WO2018034467A1 - Islanding detection system and islanding detection method - Google Patents

Islanding detection system and islanding detection method Download PDF

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Publication number
WO2018034467A1
WO2018034467A1 PCT/KR2017/008821 KR2017008821W WO2018034467A1 WO 2018034467 A1 WO2018034467 A1 WO 2018034467A1 KR 2017008821 W KR2017008821 W KR 2017008821W WO 2018034467 A1 WO2018034467 A1 WO 2018034467A1
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Prior art keywords
reactive power
signal
power
inverter
pulse
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PCT/KR2017/008821
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French (fr)
Korean (ko)
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강병관
이상호
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디아이케이(주)
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/18—Arrangements for adjusting, eliminating or compensating reactive power in networks
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/56—Power conversion systems, e.g. maximum power point trackers
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y04—INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
    • Y04S—SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
    • Y04S10/00—Systems supporting electrical power generation, transmission or distribution
    • Y04S10/12—Monitoring or controlling equipment for energy generation units, e.g. distributed energy generation [DER] or load-side generation
    • Y04S10/123—Monitoring or controlling equipment for energy generation units, e.g. distributed energy generation [DER] or load-side generation the energy generation units being or involving renewable energy sources

Definitions

  • the present invention relates to a single operation detection system and a single operation detection method, and more particularly, to a single operation detection system and a single operation detection method for detecting single operation in a photovoltaic power generation system or energy storage system.
  • the solar power system or energy storage system balances the output of the solar power system or energy storage system with the power consumption of the distribution line load.
  • Photovoltaic systems or energy storage systems take over the load on the distribution lines and continue operation. This phenomenon is called stand-alone operation.
  • Figure 1 shows the power flow of a typical grid-connected photovoltaic power generation system, for example, in a state in which the main power supply, such as a large synchronous inverter, is disconnected from the power conditioning system (PCS) connected to the power system by substation shutdown. Without detecting this, the operating state that supplies power to the connected load can be viewed as a stand-alone operation.
  • PCS power conditioning system
  • the passive method detects changes in harmonic components in power generation, load, line voltage, frequency, phase or voltage in a single operation, using overvoltage / low voltage and overfrequency / low frequency of the inverter. Current phase difference and THD are monitored and sensed.
  • Active methods include frequency drifts, voltage drifts, grid impedance estimation, PLL-based estimation, and negative sequence detection. Recently, a method of inputting reactive power among active methods has been used, and Korean Patent No. 10-1398457 discloses a method of detecting stand-alone operation by inputting reactive power.
  • Such a conventional method of detecting stand-alone operation by inputting reactive power has a problem of degrading the output quality of the power converter. That is, while the magnitude of the voltage increases and decreases, flickering of a lighting device such as a fluorescent lamp is generated. In addition, since the power factor value fluctuates periodically, there is a problem that it is difficult to satisfy the current grid connection regulation.
  • the present invention has been made to solve the above problems, the problem to be solved in the present invention is to prevent the power factor value is periodically changed to satisfy the grid linkage regulations, and to improve the output of the power converter
  • the present invention provides a single operation detection system and a single operation detection method capable of improving single operation and detecting single operation faster than before.
  • a signal detection unit for detecting a signal transmitted from the at least one inverter in a system in which the power output from the at least one inverter is transmitted to the grid via a line ;
  • the reactive power generator generates reactive power based on the signal detected by the signal detector and a reactive power generated by the reactive power generator to generate a pulse to input the reactive power to the line, It is a technical feature to include a control unit for controlling to gradually increase the magnitude of the pulse when the variation value of the frequency of the detected signal is greater than or equal to the reference value.
  • the single operation detection method for solving the above problems in the single operation detection method of the system in which power generated in at least one or more inverters are transmitted to the grid via a line, the signal transmitted from the at least one inverter Detecting a signal;
  • the reactive power generation step of generating reactive power based on the signal detected in the signal detecting step and the reactive power generated in the reactive power generating step are generated so that the reactive power is input to the line, but the signal detection is performed. If the variation value of the frequency of the signal detected in the step is greater than the reference value is characterized in that it comprises a reactive power adjustment step of controlling to gradually increase the magnitude of the pulse.
  • the single operation detection system and the single operation detection method according to the present invention have a short period of reactive power input, there is no influence of power factor and voltage drop, and a reactive power input device operates the reactive power for a quick time not detected by the eye. It is possible to prevent the quality of the output from deteriorating.
  • the single operation detection system and the single operation detection method according to the present invention can minimize the voltage fluctuation range when the single operation does not occur, thereby minimizing the influence of the system to improve the stability and durability of the entire system. .
  • the single operation detection system and the single operation detection method according to the present invention can detect the independent operation more accurately and quickly by changing the magnitude of the voltage by complementarily changing the magnitude of the active power in the same way as the reactive power. have.
  • FIG. 1 is a view showing the power flow of a conventional general grid-connected photovoltaic power generation system
  • FIG. 2 and 3 is a view showing a schematic configuration of a single operation detection system according to the present invention
  • FIG. 4 is a view for explaining a signal detection unit of a single operation detection system according to the present invention.
  • 5 and 6 are graphs of Id, Iq, f, and V for explaining control of reactive power according to an embodiment of a single operation detection system of the present invention.
  • FIG. 7 and 8 are graphs of Id, Iq, f, and V for explaining control of reactive power according to another embodiment of the single operation detection system of the present invention.
  • FIG. 9 is a view showing a procedure of a single operation detection method according to the present invention.
  • FIG. 2 and 3 is a view showing a schematic configuration of a single operation detection system according to the present invention, referring to Figures 2 and 3 is a single operation detection system according to the present invention is transmitted from at least one inverter 100 A signal detector 210 detecting a signal; A reactive power generator 220 generating reactive power based on the signal detected by the signal detector 210; And a controller 230 connected to the signal detector 210 and the reactive power generator 220 to control operations of the signal detector 210 and the reactive power generator 220.
  • the single operation detection system according to the present invention deals with the power of the AC type because it is assumed to be connected to the grid (Grid, 300), in the case of photovoltaic power generation, the inverter 100 is connected to the PV cell and the DC of the PV cell. Convert the output to AC.
  • the signal detector 210 is a component that detects signals transmitted from at least one inverter 100, and the reactive power generator 220 generates reactive power based on the signal detected by the signal detector 210. Element.
  • the controller 230 is connected to the signal detector 210 and the reactive power generator 220 to control operations of the signal detector 210 and the reactive power generator 220, in particular, the signal detected by the signal detector 210. If the frequency variation is greater than or equal to the reference value, the pulse size is increased step by step, and the reactive power is periodically shorted.
  • the cycle may be a time specified in grid linkage (grid code) (must cut off power within a predetermined time when a standalone operation is detected), and detect a standalone operation to cut off power delivered to the system 300. May be time. In addition, it may be a time selected based on the time while the grid connection regulation and the stand-alone operation is detected to cut off the power delivered to the system (300).
  • grid code grid linkage
  • the cycle may be a time specified in grid linkage (grid code) (must cut off power within a predetermined time when a standalone operation is detected), and detect a standalone operation to cut off power delivered to the system 300. May be time. In addition, it may be a time selected based on the time while the grid connection regulation and the stand-alone operation is detected to cut off the power delivered to the system (300).
  • short may mean a time shorter than a period. For example, when the frequency is 60Hz, the period is 0.0167 seconds, but when the frequency of the signal transmitted from the inverter 100 is 60Hz, reactive power may be input for a time shorter than the period (0.0167 seconds).
  • FIGS. 4 and 6 are views Id, Iq for explaining the control of reactive power according to an embodiment of the stand-alone operation detection system of the present invention.
  • a graph of f, V a method of controlling the operation of the signal detector 210 and the reactive power generator 220 will be described in more detail with reference to FIGS. 4 to 6.
  • the signal detector 210 may include a current transformer 211, a first current converter 212, and a second current converter 213.
  • Current transformer 211 is a component for measuring the output of the inverter 100
  • the first current converter 212 is a three-phase current coordinates (Ia, Ib, Ic) transmitted from the current transformer 211 two-phase stop coordinate system ( It is a component converting into the two-phase stop current signals I ⁇ and I ⁇ of ⁇ and ⁇ .
