JP2019154219A - Control arrangement and control method - Google Patents

Abstract

To prevent power swing when performing control simulating synchronous generator, for an inverter device converting DC power into AC power.SOLUTION: A control arrangement 1 controlling an inverter device 3 for converting DC power into AC power and outputting to a power system includes a generator simulation section 100 for simulating the frequency maintenance characteristics of the body of rotation in a prescribed synchronous generator on the basis of the AC voltage and the AC current in a power system 20, and calculating the phase of the AC voltage outputted from the inverter device 3, and a control signal generation part 110 generating a control signal for the inverter device 3 on the basis of the phase of the AC voltage calculated by the generator simulation section 100. The generator simulation section 100 includes an angular frequency adjustment section 102 generating information for adjusting the angular frequency used in calculation of the phase of the AC voltage, so that the phase difference of the phase of the AC voltage in the power system 20, and the phase of the AC voltage outputted from the generator simulation section 100 to the control signal generation part 110 falls within a predetermined range.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a control device and a control method for controlling an inverter device that converts DC power into AC power.

  The power generation facility that outputs AC power to the power system is a power generation facility that generates and outputs AC power, such as a synchronous generator, and DC power such as a photovoltaic power generation system and a storage battery system is converted to AC power and output. There is a power generation facility. In particular, from the viewpoint of effective use of renewable energy, in recent years, power generation facilities that convert DC power into AC power and output it are increasing.

  A power generation facility that converts DC power into AC power and outputs the power includes a generator or a storage battery that outputs DC power, an inverter device that converts DC power into AC power, and a control device that controls the inverter device. The inverter device in this type of power generation equipment is controlled by the control device so as to follow the system voltage at high speed. However, unlike the synchronous generator, the inverter device in the power generation facility does not have the characteristic of maintaining the frequency independently. For this reason, in an electric power system with a low ratio of synchronous generators, the ability to maintain the frequency is lowered, and the stability of the system power is lowered.

  As one of the techniques for preventing a reduction in the stability of the system power, there is a technique in which the control device controls the inverter device by simulating the frequency maintenance characteristic of the rotating body of the synchronous generator. In this type of technology, the angular frequency of the synchronous generator is calculated based on the difference between the measured value of the active power output from the inverter device and the predetermined output target value of the active power, and the voltage of the calculated angular frequency is calculated. Is output from the inverter device (see, for example, Non-Patent Document 1).

  Patent Document 1 discloses a rotating body that integrates a difference between a measured value of active power output from an inverter device and a predetermined output target value of active power with a time constant of an inertia constant, and simulates the result of the integration. The angular frequency is disclosed. Further, Patent Document 1 discloses that an angular frequency is integrated to calculate a target phase difference from the system, and a voltage that becomes the phase difference is output from an inverter device.

JP 2007-318833 A

Toshiyuki Matoba et al., “Basic Study on Synchronous Power Inverter Device with Distributed Power Source”, 2012 Annual Conference of the IEEJ National Conference, March 2012, 6th volume, p.390-391

  However, in the control device that simulates the synchronous generator by integrating the difference between the measured value of the active power output from the inverter device and the output target value, the frequency in the power system changes rapidly in a short time. It is impossible to follow the change in the frequency, and there is a possibility that step-out (out of synchronization) may occur.

  An object of the present invention is to prevent a step-out when performing control simulating a synchronous generator for an inverter device that converts DC power into AC power.

  The control device according to the present invention is a control device that controls an inverter device that converts DC power into AC power and outputs the AC power to the power system, in a predetermined synchronous generator based on the AC voltage and AC current in the power system. A generator simulation unit for simulating the frequency maintenance characteristics of the rotating body and calculating the phase of the AC voltage output from the inverter device, and the control for the inverter device based on the phase of the AC voltage calculated by the generator simulation unit A control signal generation unit that generates a signal, and the generator simulation unit includes: a phase of the AC voltage in the power system; and a phase of the AC voltage output from the generator simulation unit to the control signal generation unit. An angular frequency adjusting unit that generates information for adjusting the angular frequency used for the calculation of the phase of the AC voltage so that the phase difference is within a predetermined range.

  The control method of the present invention is a control method of an inverter device that converts DC power into AC power and outputs the AC power to the power system, and the control device that controls the inverter device includes AC voltage and AC in the power system. Based on the current, the frequency maintenance characteristic of the rotating body in a predetermined synchronous generator is simulated, the phase of the AC voltage output from the inverter device is calculated, and the control signal for the inverter device is calculated based on the calculated phase of the AC voltage The process of calculating the phase of the AC voltage includes the process of generating the AC voltage in the power system so that the phase difference between the phase of the AC voltage and the calculated phase of the AC voltage is within a predetermined range. It includes processing for generating information for adjusting the angular frequency used to calculate the phase of the AC voltage.

  According to the control device and the control method of the present invention, it is possible to prevent step-out when performing control simulating a synchronous generator for an inverter device that converts DC power into AC power.

It is a figure which shows the functional structure of the control apparatus which concerns on 1st Embodiment. It is a figure which shows the structure of the generator simulation part in the control apparatus which concerns on 1st Embodiment. It is a figure explaining the relationship between internal phase angle (delta) and output (DELTA) omega of a 1st integrator. It is a figure which shows the example of the time change of a system | strain frequency. It is a figure which shows the simulation result when not adjusting the angular frequency based on an internal phase angle. It is a figure which shows the simulation result at the time of performing control by the control apparatus which concerns on 1st Embodiment. It is a figure which shows the structure of the generator simulation part in the control apparatus which concerns on 2nd Embodiment. It is a figure which shows the functional structure of the control apparatus which concerns on 3rd Embodiment. It is a figure which shows the structural example of the generator simulation part in the control apparatus which concerns on 3rd Embodiment. It is a figure explaining the voltage estimation method by a remote voltage estimation part. It is a figure explaining the phenomenon which may occur when adjusting an angular frequency based on a terminal voltage. It is a figure which shows the 2nd example of the time change of a system frequency. It is a figure which shows another example of the simulation result at the time of performing control by the control apparatus which concerns on 1st Embodiment. It is a figure which shows the example of the simulation result at the time of performing control by the control apparatus which concerns on 3rd Embodiment. It is a figure which shows another structural example of the generator simulation part in the control apparatus which concerns on 3rd Embodiment.

  Embodiments of the present invention will be described below with reference to the drawings.

[First Embodiment]
FIG. 1 is a diagram illustrating a functional configuration of a control device according to the first embodiment. As shown in FIG. 1, the control device 1 according to the present embodiment controls the operation of the inverter device 3 that converts the DC power generated by the DC power source 2 into AC power and outputs (transmits) the power to the power system 20. Device. The AC power converted in the inverter device 3 is smoothed by the smoothing reactor (filter) 4 and then output to the power system 20 by the power transmission line 5.

  The control device 1 of the present embodiment includes a generator simulation unit 100, a control signal generation unit 110, an output target setting unit 120, and a reference frequency setting unit 130.

The generator simulation unit 100 simulates the inertia of the rotating body included in the synchronous generator based on the AC voltage and AC current of the power system, and determines the phase θ of the voltage output from the inverter device 3. In the control device 1 of the present embodiment, the AC voltage V _{a, b, c} detected in the power transmission line 5 connecting the inverter device 3 and the power system 20 as the AC voltage and AC current of the power system _, and the AC voltage I _{a , b, and c} are used. Here, the AC voltage V _{a, b, c} is a collective representation of the three-phase AC voltages V _a , V _b , and V _c detected by the voltage detector 6. Further, the alternating currents I _{a, b, c} are collectively expressed as the three-phase alternating currents I _a , I _b , and I _c detected by the current detector 7.

The generator simulation unit 100 includes a phase calculation unit 101 and an angular frequency adjustment unit 102.
The phase calculation unit 101 is input from the AC voltage V _{a, b, c} and AC current I _{a, b, c of} the power system, the output target, the reference frequency ω ₀ of the power system 20, and the angular frequency adjustment unit 102. The phase θ of the voltage output from the inverter device 3 is calculated based on the information. The phase calculation unit 101 acquires an output target value of active power output from the inverter device 3 from the output target setting unit 120. In addition, the phase calculation unit 101 acquires the reference frequency ω ₀ of the power system 20 from the reference frequency setting unit 130.

The angular frequency adjustment unit 102 adjusts the value of the angular frequency used by the phase calculation unit 101 to calculate the phase based on the AC voltage of the power system and the phase θ of the voltage calculated and output by the phase calculation unit 101. Information to be generated is output to the phase calculation unit 101. Specifically, the angular frequency adjusting unit 102 controls the control device so that the phase difference (internal phase angle) δ calculated based on the phase of the AC voltage of the power system and the voltage phase θ does not deviate from a predetermined range. Information for adjusting the angular frequency of the rotating body in the synchronous generator simulated by 1 is generated. The angular frequency adjusting unit 102 in the control device 1 of the present embodiment uses the AC voltage Va _{, b, c} detected by the voltage detector 6 as the AC voltage of the power system. The angular frequency adjustment unit 102 calculates the phase according to whether the absolute value of the internal phase angle δ calculated based on the detected AC voltage V _{a, b, c} and the voltage phase θ is within a predetermined range. The unit 101 is made to switch the value of the angular frequency used for calculating the phase. When the absolute value of the internal phase angle δ is within a predetermined range, the angular frequency adjustment unit 102 calculates the phase calculation unit 101 based on the detected AC voltage V _{a, b, c} and AC current I _{a, b, c.} The phase θ is calculated based on the angular frequency adjustment value Δω obtained by integrating the difference between the effective power and the output target value. On the other hand, when the absolute value of the internal phase angle δ is within a predetermined range, the angular frequency adjustment unit 102 causes the phase calculation unit 101 to detect the frequency of the power system detected from the AC voltage V _{a, b, c of the} power system. and omega, to calculate the phase θ on the basis of the difference omega-omega ₀ of a reference frequency omega _0.

