluctuations. In the inboard power supply system (101) as shown in FIG. 11, when the bow thruster (108) that consumes a large amount of power is activated, the voltage and frequency of the inboard power supply system (101) vary greatly. Moreover, the output of the solar power generator composed of the solar cell unit (103) and the power conversion device (104) fluctuates depending on the sunshine conditions, and gives a disturbance to the independent power system (101). In general, a self-sustained power system has a small power capacity and is susceptible to fluctuations in the load and so on, so that it is difficult to maintain power quality.

  In order to maintain power quality, output fluctuations of generators, etc. are compensated by measuring output fluctuations of wind power generators and motor load fluctuations and controlling charging / discharging from a separately provided secondary battery. The technique which performs is proposed (for example, patent document 4, patent document 5). According to this method, it is necessary to measure the output for each generator and to measure the load for each motor to calculate the amount of fluctuation of the output and the load, and the control becomes complicated. In particular, if the number of generators and the number of motors increase, it becomes more complicated and difficult to deal with. This is because the electric power is calculated by measuring the current and voltage for each generator and motor, and the variation is calculated. Furthermore, power measurement takes time compared to frequency and voltage measurement. If power generation and load power are measured and power control is performed, a delay in power measurement occurs and obstructs stable and accurate control.

  In order to maintain power quality, a system that is not affected by the voltage and frequency of the power system due to the output fluctuation of the solar power generator by stopping the operation of the separately provided generator has been proposed (for example, Patent Document 2 and Patent Document 3). In the self-sustained power system in FIG. 11, if the diesel generator (107) is excessively operated in order to maintain the power quality, it is necessary to always operate the excessive diesel generator, resulting in energy loss.

  The present invention has been made in order to solve the problem, and it is possible to maintain power quality by suppressing disturbances caused by load fluctuations and natural energy power generation without performing complicated measurement, and for maintaining power quality. It is an object of the present invention to provide an adjusting device and an adjusting method for reducing an excessively operated diesel generator.

(Claim 1)
In order to achieve the above object, a self-sustained power supply system adjustment device according to the present invention is a self-supporting power supply system having a prime mover generator and a load facility, a power storage facility having a secondary battery and a power converter, The frequency measurement means for measuring the frequency of the power supply system, the voltage measurement means for measuring the voltage of the independent power supply system, the measured values from the frequency measurement means and the voltage measurement means, The system control part which calculates the target value of reactive power, and the power converter which outputs active power and reactive power according to the target value of active power and reactive power from the system control part are provided.

  According to this configuration, in the power storage facility including the secondary battery and the power converter, the active power and reactive power output from the power converter are controlled to adjust the frequency and voltage of the power supply system. Here, outputting active power and reactive power may be described without including distinction between inflow and outflow, including the reference numerals. In the power storage facility, a capacitor may be used instead of the secondary battery. If a capacitor is used, the responsiveness of the power storage facility is improved.

  The prime mover generator may be, for example, an induction generator that uses a diesel engine as a prime mover, and may be a gas turbine or a steam turbine as the prime mover. The generator may be a synchronous generator.

  The independent power system referred to in the present invention refers to a power system independent of a commercial power system. In an independent power system, there is no element that controls the system voltage and system frequency like a commercial power system, and the frequency and voltage are determined by the supply and demand of power.

(Claim 2)
An independent power supply system adjustment device according to the present invention includes a battery state detector attached to the secondary battery, SOC measuring means for calculating the SOC of the secondary battery based on a signal from the battery state detector, and the SOC Means for correcting the target value of the active power based on a deviation between the output from the measuring means and a predetermined SOC target value is provided.

  According to this structure, you may provide the detector which detects battery conditions, such as the terminal voltage of a secondary battery, charging / discharging electric current, battery temperature, and cell pressure. In order to monitor whether the detection value from the battery state detector is abnormal, a battery monitoring device may be provided, and the battery monitoring device may calculate the SOC (State of Charge) of the battery.

  Here, the SOC is a value indicating the state of charge of the secondary battery, and the fully charged state is referred to as 100% SOC, and the state where the secondary battery has no electricity is referred to as 0% SOC. In general, the secondary battery is often used between 20% SOC and 80% SOC because the secondary battery is overcharged or overdischarged because it affects the battery life.

