KR101699500B1 - Photovoltaic System Having Function Charging Energy And Sensing Ground fault - Google Patents

Abstract

The present invention relates to a power saving function having a ground fault detection function capable of detecting a ground fault by constituting a simple detection circuit between a ground and three-phase systems R, S, T without any additional equipment such as an image transformer (GPT) or ground fault relay (OVGR) And more particularly, to a solar power generation system having a solar battery unit that is composed of one or more solar cells and generates electric power; A battery unit for storing electric power produced by the solar battery unit; And a solar photovoltaic power generation unit for selectively supplying power stored in the battery unit to a load requiring power supply when the power generated from the solar battery unit is processed and stored in the battery unit, A ground fault detecting unit for detecting in real time a voltage between a line and a ground of the system and a voltage of each phase of the system and analyzing the voltage to determine whether or not the system is grounded; A control unit for receiving a determination result of the ground fault detection unit and generating and outputting a control signal and an alarm signal for selectively stopping the system in response to a ground fault of the system; And a monitoring unit connected to the control unit through a wired or wireless communication network and receiving an alarm signal output from the control unit and displaying the alarm signal.

Description

Technical Field [0001] The present invention relates to a photovoltaic system having a storage function with a ground fault detection function,

The present invention relates to a power saving function having a ground fault detection function capable of detecting a ground fault by constituting a simple detection circuit between a ground and three-phase systems R, S, T without any additional equipment such as an image transformer (GPT) or ground fault relay (OVGR) And more particularly to a solar power generation system.

Recently, natural disasters have been experienced all over the world due to the abnormal weather phenomenon caused by global warming problem. This is due to the emission of carbon dioxide from the use of fossil fuels, and efforts are being made to reduce carbon dioxide emissions globally.

However, as the industry develops and civilization develops, the amount of energy consumed by mankind increases exponentially. Thus, the demand for and utilization of clean, unlimited alternative energy is increasing. Among these alternative energies, the photovoltaic power generation system using solar energy is an energy that can be supplied almost indefinitely and its use is increasing worldwide.

In recent years, research on photovoltaic energy storage system (PV ESS) with a storage device in a photovoltaic power generation system has been carried out in order to overcome the problem of time limitation of photovoltaic energy and to use it efficiently It is active and the supply is actively progressing.

In the solar power generation system and the photovoltaic energy storage system, if the ground of the solar cell or the system is grounded, the loss or the loss of life due to the failure of the system may lead to an accident.

Conventionally, the ground fault detection method of three-phase alternating current (AC) is performed by using a video transformer (GPT) on a three-phase line as described in Korean Patent Application No. 10-0532925 entitled "Non- Is connected to the primary side Y connection and the secondary side uses the open delta method to detect the ground fault in the ground relay (OVGR).

However, this method uses three video transformers and connects the neutral point of the image transformer to the ground. The transformer-type solar power generation facility has a large capacitance of the solar battery, and leakage current is generated through it .

This leakage current flows through the neutral transformer grounding wire at the primary side of the transformer Y. This causes excessive leakage current to flow into the image transformer, causing the image transformer to break down and the grounding (earth) and R, S, The voltage transformer is damaged due to high harmonics of the voltage of the transformer.

Korean Patent No. 0532925

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above problems and it is an object of the present invention to provide a photovoltaic power generation system capable of simple detection between a ground and a three-phase system R, S and T without additional facilities such as an image transformer (GPT) The present invention is directed to a photovoltaic power generation system having a power storage function with a ground fault detection function capable of detecting a ground fault by constituting a circuit.

According to an aspect of the present invention, there is provided a solar-power-generating photovoltaic generation system having a ground fault detection function, comprising: a solar battery unit including at least one solar cell and generating electric power; A battery unit for storing electric power produced by the solar battery unit; And a solar photovoltaic power generation unit for selectively supplying power stored in the battery unit to a load requiring power supply when the power generated from the solar battery unit is processed and stored in the battery unit, A ground fault detecting unit for detecting in real time a voltage between a line and a ground of the system and a voltage of each phase of the system and analyzing the voltage to determine whether or not the system is grounded; A control unit for receiving a determination result of the ground fault detection unit and generating and outputting a control signal and an alarm signal for selectively stopping the system in response to a ground fault of the system; And a monitoring unit connected to the control unit through a wired or wireless communication network and receiving an alarm signal output from the control unit and displaying the alarm signal.