  The control signal generation unit 110 generates a control signal including information indicating the phase θ of the voltage output from the inverter device 3 based on the phase θ input from the generator simulation unit 100 and outputs the control signal to the inverter device 3. The control signal generation unit 110 includes a sine wave generation unit 111 and a pulse width modulation unit 112.

The sine wave generation unit 111 generates a sine wave indicating each of the voltages V ^* _a , V ^* _b , and V ^* _c of each phase in the three-phase alternating current based on the phase θ input from the generator simulation unit 100. To do. For example, the sine wave generation unit 111 generates a sine wave according to the following formula (1-1), formula (1-2), and formula (1-3).

V ^* _a = sin {θ} (1-1)
V ^* _b = sin {θ + (2π / 3)} (1-2)
V ^* _c = sin {θ + (4π / 3)} (1-3)

The pulse width modulation unit 112 performs pulse width modulation (PWM) on each of the sine waves (voltages V ^* _a , V ^* _b , and V ^* _c ) generated by the sine wave generation unit 111, The modulated pulse signal is output to the inverter device 3.

  As described above, when the generator simulation unit 100 simulates the angular frequency of the rotating body of the synchronous generator, the control device 1 of the present embodiment has an angle so that the absolute value of the internal phase angle δ does not deviate from a predetermined range. Adjust the frequency. For example, the generator simulation unit 100 adjusts the angular frequency of the rotating body of the synchronous generator so that the absolute value of the internal phase angle δ is π / 4 or less (| δ | ≦ π / 4).

  FIG. 2 is a diagram illustrating a configuration of a generator simulation unit in the control device according to the first embodiment. As shown in FIG. 2, the phase calculation unit 101 of the generator simulation unit 100 includes an active power measurement unit 101a, a subtractor 101b, a first integrator 101c, an adder 101d, and a second integrator 101e. Including.

The active power measuring unit 101a is configured to detect the current power system 20 based on the AC voltage V _{a, b, c} detected by the voltage detector 6 and the AC current I _{a, b, c} detected by the current detector 7. The effective power P is measured. The active power measurement unit 101a measures the active power P of the power system 20 according to a known measurement method.

  The subtractor 101b calculates the difference between the target value (output target) of the active power to be output to the inverter device 3 and the measured active power P. The output target is input from the output target setting unit 120 (see FIG. 1).

The first integrator 101c time-integrates the difference between the output target and the active power P measured by the active power measuring unit 101a. When the output set signal SS input from the angular frequency adjustment unit 102 is OFF (OFF), the first integrator 101c converts the result of time integration for the difference between the output target and the active power P into the angular frequency adjustment. Output as the value Δω. The angular frequency adjustment value Δω is a value for adjusting the angular frequency of the rotating body in the synchronous generator to be simulated to the angular frequency of the power system, and corresponds to the difference between the angular frequency of the power system and the reference frequency at the present time. On the other hand, when the output set signal SS input from the angular frequency adjusting unit 102 is ON (ON), the first integrator 101c outputs the set value output ω−ω ₀ input from the angular frequency adjusting unit 102, Output as an angular frequency adjustment value Δω.

The adder 101d adds the angular frequency adjustment value Δω output from the first integrator 101c and the reference frequency ω ₀ and outputs the result. The reference frequency ω ₀ is input from the reference frequency setting unit 130. The reference frequency ω ₀ is a reference frequency of power in the power system 20 and is set to 50 Hz or 60 Hz, for example.

The second integrator 101e performs time integration on the angular frequency ω ₀ + Δω input from the adder 101d, and outputs the result of the time integration as the phase θ of the voltage output from the inverter device 3. In the control device 1 of the present embodiment, the phase θ output from the second integrator 101e is input to the sine wave generation unit 111 (see FIG. 1) of the control signal generation unit 110 and the angular frequency adjustment unit 102. Is input to the internal phase angle calculation unit 102a.

The angular frequency adjusting unit 102 in the control device 1 according to the present embodiment determines the output set signal SS indicating whether or not the internal phase angle δ is within a predetermined range and the angular frequency of the synchronous generator being simulated at the present time. A set value output ω−ω ₀ that matches the system frequency is generated and output. The angular frequency adjustment unit 102 includes an internal phase angle calculation unit 102a, a comparison unit 102b, a system frequency detection unit 102c, and a subtractor 102d.

The internal phase angle calculation unit 102a calculates a phase difference (internal phase angle) δ between the phase of the AC voltage of the power system and the phase θ output by the phase calculation unit 101. In the control device 1 of the present embodiment, the AC voltage Va _{, b, c} input to the active power measuring unit 101a is used as the AC voltage of the power system. The internal phase angle calculation unit 102a calculates the internal phase angle δ using, for example, the following formula (2-1), formula (2-2), and formula (2-3).

  The comparison unit 102b generates and outputs an output set signal SS based on the magnitude relationship between the internal phase angle δ calculated by the internal phase angle calculation unit 102a and a predetermined threshold (for example, π / 4). When the absolute value of the internal phase angle δ is equal to or smaller than a threshold (for example, | δ | ≦ π / 4), the comparison unit 102b generates and outputs an off-level signal as the output set signal SS. When the absolute value of the internal phase angle δ is larger than the threshold (for example, | δ |> π / 4), the comparison unit 102b generates and outputs an on-level signal as the output set signal SS. The output set signal SS is input to the first integrator 101c of the phase calculation unit 101.

The system frequency detection unit 102 c detects the current voltage frequency ω in the power system 20. In the control device 1 of the present embodiment, the frequency ω is detected based on the AC voltage Va _{, b, c} input to the active power measuring unit 101a. The system frequency detection unit 102c detects the frequency ω of the voltage of the power system 20 according to a known detection method.

The subtractor 102 d calculates a difference ω−ω ₀ between the voltage frequency ω detected by the system frequency detection unit 102 c and the reference frequency ω ₀ of the power system 20. The reference frequency ω ₀ is input from the reference frequency setting unit 130 (see FIG. 1). The difference ω−ω ₀ calculated by the subtractor 102d is input to the first integrator 101c of the phase calculation unit 101 as a set value output.

Thus, in the generator simulation part 100 which concerns on this embodiment, the value (set) which shows the difference between active electric power P and an output target, and the system frequency at the present time to the 1st integrator 101c of the phase calculation part 101. The value output ω−ω ₀ ) is input. Then, the first integrator 101c changes the value of the output angular frequency adjustment value Δω depending on whether the output set signal SS is on or off.

  FIG. 3 is a diagram for explaining the relationship between the internal phase angle δ and the output Δω of the first integrator. The table 30 in FIG. 3 outputs the internal phase angle δ, the output set signal SS, and the first integrator 101c when the threshold value to be compared with the internal phase angle δ in the comparison unit 102b is π / 4. The relationship with the value of the angular frequency adjustment value Δω is shown.

In the table 30 of FIG. 3, the output set signal SS when the internal phase angle δ is | δ | ≦ π / 4 is OFF (off-level signal). When the output set signal SS is OFF, the first integrator 101c outputs a value obtained by integrating (time integration) the difference between the active power P and the output target as the angular frequency adjustment value Δω. On the other hand, in the table 30 of FIG. 3, the output set signal SS when the internal phase angle δ is | δ |> π / 4 is ON (on-level signal). When the output set signal SS is ON, the first integrator 101c outputs the set value output ω−ω ₀ input from the angular frequency adjustment unit 102 as the angular frequency adjustment value Δω. That is, in the generator simulation unit 100 of this embodiment, when the internal phase angle δ is | δ |> π / 4, the set value output ω−ω ₀ regardless of the difference between the active power P and the output target. Is an angular frequency adjustment value Δω. In other words, the angular frequency adjustment value Δω in the case of | δ |> π / 4 is the difference between the current system frequency and the reference frequency, so it is easy to match the frequencies. Therefore, it is possible to prevent an increase in the difference between the phase θ output from the second integrator 101e and the phase of the AC voltage in the power system when the absolute value of the internal phase angle δ is larger than the threshold value. It becomes. Therefore, in the control device 1 of the present embodiment, it is possible to prevent the step-out when performing control simulating the synchronous generator with respect to the inverter device 3 that converts DC power into AC power. Note that, when the output set signal SS is switched from ON to OFF, the first integrator 101c in the control device 1 of the present embodiment outputs the previous output Δω = ω−ω ₀ as shown in the table 30. As an initial value, integration of the difference between the active power P and the output target is started.