(Claim 3)
In the independent power supply system adjustment device according to the present invention, the frequency measurement unit and the voltage measurement unit include a voltmeter that measures the voltage of the independent power supply system, and a PLL calculation unit that performs phase synchronization calculation on the output of the voltmeter. .

  According to this structure, the instantaneous value of the voltage of a specific 2 phase (for example, RS phase, ST phase) is detected via the transformer connected to the power supply system of a three-phase alternating current. This is taken into a computer, for example, and subjected to PLL calculation (Phase Locked Loop) to calculate the frequency and voltage. Therefore, since the measurement delay is smaller than that of the wattmeter, good responsiveness can be obtained.

(Claim 4)
In the independent power supply system adjustment device according to the present invention, the control calculation in the system control unit is proportional control.

  According to this configuration, the control calculation is preferably proportional control in the active power adjustment loop and the reactive power adjustment loop. By performing the proportional control calculation, it is possible to stably share the load with other power generation facilities. Instead of performing proportional control calculation, proportional integral control (PI) calculation may be performed as a minor loop, and control with droop as a whole may be performed.

(Claim 5)
The self-sustained power supply system adjustment device according to the present invention includes a delay calculator at the output of the frequency measuring means to perform a time delay calculation to obtain a frequency target value, and a delay calculator at the output of the voltage measuring means. Time delay calculation is performed to obtain the voltage target value.

  According to this configuration, the delay calculator is a calculator that performs time delay processing, and may be, for example, a first-order delay. Further, it may be a moving average or a secondary delay. Each measurement means may be subjected to a high-pass filter processing operation for cutting off a low-frequency signal, and multiplied by a proportional constant to obtain target values for active power and reactive power.

(Claim 6)
The independent power supply system adjustment device according to the present invention has a plurality of prime mover generators, and has a unit control for starting and stopping the prime mover generators according to the load state of the prime mover generators.

  According to this configuration, the number of prime mover generators is preferably at least three. The load state of the prime mover generator refers to the ratio of the total output of the prime mover generator during operation to the total rated output of the prime mover generator during operation. However, it may also refer to the output for each rating of the prime mover generator. Unless otherwise noted, the former is referred to as the load state of the prime mover generator.

(Claim 7)
The independent power supply system adjustment device according to the present invention is formed by connecting a generator using natural energy to an independent power supply system.

  According to this configuration, the generator using natural energy may be a solar power generator using solar cells or a wind power generator using wind energy. Ships sailing in the ocean are blessed with natural energy such as sunlight and wind power. Effective utilization of natural energy can contribute to energy saving and CO2 reduction.

(Claim 8)
A self-sustained power system adjustment method according to the present invention is a self-sustained power system having a prime mover generator, a load facility, a secondary battery, and a power converter of the secondary battery. The active power target value obtained from the frequency of the independent power system is corrected according to the deviation between the SOC of the battery obtained from the state of the secondary battery and the SOC target value, and the reactive power target value and The reactive power and the active power from the power converter are adjusted so as to be the target value of the active power.

(Claim 9)
In the independent power supply system adjustment method according to the present invention, the frequency and voltage of the independent power supply system are calculated from the voltage signal of the independent power supply system by phase synchronization calculation.

  The present invention has the above-described configuration, and can easily adjust the system frequency and the system voltage without causing a delay in measurement. In addition, it is possible to maintain the power quality by suppressing disturbance due to load fluctuation and natural energy power generation, and to improve the power quality of the independent power system. Furthermore, energy saving can be achieved by reducing the number of diesel generators that are operated excessively to maintain power quality.