  • the second current converter 213 transmits the two-phase stop current signals I ⁇ and I ⁇ of the two-phase stop coordinate systems ⁇ and ⁇ to the two-phase rotation current signals Id and Iq of the two-phase rotation coordinate systems d and q.
  • the amplitude and phase of the output current can be adjusted using the d-axis and the q-axis.
  • the d-axis current Id controls the active power and the q-axis current Iq controls the reactive power.
  • the d-axis current Id controls the reactive power
  • the q-axis current Iq controls the active power.
  • the reactive power generator 220 The step of controlling the amount of reactive power generated in the step) in step form, the step of increasing the reactive power of step Id or Iq, one of the two-phase rotation current signal in step form.
  • the controller 230 may increase the size of the effective power in the form of stairs by increasing Id or Iq in the form of stairs as necessary.
  • FIGS. 5 and 6 a case in which the variation value of the frequency f is greater than or equal to the reference value is shown in the right part of the graph.
  • the controller 230 rotates two-phase. By raising the current signal Id or Iq in a stepped form, the reactive power or the active power can be increased in a stepped form.
  • Id adjusts (controls) f (frequency) and Iq adjusts (controls) V (voltage), where Id controls reactive power and Iq controls active power. It can be seen that. However, this is only one embodiment, and Id can control active power by adjusting V, and Iq can control reactive power by adjusting f.
  • Single operation can be sensed by inputting reactive power, which has been raised (amplified) in this manner, to a line (a line between the inverter 100 and the system 300).
  • a line a line between the inverter 100 and the system 300.
  • the controller 230 may determine that it is not a stand-alone operation because there is no change in f (frequency) detected when a pulse is applied to Id once (because the change in f is less than or equal to the reference value).
  • f frequency
  • the controller 230 may determine that it is not a stand-alone operation because there is no change in f (frequency) detected when a pulse is applied to Id once (because the change in f is less than or equal to the reference value).
  • single pulse is applied to Id, single operation is not detected.
  • the pulse applied to Id is repeatedly injected in the next cycle (right part of the graph)
  • the frequency change value is larger than the reference value (threshold value)
  • single operation In order to figure out the fluctuation of f can be detected by stepping (amplifying) the pulse applied to Id.
  • the controller 230 may determine that the operation f is greater than or equal to the predetermined value and to cut off the power transmitted to the system 300. That is, the controller 230 according to the present invention can increase the reactive power input in a step form (gradually grow) to quickly detect a single operation.
  • controller 230 may control the input of the reactive power to be shorter. By controlling the period of change of Id and Iq more and more rapidly, the period which inputs reactive power can be shortened more. This control allows the frequency to exceed the threshold more quickly, which allows for the detection of single operation faster.
  • FIG. 7 and 8 are graphs of Id, Iq, f, and V for explaining the control of reactive power according to another embodiment of the single operation detection system of the present invention. Increasing (increasing) the shape to detect a change in f is shown, decreasing the width as the pulse increases in steps.
  • the controller 230 increases (amplifies) a pulse applied to Id in a next cycle to detect a change in f.
  • Increasing the pulse in a step form reduces the width of the pulse so that the frequency can exceed the threshold more quickly, allowing for faster detection of stand-alone operation.
  • width means time, so decreasing the width means shortening the time.
  • control unit 230 may limit the amount of reactive power input to the line to 10 to 20% of the active power, the voltage fluctuation range can be minimized when the single operation does not occur by this control, thereby the system By minimizing the effects of the system, the stability and durability of the entire system can be improved.
  • the controller 230 may control to change the magnitude of the active power transmitted from the at least one generator 100 when the variation value of the frequency of the signal detected by the signal detector 210 is greater than or equal to the reference value. That is, the magnitude of the active power can be changed in the same way as the reactive power. For example, if the variation value of the frequency of the signal detected by the signal detector 210 is greater than or equal to the reference value, a method of increasing the magnitude of the effective power transmitted from the at least one inverter 100 in a staircase form may be exemplified.
  • the controller 230 may control to reduce the magnitude of the active power when it is determined that the system 300 is unstable. This control minimizes the impact of the system, improving the stability and durability of the entire system.
  • the single operation detection method according to the present invention includes a signal detection step (S10) of detecting a signal transmitted from at least one inverter 100; A reactive power generation step (S20) of generating reactive power based on the signal detected in the signal detection step (S10); And injecting the reactive power into the line 300 by generating a pulse at the reactive power generated in the reactive power generation step S20, and if the variation value of the frequency of the signal detected in the signal detection step S10 is greater than or equal to the reference value. It may be configured to include a reactive power control step (S30) to control to gradually increase the magnitude of the pulse.
  • the single operation detection method according to the present invention is effective to be transmitted from the at least one inverter 100 after the reactive power adjustment step (S30), if the change value of the frequency of the signal detected in the signal detection step (S10) is greater than or equal to the reference value.
  • an active power control step (S40) for changing the size of the power or after the active power control step (S40), if the system 300 is determined to be unstable active power size to reduce the degree of change in the size of the active power It may be configured to further include a reduction step (S50).
  • the signal detection step S10 is a step of detecting a signal transmitted from at least one inverter 100
  • the reactive power generation step S20 is a step of generating reactive power based on the signal detected in the signal detection step S10.
  • Reactive power adjustment step (S30) is a pulse is generated in the reactive power generated in the reactive power generation step (S20) to input the reactive power to the line 300, but detected in the signal detection step (S10) If the change in the frequency of the signal is greater than or equal to the reference value is a step of controlling to gradually increase the magnitude of the pulse.
  • Such signal detection step (S10), reactive power generation step (S20), reactive power control step (S30) can be performed using the stand-alone detection system described above with reference to Figures 2 to 4, in particular, reactive power control step ( In operation S30, when the variation value of the frequency f is greater than or equal to the reference value as illustrated in FIGS. 5 and 6, the controller 230 increases the magnitude of the reactive power by raising Iq, which is one of the two-phase rotation current signals, in the form of steps. It can be raised in the form of stairs.
  • the input period of the reactive power can be shortened in the reactive power generation step (S20).
  • the reactive power is controlled by simultaneously controlling Id and Iq. In other words, by controlling the period of change of Id and Iq more and more rapidly, the period of inputting reactive power can be shortened.
  • the pulse can be raised in the form of steps, but the width can be controlled. This control allows the frequency to exceed the threshold more quickly, which allows for the detection of single operation faster.
  • it may be controlled to input the reactive power as a time shorter than a period.
  • the reactive power control step (S30) it can limit the size of the reactive power generated in the reactive power generation step (S20) to the range of 10% to 20% of the size of the active power transmitted from the at least one inverter 100. have.
  • the voltage fluctuation range can be minimized when the single operation does not occur, thereby minimizing the influence of the system and improving the stability and durability of the entire system.
  • the active power transmitted from the at least one inverter 100 In the case of further comprising an active power control step (S40) to change the size of the complementary power supply to change the size of the active power in the same way as the reactive power to detect a change in the voltage, more accurate and faster operation alone It can be detected.
  • the single operation detection method according to the present invention is configured to further include an active power size reduction step (S50) for reducing the size of the active power if the system 300 is determined to be unstable after the active power adjustment step (S40).
  • S50 active power size reduction step
  • the single operation detection method according to the present invention is configured to further include an active power size reduction step (S50) for reducing the size of the active power if the system 300 is determined to be unstable after the active power adjustment step (S40).
  • first current converter 213 second current converter

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Abstract

The present invention relates to an islanding detection system and an islanding detection method for detecting islanding in a photovoltaic power generation system or an energy storage system. In a system in which power output from at least one inverter is transmitted to a grid through a line, the islanding detection system according to the present invention comprises: a signal detection unit for detecting a signal transmitted from the at least one inverter; a reactive power generation unit for generating reactive power on the basis of a signal detected by the signal detection unit; and a control unit for generating a pulse in reactive power generated by the reactive power generation unit and feeding the reactive power into the line while controlling the same such that the amplitude of the generated pulse is gradually increased when the frequency drift of the signal detected by the signal detection unit is equal to or greater than a reference value.