As one example, the ground fault detection unit includes a voltage sensing module connected to each phase of the three-phase system for detecting the line-to-line voltage and the ground on the three-phase system and the voltages on the lines R, S and T, In the case of a system, if it is detected that the voltage with respect to the ground of any one of the R, S, and T phases of the system is '0V' and the voltage and phase of the other two phases are fluctuated, Is determined to have occurred.

As one example, the ground fault detection unit may include a voltage sensing module connected to each phase of the three-phase system for detecting a line-to-line voltage and ground of the three-phase system and voltages on the systems R, S and T, And a current sensing module connected to the current sensor and detecting a current on the system R, S and T. When the system is a ground system, the voltage with respect to the ground of any one of R, S and T phases of the system is '0V' , It is determined that a ground fault has occurred in the system if it is detected that the sum of the currents on the R, S, and T phases is not equal to 0A but is equal to or greater than the set value.

As an example, the ground fault detecting unit determines that a ground fault or leakage occurs in the solar battery unit when it is detected that the sum of the currents on the R, S, and T phases of the system is not '0A'

As one example, the ground fault detection unit includes a voltage sensing module connected to each phase of the three-phase system for detecting the line-to-line voltage and the ground on the three-phase system and the voltages on the lines R, S and T, In case of the grid, if the voltage on R, S, T of the grid is '0V' reference potential and the sum of positive voltage and negative voltage is not '0V', it is judged that a ground fault occurs in the solar panel to be.

As an example, the ground fault detection unit may sum up the positive voltage value and the negative voltage value in the voltage on the ground and the systems R, S, and T in one cycle unit, and when the summed voltage value has a positive value , And if it is larger than the preset positive DC value, it is determined that a ground fault has occurred in the negative electric line of the solar battery unit.

As an example, the ground fault detection unit may sum up positive voltage values and negative voltage values in the voltage on the ground and the systems R, S, and T in one cycle unit, and when the summed voltage value has a negative value , It is determined that a ground fault has occurred in the positive electric line of the solar battery section if it is smaller than the preset negative DC value.

As described above, the photovoltaic power generation system having a ground fault detection function according to the present invention can detect a system ground fault without an additional detection device such as an image transformer (GPT) and a ground fault relay (OVGR) And it is possible to detect the ground fault of the solar battery unit, so that the cost is reduced. In addition, the solar power generation system installed without a power plant can reduce the risk of ground fault.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram schematically showing a power storage solar power generation system having a ground fault detection function according to the present invention. FIG.
2 is a circuit configuration diagram of a photovoltaic generation energy storage system according to an embodiment of the present invention.
3 is a circuit configuration diagram of a photovoltaic power generation system according to an embodiment of the present invention.
4 is a block diagram of an AC / DC ground fault detection circuit according to an embodiment of the present invention;
5 is a block diagram of a grid AC voltage detection circuit according to an embodiment of the present invention.
6 is a graph showing voltage fluctuation waveforms on ground and system R, S, T on a system R ground fault in a system in accordance with an embodiment of the present invention.
FIG. 7 is a diagram showing ground potentials of a grid voltage according to a ground fault of a solar battery unit in a non-grounded system according to an embodiment of the present invention and a voltage fluctuation waveform on the systems R, S, and T; FIG.
FIG. 8 is a graph showing voltage fluctuation waveforms on the ground and the systems R, S, and T in the partial ground fault of the solar battery part in a non-grounded system according to an embodiment of the present invention;
FIG. 9 is a diagram showing a voltage fluctuation magnified waveform on a ground and a system R, S, T on a partial ground fault of a negative terminal of a solar battery in a non-ground system according to an embodiment of the present invention.
10 is a flowchart showing a ground fault detection method in a DC electric line or an AC electric line of a solar battery unit according to an embodiment of the present invention.