1 is a power system diagram of a self-sustained power system according to an embodiment of the present invention. It is a figure which shows the control block of the adjustment apparatus of the independent power supply system concerning embodiment of this invention. FIG. 3 is an explanatory diagram of a PLL calculation unit that calculates a system voltage and a system frequency in the control block of FIG. 2. FIG. 3 is a block diagram showing a voltage stabilization control circuit in the system control unit in the control block of FIG. 2. FIG. 3 is a block diagram illustrating a frequency voltage stabilization control circuit in the system control unit in the control block of FIG. 2. FIG. 3 is a block diagram showing an SOC correction control circuit in the system control unit in the control block of FIG. 2. It is a figure explaining the detail of a power control part in the control block of FIG. It is a figure explaining the calculation method of SOC. It is a flowchart for demonstrating the number control of a diesel generator. It is a figure which shows the simulation test result of the independent power supply system control apparatus which concerns on this invention. It is a figure which shows the power supply system in the ship by a prior art.

  Hereinafter, embodiments according to the present invention will be described with reference to the drawings. However, the present invention is not limited to the embodiments.

  FIG. 1 shows a power system diagram of a self-supporting power system according to an embodiment of the present invention. The power supply system (1) is not particularly substantial, and to be strong, it can be said that the power supply system (1) is composed of wiring and various generators and load facilities connected thereto.

  The three-phase AC power flows through the self-supporting power supply system (1) (hereinafter simply referred to as “power supply system (1)”), and is represented as a single-line system diagram for the sake of simplicity. Although the power supply system shown in FIG. 1 is in a ship, the present invention can be applied to any power supply system other than a ship as long as it is an independent power supply system.

  The power supply system (1) is a three-phase alternating current with a nominal voltage of 440 V and a nominal frequency of 60 Hz, and various facilities are connected to the system. That is, a solar power generator (10) composed of a solar cell unit (3) and a power converter (4), a power storage facility (11) and 3 composed of a secondary battery (5) and a power conversion control device (6). One diesel generator (7a, 7b, 7c) is connected to the left side of FIG.

  On the right side of FIG. 1, an inboard power load (2) and a bow thruster (8) are connected. In addition to inboard lighting and air conditioning, the power consumed in the ship becomes the inboard power load (2). The bow thruster (8) is provided to move the ship to the quay when entering the port without the assistance of a tugboat, and is driven by a large induction motor. When the bow thruster is started, a large starting current flows, which greatly affects the power supply system (1), such as a drop in ship voltage.

  When the bow thruster (8) is not operated, usually one diesel generator (for example, 7a) is operated to supply necessary power to the ship. The rated output of the diesel generator (7) is 1,080 kW, and the rated output of an induction motor (not shown) that drives the bow thruster (8) is 1,350 kW.

  Prior to the installation of the power system adjusting apparatus according to the present invention, before the bow thruster (8) is operated, two diesel generators (7) are operated to supply the required power, and the induction motor is started. In order to stabilize the power supply system, one diesel generator (7) is further operated, and a total of three diesel generators (7) are operated. However, when the power supply system adjustment device is installed as shown in FIG. 1, one diesel generator (7) is operated to compensate for the insufficient power before the operation of the bow thruster (8). There is no need to operate the diesel generator (7) to stabilize the power system. A total of two diesel generators (7) are operated.

  An independent power supply system adjusting apparatus according to an embodiment of the present invention will be described using a control block shown in FIG. In FIG. 2, the diesel generator (7), the solar power generator (10), the bow thruster (8), etc. are omitted.

  The secondary battery (5) is connected to the power conversion circuit (20) of the power conversion control device (6) via the DC power line (25). This power conversion circuit (20) converts the DC power from the secondary battery (5) into a predetermined AC power and outputs it to the power supply system (1) by turning ON / OFF a power semiconductor element (not shown) at high speed. Or the AC power from the power supply system (1) is converted into DC power to charge the secondary battery (5).

  The power system (1) is provided with a voltage detector (14) for detecting the power system voltage, and the output of the voltage detector (14) is connected to the system controller (15) via the wiring (24). Are connected to the PLL calculation unit (16). The voltage detector (14) is a transformer known as PT.

  The system control device (15) includes a PLL calculation unit (16), a system control unit (17), and a power control unit (18), and a system state signal (27) from the PLL calculation unit (16) is a system. The power command signal (28) from the system control unit (17) is sent to the power control unit (18).