Description

단독운전 감지 시스템 및 단독운전 감지 방법Single operation detection system and single operation detection method
본 발명은 단독운전 감지 시스템 및 단독운전 감지 방법에 관한 것으로, 더욱 상세하게는 태양광 발전 시스템 또는 에너지 저장 시스템에 있어 단독운전을 감지하는 단독운전 감지 시스템 및 단독운전 감지 방법에 관한 것이다.The present invention relates to a single operation detection system and a single operation detection method, and more particularly, to a single operation detection system and a single operation detection method for detecting single operation in a photovoltaic power generation system or energy storage system.
다수의 태양광 발전 시스템 또는 에너지 저장 시스템에 있어서, 배전선이 각종 작업으로 인한 정전 사고 또는 기타 원인으로 계통에서 분리되더라도 태양광 발전 시스템 또는 에너지 저장 시스템의 출력과 배전선 부하의 소비전력이 균형을 이루면 태양광 발전 시스템 또는 에너지 저장 시스템이 배전선 부하를 떠맡아 운전을 계속 하는데, 이러한 현상을 단독운전이라고 한다.In many solar power systems or energy storage systems, even if the distribution lines are disconnected from the grid due to power outages or other causes of various tasks, the solar power system or energy storage system balances the output of the solar power system or energy storage system with the power consumption of the distribution line load. Photovoltaic systems or energy storage systems take over the load on the distribution lines and continue operation. This phenomenon is called stand-alone operation.
도 1에는 일반적인 계통연계형 태양광 발전 시스템의 전력흐름이 도시되어 있는데, 예를 들어 전력계통에 연결된 PCS(Power Conditioning System)가 변전소 차단 등에 의해 대형 동기 인버터와 같은 주 전력 공급원이 분리된 상태에서 이를 감지하지 못하고 연결된 부하에 전력을 공급하는 운전 상태를 단독운전 상태로 볼 수 있다.Figure 1 shows the power flow of a typical grid-connected photovoltaic power generation system, for example, in a state in which the main power supply, such as a large synchronous inverter, is disconnected from the power conditioning system (PCS) connected to the power system by substation shutdown. Without detecting this, the operating state that supplies power to the connected load can be viewed as a stand-alone operation.
이러한 단독운전 상태가 지속 된다면, 선로의 유지·보수를 하는 작업자의 감전사고가 발생할 우려가 높아지고, 전기설비에 나쁜 영향을 줄 수 있다. 또한 태양광 발전 시스템 또는 에너지 저장 시스템의 단독운전 시 위상의 오차로 인한 태양광 발전 시스템 또는 에너지 저장 시스템의 계통 시스템에 손상을 일으킬 수도 있다.If such a stand-alone operation continues, there is a high risk of electric shock of the worker who maintains and repairs the track, which may adversely affect the electrical installation. In addition, it may cause damage to the grid system or the grid system of the energy storage system due to the phase error when the solar power system or energy storage system is operated alone.
이러한 이유로 계통에서의 전원 공급이 끊겼을 경우에는 시스템의 동작도 멈추도록 해야 한다. 이러한 단독운전의 감지 방법으로 라인에 변화가 있을 때만 감지하는 수동적인 방식과 인버터 출력 전류에 변동을 주어 이를 이용하는 능동적인 방식이 있다.For this reason, if the system loses power, the system should stop working. There are two methods of detecting a single operation, a passive method for detecting only a change in a line and an active method using a change in an inverter output current.
수동적인 방식은 단독운전 상태에서 발전량과 부하량, 선로전압, 주파수, 위상 또는 전압에 고조파 성분의 변화를 검출하는 방식으로, 인버터의 과전압/저전압 및 과주파/저주파를 이용하는 방식, PCC전압과 인버터 출력전류의 위상차와 THD를 모니터링 하여 감지하는 방식 등이 있다.The passive method detects changes in harmonic components in power generation, load, line voltage, frequency, phase or voltage in a single operation, using overvoltage / low voltage and overfrequency / low frequency of the inverter. Current phase difference and THD are monitored and sensed.
능동적인 방식은 Frequency drifts 방법, Voltage drifts 방법, Grid impedance estimation 방법, PLL-baseed estimation 방법, Negative sequence detection 방법 등이 있다. 최근 능동적인 방식 중에서 무효전력을 투입하는 방식이 이용되고 있는데, 대한민국 등록특허 제10-1398457호에는 무효전력을 투입하여 단독운전을 감지하는 방법이 개재되어 있다.Active methods include frequency drifts, voltage drifts, grid impedance estimation, PLL-based estimation, and negative sequence detection. Recently, a method of inputting reactive power among active methods has been used, and Korean Patent No. 10-1398457 discloses a method of detecting stand-alone operation by inputting reactive power.
이러한 종래의 일반적인 무효전력을 투입하여 단독운전을 감지하는 방법은 전력변환장치의 출력의 품질을 떨어뜨리는 문제점이 있다. 즉, 전압의 크기가 커졌다 작아졌다를 반복하면서 형광등과 같은 조명기구의 깜빡거림을 발생시키게 된다. 또한 역률값이 주기적으로 변동되므로 현재의 계통연계 규정을 만족하기 힘든 문제점이 있다.Such a conventional method of detecting stand-alone operation by inputting reactive power has a problem of degrading the output quality of the power converter. That is, while the magnitude of the voltage increases and decreases, flickering of a lighting device such as a fluorescent lamp is generated. In addition, since the power factor value fluctuates periodically, there is a problem that it is difficult to satisfy the current grid connection regulation.
본 발명은 위와 같은 문제점을 해결하기 위하여 안출된 것으로, 본 발명에서 해결하고자 하는 과제는 역률값이 주기적으로 변동되는 것을 방지하여 효율적으로 계통연계 규정을 만족시킬 수 있고, 전력변환장치의 출력을 품질을 향상시킬 수 있으면서 종래보다 빠르게 단독운전을 감지할 수 있는 단독운전 감지 시스템 및 단독운전 감지 방법을 제공하는 것에 있다.The present invention has been made to solve the above problems, the problem to be solved in the present invention is to prevent the power factor value is periodically changed to satisfy the grid linkage regulations, and to improve the output of the power converter The present invention provides a single operation detection system and a single operation detection method capable of improving single operation and detecting single operation faster than before.
위와 같은 과제를 해결하기 위한 본 발명에 따른 단독운전 감지 시스템은 적어도 하나 이상의 인버터에서 출력되는 전력이 라인을 통해 계통으로 전송되는 시스템에 있어서, 상기 적어도 하나 이상의 인버터로부터 전송된 신호를 검출하는 신호 검출부; 상기 신호 검출부에서 검출된 신호를 근거로 무효전력을 발생시키는 무효전력 발생부 및 상기 무효전력 발생부에서 발생되는 무효전력에 펄스가 발생되도록 하여 상기 무효전력을 상기 라인으로 투입하되, 상기 신호 검출부에서 검출된 신호의 주파수의 변동값이 기준값 이상이면 상기 펄스의 크기를 점진적으로 증가시켜 투입하도록 제어하는 제어부를 포함하는 것에 기술적 특징이 있다.In the single operation detection system according to the present invention for solving the above problems is a signal detection unit for detecting a signal transmitted from the at least one inverter in a system in which the power output from the at least one inverter is transmitted to the grid via a line ; The reactive power generator generates reactive power based on the signal detected by the signal detector and a reactive power generated by the reactive power generator to generate a pulse to input the reactive power to the line, It is a technical feature to include a control unit for controlling to gradually increase the magnitude of the pulse when the variation value of the frequency of the detected signal is greater than or equal to the reference value.
위와 같은 과제를 해결하기 위한 본 발명에 따른 단독운전 감지 방법은 적어도 하나 이상의 인버터에서 발생되는 전력이 라인을 통해 계통으로 전송되는 시스템의 단독운전 감지 방법에 있어서, 상기 적어도 하나 이상의 인버터로부터 전송된 신호를 검출하는 신호 검출단계; 상기 신호 검출단계에서 검출된 신호를 근거로 무효전력을 발생하는 무효전력 발생 단계 및 상기 무효전력 발생단계에서 발생하는 무효전력에 펄스가 발생되도록 하여 상기 무효전력을 상기 라인으로 투입하되, 상기 신호 검출단계에서 검출된 신호의 주파수의 변동값이 기준값 이상이면 상기 펄스의 크기를 점진적으로 증가시켜 투입하도록 제어하는 무효전력 조절단계를 포함하여 구성되는 것에 기술적 특징이 있다.In the single operation detection method according to the present invention for solving the above problems in the single operation detection method of the system in which power generated in at least one or more inverters are transmitted to the grid via a line, the signal transmitted from the at least one inverter Detecting a signal; The reactive power generation step of generating reactive power based on the signal detected in the signal detecting step and the reactive power generated in the reactive power generating step are generated so that the reactive power is input to the line, but the signal detection is performed. If the variation value of the frequency of the signal detected in the step is greater than the reference value is characterized in that it comprises a reactive power adjustment step of controlling to gradually increase the magnitude of the pulse.