Hereinafter, the structure and operation of the present invention will be described in more detail with reference to the accompanying drawings. In describing the present invention, terms and words used in the present specification and claims are to be construed in accordance with the principles of the present invention, on the basis that the inventor can properly define the concept of a term in order to best explain his invention It should be construed as meaning and concept consistent with the technical idea of.

The present invention is to detect the line-to-line voltage and ground and the voltages on R, S, and T of a system in a conventional three-phase system photovoltaic power generation energy storage system or three-phase system photovoltaic generation system, (Hereinafter referred to as " photovoltaic power generation system ") having a ground fault detection function capable of detecting ground fault detection of the solar battery unit 100. [

As shown in FIG. 1, the solar power generation system includes a solar cell unit 100 including at least one solar cell and generating electric power, a battery unit 100 for storing electric power produced by the solar cell unit 100, (250) and the solar battery unit (100) and stores the same in the battery unit (250). When the power supply or the power supply is insufficient, the battery unit And a photovoltaic generation ESS unit 200 for selectively supplying power.

The solar power generation ESS unit 200 stores the electric power generated by the solar battery unit 100 in the battery unit 250 and temporarily stores the electric power generated by the solar battery unit 100 in the battery unit 250 A configuration for supplying power to a load, and a configuration of a conventional energy storage system (ESS).

For example, as shown in FIG. 2, the solar power generation ESS unit 200 may include an inverter circuit configuration including a PV boosting unit, a battery charging unit, a DC link unit, a DC / AC converter, And a power control software for sensing the power state of the load and the system in real time and selectively supplying power stored in the battery unit to the load in an emergency situation where the power failure or the power supply is insufficient.

1, the photovoltaic power generation system of the present invention detects a line-to-line voltage of a system and a voltage of each phase of a ground and a system in real time and analyzes it to determine whether or not the system is grounded. A control unit 400 for generating and outputting a control signal and an alarm signal for selectively stopping the system in response to a ground fault of the system and receiving a determination result of the ground fault detection unit 300; And a monitoring unit 500 for receiving an alarm signal output from the control unit 400 and displaying the received alarm signal through the wireless communication network. Thus, it is possible to allow a manager to recognize the occurrence of a ground fault in the system, .

The ground fault detection configuration can be applied to the solar power generation system having the energy storage function described in the above embodiment as well as the general solar power generation system shown in FIG. 3. In this case, the solar power generation ESS unit 200, a conventional inverter unit 200a including a PV boost unit, a DC link unit, a DC / AC converter, and the like can be applied.

Hereinafter, the ground fault detection configuration of the present invention will be described in more detail.

4 and 5, the ground fault detection unit 300 may include a detection circuit for measuring ground and system voltages R, S, and T, and a detection circuit for measuring a line-to-line voltage of the system, respectively .

FIG. 4 shows an example of a detection circuit for measuring ground voltage and system R, S, T phase voltages. Referring to FIG. 4, the voltage divider resistor and the amplifier and the control power source match the ground voltage and the 0V voltage of the system voltage at half- And may include an input voltage limiting diode for protecting the control unit 400 and the voltage shift circuit.

Referring to FIG. 5, a voltage shift for matching the ground voltage and the 0V voltage of the system voltage at the half-point of the voltage-dividing resistor, the amplifying unit, and the control power source ) Circuit and an input voltage limiting diode for protecting the control unit 400.

According to an embodiment of the present invention, the ground fault detection unit 300 is connected to each phase of a three-phase system to detect a voltage between a line-to-line system of three-phase systems and ground and a voltage on the systems R, S, ).

If the ground fault detection unit 300 senses that the voltage with respect to the ground of any one of the R, S, and T phases of the system is '0V' and the voltage and phase of the other two phases are fluctuated, It can be determined that a ground fault has occurred in the corresponding phase having the voltage of " 0V "

Specifically, when the system is a non-grounded system (three-phase three-wire system), the voltage on ground, R, S, T represents the phase voltage value of the system voltage in a steady state where no earth fault occurs. However, if a ground fault occurs on one of the R, S, and T phases of the system, the voltage with ground to the ground will appear to be 0V, and the voltage to ground with the other two phases may vary in phase and voltage magnitude.