  Thus, the control device 1 of the present embodiment simulates the synchronous generator when the phase difference between the AC voltage of the power system 20 and the AC voltage output from the inverter device 3 exceeds a predetermined range. The phase of the AC voltage output from the inverter device 3 is adjusted by matching the angular frequency of the rotating body with the system frequency. For this reason, in the control apparatus 1 of this embodiment, even when the frequency (system frequency) of the electric power system 20 changes rapidly, it is possible to prevent a step-out (out of synchronization) due to a rapid increase in the internal phase angle. Become.

  Hereinafter, with reference to FIGS. 4-6, the effect at the time of controlling the inverter apparatus 3 with the control apparatus 1 of this embodiment is demonstrated.

  FIG. 4 is a diagram illustrating an example of a time change of the system frequency. FIG. 5 is a diagram illustrating a simulation result when the angular frequency is not adjusted based on the internal phase angle. FIG. 6 is a diagram illustrating a simulation result when control is performed by the control device according to the first embodiment.

  The inventors of the present invention have made it possible to perform an inverter without adjusting the internal phase angle δ over time when the inverter device 3 is controlled by the control device 1 of the present embodiment and adjusting the angular frequency by the angular frequency adjusting unit 102 by computer simulation. The time variation of the internal phase angle δ when the device 3 was controlled was examined.

In the simulation, a model (one machine infinite bus system) in which a power generation facility including one generator (DC power supply 2) as shown in FIG. 1 is directly connected to the power system 20 (infinity bus). It was used. The generator (DC power supply 2) was a storage battery. Further, the output side filter unit (smoothing reactor 4) of the inverter device 3 and the transmission line simulation unit not shown in FIG. 1 each have a reactance of 5% on the basis of the equipment capacity. The transmission line simulation unit is a reactor that simulates reactance in a section from the position where the AC voltage V _{a, b, c} is detected to the power system 20 in the transmission line 5.

Further, in the simulation, when the infinite bus is an ideal voltage source and the system frequency is changed with time as shown by the frequency ratio ω _s / ω ₀ shown in the graph 40 of FIG. The time change of the AC voltage V _{a, b, c} was calculated. The frequency ratio ω _s / ω ₀ is a ratio between the frequency ω _s of the power system 20 and the reference frequency ω ₀ .

For the first second in graph 40, the frequency ratio is 1.00. That is, for the first second in the simulation, the frequency ω _s of the power system 20 is matched with the reference frequency ω ₀ . In the period from time 1.0 seconds to 1.5 seconds in the graph 40, the frequency ratio increases to 1.02, returns to 1.00, and increases again to 1.02. In particular, in the graph 40, the frequency ratio instantaneously increases from 1.00 to 1.02 at the timing when the time becomes 1.5 seconds. In the period from time 1.5 seconds to 2.0 seconds in the graph 40, the frequency ratio is 1.02. In the period from time 2.0 seconds to 3.0 seconds in graph 40, the frequency ratio decreases from 1.02 to 0.98 in 0.1 seconds from time 2.1 seconds, and then reaches 0. The frequency ratio is reduced to 925.

When the frequency ω _s of the power system 20 changes with time as shown in the graph 40, a simulation for controlling the inverter device 3 without adjusting the angular frequency based on the internal phase angle δ is performed in FIG. The results shown were obtained. That is, FIG. 5 shows a simulation result when the inverter device 3 is controlled by the phase θ calculated using only the angular frequency adjustment value Δω obtained by time-integrating the difference between the active power P and the output target.

FIG. 5 shows four graphs 51 to 54. The graph 51 shows the time change of the terminal voltage, that is, the time change of the AC voltage V _{a, b, c} detected by the voltage detector 6. The graph 52 shows the time change of the output current, that is, the time change of the alternating currents I _{a, b, c} detected by the current detector 7. The graph 53 shows the time change of the two frequency ratios ω _s / ω ₀ and (Δω + ω ₀ ) / ω ₀ . The graph 54 shows the time change of the internal phase angle δ (radian). Note that the graphs 51 to 54 in FIG. 5 omit the simulation results during the period from time 0 seconds to 1 second in the graph 40 in FIG. 4.

As shown in the graph 53, the frequency ratio ω _s / ω ₀ of the power system 20 increases from 1.00 to 1.02 in the period from time 1 second to 1.2 seconds. Thereafter, the frequency ratio ω _s / ω ₀ of the power system 20 returns from 1.02 to 1.00 during the period from 1.3 seconds to 1.4 seconds, but when the time becomes 1.5 seconds. It rises to 1.02, and the state of 1.02 continues until time 2.0 seconds. However, when the temporal change amount of the frequency ratio ω _s / ω ₀ of the power system 20 is such a relatively small change amount, the first integration can be performed without adjusting the angular frequency by the angular frequency adjusting unit 102. The angular frequency adjustment value Δω output from the device 101 c follows the change in the frequency ω _s of the power system 20. For this reason, the value of the internal phase angle δ during the period from 1 second to 2 seconds changes at a relatively small value. When the angular frequency adjustment by the angular frequency adjustment unit 102 is not performed, the angular frequency adjustment value Δω output from the first integrator 101c is a value obtained by time-integrating the difference between the active power P and the output target. That is, when the amount of time change of the frequency ω _s of the power system 20 is relatively small, the frequency ω _s of the AC voltage in the power system 20 and the inverter device are not required without adjusting the angular frequency by the angular frequency adjustment unit 102. The difference from the frequency of the AC voltage output by 3 does not increase. Therefore, the phase difference (internal phase angle δ) between the phase of the terminal voltage V _{a, b, c} and the phase θ of the AC voltage output from the inverter in the period from 1 second to 2 seconds is as shown in the graph 54, for example. In the range from 0 (radian) to -0.5 radians (<π / 4).

Thereafter, as shown in the graph 53, the frequency ratio ω _s / ω ₀ of the power system 20 significantly decreases during the period from time 2 seconds to 2.1 seconds, and continues to decrease until time 3 seconds. The frequency ratio ω _s / ω ₀ decreases by 0.04 in 0.1 second from time 2 seconds to 2.1 seconds. That is, when the reference frequency ω ₀ of the power system 20 is 50 Hz, the frequency ω _s of the power system 20 changes by 2 Hz in 0.1 seconds from the time 2 seconds to 2.1 seconds. As described above, when the frequency ω _s of the power system 20 changes rapidly, the difference between the active power P and the output target increases, and the angular frequency adjustment value Δω, which is the time integration of the difference, and the synchronous generator to be simulated The difference with the angular frequency of the rotating body at is increased. As a result, as shown in the graph 54 of FIG. 5, the internal phase angle δ rapidly increases after the time 2 seconds, and the internal phase angle δ becomes π / 2 radians (at the time t2 (about 2.34 seconds)). ≒ 1.57 radians). Moreover, after that, the frequency ω _s of the power system 20 continues to decrease, and although the frequency ratio (Δω + ω ₀ ) / ω ₀ decreases once and approaches the frequency ratio ω _s / ω ₀ as shown in the graph 53, The difference between the two frequency ratios has increased again since about 2.5 seconds have passed. Therefore, the internal phase angle δ continues to increase after time t2, and the internal phase angle δ exceeds π / 2 radians at time t4 (about 2.88 seconds). That is, in the simulation result of FIG. 5, at time t4, the internal phase angle δ exceeded π radians (= 180 degrees), and step-out (out of synchronization) occurred. When the step-out occurs, for example, as shown in the graph 51 of FIG. 5, the terminal voltage V _{a, b, c} decreases before and after the time t4 when the step-out occurs. Further, when the step-out occurs, the output current I _{a, b, c} decreases as shown in the graph 52 of FIG. Thus, when controlling the phase θ of the power output from the inverter device 3 based only on the difference between the active power P and the output target, if the frequency ω _s of the power system 20 changes rapidly, the change in the frequency ω _s . Cannot follow up, and step-out (out of synchronization) may occur.

  On the other hand, when the simulation which controls the inverter apparatus 3 by the control apparatus 1 which concerns on this embodiment was performed, the result as shown in FIG. 6 was obtained.

In FIG. 6, four graphs 61 to 64 are shown. The graph 61 shows the time change of the terminal voltage, that is, the time change of the AC voltage V _{a, b, c} detected by the voltage detector 6. The graph 62 shows the time change of the output current, that is, the time change of the alternating currents I _{a, b, c} detected by the current detector 7. The graph 63 shows the time change of the two frequency ratios ω _s / ω ₀ and (Δω + ω ₀ ) / ω ₀ . A graph 64 shows a time change of the internal phase angle δ (radian). Note that the graphs 61 to 64 in FIG. 6 omit the simulation results during the period from time 0 seconds to 1 second in the graph 40 in FIG. 4.