  The gate drive signal (29) from the power control unit (18) is sent to the power conversion circuit (19). The gate drive signal (29) converts the DC power of the secondary battery (5) into AC power having a desired voltage, frequency, and phase while PWM-controlling the gate of the power semiconductor element, and the power supply system (1). AC power from is converted to DC power to charge the secondary battery (5).

  The secondary battery (5) is provided with a battery state detector (19) such as voltage, current, temperature, pressure, etc. for detecting the state of the secondary battery. In addition to monitoring the state of the secondary battery, the SOC of the secondary battery (5) is calculated.

  The secondary battery monitoring device (22) is connected to the system control unit (17) of the system control device (15) via the wiring 26a, and the SOC calculated by the secondary battery monitoring device (22) is the system control unit (17). ). The abnormality signal of the secondary battery is sent from the secondary battery monitoring device (22) to the power control unit (18) via the wiring 26b.

Next, the operation of the adjustment device for the independent power supply system according to the embodiment of the present invention will be described with reference to FIGS.
(1) PLL Calculation FIG. 3 is a diagram illustrating a PLL calculation unit that calculates the voltage and frequency of the power supply system (1). That is, FIG. 3A is a PLL operation block diagram, and FIG. 3B is a block diagram showing operation processing in the PLL operation unit (16).

The frequency and phase of the power supply system (1) are obtained by calculation in the PLL calculation unit (16) based on the voltage value from the voltage detector (14). That is, the instantaneous values V _RS and V _ST of the line voltage of the power supply system (1) are measured by the voltage detector (14) installed in the power conversion control device (6) and input to the PLL calculation unit (16). (See FIG. 7). In the PLL calculation unit (16), the frequency and phase of the power supply system (1) are estimated using the instantaneous values V _RS and V _ST of the voltage.

A calculation block diagram of the PLL calculation unit (16) is shown in FIG. The PLL operation unit (16) is a phase comparator (determining a deviation between a part for calculating the phase θ from the line voltage values (V _RS , V _ST ) and the phase θ ′ estimated in the PLL operation unit (16)). 32) and a loop filter (34) for estimating the angular velocity (frequency) of the power supply system (1) from the phase deviation and an integrator (35) for integrating the estimated angular velocity and calculating the estimated phase θ ′. ing.

The phase of the power supply system is obtained by subjecting the instantaneous values ν _ab (= V _RS ) and ν _bc (= V _ST ) of the system line voltage obtained from the voltage detector (14) to αβ conversion. The instantaneous value of the phase voltage of each phase on the grid side
_Let ν _a , ν _b , and ν _c, and define the instantaneous value vector ν _αβ as follows:

From Euler's equation (ε ^jθ = cos θ + jsin θ), the instantaneous value ν vector ν _αβ can be expressed as follows.

Here, the instantaneous value vector ν _αβ is a vector that rotates the fixed coordinate system (αβ axis) based on the a phase at the angular velocity ω.

The system instantaneous line voltages ν _ab , ν _bc and the instantaneous phase voltages ν _a , ν _b , ν _c measured by the voltage detector (14) in the actual power conversion control device (6) have the following relationship: is there.

  Therefore, the instantaneous value vector is calculated from the instantaneous line voltage,

  Is required. Further, cos θ and sin θ are calculated from the following equations, and the phase θ is obtained.

  The phase comparator (32) obtains a deviation between the phase θ obtained from the instantaneous value of the system voltage and the phase θ ′ estimated in the PLL calculation unit (16). The phase deviation θ-θ 'is calculated from Euler's equation

When θ−θ ′ is sufficiently small, this value is determined to be substantially a phase difference.
The loop filter (34) obtains the system angular velocity ω from the phase deviation obtained by the phase comparator (32). The system frequency is obtained from the output ω of the loop filter (34). The transfer function G (s) of the loop filter is expressed by the following equation.

The estimated angular velocity ω is integrated by the integrator (35) to estimate the phase θ ′. The system voltage V is obtained from the instantaneous value vector ν _αβ by the following equation.

  Since the voltage and frequency detection methods described above are incorporated in the power conversion control device linked to the power supply system, it is not necessary to add a new detection device when implementing the present invention.

  Further, since the frequency and phase are obtained by calculation with a computer program, the response speed is fast. In the present invention, the response speed of frequency / voltage measurement affects the performance of the equipment, but sufficient performance can be obtained by this method.