Accordingly, the ground fault detection unit 300 of the present invention detects voltages on the ground and the systems R, S, and T through (1) to (5) of the following formula (1) can do.

Equations (1) to (3) in Equation (1) indicate that when the system is in a steady state in connection with a non-ground system (three- Voltage.

(4) of Equation (1) represents the sum of voltages on the ground and the systems R, S and T, and Equation (5) Lt; / RTI >

[Equation 1]

(1) V _gr = V _m x sin (wt) + V _lr

(2) V _gs = V _m x sin (wt - 120) + V _ls

_{(3) V gt = V m} × sin (wt + 120 °) + V lt

_{(4) V gr + V gs} + V gt = 0 + V l

(5) V _lr + V _ls + V _lt = V _l

Where _Vgr is the voltage on ground and system R, _Vgs V _gt is the voltage on ground and system T, V _m is the phase voltage, wt is 2πf (f = grid frequency), V _lr , V _ls , V _lt is the leakage due to parasitic capacitance Represents the voltage of each phase that has occurred, and when there is no leakage, V _l has a value of "0".

= 380V의 전압이 검출된다. 그리고 접지와 T상은 위상은 30°앞서게 되면서 전압의 크기는 마찬가지로 220V ×

= 380V의 전압의 검출 된다. 이때 3상 전압의 합은 220 × 3 = 660V의 전압이 나타난다. For example, in a 3-phase line voltage system of 380V in a non-grounded system, when a ground fault occurs in the R phase of the system, the voltage of ground and R phase becomes 0V at 220V and the phase of ground and S phase becomes 30 ° delay, 220V x

= 380V is detected. The ground and the T phase are 30 ° out of phase and the voltage is 220V ×

= 380V is detected. At this time, the sum of the three-phase voltages shows a voltage of 220 × 3 = 660V.

(1), (2), and (3) in the following equation (2) represent the voltage when the system R phase has a complete ground fault.

&Quot; (2) "

(1) V _gr = 0

+ V_ls (2) V _gs = V _m × sin (wt - 150 °) ×

+ V _ls

+ V_{lt (3) V gt = V m} × sin (wt + 150 °) ×

+ V _lt

As described above, the photovoltaic generation system of the present invention can accurately detect the voltage of the phase where the ground fault has occurred. Fig. 6 shows the resultant waveforms through the PSIM (simulation program) simulation of the ground voltage at the time of the system R phase and the voltage waveforms of the systems R, S, and T. Fig.

According to an embodiment of the present invention, when the system of the system is a non-grounded system, the ground fault detection unit 300 detects that the voltage on R, S, and T of the system is a positive voltage and a negative voltage It can be determined that a ground fault has occurred in the solar cell unit 100. [

That is, when the solar battery 100 is grounded in a non-grounded system (three-phase three-wire system), the ground fault current does not flow similarly to the ground fault in the system described above.

In the steady state where no ground fault occurs, the sum of the positive voltage and the negative voltage becomes 0V based on the ground voltage and the voltage on the system R, S, and T as 0V. However, when a ground fault occurs in the solar cell unit 100, the reference voltage is varied by the voltage of the ground and the battery unit 100.

Therefore, the ground fault detecting unit 300 can detect whether a negative voltage or a ground voltage has occurred in the positive voltage of the solar cell unit 100 according to the result of the sum of the negative voltage and the positive voltage.

That is, when a ground fault occurs in a portion of the ground, the potentials of the systems R, S, and T are positive in the portion of the sun electrode unit 100, the reference 0V potential increases by the voltage of the ground and the solar battery unit 100, ) When a ground fault occurs in the negative portion, the reference 0V potential falls to the ground and the negative voltage of the solar battery 100.

7 shows a variation of the reference voltage when a positive voltage or a negative voltage of the solar battery unit 100 occurs. 8 is a result of the potential variation on the ground and the system R, S, T when a ground fault occurs in the negative power line of the solar battery 100 using the PSIM simulation program. 9 shows waveforms obtained by enlarging the potential fluctuations on the ground and the systems R, S, and T, and it can be seen that the reference potential of 0V fluctuates downward with reference to FIG.