Also when the inverter device 3 is controlled by the control device 1 of the present embodiment, as described above, the internal phase angle δ is within a predetermined range (| δ | ≦ π / 4 radians, ie, | δ | ≦ 45 degrees). If there is, the angular frequency adjustment value Δω output from the first integrator 101c is a value obtained by time-integrating the difference between the active power P and the output target. Then, like the period from the time 1 second to 2 seconds in the graphs 63 and 64 shown in FIG. 6, the amount of time change of the frequency ω _s of the power system 20 is relatively small, and the internal phase angle δ is in a predetermined range. If the frequency is within the range, the frequency Δω + ω ₀ calculated based on the angular frequency adjustment value Δω obtained by time-integrating the difference between the active power P and the output target follows the change in the frequency ω _s . For this reason, the value of the internal phase angle δ during the period from time 1 second to time 2 seconds changes at a relatively small value whose absolute value is π / 4 or less.

Further, as shown in the graph 63, the frequency ratio ω _s / ω ₀ of the electric power system 20 is remarkably reduced between the time 2 seconds and 2.1 seconds, and continues to decrease until the time 3 seconds. When the frequency ω _s of the power system 20 changes rapidly, the difference between the active power P and the output target increases as described above, and the angular frequency adjustment value Δω that is the time integration of the difference and the synchronous power generation to be simulated The difference with the angular frequency of the rotating body in the machine increases. Therefore, as in the simulation result of FIG. 5, the internal phase angle δ increases after a time of 2 seconds, and the internal phase angle δ becomes π / 4 radians (≈0. 785 radians).

However, in the control device 1 of the present embodiment, as described above, when the absolute value of the internal phase angle δ becomes larger than π / 4 radians (= 45 degrees), the output set signal SS is turned on, and the first set The angular frequency adjustment value Δω output from the integrator 101 c is changed to the set value output ω−ω ₀ input from the angular frequency adjustment unit 102. The set value output is a value obtained by subtracting the reference frequency ω ₀ from the system frequency (frequency of the power system) ω detected from the terminal voltage V _{a, b, c} . Therefore, at time t1 (about 2.22 seconds) when | δ |> π / 4, the angular frequency adjustment value Δω output from the first integrator 101c is changed to the set value output ω−ω ₀ , The frequency ratio (Δω + ω ₀ ) / ω ₀ indicated by the dotted line in the graph 63 is the frequency ratio ω / ω ₀ (≈ω _s / ω ₀ ). Thereby, the frequency of the power output from the inverter device 3 can be matched with the frequency of the power system, and the phase θ output from the phase calculation unit 101 and the phase of the AC power of the power system 20 (AC voltage V _{a, b, c} Increase in the absolute value of the phase difference (that is, the internal phase angle δ) can be suppressed.

When the angular frequency adjustment value Δω is changed to the set value output ω−ω ₀ to become (Δω + ω ₀ ) / ω ₀ ≈ω _s / ω ₀ and the internal phase angle δ is 45 degrees or less, the output set signal SS is Switch from on to off. When the output set signal SS is turned off from on, the control device 1 uses the set value output ω−ω ₀ input immediately before turning off as an initial value, and integrates the difference between the active power P and the output target over time. The voltage phase θ is calculated based on the obtained angular frequency adjustment value Δω. For this reason, when the frequency of the power system continues to decrease, the internal phase angle δ again exceeds 45 degrees at time t3 (about 2.67 seconds) as shown in the graph 64 of FIG. However, also at this time, the control device 1 changes the angular frequency adjustment value Δω output from the first integrator 101c to the set value output ω−ω ₀ input from the angular frequency adjustment unit 102, so that the internal phase The increase in the angle δ is suppressed. Therefore, in the control device 1 according to the present embodiment, as shown in the graph 64, the internal phase angle δ after the time t1 when the frequency ω _s of the power system 20 rapidly decreases maintains a value of about π / 4 radians, Step-out (out of synchronization) can be prevented.

As described above, by switching the angular frequency adjustment value Δω used for calculating the phase θ so that the internal phase angle δ is within a predetermined range, the frequency ω _s of the power system 20 is obtained as shown by the graphs 61 and 62 in FIG. It is possible to quickly follow even when the voltage decreases rapidly and output a stable AC voltage and AC current. For example, in the graph 61 of FIG. 6, the terminal voltages V _{a, b, c} are stable even after time 2.1 seconds when the frequency of the power system has rapidly decreased. Similarly, in the graph 62 in FIG. 6, the output current I _{a, b, c} is remarkably reduced around time 2.1 seconds _, but is stable after time t1.

  As can be seen from FIGS. 5 and 6, when the inverter device 3 is controlled by adjusting the angular frequency adjustment value Δω by the angular frequency adjusting unit 102 as in the control device 1 of the present embodiment, the time is from 2 seconds to 3 seconds. No step-out occurs during this period. Therefore, by controlling the inverter device 3 by the control device 1 of the present embodiment, it is possible to prevent the terminal voltage and the output current from being disturbed due to step-out.

  Note that the configurations of the phase calculation unit 101 and the angular frequency adjustment unit 102 in FIG. 2 are merely examples of the configuration of the phase calculation unit 101 and the angular frequency adjustment unit 102 according to the present embodiment, respectively. The configurations of the phase calculation unit 101 and the angular frequency adjustment unit 102 can be changed as appropriate without departing from the scope of the present embodiment. The control device 1 shown in FIGS. 1 and 2 can also be realized by a computer and a program executed by the computer.

  Moreover, in this embodiment, although the control apparatus 1 of the inverter apparatus 3 in the power generation facility which uses a storage battery as the DC power supply 2 was taken as an example, the DC power supply 2 generates DC power such as a solar panel without being limited thereto. It may be a generator.

Furthermore, the AC voltage V _{a, b, c} and the AC current I _{a, b, c} acquired in the control device 1 are not limited to the power generation facility, but the AC voltage V _{a, b, c} and alternating current I _{a, b, c} may be used.

[Second Embodiment]
In the present embodiment, another example of the generator simulation unit 100 in the control device 1 of FIG. 1 will be described. That is, the control device 1 described in the present embodiment is a device that controls the inverter device 3 that converts DC power generated by the DC power source 2 into AC power and outputs the AC power to the power system 20. As illustrated in FIG. 1, the control device 1 includes a generator simulation unit 100, a control signal generation unit 110, an output target setting unit 120, and a reference frequency setting unit 130. The generator simulation unit 100 includes a phase calculation unit 101 and an angular frequency adjustment unit 102. The control signal generation unit 110 includes a sine wave generation unit 111 and a pulse width modulation unit 112.

  FIG. 7 is a diagram illustrating a configuration of a generator simulation unit in the control device according to the second embodiment. As shown in FIG. 7, the phase difference calculation unit 101 in the generator simulation unit 100 according to the present embodiment includes an active power measurement unit 101a, a subtractor 101b, a first integrator 101c, an adder 101f, And a second integrator 101e.

The active power measuring unit 101a is configured to detect the current power system 20 based on the AC voltage V _{a, b, c} detected by the voltage detector 6 and the AC current I _{a, b, c} detected by the current detector 7. The effective power P is measured. The active power measurement unit 101a measures the active power P of the power system 20 according to a known measurement method.

  The subtractor 101b calculates the difference between the target value (output target) of the active power to be output to the inverter device 3 and the measured active power P. The output target is input from the output target setting unit 120 (see FIG. 1).

  The first integrator 101c time-integrates and outputs the difference between the output target and the active power P measured by the active power measuring unit 101a. That is, in the phase calculation unit 101 in the control device 1 of the present embodiment, the first integrator 101c always obtains the difference between the active power P and the output target by time integration regardless of the value of the internal phase angle δ. Is output as the angular frequency adjustment value Δω.

The adder 101d adds the angular frequency adjustment value Δω output from the first integrator 101c, the reference frequency ω _0, and the adjustment amount input from the angular frequency adjustment unit 102, and outputs the result. The reference frequency ω ₀ is input from the reference frequency setting unit 130 (see FIG. 1). The reference frequency ω ₀ is a reference frequency of power in the power system 20 and is set to 50 Hz or 60 Hz, for example. The adjustment amount input from the angular frequency adjustment unit 102 is an adjustment amount of the angular frequency calculated based on the magnitude of the internal phase angle δ and a predetermined function f (δ). The function f (δ) is a function for calculating a value that changes the angular frequency ω in the direction in which the internal phase angle δ decreases, and is a function that increases the adjustment amount as the internal phase angle δ increases. In the following description according to the present embodiment, the angular frequency adjustment value Δω output from the first integrator 101c is also referred to as a first adjustment value Δω, and the angular frequency adjustment amount calculated by the angular frequency adjustment unit 102 is the second. It is also called the adjustment value.

  The second integrator 101e time-integrates the angular frequency input from the adder 101d and outputs the result of time integration as the phase θ of the voltage output from the inverter device 3. In the control device 1 of the present embodiment, the phase θ output from the second integrator 101 is input to the sine wave generation unit 111 (see FIG. 1) of the control signal generation unit 110 and the angular frequency adjustment unit 102. Is input to the internal phase angle calculation unit 102a.

  As shown in FIG. 7, the angular frequency adjustment unit 102 in the generator simulation unit 100 according to the present embodiment includes an internal phase angle calculation unit 102a, a first gain application unit 102f, and an adjustment amount calculation unit 102g. And a second gain application unit 102h.