  The system voltage V calculated by the PLL calculation unit (16) is sent to the system control unit (17) as the system voltage signal (41), and the system frequency F is sent as the system frequency signal (51). Further, the estimated phase θ ′ is sent from the PLL calculation unit (16) to the power control unit (18).

(2) Voltage Stabilization Control The power supply system adjustment apparatus according to the embodiment of the present invention monitors voltage fluctuations in the power supply system (1) and calculates charge / discharge power (reactive power) so as to suppress the fluctuations. The voltage of the power supply system (1) is maintained constant by the voltage control (AVR) of the diesel generator (7), but the voltage fluctuates when there is a load change or a change in the generated power of another generator. The voltage also varies depending on the reactive power consumed by the load.

The operation of voltage stabilization control will be described using the control block (FIG. 4) of the voltage stabilization control circuit (40) which is an internal circuit of the system control unit (17).
The voltage stabilization control circuit (40) shown in FIG. 4 detects fluctuations in voltage and suppresses fluctuations in system voltage by adjusting reactive power from the power storage facility (11).

  The system voltage signal (41) calculated by the PLL calculation unit (16) is input to the voltage stabilization control circuit (40). The system voltage signal (41) is subjected to time delay processing in the delay calculator (42) to become the system voltage target value Vref, and is sent to the subtracter (43). The output of the delay calculator (42) gives the target value (Vref) of the system voltage.

  The subtracter (43) subtracts the system voltage V from the system voltage target value Vref and outputs it to the proportional controller (44). The proportional controller (44) multiplies the output (= Vref−V) of the subtractor (43) by a proportional constant Kv and sends the result to the upper / lower limiter (45) of the next stage. Then, the output of the proportional controller (44) is limited between Qbat_max and Qbat_min by the upper / lower limiter (45), and is output as the reactive power command signal (46).

  The delay calculator (42) makes the system voltage target value Vref asymptotic to the set value of the system voltage. As a result, the voltage stabilization control responds only to voltage transients and does not constantly output reactive power. Here, the delay calculator (42) is preferably constituted by a first-order delay calculation. The time constant T is adjusted during the test operation, but is set to 1 minute in the present embodiment. The delay calculator (42) may be a second-order delay calculation, or may be another calculation as long as it performs time delay processing. The difference between the system voltage target value Vref and the system voltage V, which is the process amount, becomes the control error εv. In calculating the control error εv, the system voltage signal (41) may be obtained by performing a high-pass filter operation.

(3) Frequency Stabilization Control Unit The power supply system adjustment apparatus according to the embodiment of the present invention monitors the frequency fluctuation of the power supply system (1) and calculates charge / discharge power (active power) so as to suppress the fluctuation. . The frequency of the power system (1) is kept constant by the rotational speed control device (governor) of the diesel generator (7). The output of the machine (7) and the load power are not balanced, and as a result, the frequency fluctuates temporarily.

  The operation of the frequency stabilization control will be described using the control block (FIG. 5) of the frequency stabilization control circuit (50) which is an internal circuit of the system control unit (17). The frequency stabilization control circuit (50) shown in FIG. 5 detects frequency fluctuations and compensates for the unbalance between the output of the diesel generator (7) and the load power with the effective power generated by the power storage facility (11). This suppresses temporary frequency fluctuations.

  The system frequency signal (51) calculated by the PLL calculation unit (16) is input to the frequency stabilization control circuit (50). The system frequency signal (51) is subjected to time delay processing in the delay computing unit (52) to become the system frequency target value Fref, and is sent to the subtracter (53). The output of the delay calculator (52) gives the target value (Fref) of the system frequency.

  The subtracter (53) subtracts the system frequency F from the system frequency target value Fref and outputs it to the proportional controller (54). The proportional controller (54) multiplies the output of the subtractor (= Fref−F) by a proportional constant Kf and sends the result to the upper / lower limiter (55) of the next stage. The output of the proportional controller (54) is limited between Pbat_max and Pbat_min by the upper / lower limiter (55). The output of the upper / lower limiter (55) is added with the active power correction Psoc_cmp from the SOC correction control circuit (60) by the adder (57), and the frequency stabilization control circuit (56) is obtained as the active power command signal (56). 50).