The ideal ground and the waveforms of the R, S and T waveforms in Fig. 7 fluctuate as shown in Figs. 8 and 9 in that the wye (Y) capacitors of the ac side EMI filter of the photovoltaic power generation system and the grid lines R, S, T This is because leakage current occurs due to parasitic capacitance between phases.

(1), (2), and (3) in the following Equation (3) show that when a ground fault occurs in the negative electric line of the solar battery 100, the voltage fluctuation between the ground and the R, S, The ground fault detecting unit 300 detects the voltage fluctuation through (1) to (3) of the above-mentioned formula (3) and judges the ground fault in the solar cell unit 100. At this time, when a ground fault occurs in the positive electric line of the solar battery 100, the value of V _dc / 2 has a negative value.

&Quot; (3) "

(1) V _gr = (V _m × sin (wt) + V _lr ) + V _dc / 2

(2) V _gs = (V _m × sin (wt - 120 °) + V _ls + V _dc / 2

(3) V _gt = (V _m × sin (wt + 120 °) + V _lt + V _dc / 2

Where V _dc is the DC link voltage.

In photovoltaic systems, the ground potential of the system at 0V and the same potential point of the DC system are formed at the half voltage point of the DC link. This is because the conversion reference from DC to AC is converted to 0V at a point where the 0V reference of the phase voltage of the system and 1/2 of the DC link DC voltage.

At this time, the magnitude of the ground and the positive voltage or the ground and the negative voltage of the solar battery unit 100 varies depending on the presence or absence of a boost circuit for boosting in the input unit. If there is a boost boost, The voltage of the solar battery unit and the voltage of the DC link unit are equal to one half of the voltage of the solar battery unit 100, respectively.

However, when the system operates and the difference between the DC link voltage and the PV voltage occurs, the point at which 1/2 of the DC link voltage is equal to the ground voltage is based on the DC link voltage due to the inverter operation characteristics.

Accordingly, since the negative voltage of the solar battery unit 100 is common to the solar battery unit 100 and the DC link voltage, the negative voltage of the ground and the solar battery unit 100 represents a half of the DC link voltage, The positive voltage of the ground and the solar battery unit 100 represents a value obtained by subtracting the ground voltage from the output voltage of the solar battery 100 and the negative voltage of the solar battery 100.

For example, when the voltage of the solar battery unit 100 is 500 Vdc and the DC link voltage is 700 V, the negative voltage of the ground and the solar battery unit 100 is -350 V, and the voltage of the ground and the solar battery unit 100 is + 150V voltage appears. Therefore, the ground fault detecting unit 300 of the present invention can detect the voltage fluctuation portion due to the occurrence of the ground fault in consideration of the difference between the positive voltage and the negative voltage.

(1), (2), and (3) in the following equation (4) are obtained when a difference occurs between the output voltage of the solar cell and the DC link voltage, Voltage.

&Quot; (4) "

(1) V _gr = (V _m × sin (wt) + V _lr ) + (V _pv -V _dc / 2)

(2) V _gs = (V _m × sin (wt - 120 °) + V _ls ) + (V _pv - V _dc / 2)

(3) V _gt = (V _m × sin (wt + 120 °) + V _lt ) + (V _pv - V _dc / 2)

When there is no boosting boost in the solar cell unit 100, the DC link voltage and the output voltage of the solar cell are the same.

The ground fault detection unit 400 adds the positive voltage value and the negative voltage value to the ground and the voltages on the systems R, S, and T, and when the summed voltage value has a positive value, It can be determined that a ground fault has occurred in the negative electric line of the solar battery unit 10).

The ground fault detection unit 300 adds the positive voltage value and the negative voltage value to the ground and the voltages on the systems R, S, and T, and when the summed voltage value has a negative value, If it is smaller than the DC value, it can be determined that a ground fault has occurred in the positive electric line of the solar cell unit 100.