As described in the first embodiment, the internal phase angle calculation unit 102a calculates a phase difference (internal phase angle) δ between the phase of the AC voltage of the power system 20 and the phase θ calculated by the phase calculation unit 101. . In the present embodiment, the AC voltage V _{a, b, c} input to the active power measuring unit 101 a is used as the AC voltage of the power system 20. The internal phase angle calculation unit 102a calculates the internal phase angle δ using, for example, the above equations (2-1), (2-2), and (2-3).

  The first gain application unit 102f applies a predetermined gain a to the internal phase angle δ calculated by the internal phase angle calculation unit 102a. For example, the first gain application unit 102f calculates and outputs a value a · δ obtained by applying the gain a to the internal phase angle δ. The gain a is an arbitrary positive value and may be a = 1.

  The adjustment amount calculation unit 102g calculates an adjustment amount of an angular frequency corresponding to the internal phase angle δ by a function f (δ) having the internal phase angle δ (or a · δ) as a parameter. Here, the function f (δ) is a function that can calculate a value by which the angular frequency of the rotating body in the simulated synchronous generator is accelerated or decelerated in the direction in which the internal phase angle δ decreases. For example, the function f (δ) is set to f (δ) = tan (δ).

  The second gain application unit 102h applies a predetermined gain b to the adjustment amount calculated by the adjustment amount calculation unit 102g. For example, the second gain application unit 102h outputs a value obtained by multiplying or adding the gain b to the adjustment amount calculated by the adjustment amount calculation unit 102g. The gain b is an arbitrary positive value and may be b = 1. The second gain application unit 102 h inputs the angular frequency adjustment amount to which the gain b is applied to the adder 101 f of the phase calculation unit 101.

The generator simulation unit 100 in the control device 1 of the present embodiment calculates an adjustment amount according to the magnitude of the internal phase angle δ calculated by the internal phase angle calculation unit 102a as described above, and the phase calculation unit 101 The angular frequency input to the second integrator 101e is adjusted. At this time, when the adjustment amount is calculated by the function f (δ) = tan (δ) in the adjustment amount calculation unit 102g, the value of the adjustment amount increases as the internal phase angle δ increases. Therefore, for example, by adding or subtracting the adjustment amount calculated by the function f (δ) = tan (δ) to the angular frequency adjustment value Δω + ω ₀ of the rotating body of the synchronous generator to be simulated, the internal phase angle δ It is possible to prevent step-out due to increase.

  Further, when the adjustment amount is calculated by the function f (δ) = tan (δ) as in this embodiment, if the internal phase angle δ is a value close to 0, the adjustment amount becomes a small value and the internal phase angle As δ increases, the adjustment amount increases continuously. For this reason, in the control apparatus 1 of this embodiment, the angular frequency of the rotary body of the synchronous generator simulated in the generator simulation part 100 changes continuously. Therefore, according to the control device 1 of the present embodiment, the control of the inverter device 3 can be made closer to the change mode of the angular frequency of the rotating body in the synchronous generator, and more natural control is possible.

Note that the configuration of the angular frequency adjustment unit 102 in FIG. 7 is merely an example of the configuration of the angular frequency adjustment unit 102 according to the second embodiment. The configuration of the angular frequency adjusting unit 102 according to the present embodiment can be changed as appropriate without departing from the gist of the present embodiment. For example, the function f (δ) for calculating the adjustment amount in the adjustment amount calculation unit 102g is not limited to f (δ) = tan (δ), and may be another function. For example, the function f (δ) for calculating the adjustment amount is selected from functions whose signs are the same as the internal phase angle δ and the adjustment amount increases as the absolute value of the internal phase angle δ increases. It is possible. For example, the function f (δ) may be f (δ) = tan (δ) −δ. Further, the function f (δ) may be, for example, f (δ) = δ ³ or f (δ) = δ ⁵ .

  The control device 1 including the phase calculation unit 101 and the angular frequency adjustment unit 102 according to the present embodiment can also be realized by a computer and a program executed by the computer.

  Moreover, in this embodiment, although the control apparatus 1 of the inverter apparatus 3 in the power generation facility which uses a storage battery as the DC power supply 2 was taken as an example, the DC power supply 2 generates DC power such as a solar panel without being limited thereto. It may be a generator.

Furthermore, the AC voltage V _{a, b, c} and the AC current I _{a, b, c} acquired in the control device 1 are not limited to the power generation facility, but the AC voltage V _{a, b, c} and alternating current I _{a, b, c} may be used.

[Third Embodiment]
FIG. 8 is a diagram illustrating a functional configuration of the control device according to the third embodiment. As shown in FIG. 8, the control device 1 according to the present embodiment includes a generator simulation unit 100, a control signal generation unit 110, an output target setting unit 120, and a reference frequency setting unit 130. The control signal generation unit 110, the output target setting unit 120, and the reference frequency setting unit 130 in the control device 1 of the present embodiment each have the functions described in the first embodiment. The control signal generation unit 110 includes a sine wave generation unit 111 and a pulse width modulation unit 112.

  The generator simulation unit 100 in the control device 1 of the present embodiment includes a phase calculation unit 101, an angular frequency adjustment unit 102, and a far voltage estimation unit 103.

The phase calculation unit 101 in the control device 1 of the present embodiment calculates the phase θ of the electric power output from the inverter device 3 by the method described in the first embodiment or the method described in the second embodiment. That is, the phase calculation unit 101 includes the AC voltage V _{a, b, c} and AC current I _{a, b, c} detected at the position D1 of the power transmission line 5, the output target, the reference frequency ω ₀ of the power system 20, and Based on the information input from the angular frequency adjustment unit 102, the phase θ of the voltage output from the inverter device 3 is calculated.

The far voltage estimation unit 103 detects the AC voltage V _{a, b, c} detected at the position D1 of the transmission line 5 and the first section from the output terminal (position D0) of the inverter device 3 in the transmission line 5 to the position D1. Based on the ratio of the reactance X and the reactance n · X in the second section from the position D1 to the position D2, the AC voltage _Vsys at the position D2 is estimated. The reactance X of the first section is approximated by the reactance of the smoothing reactor (filter) 4, and the reactance n · X of the second section is regarded as one resistance (transmission line simulation unit 10). This is the reactance of the resistance. For example, the far voltage estimation unit 103 divides the line segment connecting the end point of the first vector V1 and the end point of the second vector V2 into 1: n in two vectors V1 and V2 starting from the origin O. Is a vector having an origin O as a starting point and a magnitude equal to the first vector V1, and a third vector V3 having the same magnitude as the first vector V1 is obtained, and the AC voltage _Vsys is estimated based on the third vector V3. The first vector V1 is a vector corresponding to the voltage V _vsg in the power transmission line 5 between the inverter device 3 and the smoothing reactor 4 (for example, the position D0 serving as the output terminal of the inverter device 3). The second vector V2 is a vector corresponding to the AC voltage V _t (V _{a, b, c} ) detected at the position D1 on the power transmission line 5.

The angular frequency adjustment unit 102 in the control device 1 of the present embodiment is the angular frequency that the phase calculation unit 101 uses for calculating the phase by the method described in the first embodiment or the method described in the second embodiment. The information for adjusting the value of is generated and output to the phase calculation unit 101. That is, the angular frequency adjustment unit 102 uses the phase calculation unit 101 to calculate the phase based on the phase of the AC voltage of the power system 20 and the phase θ of the voltage calculated and output by the phase calculation unit 101. Information for adjusting the frequency value is generated and output to the phase calculation unit 101. The angular frequency adjusting unit 102 according to the present embodiment uses the AC voltage _Vsys estimated by the remote voltage estimating unit 103 as the AC voltage of the power system 20 instead of the AC voltage V _{a, b, c} detected at the position D1. And That is, the angular frequency adjusting unit 102 according to the present embodiment uses the phase difference between the phase of the AC voltage V _sys estimated by the remote voltage estimating unit 103 and the phase calculated by the phase calculating unit 101 as the internal phase angle δ, and the angular frequency. Generate information to adjust the value of.

As described above, the generator simulation unit 100 in the control device 1 according to the present embodiment is configured so that the AC voltage V _{sys at the} position D2 far from the position D1 where the AC voltage V _{a, b, c} is detected when viewed from the inverter device 3. And the synchronous generator is simulated using the estimated AC voltage _Vsys . Each of the phase difference calculation unit 101 and the angular frequency adjustment unit 102 in the generator simulation unit 100 may have the configuration described in the first embodiment, for example.

  FIG. 9 is a diagram illustrating a configuration example of a generator simulation unit in the control device according to the third embodiment.

  As shown in FIG. 9, the phase calculation unit 101 of the generator simulation unit 100 includes an active power measurement unit 101a, a subtractor 101b, a first integrator 101c, an adder 101d, and a second integrator 101e. including. The active power measurement unit 101a, the subtractor 101b, the first integrator 101c, the adder 101d, and the second integrator 101e in the phase calculation unit 101 have the functions described in the first embodiment.