  The delay calculator (52) makes the frequency target value of the frequency stabilization control circuit (50) asymptotic to the system frequency settling value. As a result, the frequency stabilization control responds only to a transient change in frequency and does not continuously output active power. Here, the delay calculator (52) is preferably configured by a first-order delay calculation. The time constant T is adjusted during the test operation, but is set to 1 minute in the present embodiment. The delay calculator (42) may be a second-order delay calculation, or may be another calculation as long as it performs time delay processing. The difference between the system frequency target value Fref and the system frequency F, which is the process amount, becomes the control error εf. In calculating the control error εf, the system frequency signal (51) may be obtained by performing a high-pass filter operation.

(4) SOC correction control The secondary battery (5) is equipped with a battery state detector (21) such as a voltmeter, an ammeter, a thermometer, and a pressure gauge for detecting the state of the secondary battery. The secondary battery monitoring device (22) monitors the state of the secondary battery and calculates the SOC of the secondary battery. Before describing the SOC control, a method for obtaining the SOC will be described.

  As a method for calculating the state of charge (SOC) of the battery, there are a method of integrating charge / discharge current (integrated SOC method) and a method of estimating the state of charge from battery voltage, current, temperature, etc. (instantaneous SOC method). Here, while the integrated SOC method can be accurately measured in a short-term operation, there is a problem that the error of current measurement error and the influence of self-discharge are accumulated, and the error increases when operated for a long time.

  On the other hand, the instantaneous SOC method is not affected by the accumulated error, but an error occurs due to a change in charging / discharging current over time. In the embodiment according to the present invention, the SOC is calculated using the corrected SOC method (see FIG. 8). That is, the SOC is calculated by the integrated SOC method, a deviation from the instantaneous SOC is obtained, and a correction SOC is obtained by correcting the charge / discharge current value so as to correct the deviation. In this method, the accumulated error caused by the integrated SOC method is corrected by the instantaneous SOC method, so that accumulation of errors is suppressed by long-term use, and long-term operation is possible.

  If the secondary battery is overcharged (SOC> 100%) or overdischarged (SOC <0%), the battery performance may be deteriorated, and if the battery voltage is too low, the apparatus may be stopped. Accordingly, the upper limit of the battery usage range is set to 80%, and the lower limit is set to 20% to operate the secondary battery. Therefore, an intermediate value (50%) between 80% and 20% is set as the SOC target value SOCref.

  In order to maintain the secondary battery (5) in an appropriate state of charge, the SOC correction power is calculated from the predetermined SOC target value (SOCref) and the SOC deviation calculated by the secondary battery monitoring device (22). calculate. The operation of the SOC correction control will be described with reference to FIG.

  FIG. 6 is a diagram showing a control block of the SOC correction control circuit (60) which is an internal circuit of the system control unit (17). The SOC of the secondary battery calculated by the secondary battery monitoring device (22) is input to the SOC correction control circuit (60) via the wiring (26). This SOC is compared and subtracted by the subtracter (63) with the SOC target value SOCref set in the SOC correction control circuit (60).

  When the SOC is lower than the target value (SOCref), the active power command value (Pbat_ref) output from the frequency stabilization control circuit (50) is corrected to be on the charging side (Psoc_cmp <0).

  Conversely, when the SOC exceeds the target value (SOCref), the active power command value (Pbat_ref) is corrected to be on the discharge side (Psoc_cmp> 0). As described above, the state of charge of the secondary battery is controlled to be kept constant by the SOC correction control.

  The output of the subtracter (63) is subjected to unit conversion and upper / lower limit by the upper / lower limiter (64). The output of the upper / lower limiter (64) is subjected to the first-order lag processing with a time constant of one minute by the first-order lag calculator (66) and sent to the frequency stabilization control circuit (50) as the SOC correction signal (65). Is done.

(5) Power control As described above, the system frequency and the system voltage are calculated by the PLL calculation unit (16) based on the signal from the voltage detector (14), and the active power command Pbat_ref is invalidated by the system control unit (17). A power command Qbat_ref is calculated and sent to the power control unit (18) as a power command signal (28).