본 발명에 따른 단독운전 감지 시스템 및 단독운전 감지 방법은 무효전력을 주기적으로 짧게 투입하기 때문에 역률 및 전압 강하의 영향성이 없고, 눈으로 감지되지 않는 빠른 시간 동안 무효전력을 투입하기 때문에 전력변환장치의 출력의 품질이 저하되는 것을 방지할 수 있다.Since the single operation detection system and the single operation detection method according to the present invention have a short period of reactive power input, there is no influence of power factor and voltage drop, and a reactive power input device operates the reactive power for a quick time not detected by the eye. It is possible to prevent the quality of the output from deteriorating.
또한 본 발명에 따른 단독운전 감지 시스템 및 단독운전 감지 방법은 단독운전이 발생하지 않을 경우 전압 변동 폭을 최소화할 수 있고, 이로써 계통의 영향을 최소화하여 시스템 전체의 안정성 및 내구성 향상을 도모할 수 있다.In addition, the single operation detection system and the single operation detection method according to the present invention can minimize the voltage fluctuation range when the single operation does not occur, thereby minimizing the influence of the system to improve the stability and durability of the entire system. .
또한 본 발명에 따른 단독운전 감지 시스템 및 단독운전 감지 방법은 상호 보완적으로 유효전력의 크기를 무효전력과 같은 방법으로 변화시켜 전압을 크기의 변화를 감지함으로써 보다 정확하고 빠르게 단독운전을 감지할 수 있다.In addition, the single operation detection system and the single operation detection method according to the present invention can detect the independent operation more accurately and quickly by changing the magnitude of the voltage by complementarily changing the magnitude of the active power in the same way as the reactive power. have.
도 1은 종래의 일반적인 계통연계형 태양광 발전 시스템의 전력흐름을 나타낸 도면1 is a view showing the power flow of a conventional general grid-connected photovoltaic power generation system
도 2 및 도 3은 본 발명에 따른 단독운전 감지 시스템의 개략적인 구성을 나타낸 도면2 and 3 is a view showing a schematic configuration of a single operation detection system according to the present invention
도 4는 본 발명에 따른 단독운전 감지 시스템의 신호 검출부를 설명하기 위한 도면4 is a view for explaining a signal detection unit of a single operation detection system according to the present invention;
도 5 및 도 6는 본 발명의 단독운전 감지 시스템의 일 실시예에 따른 무효전력을 제어를 설명하기 위한 Id, Iq, f, V의 그래프5 and 6 are graphs of Id, Iq, f, and V for explaining control of reactive power according to an embodiment of a single operation detection system of the present invention.
도 7 및 도 8은 본 발명의 단독운전 감지 시스템의 다른 실시예에 따른 무효전력을 제어를 설명하기 위한 Id, Iq, f, V의 그래프7 and 8 are graphs of Id, Iq, f, and V for explaining control of reactive power according to another embodiment of the single operation detection system of the present invention.
도 9는 본 발명에 따른 단독운전 감지 방법의 절차를 나타낸 도면9 is a view showing a procedure of a single operation detection method according to the present invention
아래에서는 본 발명에 따른 단독운전 감지 시스템을 첨부된 도면을 통해 더욱 상세히 설명한다.Hereinafter, a single operation detection system according to the present invention will be described in more detail with reference to the accompanying drawings.
도 2 및 도 3은 본 발명에 따른 단독운전 감지 시스템의 개략적인 구성을 나타낸 도면으로, 도 2 및 도 3을 참고하면 본 발명에 따른 단독운전 감지 시스템은 적어도 하나 이상의 인버터(100)로부터 전송된 신호를 검출하는 신호 검출부(210); 신호 검출부(210)에서 검출된 신호를 근거로 무효전력을 발생시키는 무효전력 발생부(220); 신호 검출부(210) 및 무효전력 발생부(220)에 연결되어 신호 검출부(210) 및 무효전력 발생부(220)의 동작을 제어하는 제어부(230)를 포함하여 구성된다.2 and 3 is a view showing a schematic configuration of a single operation detection system according to the present invention, referring to Figures 2 and 3 is a single operation detection system according to the present invention is transmitted from at least one inverter 100 A signal detector 210 detecting a signal; A reactive power generator 220 generating reactive power based on the signal detected by the signal detector 210; And a controller 230 connected to the signal detector 210 and the reactive power generator 220 to control operations of the signal detector 210 and the reactive power generator 220.
본 발명에 따른 단독운전 감지 시스템은 계통(Grid, 300)에 연결되는 것을 전제로 하기 때문에 교류형태의 전력을 다루고 있는데, 태양광 발전의 경우 인버터(100)는 PV CELL에 연결되어 PV CELL의 DC 출력을 AC로 변환한다.The single operation detection system according to the present invention deals with the power of the AC type because it is assumed to be connected to the grid (Grid, 300), in the case of photovoltaic power generation, the inverter 100 is connected to the PV cell and the DC of the PV cell. Convert the output to AC.
신호 검출부(210)는 적어도 하나 이상의 인버터(100)로부터 전송되는 신호를 검출하는 구성요소이고, 무효전력 발생부(220)는 신호 검출부(210)에서 검출된 신호를 바탕으로 무효전력을 발생시키는 구성요소이다. 제어부(230)는 신호 검출부(210) 및 무효전력 발생부(220)에 연결되어 신호 검출부(210) 및 무효전력 발생부(220)의 동작을 제어하는데, 특히 신호 검출부(210)에서 검출된 신호의 주파수의 변동값이 기준값 이상이면 펄스의 크기를 주기마다 단계적으로 증가시켜 투입하되, 무효전력을 주기적으로 짧게 투입하도록 하는 제어를 한다. The signal detector 210 is a component that detects signals transmitted from at least one inverter 100, and the reactive power generator 220 generates reactive power based on the signal detected by the signal detector 210. Element. The controller 230 is connected to the signal detector 210 and the reactive power generator 220 to control operations of the signal detector 210 and the reactive power generator 220, in particular, the signal detected by the signal detector 210. If the frequency variation is greater than or equal to the reference value, the pulse size is increased step by step, and the reactive power is periodically shorted.
이때 주기는 계통연계 규정(그리드 코드)에서 규정된 시간(단독운전이 감지되었을 때 소정 시간 안에 전력을 차단해야만 함)일 수 있고, 단독운전을 감지하여 계통(300)으로 전달되는 전력을 차단하는 동안의 시간일 수 있다. 또한, 계통연계 규정 및 단독운전을 감지하여 계통(300)으로 전달되는 전력을 차단하는 동안의 시간을 근거로 선정된 시간일 수 있다.At this time, the cycle may be a time specified in grid linkage (grid code) (must cut off power within a predetermined time when a standalone operation is detected), and detect a standalone operation to cut off power delivered to the system 300. May be time. In addition, it may be a time selected based on the time while the grid connection regulation and the stand-alone operation is detected to cut off the power delivered to the system (300).
또한 '짧게'의 의미는 주기보다 짧은 시간을 의미하는 것일 수 있다. 예를 들어 주파수가 60Hz인 경우 주기는 0.0167초인데, 인버터(100)로부터 전송되는 신호의 주파수가 60Hz인의 경우 주기(0.0167초)보다 짧은 시간 동안 무효전력을 투입할 수 있다.In addition, the term “short” may mean a time shorter than a period. For example, when the frequency is 60Hz, the period is 0.0167 seconds, but when the frequency of the signal transmitted from the inverter 100 is 60Hz, reactive power may be input for a time shorter than the period (0.0167 seconds).