It is to be understood that the DC value may be selectively set by the controller 400.

According to an embodiment of the present invention, the ground fault detection unit 300 is connected to each phase of the three-phase system together with the above-described voltage sensing module 310 to detect currents flowing through the system R, S, Module 320. In the case where the system is a ground system, if the voltage with respect to the ground of any one of R, S, and T phases of the system is '0V', or if the voltage of R, S, If it is detected that the sum is not equal to '0A' and is equal to or greater than the set value, it can be determined that a ground fault has occurred in the system.

Specifically, if the system configuration is a ground system (three-phase four-wire type, Y-type neutral point grounding system) When a ground fault occurs, the ground and ground fault voltages are 0V, and ground and other phase voltages can be detected by maintaining the voltage of 220V without phase change due to the effect of the neutral point of the system.

At this time, since the ground fault current flows between the neutral point of the system and the phase, it can be easily detected from the system side. It is also possible to detect the occurrence of a ground fault between the phases R, S and T of the inverter unit 200 during the operation of the system.

However, in this case, since the flow of ground fault current can be monitored more quickly, the sum of the currents on the system R, S, and T of the system is 0A. Therefore, when a ground fault current is generated, And detection of ground fault can be duplicated by voltage.

The ground fault detection unit 300 may determine that a ground fault or leakage occurs in the solar cell unit 100 when it is detected that the sum of the currents on the R, S, and T phases of the system is not '0A'

In other words, when the system configuration is the grounding system (3-phase 4-wire neutral point grounding), unlike the ungrounded system (3-phase 3-wire system) The potentials of the ground and the systems R, S, and T do not fluctuate due to the influence of the neutral point grounding. In this case, a ground fault current is generated. Therefore, when the current value detected through the current sensing module 320 is '0A', it is determined to be normal. If a ground fault occurs in the solar battery 100, It is possible.

Therefore, the ground fault detecting unit 30 of the present invention detects ground fault and leakage current at three-phase output current by applying Equation (5) below.

&Quot; (5) "

I _r + I _s + I _t = I _sum

Where I _sum is the _sum of the three-phase currents. If there is no ground or leakage, the value of I _sum is '0'.

FIG. 10 is a flowchart showing a method of detecting a ground fault in a DC line or an AC electric line of the solar cell unit 100 according to an embodiment of the present invention. When an operation voltage is first input to the solar power generation system, And collects the output voltage Vpv of the solar battery unit 100 and the three-phase system voltages Vr, Vs and Vt and the grid currents Ir, Is and It.

The control unit 400 checks the output voltage of the solar cell unit 100 and the voltage and output current of the system through the information collected by the ground fault detection unit 300 to determine whether the system is in a normal state, If the system is operating.

Since the ground fault detector 300 generates a serious problem in the system if the sum of the collected output currents Isum is greater than the set value, the controller 400 immediately generates and outputs a control signal and an alarm signal, And displays a warning through the monitoring unit 400 in addition to generating a warning.

When the sum of the output currents Isum is normal, the voltages on the ground and the systems R, S, and T are checked. When the AC ground fault occurs, the AC ground fault occurs. A warning is displayed.

Then, when the voltage on the ground and the system R, S, T is normal, the voltages on the ground and the systems R, S and T are respectively read and the sum (Vsgr, Vsgs, Vsgt) of the positive voltage value and the negative voltage value Calculate in one cycle unit. If the sum of the calculated positive voltage value and the negative voltage value is greater than 0, it is compared with the positive DC set value, and if it is in the normal range, the operation is performed again from the beginning, The detection unit 300 determines that a ground fault has occurred in the negative electric line of the solar battery unit 100. The control unit 400 stops the system and generates an alarm and displays an alarm through the monitoring unit 400 .

If the sum of the positive voltage value and the negative voltage value (Vsgr, Vsgs, Vsgt) is less than '0', it is compared with the negative DC setting value and if it is within the normal range, The ground fault detecting unit 300 determines that a ground fault has occurred in the positive electric line of the solar battery unit 100. The control unit 400 stops the system and generates an alarm and sends an alarm through the monitoring unit 400 Display.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification, but should be defined by the claims.