Further, the angular frequency adjustment unit 102 of the generator simulation unit 100 includes an internal phase angle calculation unit 102a, a comparison unit 102b, a system frequency detection unit 102c, and a subtractor 102d. The internal phase angle calculation unit 102a, the comparison unit 102b, the system frequency detection unit 102c, and the subtractor 102d in the angular frequency adjustment unit 102 have the functions described in the first embodiment. The internal phase angle calculation unit 102a in the control device 1 of the present embodiment calculates the phase difference between the phase of the AC voltage _Vsys estimated by the far voltage estimation unit 103 and the phase θ of the voltage calculated by the phase calculation unit 101. Calculated as the internal phase angle δ. The internal phase angle calculation unit 102a calculates the internal phase angle δ using, for example, the above equations (2-1), (2-2), and (2-3). In addition, the system frequency detection unit 102 c in the control device 1 of the present embodiment detects the current voltage frequency ω in the power system 20 based on the AC voltage V _sys estimated by the far voltage estimation unit 103.

FIG. 10 is a diagram for explaining a voltage estimation method by the remote voltage estimation unit.
When the far voltage estimation unit 103 estimates the far voltage, a vector corresponding to the voltage V _{vsg at the} position D0 on the circumference C of the radius r = | V _vsg | with the origin O as the center, as shown in FIG. and endpoint PD0, utilizing that there is an end point PD2 of vectors corresponding to the voltage V _sys position D2. The vector corresponding to the voltage V _vsg and the vector corresponding to the voltage V _sys are vectors having the origin O as the start point and the end points PD0 and PD2 on the circumference C, and have different phases (directions). The voltage V _vsg is an AC voltage output from the inverter device 3 based on the phase θ of power calculated by the phase calculation unit 101. Therefore, the angle δ2 between the vector corresponding to the voltage V _vsg and the vector corresponding to the voltage V _sys is the phase difference (internal phase angle) between the two voltages V _vsg and V _sys .

In this case, the vector corresponding to the voltage V _t of the position D1 is a on the line segment connecting the two points PD0 and PD2 on the circumference C, end point PD1 point which internally divides the line segment to the one-to-n And represented by a vector starting from the origin O. The voltage V _vsg is an AC voltage output from the inverter device 3 based on the power phase θ calculated by the phase calculation unit 101 as described above. Therefore, the angle δ1 between the vector corresponding to the voltage V _vsg and the vector corresponding to the voltage V _t is the phase difference (internal phase angle) between the two voltages V _vsg and V _t .

Far voltage estimation unit 103, a vector corresponding to the voltage V _vsg the position D0, corresponding vector to the voltage V _t of the position D1, and on the basis of the relationship of the corresponding vector and voltage V _sys position D2, the position D2 _Is estimated. Specifically, the far voltage estimation unit 103 determines the AC voltage V _t (V _{a, b, c} ) detected at the position D1, the reactance X in the first section, and the reactance n · X in the second section. _{Is used} to estimate the AC voltage _Vsys at position D2.

As described above, in the control device 1 of the present embodiment, the internal phase angle δ is calculated based on the AC voltage _Vsys at the position D2 estimated by the far voltage estimation unit 103, and the phase calculation unit based on the internal phase angle δ. The angular frequency used for calculating the phase θ by 101 is adjusted. Thereby, for example, even when the impedance of the transmission line 5 is large (in other words, when the ratio n between the reactance X in the first section and the reactance n · X in the second section is large), the internal phase angle δ The increase can be detected at an early stage, and step-out (out of synchronization) can be prevented.

Hereinafter, with reference to FIG. 11, this may occur when the angular frequency is adjusted based on the internal phase angle δ calculated using the AC voltage V _{a, b, c} (terminal voltage V _t ) detected at the position D1. Explain the phenomenon. FIG. 11 is a diagram illustrating a phenomenon that may occur when the angular frequency is adjusted based on the terminal voltage.

The (a) of FIG. 11, when the internal phase angle δ1 of the AC voltage V _t of the AC voltage V _vsg the position D1 of the position D0 is within a predetermined range, the AC voltage V _vsg position D0, position D1 The relationship between the AC voltage V _t of the current and the AC voltage V _{sys at} the position D2 is shown. Thus, even if the absolute value of the internal phase angle δ1 of the AC voltage V _t of the AC voltage V _vsg the position D1 of the position D0 is smaller than [pi / 4 radians, and the AC voltage V _vsg position D0, position D1 In some cases, the internal phase angle δ2 with respect to the AC voltage _Vsys at the position D2 on the power system 20 side may be a value close to π / 4 radians.

Further, when the reactance ratio n is large, for example, as shown in FIGS. 11B _{and 11C} , the internal phase angle δ1 based on the AC voltage V _t (V _{a, b, c} ) detected at the position D1. Even though the absolute value is smaller than π / 4 radians, the internal phase angle δ2 may exceed π / 2 radians (= 90 degrees) and approach π radians (= 180 degrees).

That is, when the reactance ratio n in the transmission line 5 is large, the position is determined even though the internal phase angle δ1 based on the AC voltage V _t (V _{a, b, c} ) detected at the position D1 is within a predetermined range. The internal phase angle δ2 at the position D2 closer to the power system 20 than D1 exceeds 180 degrees, and step-out (out of synchronization) may occur. Further, if the ratio n of the reactance in the transmission line 5 is great, the frequency of the AC voltage V _t detected by the position D1, the deviation between the frequency of the AC voltage V _sys which is detected by the position D2 increases. Therefore, when controlling the frequency of the power output from the inverter device 3 on the basis of the frequency of the AC voltage V _t, it is difficult to match the frequency of the power inverter 3 is output to the frequency of the power system 20.

  Further, when the AC voltage is detected at a position closer to the power system 20 like the position D <b> 2 in the power transmission line 5, the transmission path for transmitting the detected AC voltage to the control device 1 becomes long. For this reason, for example, the calculation accuracy of the internal phase angle δ is lowered due to a voltage drop or a transmission loss in the transmission line, and it becomes difficult to calculate an appropriate phase θ. In addition, the length of the transmission path increases the cost for installation and maintenance of the transmission path.

In contrast, the control device 1 of the present embodiment, on the basis of the AC voltage V _t detected by the position D1 close to the output terminal of the inverter device 3, and the ratio n of the reactance in the transmission line 5, the power of the position D1 An AC voltage _Vsys at a position D2 close to the system 20 is estimated. Thus, for example, by detecting an AC voltage V _t in the power plant, it is possible to prevent a voltage drop and a transmission loss of the AC voltage V _t. Further, since it is possible to prevent the transmission line from being extended, it is possible to suppress an increase in cost for installation and maintenance of the transmission line. That is, the power generation facility including the control device 1 of the present embodiment has the same configuration as the power generation facility including the control device 1 of the first embodiment, but is out of synchronization (out of synchronization) when the impedance of the transmission line 5 is large. ) Can also be prevented.

  Hereinafter, with reference to FIGS. 12-14, the effect at the time of controlling the inverter apparatus 3 with the control apparatus 1 of this embodiment is demonstrated.

  FIG. 12 is a diagram illustrating a second example of a time change in the system frequency. FIG. 13 is a diagram illustrating another example of the simulation result when the control by the control device according to the first embodiment is performed. FIG. 14 is a diagram illustrating an example of a simulation result when control is performed by the control device according to the third embodiment.

  The inventors of the present invention control the inverter device 3 with the time change of the internal phase angle δ when the inverter device 3 is controlled by the control device 1 of the first embodiment and the control device 1 of the present embodiment by computer simulation. The time variation of the internal phase angle δ was investigated.

  In the simulation, a model (one machine infinite bus system) in which power generation equipment including one generator (DC power supply 2) as shown in FIG. 8 is directly connected to the power system 20 (infinite bus system). It was used. The generator (DC power supply 2) was a storage battery. Further, the output side filter unit (smoothing reactor 4) of the inverter device 3 has a reactance of 5% on the basis of the equipment capacity, and the transmission line simulation unit 10 on the power system 20 side from the position D1 is 50% on the basis of the equipment capacity. Reactance was used.

In the simulation, when the infinite bus is an ideal voltage source and the system frequency is changed with time as shown by the frequency ratio ω _s / ω ₀ shown in the graph 41 of FIG. The time change of the AC voltage V _{a, b, c} was calculated. The frequency ratio ω _s / ω ₀ is a ratio between the frequency ω _s of the power system 20 and the reference frequency ω ₀ .

The time change of the frequency ratio ω _s / ω ₀ from time 0 seconds to 2.0 seconds in the graph 41 is the same as the time change in the graph 40 of FIG. The period from time 2.0 seconds to 4.0 seconds in graph 41 is maintained at 0.99 after the frequency ratio decreases from 1.02 to 0.99 in 0.1 seconds from time 2.1 seconds. is doing.

When the frequency ω _s of the power system 20 changes with time as shown in the graph 41, a simulation for controlling the inverter device 3 by the method described in the first embodiment results in the result shown in FIG. was gotten. In FIG. 13, the internal phase angle δ is calculated from the AC voltage V _{a, b, c} detected at the position D1 and the phase θ, and the internal phase angle δ is within a predetermined range (π / 3 radians = 60 degrees). ) Shows a simulation result when the inverter device 3 is controlled so that.