도 4는 본 발명에 따른 단독운전 감지 시스템의 신호 검출부를 설명하기 위한 도면, 도 5 및 도 6은 본 발명의 단독운전 감지 시스템의 일 실시예에 따른 무효전력을 제어를 설명하기 위한 Id, Iq, f, V의 그래프로서, 도 4 내지 도 6을 참고하여 제어부(230)가 신호 검출부(210) 및 무효전력 발생부(220)의 동작을 제어하는 방법을 더욱 상세히 살펴본다.4 is a view for explaining a signal detection unit of the stand-alone detection system according to the present invention, FIGS. 5 and 6 are views Id, Iq for explaining the control of reactive power according to an embodiment of the stand-alone operation detection system of the present invention. As a graph of f, V, a method of controlling the operation of the signal detector 210 and the reactive power generator 220 will be described in more detail with reference to FIGS. 4 to 6.
신호 검출부(210)는 변류기(211), 제1 전류변환기(212), 제2 전류변환기(213)를 포함하여 구성될 수 있다. 변류기(211)는 인버터(100)의 출력을 측정하는 구성요소이고, 제1 전류변환기(212)는 변류기(211)로부터 전달되는 3상의 전류신호(Ia, Ib, Ic)를 2상 정지 좌표계(α, β)의 2상 정지 전류 신호(Iα, Iβ)로 변환하는 구성요소이다. The signal detector 210 may include a current transformer 211, a first current converter 212, and a second current converter 213. Current transformer 211 is a component for measuring the output of the inverter 100, the first current converter 212 is a three-phase current coordinates (Ia, Ib, Ic) transmitted from the current transformer 211 two-phase stop coordinate system ( It is a component converting into the two-phase stop current signals Iα and Iβ of α and β.
또한 제2 전류변환기(213)는 2상 정지 좌표계(α, β)의 2상 정지 전류 신호(Iα, Iβ)를 2상 회전 좌표계(d, q)의 2상 회전 전류 신호(Id, Iq)로 변환하는 구성요소이다. 이때 d축과 q축을 이용하여 출력전류의 진폭과 위상을 조절할 수 있다.In addition, the second current converter 213 transmits the two-phase stop current signals Iα and Iβ of the two-phase stop coordinate systems α and β to the two-phase rotation current signals Id and Iq of the two-phase rotation coordinate systems d and q. The component that converts to. At this time, the amplitude and phase of the output current can be adjusted using the d-axis and the q-axis.
즉, 제1 전류변환기(212), 제2 전류변환기(213) 및 제어부(230)를 적절하게 구성함으로써, d축 전류(Id)가 유효전력을 제어하고 q축 전류(Iq)가 무효전력을 제어하도록 구성할 수 있으며, d축 전류(Id)가 무효전력을 제어하고, q축 전류(Iq)가 유효전력을 제어하도록 구성할 수 있다.That is, by properly configuring the first current converter 212, the second current converter 213, and the controller 230, the d-axis current Id controls the active power and the q-axis current Iq controls the reactive power. The d-axis current Id controls the reactive power, and the q-axis current Iq controls the active power.
제어부(230)는 신호 검출부(210)에서 검출된 신호의 주파수의 변동값이 기준값 이상이면{이때 주파수의 변동값에 대한 기준값은 제어부(230)에 미리 저장될 수 있다} 무효전력 발생부(220)에서 발생되는 무효전력의 크기를 계단형태로 키우는 제어를 하는데, 2상 회전 전류 신호 중 하나인 Id 또는 Iq를 계단형태로 키움으로써 무효전력의 크기를 계단형태로 키울 수 있다. 또한 제어부(230)는 필요에 따라 Id 또는 Iq를 계단형태로 키움으로써 유효전력의 크기를 계단형태로 키울 수도 있다.If the variation value of the frequency of the signal detected by the signal detector 210 is greater than or equal to the reference value (the reference value for the variation value of the frequency may be stored in the controller 230 in advance), the reactive power generator 220 The step of controlling the amount of reactive power generated in the step) in step form, the step of increasing the reactive power of step Id or Iq, one of the two-phase rotation current signal in step form. In addition, the controller 230 may increase the size of the effective power in the form of stairs by increasing Id or Iq in the form of stairs as necessary.
도 5 및 도 6을 참조하면 그래프의 오른쪽 부분에서 주파수(f)의 변동값이 기준값 이상인 경우가 도시되어 있는데, 이렇게 주파수(f)의 변동값이 기준값 이상이면, 제어부(230)가 2상 회전 전류 신호 중 하나인 Id 또는 Iq를 계단형태로 키움으로써 무효전력 또는 유효전력의 크기를 계단형태로 키울 수 있다. 도 5의 경우는 Id가 f(주파수)를 조절(제어)하고 Iq가 V(전압)을 조절(제어)하는 것이 도시되어 있는데, 이때에는 Id가 무효전력을 제어하고, Iq가 유효전력을 제어하는 것으로 볼 수 있다. 그러나 이는 하나의 실시예에 불과할 뿐 Id가 V를 조절하여 유효전력을 제어할 수 있고, Iq가 f를 조절하여 무효전력을 제어할 수도 있다.Referring to FIGS. 5 and 6, a case in which the variation value of the frequency f is greater than or equal to the reference value is shown in the right part of the graph. When the variation value of the frequency f is greater than or equal to the reference value, the controller 230 rotates two-phase. By raising the current signal Id or Iq in a stepped form, the reactive power or the active power can be increased in a stepped form. In FIG. 5, Id adjusts (controls) f (frequency) and Iq adjusts (controls) V (voltage), where Id controls reactive power and Iq controls active power. It can be seen that. However, this is only one embodiment, and Id can control active power by adjusting V, and Iq can control reactive power by adjusting f.
이와 같은 방식으로 키워진(증폭된) 무효전력을 라인{인버터(100)와 계통(300) 사이의 라인}으로 투입함으로써 단독운전을 감지할 수 있다. 이때 무효전력을 주기적으로 짧게 투입하기 때문에 역률 및 전압 강하의 영향성이 없고, 눈으로 감지되지 않는 빠른 시간 동안 무효전력을 투입하기 때문에 전력변환장치의 출력의 품질이 저하되는 것을 방지할 수 있다.Single operation can be sensed by inputting reactive power, which has been raised (amplified) in this manner, to a line (a line between the inverter 100 and the system 300). At this time, since reactive power is periodically inputted shortly, there is no influence of power factor and voltage drop, and reactive power is input for a short time which is not detected by eyes, thereby preventing the output quality of the power converter from being degraded.
또한 도 6을 참조하면, 제어부(230)는 Id에 펄스를 한번 가했을 때 감지된 f(주파수)의 변동이 없기 때문에(f의 변동값이 기준값 이하이기 때문에) 단독운전이 아니라고 판단할 수 있고, 이렇게 Id에 펄스를 한번 가했을 때 단독운전이 감지되지 않았기 때문에 다음 주기에(그래프의 오른쪽 부분) Id에 가하는 펄스를 반복해서 주입했을 때, 주파수의 변화값이 기준값(임계값) 이상 커졌을 경우 단독운전의 파악을 위해 Id에 가하는 펄스를 계단 형태로 (증폭하여) f의 변동값을 감지할 수 있다. In addition, referring to FIG. 6, the controller 230 may determine that it is not a stand-alone operation because there is no change in f (frequency) detected when a pulse is applied to Id once (because the change in f is less than or equal to the reference value). When single pulse is applied to Id, single operation is not detected. When the pulse applied to Id is repeatedly injected in the next cycle (right part of the graph), if the frequency change value is larger than the reference value (threshold value), single operation In order to figure out the fluctuation of f can be detected by stepping (amplifying) the pulse applied to Id.
이때 제어부(230)는 f의 변동값이 소정값 이상이면 단독운전으로 판단하고 계통(300)으로 전달되는 전력을 차단하도록 제어할 수 있다. 즉, 본 발명에 따른 제어부(230)는 투입되는 무효전력을 계단 형태로 키워(점진적으로 키워) 빠르게 단독운전을 감지할 수 있다.At this time, the controller 230 may determine that the operation f is greater than or equal to the predetermined value and to cut off the power transmitted to the system 300. That is, the controller 230 according to the present invention can increase the reactive power input in a step form (gradually grow) to quickly detect a single operation.