  Based on the active power command Pbat_ref and the reactive power command Qbat_ref, the power control unit (18) sends a gate drive signal (29) for turning on / off the power semiconductor element to the power conversion circuit (20). The power semiconductor is PWM controlled so that the active power and the reactive power become the active power command Pbat_ref and the reactive power command Qbat_ref, respectively.

  Details of the power control will be described with reference to a power control block diagram shown in FIG. The instantaneous value of the line current flowing through the power storage facility (11) is measured by the current detector (13) installed in the power conversion control device (6) and transmitted to the power control unit (18). This current value is subjected to dq conversion based on the phase θ sent from the PLL calculation unit (16), and the d-axis current and the q-axis current are calculated.

  On the other hand, the active power command Pbat_ref and the reactive power command Qbat_ref sent from the system control unit (17) are converted into a d-axis current target value and a q-axis current target value, and d obtained from the current detector (13). It is compared with the axial current and the q-axis current, passes through the PI controller, is inversely converted by dq, and is sent to the power conversion circuit (20) as a gate drive signal (29).

  In the secondary battery monitoring device (22), if an abnormality is found in the secondary battery, a battery abnormality signal is sent to the power control unit (18) of the system control device (15) via the wiring 26b, and the gate drive signal (29). Is stopped, the operation of the power conversion circuit (20) is stopped, and the secondary battery (5) is protected. Examples of secondary battery abnormalities include overcurrent, voltage drop, overvoltage, overcharge, overdischarge, battery temperature abnormality, battery pressure abnormality, and device abnormality.

(7) Number control of diesel generators The operation control of the diesel generators (7a, 7b, 7c) shown in FIG. 1 will be described. When the bow thruster (8) is not operated, one diesel generator (7) is operated to cover the inboard power load (2).

  Before operating the bow thruster (8) during entry / exit, the diesel generator (7) is activated in advance to stabilize the power system in the ship. That is, one diesel generator (7) is started to supply power necessary for the operation of the bow thruster (8), and further, the diesel generator (7) is used to stabilize the power supply system when the induction motor is started. Is activated, and two diesel generators (7) are operated for convenience. The diesel generator (7) is started or stopped by the operator pressing the operation button. The diesel generator (7) can be operated / stopped manually.

  Basically, the power required on board the ship is provided by a diesel generator (7), and the power storage facility (11) according to the present invention is capable of transient load fluctuations and solar power that the diesel generator (7) cannot follow. It is provided to compensate for disturbances to the system caused by the photovoltaic generator (10).

  The diesel generator (7) is provided with a DG number control device (9), and the number of operating diesel generators (7) is automatically controlled according to the flowchart shown in FIG. When the state where the load of the diesel generator (7) is 80% or more continues for 5 minutes or more (S6), the number of operating diesel generators (7) is reduced (S7, S8), and the load is 30% or less Is continued for more than 5 minutes (S9), the number of operating diesel generators (7) is increased (S10, S11).

  If the power supply system adjusting device according to the present invention is installed, it is not necessary to operate the diesel generator (7) excessively in order to stabilize the power supply system, and the fuel consumption rate can be improved.

(8) Test results In FIG. 10, when the load suddenly changes from 400 kW (power factor 0.8) to 600 kW (power factor 0.8) in the power supply system (1) and then decreases to 400 kW (power factor 0.8). About the difference of the voltage and frequency fluctuation | variation with and without the control by the power supply system adjustment apparatus concerning this invention. FIG. 10A shows the influence of loading by taking the system voltage on the vertical axis and time (seconds) on the horizontal axis. FIG. 10B shows the influence of loading by taking the system frequency on the vertical axis and the time (seconds) on the horizontal axis. It can be seen that by introducing the power storage facility (11) that performs system stabilization control, voltage and frequency fluctuations are suppressed, the power supply quality of the system is improved, and system stability is increased.

  Since the stability of the power supply system (1) has increased, it is possible to stop the diesel generator that is operating excessively and to improve fuel consumption efficiency in order to ensure system stability. Yes.