FIG. 13 shows four graphs 71 to 74. The graph 71 shows the time change of the terminal voltage, that is, the time change of the AC voltage V _{a, b, c} at the position D 1 detected by the voltage detector 6. The graph 72 shows the time change of the output current, that is, the time change of the alternating currents I _{a, b, c} detected by the current detector 7. The graph 73 shows temporal changes of three frequency ratios ω _s / ω ₀ , (Δω + ω ₀ ) / ω ₀ , and ω / ω ₀ . The frequency ratio ω / ω ₀ in the graph 73 is the frequency ratio for the frequency ω detected from the AC voltage V _{a, b, c} (V _t ) in the system frequency detection unit 102c. The graph 74 shows the time change of the internal phase angle δ (degrees). Note that the graphs 71 to 74 in FIG. 13 omit the simulation results during the period from time 0 seconds to 1 second in the graph 41 in FIG.

As shown in the graph 73, the frequency ratio ω _s / ω ₀ of the power system 20 increases from 1.00 to 1.02 in the period from time 1 second to 1.2 seconds. Thereafter, the frequency ratio ω _s / ω ₀ of the power system 20 returns from 1.02 to 1.00 during the period from 1.3 seconds to 1.4 seconds, but when the time becomes 1.5 seconds. It rises to 1.02, and the state of 1.02 continues until time 2.0 seconds. However, when the temporal change amount of the frequency ratio ω _s / ω ₀ of the power system 20 is such a relatively small change amount, the first integration can be performed without adjusting the angular frequency by the angular frequency adjusting unit 102. The angular frequency adjustment value Δω output from the device 101 c follows the change in the frequency ω _s of the power system 20. For this reason, the value of the internal phase angle δ during the period from 1 second to 2 seconds changes at a relatively small value. Therefore, the phase difference (internal phase angle δ) between the phase of the terminal voltage V _{a, b, c} and the phase θ of the AC voltage output from the inverter device 3 in the period from time 1 second to time 2 seconds is, for example, a graph 74. As shown in the figure, it changes within a range from 60 degrees to -60 degrees.

After that, as shown in the graph 73, the frequency ratio ω _s / ω ₀ of the power system 20 significantly decreases in the period from time 2 seconds to 2.1 seconds, and is constant from 2.1 seconds to 4 seconds. It becomes the value of. The frequency ratio ω _s / ω ₀ decreases by 0.03 in 0.1 second from time 2 seconds to 2.1 seconds. That is, when the reference frequency ω ₀ of the power system 20 is 50 Hz, the frequency ω _s of the power system 20 changes by 1.5 Hz in 0.1 seconds from the time 2 seconds to 2.1 seconds. As described above, when the frequency ω _s of the power system 20 changes rapidly, the difference between the active power P and the output target increases, and the angular frequency adjustment value Δω, which is the time integration of the difference, and the synchronous generator to be simulated The difference with the angular frequency of the rotating body at is increased. As a result, as shown in the graph 74, the internal phase angle δ rapidly increases after the time of 2 seconds, and the internal phase angle δ exceeds 60 degrees at the time t12 (about 2.22 seconds). Therefore, in the control device 1 according to the first embodiment, the output set signal SS output from the angular frequency adjusting unit 102 is turned on at time t12, and the angular frequency output from the first integrator 101c of the phase calculating unit 101. The adjustment value Δω becomes the set value output ω−ω ₀ output by the angular frequency adjustment unit 102.

However, when the ratio n between the reactance X in the first section (from the position D0 to the position D1) and the reactance n · X in the second section (from the position D1 to the position D2) in the transmission line 5 is large, As described above, the frequency difference between the AC voltage V _{a, b, c} (V _t ) and the AC voltage V _{sys at the} position D2 closer to the power system 20 than the position D1 increases. That is, as in this simulation, the reactance of the first section (smoothing reactor 4) is 5% on the equipment capacity basis, and the reactance of the second section (transmission line simulator 10) is 50% on the equipment capacity basis. , The frequency divergence between the AC voltage V _{a, b, c} (V _t ) at the position D1 and the AC voltage V _sys at the position D2 becomes large. For this reason, even if the angular frequency adjustment value Δω is switched to the set value output ω−ω ₀ output by the angular frequency adjustment unit 102 at time t12, the second integrator 101e of the phase calculation unit 101 as shown in the graph 73. There is a difference between the frequency Δω + ω ₀ input to the frequency ω _s and the frequency ω _s of the power system 20. Therefore, a shift occurs between the phase θ of the power of the inverter device 3 calculated by the phase calculation unit 101 and the phase of the power system 20, and an increase in the internal phase angle δ cannot be suppressed. Continues to increase. At time t13 (about 2.97 seconds), the internal phase angle δ exceeded 180 degrees, and step-out (out of synchronization) occurred.

  After time t13, the internal phase angle δ continues to increase, and the absolute value once becomes 60 degrees or less as shown in the graph 74, but at time t14, the internal phase angle δ again exceeds 60 degrees. Also at this time, the control device 1 according to the first embodiment cannot suppress the increase in the internal phase angle δ, and the internal phase angle δ exceeds 180 degrees at time t15, causing a step-out (out of synchronization). did.

As described above, when the reactance on the electric power system side is larger than the reactance in the section from the inverter device 3 to the position D1 than the position D1 where the AC voltage V _{a, b, c} (V _t ) is detected, the first implementation is performed. In the control device 1 of the embodiment, an increase in the absolute value of the internal phase angle δ cannot be suppressed, and step-out (out of synchronization) may occur.

  On the other hand, when the simulation which controls the inverter apparatus 3 by the control apparatus 1 which concerns on this embodiment was performed, the result as shown in FIG. 14 was obtained.

FIG. 14 shows four graphs 81-84. The graph 81 shows the time change of the terminal voltage, that is, the time change of the AC voltage V _{a, b, c} detected by the voltage detector 6. The graph 82 shows the time change of the output current, that is, the time change of the alternating current I _{a, b, c} detected by the current detector 7. The graph 83 shows three frequency ratios ω _s / ω ₀ , (Δω + ω ₀ ) / ω ₀ , and ω / ω ₀ time change. The frequency ratio ω / ω ₀ in the graph 83 is a frequency ratio for the frequency ω detected from the estimated AC voltage V _sys at the position D2. A graph 84 shows a time change of the internal phase angle δ (degrees). Note that the graphs 81 to 84 in FIG. 14 omit the simulation results during the period from time 0 seconds to 1 second in the graph 41 in FIG.

Even when the inverter device 3 is controlled by the control device 1 of the present embodiment, as described above, if the internal phase angle δ is within a predetermined range (| δ | ≦ 60 degrees), the first integrator 101c The output angular frequency adjustment value Δω is a value obtained by time-integrating the difference between the active power P and the output target. Then, like the period from time 1 second to time 2 seconds in the graphs 83 and 84 shown in FIG. 14, the amount of time change of the frequency ω _s of the power system 20 is relatively small, and the internal phase angle δ is in a predetermined range. If the frequency is within the range, the frequency Δω + ω ₀ calculated based on the angular frequency adjustment value Δω obtained by time-integrating the difference between the active power P and the output target follows the change in the frequency ω _s . For this reason, the value of the internal phase angle δ during the period from 1 second to 2 seconds changes at a relatively small value with an absolute value of 60 degrees or less.

Further, as shown in the graph 83, the frequency ratio ω _s / ω ₀ of the electric power system 20 significantly decreases from the time 2 seconds to 2.1 seconds, and thereafter becomes a constant value until 4 seconds. When the frequency ω _s of the power system 20 changes rapidly, the difference between the active power P and the output target increases as described above, and the angular frequency adjustment value Δω that is the time integration of the difference and the synchronous power generation to be simulated The difference with the angular frequency of the rotating body in the machine increases. Therefore, as in the simulation result of FIG. 13, the internal phase angle δ increases after the time of 2 seconds. Moreover, the control apparatus 1 of this embodiment, the AC voltage V _{a, b,} estimates of the AC voltage V _sys position D2 as the electric power system 20 side from the position D1 of detecting the _c, phase of the AC voltage V _sys And the phase difference between the phase θ calculated by the phase calculation unit 101 and the internal phase angle δ. Therefore, as described above, the internal phase angle δ calculated by the control device 1 of the present embodiment increases faster than the internal phase angle δ calculated by the control device 1 of the first embodiment. Therefore, in the control device 1 of the present embodiment, the internal phase angle δ exceeds 60 degrees at time t11 (about 2.17 seconds) prior to time t12 shown in FIG. Therefore, in the control device 1 of the present embodiment, the output set signal SS output from the angular frequency adjusting unit 102 is turned on at time t11, and the first integrator 101c of the phase calculating unit 101 is the angular frequency adjusting unit 102. There outputs a set value output omega-omega ₀ outputted as angular frequency adjustment value [Delta] [omega. Here, the frequency ω in the set value output ω−ω ₀ is the frequency of the AC voltage V _{sys at} the position D2 on the power system 20 side of the position D1 where the AC voltage V _{a, b, c} is detected. The difference between 20 frequencies ω _s is very small. For this reason, in the control device 1 of the present embodiment, the difference between the phase θ calculated by time integration of the set value output ω−ω ₀ and the phase of the power of the power system 20 becomes small, and the AC output from the inverter device 3 It is easy to match the frequency of the voltage V _vsg with the frequency ω _s of the power system 20. Therefore, in the control device 1 of the present embodiment, as shown in the graphs 83 and 84, the frequency Δω + ω ₀ after the time t11 follows the frequency ω _s of the power system 20, and the internal phase angle δ maintains 60 degrees. Therefore, in the control device 1 of this embodiment, even when the impedance of the power transmission line 5 is large, it is possible to prevent the occurrence of step-out (out of synchronization) due to the increase in the internal phase angle δ.