또한 제어부(230)는 무효전력을 투입하는 주기를 더욱 짧게 하여 투입하도록 제어할 수 있다. Id와 Iq의 변화의 주기를 점점 빠르게 제어함으로써 무효전력을 투입하는 주기를 더욱 짧게 할 수 있다. 이러한 제어에 의해 더 빨리 주파수가 기준치를 초과하게 할 수 있고, 이로써 더욱 빨리 단독운전을 감지할 수 있게 된다.In addition, the controller 230 may control the input of the reactive power to be shorter. By controlling the period of change of Id and Iq more and more rapidly, the period which inputs reactive power can be shortened more. This control allows the frequency to exceed the threshold more quickly, which allows for the detection of single operation faster.
도 7 및 도 8은 본 발명의 단독운전 감지 시스템의 다른 실시예에 따른 무효전력의 제어를 설명하기 위한 Id, Iq, f, V의 그래프로서, 도 7 및 도 8에는 Id에 가하는 펄스를 계단 형태로 증가시켜(키워) f의 변동값을 감지하는 것이 도시되어 있는데, 펄스를 계단 형태로 증가시킬 때 그 폭을 감소시키는 것이 도시되어 있다.7 and 8 are graphs of Id, Iq, f, and V for explaining the control of reactive power according to another embodiment of the single operation detection system of the present invention. Increasing (increasing) the shape to detect a change in f is shown, decreasing the width as the pulse increases in steps.
도 8을 참조하면, 제어부(230)는 Id에 펄스를 한번 가했을 때 f의 변동이 없는 경우 다음 주기에 Id에 가하는 펄스를 계단 형태로 키워(증폭하여) f의 변동값을 감지하는 것이 도시되어 있는데, 펄스를 계단 형태로 증가시킬 때 그 폭을 감소시키는 제어를 통해 더 빨리 주파수가 기준치를 초과하게 할 수 있고, 이로써 더욱 빨리 단독운전을 감지할 수 있게 된다. 여기서 폭은 시간을 의미하므로, 폭의 감소는 결국 시간 단축을 의미한다.Referring to FIG. 8, when there is no change in f when a pulse is once applied to Id, the controller 230 increases (amplifies) a pulse applied to Id in a next cycle to detect a change in f. Increasing the pulse in a step form reduces the width of the pulse so that the frequency can exceed the threshold more quickly, allowing for faster detection of stand-alone operation. Here, width means time, so decreasing the width means shortening the time.
또한 제어부(230)는 라인에 투입되는 무효전력의 크기를 유효전력의 10 내지 20%로 제한할 수 있는데, 이러한 제어에 의해 단독운전이 발생하지 않을 경우 전압 변동 폭을 최소화할 수 있고, 이로써 계통의 영향을 최소화하여 시스템 전체의 안정성 및 내구성 향상을 도모할 수 있다.In addition, the control unit 230 may limit the amount of reactive power input to the line to 10 to 20% of the active power, the voltage fluctuation range can be minimized when the single operation does not occur by this control, thereby the system By minimizing the effects of the system, the stability and durability of the entire system can be improved.
또한 제어부(230)는 신호 검출부(210)에서 검출된 신호의 주파수의 변동값이 기준값 이상이면, 적어도 하나 이상의 발전기(100)로부터 전송되는 유효전력의 크기를 변화시키는 제어를 할 수 있다. 즉, 유효전력의 크기를 무효전력과 같은 방법으로 변화시킬 수 있다. 예를 들어 신호 검출부(210)에서 검출된 신호의 주파수의 변동값이 기준값 이상이면, 적어도 하나 이상의 인버터(100)로부터 전송되는 유효전력의 크기를 계단형태로 키우는 방법을 예로 들 수 있다.In addition, the controller 230 may control to change the magnitude of the active power transmitted from the at least one generator 100 when the variation value of the frequency of the signal detected by the signal detector 210 is greater than or equal to the reference value. That is, the magnitude of the active power can be changed in the same way as the reactive power. For example, if the variation value of the frequency of the signal detected by the signal detector 210 is greater than or equal to the reference value, a method of increasing the magnitude of the effective power transmitted from the at least one inverter 100 in a staircase form may be exemplified.
이렇게 상호 보완적으로 유효전력의 크기를 무효전력과 같은 방법으로 변화시켜 전압을 크기의 변화를 감지하면, 보다 정확하고 빠르게 단독운전을 감지할 수 있다.In this way, if the magnitude of the active power is changed in the same way as the reactive power to detect the change in the voltage, single operation can be detected more accurately and quickly.
제어부(230)가 유효전력의 크기를 변화시키는 제어를 할 때, 제어부(230)는 계통(300)이 불안정하다고 확인되면 유효전력의 크기를 감소시키는 제어를 할 수 있다. 이러한 제어를 통해 계통의 영향을 최소화하여 시스템 전체의 안정성 및 내구성 향상을 도모할 수 있다.When the controller 230 controls to change the magnitude of the active power, the controller 230 may control to reduce the magnitude of the active power when it is determined that the system 300 is unstable. This control minimizes the impact of the system, improving the stability and durability of the entire system.
도 9는 본 발명에 따른 단독운전 감지 방법의 절차를 나타낸 도면이다. 도 9를 참고하면, 본 발명에 따른 단독운전 감지 방법은 적어도 하나 이상의 인버터(100)로부터 전송된 신호를 검출하는 신호 검출단계(S10); 신호 검출단계(S10)에서 검출된 신호를 근거로 무효전력을 발생하는 무효전력 발생단계(S20); 및 무효전력 발생단계(S20)에서 발생하는 무효전력에 펄스가 발생되도록 하여 상기 무효전력을 라인(300)으로 투입하되, 신호 검출단계(S10)에서 검출된 신호의 주파수의 변동값이 기준값 이상이면 상기 펄스의 크기를 점진적으로 증가시켜 투입하도록 제어하는 무효전력 조절단계(S30)를 포함하여 구성될 수 있다.9 is a view showing a procedure of a single operation detection method according to the present invention. 9, the single operation detection method according to the present invention includes a signal detection step (S10) of detecting a signal transmitted from at least one inverter 100; A reactive power generation step (S20) of generating reactive power based on the signal detected in the signal detection step (S10); And injecting the reactive power into the line 300 by generating a pulse at the reactive power generated in the reactive power generation step S20, and if the variation value of the frequency of the signal detected in the signal detection step S10 is greater than or equal to the reference value. It may be configured to include a reactive power control step (S30) to control to gradually increase the magnitude of the pulse.
또한 본 발명에 따른 단독운전 감지 방법은 무효전력 조절단계(S30) 이후, 신호 검출단계(S10)에서 검출된 신호의 주파수의 변동값이 기준값 이상이면, 적어도 하나 이상의 인버터(100)로부터 전송되는 유효전력의 크기를 변화시키는 유효전력 조절단계(S40)를 더 포함하거나, 유효전력 조절 단계(S40) 이후, 계통(300)이 불안정하다고 확인되면 유효전력의 크기의 변화의 정도를 감소시키는 유효전력 크기 감소단계(S50)를 더 포함하여 구성될 수 있다.In addition, the single operation detection method according to the present invention is effective to be transmitted from the at least one inverter 100 after the reactive power adjustment step (S30), if the change value of the frequency of the signal detected in the signal detection step (S10) is greater than or equal to the reference value. Further comprising an active power control step (S40) for changing the size of the power, or after the active power control step (S40), if the system 300 is determined to be unstable active power size to reduce the degree of change in the size of the active power It may be configured to further include a reduction step (S50).
신호 검출단계(S10)는 적어도 하나 이상의 인버터(100)로부터 전송되는 신호를 검출하는 단계이고, 무효전력 발생단계(S20)는 신호 검출단계(S10)에서 검출된 신호를 근거로 무효전력을 발생하는 단계이며, 무효전력 조절단계(S30)는 무효전력 발생단계(S20)에서 발생하는 무효전력에 펄스가 발생되도록 하여 상기 무효전력을 라인(300)으로 투입하되, 신호 검출단계(S10)에서 검출된 신호의 주파수의 변동값이 기준값 이상이면 상기 펄스의 크기를 점진적으로 증가시켜 투입하도록 제어하는 하는 단계이다.The signal detection step S10 is a step of detecting a signal transmitted from at least one inverter 100, and the reactive power generation step S20 is a step of generating reactive power based on the signal detected in the signal detection step S10. Reactive power adjustment step (S30) is a pulse is generated in the reactive power generated in the reactive power generation step (S20) to input the reactive power to the line 300, but detected in the signal detection step (S10) If the change in the frequency of the signal is greater than or equal to the reference value is a step of controlling to gradually increase the magnitude of the pulse.