100: Solar power section 200: Photovoltaic power generation ESS department
250: battery section 300: ground fault detection section
310: voltage sensing module 320: current sensing module
400: control unit 500: monitoring unit

Claims (7)

A solar battery unit comprising at least one solar cell and generating electric power; A battery unit for storing electric power produced by the solar battery unit; And a solar photovoltaic power generation unit for selectively supplying power stored in the battery unit to a load requiring power supply when the power generated from the solar battery unit is processed and stored in the battery unit, 1. A photovoltaic power generation system having a power storage function having a ground fault detection function including:
A ground fault detection unit for detecting in real time the voltage between the line and ground of the system and the voltage of each phase of the system including the voltage shift circuit and the input voltage limiting diode and analyzing the voltage to determine whether or not the system is grounded;
A control unit for receiving a determination result of the ground fault detection unit and generating and outputting a control signal and an alarm signal for selectively stopping the system in response to a ground fault of the system; And
And a monitoring unit connected to the control unit through a wired or wireless communication network and receiving an alarm signal output from the control unit and displaying the alarm signal,
The ground fault detection unit is composed of (1) to (5) in the following equation,
[Mathematical Expression]
(1) V _gr = V _m sin (wt) + V _lr
(2) V _gs = V _m sin (wt - 120) + V _{ls
(3) V gt = V m} × sin (wt + 120 °) + V lt
_{(4) V gr + V gs} + V gt = 0 + V l
(5) V _lr + V _ls + V _lt = V _l
Here, V _gr is the voltage on the ground and the system R, V _gs is the voltage on the ground and the system S, V _gt is the voltage on the ground and the system T, V _m is the voltage, wt is 2πf (f = system frequency), V _lr , V _ls , V _lt represents the voltage of each phase caused by leakage due to the parasitic capacitance, and V _l has a value of " 0 " when leakage does not occur. Photovoltaic power generation system.
The method according to claim 1,
The ground fault detection unit includes:
And a voltage sensing module connected to each phase of the three-phase system for detecting the line-to-line voltage and ground of the three-phase system and the voltages on the systems R, S, T,
If the system is in a non-grounded system, sensing that the voltage to ground on any one of the R, S, and T phases of the system is '0V' and the voltage and phase of the other two phases are varied, And a ground fault is detected in said ground fault detection means.
The method according to claim 1,
The ground fault detection unit includes:
A voltage sensing module connected to each phase of the three-phase system for detecting the line-to-line voltage and ground of the three-phase system and the voltages on the lines R, S and T, and a voltage sensing module connected to each phase of the three- A current sensing module,
If the system is a grounded system, the voltage to ground of any one of the R, S, and T phases of the system is '0V', or the sum of the currents on the R, S, and T phases of the system is not '0A' And when it is detected, judges that a ground fault has occurred in the system.
The method according to claim 1,
The ground fault detection unit includes:
When the sum of the currents on the R, S, and T phases of the system is not '0A' but is greater than a predetermined value, it is determined that a ground fault or leakage occurs in the solar battery section. Power generation system.
The method according to claim 1,
The ground fault detection unit includes:
And a voltage sensing module connected to each phase of the three-phase system for detecting the line-to-line voltage and ground of the three-phase system and the voltages on the systems R, S, T,
If the system is a non-grounded system, if the voltage on the R, S, and T lines of the system is '0V' and the sum of the positive and negative voltages is not '0V' And a ground fault detection function for detecting a ground fault.
6. The method of claim 5,
The ground fault detection unit includes:
The positive voltage value and the negative voltage value in the voltage on the ground and the system R, S, T are summed in one cycle unit, and when the summed voltage value is positive, if it is larger than the predetermined positive DC value, And a ground fault is detected in the negative power line of the solar battery unit.
6. The method of claim 5,
The ground fault detection unit includes:
If the sum of positive and negative voltage values on the ground and the voltages on the system R, S, and T is added in one cycle unit and the summed voltage value is negative, if it is smaller than the predetermined negative DC value And a ground fault is detected in the positive electric line of the solar battery unit.

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