  Note that the configurations of the phase calculation unit 101 and the angular frequency adjustment unit 102 in FIG. 9 are merely examples of the configuration of the phase calculation unit 101 and the angular frequency adjustment unit 102 according to the present embodiment, respectively. The configurations of the phase calculation unit 101 and the angular frequency adjustment unit 102 can be changed as appropriate without departing from the scope of the present embodiment. For example, the phase calculation unit 101 and the angular frequency adjustment unit 102 in the control device 1 of the present embodiment may be configured as shown in FIG.

FIG. 15 is a diagram illustrating another configuration example of the generator simulation unit in the control device according to the third embodiment. The phase calculation unit 101 and the angular frequency adjustment unit 102 in the generator simulation unit 100 of FIG. 15 have the same configurations as the phase calculation unit 101 and the angular frequency adjustment unit 102 described in the second embodiment, respectively. That is, the angular frequency adjustment unit 102 in the control device 1 of the present embodiment includes an internal phase angle calculation unit 102a, a first gain application unit 102f, an adjustment amount calculation unit 102g, and a second gain application unit 102h. It may be the composition which includes. In this case, the angular frequency adjusting unit 102 is predetermined with respect to a phase difference (internal phase angle) δ between the AC voltage _Vsys at the position D2 estimated by the remote voltage estimating unit 103 and the phase θ calculated by the phase calculating unit 101. After that, the adjustment amount calculation unit 102g calculates the adjustment amount of the angular frequency according to the magnitude of the internal phase angle δ. After that, the angular frequency adjustment unit 102 applies the gain b to the angular frequency adjustment amount and outputs it to the phase calculation unit 101.

  The phase calculation unit 101 in the generator simulation unit 100 of FIG. 15 includes an active power measurement unit 101a, a subtractor 101b, a first integrator 101c, an adder 101f, and a second integrator 101e. Each of these components in the phase calculation unit 101 has the function described in the second embodiment.

  Although not shown, the phase calculation unit 101 and the angular frequency adjustment unit 102 in the generator simulation unit 100 are not limited to the configurations shown in FIGS. 9 and 15, respectively, and do not depart from the gist of the present embodiment. In FIG.

  Furthermore, the control device 1 including the phase calculation unit 101 and the angular frequency adjustment unit 102 according to the present embodiment can be realized by a computer and a program executed by the computer.

  Moreover, in this embodiment, although the control apparatus 1 of the inverter apparatus 3 in the power generation facility which uses a storage battery as the DC power supply 2 was taken as an example, the DC power supply 2 generates DC power such as a solar panel without being limited thereto. It may be a generator.

DESCRIPTION OF SYMBOLS 1 Control apparatus 2 DC power supply 3 Inverter apparatus 4 Smoothing reactor (filter)
DESCRIPTION OF SYMBOLS 5 Transmission line 6 Voltage detector 7 Current detector 10 Transmission line simulation part 20 Electric power system 100 Generator simulation part 101 Phase calculation part 101a Active power measurement part 101b, 102d Subtractor 101c 1st integrator 101d, 101f Adder 101e Second integrator 102 angular frequency adjustment unit 102a internal phase angle calculation unit 102b comparison unit 102c system frequency detection unit 102f first gain application unit 102g adjustment amount calculation unit 102h second gain application unit 103 far voltage estimation unit 110 control Signal generator 111 Sine wave generator 112 Pulse width modulator 120 Output target setting unit 130 Reference frequency setting unit

Claims (10)

A control device that controls an inverter device that converts DC power into AC power and outputs the power to the power system,
A generator simulation unit that simulates the frequency maintenance characteristics of a rotating body in a predetermined synchronous generator based on the AC voltage and AC current in the power system, and calculates the phase of the AC voltage output from the inverter device;
A control signal generation unit that generates a control signal for the inverter device based on the phase of the AC voltage calculated by the generator simulation unit;
The generator simulation unit
Calculation of the phase of the AC voltage so that the phase difference between the phase of the AC voltage in the power system and the phase of the AC voltage output from the generator simulation unit to the control signal generation unit is within a predetermined range. Including an angular frequency adjustment unit that generates information for adjusting the angular frequency used for
A control device characterized by that. The generator simulation unit
An active power measuring unit that measures active power based on the AC voltage and the AC current of the power system;
A first integrator for time-integrating a difference between the measured active power and an output target of AC power output from the inverter device to output an angular frequency;
A second integrator that time-integrates the angular frequency and outputs a phase of the AC voltage output from the inverter device;
The angular frequency adjustment unit is
An internal phase angle calculation unit that calculates an internal phase angle based on a phase difference between the phase of the AC voltage of the power system and the phase of the AC voltage determined by simulating the synchronous generator;
A comparator that determines whether the calculated internal phase angle is within a predetermined range, generates a signal including information indicating the determination result, and inputs the signal to the first integrator;
A system frequency detection unit that detects a system frequency of the AC voltage in the power system and inputs the system frequency to the first integrator based on the AC voltage of the power system;
When the signal input from the comparison unit includes information indicating that the internal phase angle is outside a predetermined range, the first integrator receives the AC input from the system frequency detection unit. Outputting the system frequency of the voltage as the angular frequency,
The control device according to claim 1. The generator simulation unit
An active power measuring unit that measures active power based on the AC voltage and the AC current of the power system;
A first integrator for time-integrating a difference between the measured active power and an output target of AC power output from the inverter device to output an angular frequency;
A second integrator that time-integrates the angular frequency and outputs a phase of the AC voltage output from the inverter device;
The angular frequency adjustment unit is
An internal phase angle calculation unit that calculates an internal phase angle based on a phase difference between the phase of the AC voltage of the power system and the phase of the AC voltage determined by simulating the synchronous generator;
An adjustment amount calculation unit that calculates an adjustment amount of the angular frequency corresponding to the calculated internal phase angle based on a function using the value of the internal phase angle as a parameter;
The second integrator outputs, from the inverter device, a value obtained by time-integrating a value obtained by adding the adjustment amount output from the adjustment amount calculation unit to the angular frequency output from the first integrator. Output as the phase of the AC voltage,
The control device according to claim 1. The adjustment amount calculation unit calculates an adjustment amount for accelerating or decelerating the angular frequency in a direction in which the internal phase angle decreases based on the function.
The control device according to claim 3. The function for calculating the adjustment amount is a function in which the positive and negative signs are the same as the internal phase angle, and the adjustment amount increases as the absolute value of the internal phase angle increases.
The control device according to claim 4. The function for calculating the adjustment amount is a function proportional to the tangent of the internal phase angle.
The control device according to claim 4. The said angular frequency adjustment part produces | generates the said information which adjusts the said angular frequency by making the alternating voltage detected in the predetermined position in the power transmission line which connects the said inverter apparatus and the said electric power system into the said alternating voltage in the said electric power system. ,
The control device according to claim 1. The generator simulation unit is closer to the inverter device than an AC voltage detected at a predetermined position in a power transmission line connecting the inverter device and the power system, and a position where the AC voltage is detected in the power transmission line. A position closer to the power system than a position where the AC voltage is detected based on a reactance of the first section and a reactance of the second section which is closer to the power system than the position where the AC voltage is detected A voltage estimation unit for estimating the AC voltage at
The angular frequency adjustment unit generates the information for adjusting the angular frequency using the AC voltage estimated by the voltage estimation unit as the AC voltage in the power system.
The control device according to claim 1. The voltage estimation unit is configured such that the end point of the detected AC voltage vector starting from the origin O is on a line segment connecting the first point and the second point on the circumference centering on the origin O. The ratio of the distance from the first point to the distance from the second point is the ratio of the reactance of the first section to the reactance of the second section, and the first point and Determining a position of a second point, and estimating the AC voltage based on a vector having the origin O as a start point and the second point as an end point;
The control device according to claim 8. A control method for an inverter device that converts DC power into AC power and outputs the power to the power system,
A control device for controlling the inverter device,
Simulating the frequency maintenance characteristics of the rotating body in a predetermined synchronous generator based on the AC voltage and AC current in the power system, calculating the phase of the AC voltage output from the inverter device,
Including a process of generating a control signal for the inverter device based on the calculated phase of the alternating voltage,
The process of calculating the phase of the AC voltage is as follows:
Processing for generating information for adjusting the angular frequency used for calculating the phase of the AC voltage so that the phase difference between the phase of the AC voltage in the power system and the calculated phase of the AC voltage is within a predetermined range. including,
A control method characterized by that.