이러한 신호 검출단계(S10), 무효전력 발생단계(S20), 무효전력 조절단계(S30)는 앞서 도 2 내지 도 4에서 살펴본 단독운전 감지 시스템을 이용하여 수행할 수 있는데, 특히 무효전력 조절단계(S30)에서는 도 5 및 도 6에 도시된 바와 같이 주파수(f)의 변동값이 기준값 이상이면, 제어부(230)가 2상 회전 전류 신호 중 하나인 Iq를 계단형태로 키움으로써 무효전력의 크기를 계단형태로 키울 수 있다. Such signal detection step (S10), reactive power generation step (S20), reactive power control step (S30) can be performed using the stand-alone detection system described above with reference to Figures 2 to 4, in particular, reactive power control step ( In operation S30, when the variation value of the frequency f is greater than or equal to the reference value as illustrated in FIGS. 5 and 6, the controller 230 increases the magnitude of the reactive power by raising Iq, which is one of the two-phase rotation current signals, in the form of steps. It can be raised in the form of stairs.
또한 무효전력 조절 단계(S30)에서는 무효전력 발생 단계(S20)에서 무효전력의 투입 주기를 짧게 할 수 있는데, 도 7 및 도 8에 도시된 바와 같이 Id와 Iq를 동시에 제어하여 무효전력을 투입하되, Id와 Iq의 변화의 주기를 점점 빠르게 제어함으로써 무효전력을 투입하는 주기를 더욱 짧게 할 수 있다. 또한 펄스를 계단 형태로 키우되 그 폭을 줄이는 제어를 할 수 있다. 이러한 제어에 의해 더 빨리 주파수가 기준치를 초과하게 할 수 있고, 이로써 더욱 빨리 단독운전을 감지할 수 있게 된다. 그리고 무효전력 조절 단계(S30)에서는 상기 무효전력을 투입하는 시간을 주기보다 짧은 시간으로 하여 투입하도록 제어할 수도 있다.In addition, in the reactive power adjustment step (S30), the input period of the reactive power can be shortened in the reactive power generation step (S20). As shown in FIGS. 7 and 8, the reactive power is controlled by simultaneously controlling Id and Iq. In other words, by controlling the period of change of Id and Iq more and more rapidly, the period of inputting reactive power can be shortened. In addition, the pulse can be raised in the form of steps, but the width can be controlled. This control allows the frequency to exceed the threshold more quickly, which allows for the detection of single operation faster. In the reactive power adjustment step (S30), it may be controlled to input the reactive power as a time shorter than a period.
또한 무효전력 조절 단계(S30)에서는 무효전력 발생 단계(S20)에서 발생되는 무효전력의 크기를 적어도 하나 이상의 인버터(100)로부터 전송되는 유효전력의 크기의 10% 내지 20%의 범위로 제한할 수 있다. 이러한 제어에 의해 단독운전이 발생하지 않을 경우 전압 변동 폭을 최소화할 수 있고, 이로써 계통의 영향을 최소화하여 시스템 전체의 안정성 및 내구성 향상을 도모할 수 있다.In addition, in the reactive power control step (S30) it can limit the size of the reactive power generated in the reactive power generation step (S20) to the range of 10% to 20% of the size of the active power transmitted from the at least one inverter 100. have. By this control, the voltage fluctuation range can be minimized when the single operation does not occur, thereby minimizing the influence of the system and improving the stability and durability of the entire system.
본 발명에 따른 단독운전 감지 방법은 무효전력 조절단계(S30) 이후, 신호 검출단계(S10)에서 검출된 신호의 주파수의 변동값이 기준값 이상이면, 적어도 하나 이상의 인버터(100)로부터 전송되는 유효전력의 크기를 변화시키는 유효전력 조절단계(S40)를 더 포함하는 경우 상호 보완적으로 유효전력의 크기를 무효전력과 같은 방법으로 변화시켜 전압을 크기의 변화를 감지하면, 보다 정확하고 빠르게 단독운전을 감지할 수 있다.In the single operation detection method according to the present invention, after the reactive power adjustment step (S30), if the change value of the frequency of the signal detected in the signal detection step (S10) is more than the reference value, the active power transmitted from the at least one inverter 100 In the case of further comprising an active power control step (S40) to change the size of the complementary power supply to change the size of the active power in the same way as the reactive power to detect a change in the voltage, more accurate and faster operation alone It can be detected.
또한 본 발명에 따른 단독운전 감지 방법이 유효전력 조절 단계(S40) 이후, 계통(300)이 불안정하다고 확인되면 유효전력의 크기를 감소시키는 유효전력 크기 감소단계(S50)를 더 포함하여 구성되는 경우 계통의 영향을 최소화하여 시스템 전체의 안정성 및 내구성 향상을 도모할 수 있다.In addition, when the single operation detection method according to the present invention is configured to further include an active power size reduction step (S50) for reducing the size of the active power if the system 300 is determined to be unstable after the active power adjustment step (S40). By minimizing the influence of the system, it is possible to improve the stability and durability of the entire system.
[부호의 설명][Description of the code]
100: 인버터 200: 단독운전 감지 시스템100: inverter 200: single operation detection system
210: 신호 검출부 211: 변류기210: signal detector 211: current transformer
212: 제1 전류변환기 213: 제2 전류변환기212: first current converter 213: second current converter
200: 무효전력 발생부 230: 제어부200: reactive power generation unit 230: control unit
300: 계통 300: system

Claims (14)

  1. 적어도 하나 이상의 인버터(100)에서 출력되는 전력이 라인을 통해 계통(300)으로 전송되는 시스템에 있어서,In a system in which power output from at least one inverter 100 is transmitted to the grid 300 via a line,
    상기 적어도 하나 이상이 인버터(100)로부터 전송된 신호를 검출하는 신호 검출부(210);A signal detector (210) for detecting at least one signal transmitted from the inverter (100);
    상기 신호 검출부(210)에서 검출된 신호를 근거로 무효전력을 발생시키는 무효전력 발생부(220) 및A reactive power generator 220 for generating reactive power based on the signal detected by the signal detector 210;
    상기 무효전력 발생부(220)에서 발생되는 무효전력에 펄스가 발생되도록 하여 상기 무효전력을 상기 라인으로 투입하되, 상기 신호 검출부(210)에서 검출된 신호의 주파수의 변동값이 기준값 이상이면 상기 펄스의 크기를 점진적으로 증가시켜 투입하도록 제어하는 제어부(230)를 포함하며,When the reactive power generated by the reactive power generator 220 generates a pulse, the reactive power is input to the line, but when the variation value of the frequency of the signal detected by the signal detector 210 is greater than or equal to the reference value, the pulse is generated. It includes a control unit 230 for controlling to gradually increase the size of the input,
    상기 무효전력 발생부(220)에서 발생되는 무효전력에 주기적인 펄스가 발생되도록 하여 상기 무효전력을 상기 라인으로 투입하되, 상기 신호 검출부(210)에서 검출된 신호의 주파수의 변동값이 기준값 이상이면 상기 펄스의 크기를 주기마다 단계적으로 증가시켜 투입하는 것을 특징으로 하는 단독운전 감지 시스템.When the reactive power generated by the reactive power generator 220 generates a periodic pulse to input the reactive power to the line, if the variation value of the frequency of the signal detected by the signal detector 210 is greater than the reference value Single operation detection system, characterized in that for increasing the size of the pulse step by step.
  2. 청구항 1에 있어서,The method according to claim 1,
    상기 제어부(230)는,The control unit 230,
    상기 신호 검출부(210)에서 검출된 신호의 주파수의 변동값이 기준값 이상이면 상기 펄스의 주기를 점차 짧게 하여 투입하도록 제어하는 것을 특징으로 하는 단독운전 감지 시스템.If the change value of the frequency of the signal detected by the signal detector 210 is greater than or equal to the reference value, the independent operation detection system, characterized in that to control to gradually shorten the period of the pulse.