  The independent power supply system adjustment device according to the present invention can be suitably used as a control device for maintaining and managing the quality of a power supply system in a ship. It can also be used for general self-sustained power systems on land.

DESCRIPTION OF SYMBOLS 1 Independent power supply system 2 Inboard power load 3 Solar cell unit 4 Power converter 5 Secondary battery 6 Power conversion controller 7 Diesel generator 8 Bow thruster 9 D / G number control device (diesel generator number control device)
DESCRIPTION OF SYMBOLS 10 Photovoltaic generator 11 Power storage equipment 13 Current detector 14 Voltage detector 15 System control device 16 PLL calculating part 17 System control part 18 Power control part 20 Power conversion circuit 21 Battery state detector 22 Secondary battery monitoring device 24 Wiring 25 DC power line 26 Wiring 27 System state signal 28 Power command signal 29 Gate drive signal (PWM signal)
32 Phase comparator 34 Loop filter 35 Accumulator 40 Voltage stabilization control circuit 41 System voltage signal 42 Delay calculator 43 Subtractor 44 Proportional controller 45 Upper / lower limiter 46 Reactive power command 50 Frequency stabilization control circuit 51 System frequency signal 52 Delay calculator 53 Subtractor 54 Proportional controller 55 Upper / lower limit limiter 56 Active power command 57 Adder 60 SOC correction control circuit 61 SOC target value 63 Subtractor 64 Upper / lower limiter 65 SOC correction signal 66 Primary delay calculator 101 Inboard power supply system 102 Inboard power load (customer)
DESCRIPTION OF SYMBOLS 103 Solar cell unit 104 Power converter 105 Secondary battery 106 Power converter 107 Diesel generator 108 Bow thruster 109 Wind generator

Claims (9)

A self-supporting power system having a prime mover generator and load equipment,
A power storage facility having a secondary battery and a power converter;
A frequency measuring means for measuring the frequency of the independent power system;
Voltage measuring means for measuring the voltage of the independent power system,
A system control unit that calculates a target value of active power and a target value of reactive power, respectively, using measurement values from the frequency measurement unit and the voltage measurement unit;
An independent power supply system adjustment device including the power converter that outputs active power and reactive power according to target values of active power and reactive power from the system control unit. A battery state detector attached to the secondary battery;
SOC measuring means for calculating the SOC of the secondary battery according to a signal from the battery state detector;
The independent power supply system adjustment device according to claim 1, further comprising means for correcting the target value of the active power based on a deviation between an output from the SOC measuring means and a predetermined SOC target value. The frequency measuring means and the voltage measuring means are
A voltmeter to measure the voltage of the independent power system,
The independent power supply system adjustment device according to claim 1, further comprising: a PLL calculation unit that performs phase synchronization calculation on an output of the voltmeter.   The independent power system adjustment device according to any one of claims 1 to 3, wherein the control calculation in the system control unit is proportional control.   A delay calculator is provided at the output of the frequency measuring means to perform a time delay calculation to obtain a frequency target value, and a delay calculator is provided to the output of the voltage measuring means to perform a time delay calculation to obtain a voltage target value. The stand-alone power supply system adjustment device according to any one of claims 1 to 4. A plurality of the motor generators,
The independent power system adjustment device according to any one of claims 1 to 5, further comprising a unit control for starting and stopping the prime mover generator according to a load state of the prime mover generator.   The independent power supply system adjustment device according to any one of claims 1 to 6, wherein a generator using natural energy is connected to the independent power supply system. In a self-supporting power system having a prime mover generator, a load facility, a secondary battery, and a power converter of the secondary battery,
Calculate the reactive power target value from the voltage of the independent power system,
A correction according to the deviation between the SOC of the battery obtained from the state of the secondary battery and the SOC target value is performed on the target value of the active power obtained from the frequency of the independent power system
An independent power supply system adjustment method for adjusting active power and reactive power from the power converter so as to be a target value of the reactive power and a target value of the active power.   The independent power supply system adjustment method according to claim 8, wherein the frequency and voltage of the independent power supply system are calculated from a voltage signal of the independent power supply system by phase synchronization calculation.

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