  3. 청구항 1에 있어서,The method according to claim 1,
    상기 제어부(230)는,The control unit 230,
    상기 무효전력을 투입하는 시간을 0.0167초보다 짧은 시간으로 하여 투입하도록 제어하는 것을 특징으로 하는 단독운전 감지 시스템.Single operation detection system, characterized in that for controlling the input time to the reactive power input time less than 0.0167 seconds.
  4. 청구항 1에 있어서,The method according to claim 1,
    상기 제어부(230)는The control unit 230
    상기 투입되는 무효전력의 크기를 상기 적어도 하나 이상의 인버터(100)로부터 전송되는 유효전력의 크기의 10% 내지 20%의 범위로 제한하는 것을 특징으로 하는 단독운전 감지 시스템.Single power detection system, characterized in that for limiting the amount of reactive power input to the range of 10% to 20% of the size of the active power transmitted from the at least one inverter (100).
  5. 청구항 1에 있어서,The method according to claim 1,
    상기 제어부(230)는The control unit 230
    상기 신호 검출부(210)에서 검출된 신호의 주파수의 변동값이 기준값 이상이면,If the variation value of the frequency of the signal detected by the signal detector 210 is equal to or greater than a reference value,
    상기 적어도 하나 이상의 인버터(100)로부터 전송되는 무효전력 및 유효전력의 크기를 변화시키는 것을 특징으로 하는 단독운전 감지 시스템.Single operation detection system, characterized in that for changing the magnitude of the reactive power and the active power transmitted from the at least one inverter (100).
  6. 청구항 5에 있어서,The method according to claim 5,
    상기 제어부(230)는The control unit 230
    상기 신호 검출부(210)에서 검출된 신호의 주파수의 변동값이 기준값 이상이면, 상기 적어도 하나 이상의 인버터(100)로부터 전송되는 유효전력의 크기를 계단형태로 키우는 것을 특징으로 하는 단독운전 감지 시스템.When the change value of the frequency of the signal detected by the signal detector 210 is greater than or equal to the reference value, the independent operation detection system, characterized in that to increase the magnitude of the active power transmitted from the at least one or more inverters (100) in the form of steps.
  7. 청구항 5에 있어서,The method according to claim 5,
    상기 제어부(230)는The control unit 230
    상기 적어도 하나 이상의 인버터(100)로부터 전송되는 유효전력의 크기를 변화시킨 다음, 상기 계통(300)이 불안정하다고 확인되면 상기 유효전력의 크기의 변화의 정도를 감소시키는 것을 특징으로 하는 단독운전 감지 시스템.After the magnitude of the active power transmitted from the at least one inverter 100 is changed, if the system 300 is determined to be unstable, the independent operation detection system, characterized in that for reducing the degree of change in the magnitude of the active power .
  8. 적어도 하나 이상의 인버터(100)에서 발생되는 전력이 라인을 통해 계통(300)으로 전송되는 시스템의 단독운전 감지 방법에 있어서,In the single operation detection method of the system in which the power generated by the at least one inverter 100 is transmitted to the system 300 via a line,
    상기 적어도 하나 이상의 인버터(100)로부터 전송된 신호를 검출하는 신호 검출단계(S10);A signal detecting step (S10) of detecting a signal transmitted from the at least one inverter (100);
    상기 신호 검출단계(S10)에서 검출된 신호를 근거로 무효전력을 발생하는 무효전력 발생단계(S20) 및 Reactive power generation step (S20) for generating a reactive power based on the signal detected in the signal detection step (S10) and
    상기 무효전력 발생단계(S20)에서 발생하는 무효전력에 펄스가 발생되도록 하여 상기 무효전력을 상기 라인으로 투입하되, 상기 신호 검출단계(S10)에서 검출된 신호의 주파수의 변동값이 기준값 이상이면 상기 펄스의 크기를 점진적으로 증가시켜 투입하도록 제어하는 무효전력 조절단계(S30)를 포함하며,When the reactive power generated in the reactive power generation step (S20) to generate a pulse to input the reactive power to the line, if the variation value of the frequency of the signal detected in the signal detection step (S10) is greater than or equal to the reference value It includes a reactive power control step (S30) for controlling to gradually increase the magnitude of the pulse,
    상기 무효전력 조절단계(S30)는,The reactive power adjustment step (S30),
    상기 무효전력 발생단계(S20)에서 발생하는 무효전력에 주기적인 펄스가 발생되도록 하여 상기 무효전력을 상기 라인으로 투입하되, 상기 신호 검출단계(S10)에서 검출된 신호의 주파수의 변동값이 기준값 이상이면 상기 펄스의 크기를 주기마다 단계적으로 증가시켜 투입하도록 제어하는 것을 특징으로 하는 단독운전 감지 방법.The reactive power is generated in the reactive power generated in the reactive power generation step S20 so that the reactive power is input to the line, but the variation value of the frequency of the signal detected in the signal detection step S10 is greater than or equal to the reference value. And controlling the input to increase the pulse size step by step.
  9. 청구항 8에 있어서,The method according to claim 8,
    상기 무효전력 조절단계(S30)는,The reactive power adjustment step (S30),
    상기 신호 검출단계(S10)에서 검출된 신호의 주파수의 변동값이 기준값 이상이면 상기 펄스의 주기를 점차 짧게 하여 투입하도록 제어하는 것을 특징으로 하는 단독운전 감지 방법.And controlling the input of the pulse by gradually shortening the period of change of the frequency of the signal detected in the signal detecting step (S10).
  10. 청구항 8에 있어서,The method according to claim 8,
    상기 무효전력 조절단계(S30)는,The reactive power adjustment step (S30),
    상기 무효전력을 투입하는 시간을 0.0167초보다 짧은 시간으로 하여 투입하도록 제어하는 것을 특징으로 하는 단독운전 감지 방법.And controlling the input of the reactive power to a time shorter than 0.0167 seconds.
  11. 청구항 8에 있어서,The method according to claim 8,
    상기 무효전력 조절단계(S30)는The reactive power adjustment step (S30) is
    상기 무효전력 발생단계(S20)에서 발생되는 무효전력의 크기를 상기 적어도 하나 이상의 인버터(100)로부터 전송되는 유효전력의 크기의 10% 내지 20%의 범위로 제한하는 것을 특징으로 하는 단독운전 감지 방법.Single power detection method, characterized in that for limiting the size of the reactive power generated in the reactive power generation step (S20) to the range of 10% to 20% of the size of the active power transmitted from the at least one inverter (100). .
  12. 청구항 8에 있어서,The method according to claim 8,
    상기 무효전력 조절단계(S30) 이후,After the reactive power adjustment step (S30),
    상기 신호 검출단계(S10)에서 검출된 신호의 주파수의 변동값이 기준값 이상이면,If the variation value of the frequency of the signal detected in the signal detection step S10 is equal to or greater than a reference value,
    상기 적어도 하나 이상의 인버터(100)로부터 전송되는 유효전력의 크기를 변화시키는 유효전력 조절단계(S40)를 더 포함하는 것을 특징으로 하는 단독운전 감지 방법.Single power detecting method further comprises an active power adjustment step (S40) for changing the magnitude of the active power transmitted from the at least one inverter (100).
  13. 청구항 12에 있어서,The method according to claim 12,
    상기 유효전력 조절단계(S40)는The active power adjustment step (S40) is
    상기 유효전력의 크기를 변화시키되, 상기 유효전력의 크기를 계단형태로 키우는 것을 특징으로 하는 단독운전 감지 방법.And varying the magnitude of the active power, and increasing the magnitude of the active power in the form of a staircase.
  14. 청구항 12에 있어서,The method according to claim 12,
    상기 유효전력 조절단계(S40) 이후,After the active power adjustment step (S40),
    상기 계통(300)이 불안정하다고 확인되면 상기 유효전력의 크기를 감소시키는 유효전력 크기 감소단계(S50)를 더 포함하는 것을 특징으로 하는 단독운전 감지 방법.If it is determined that the system 300 is unstable, the independent operation detection method further comprises a step of reducing the size of the active power active power size (S50).
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