KR101336043B1 - Control circuit for switching an emergency power system with the solar system - Google Patents

Abstract

The present invention relates to a switching control circuit of an emergency power system which has a solar energy generation system capable of automatically supplying or blocking AC power from a distributed power source, which is linked to a system power source, to a load using an inverter command current control algorithm. The present invention is able to support two types of modes, a system-linked power conditioning system (PCS) mode and a demand side management (DSM) mode, at the same time. In the system-linked PCS mode, in case of a power outage in a system power source (100), a solar energy generation system (200), a distributed power source, supplies AC power to a load system, and in order to recover the system power source from the power outage, the supply of AC power generated by the solar energy generation system is blocked for switching to a charging mode. In the DSM mode, the maximum power of the load system is reduced depending on the load conditions and the status of a secondary cell (battery). [Reference numerals] (531) Power quality compensation and load sharing ratio calculator;(532) PLL circuit;(533) Inverter command current generator;(535) PRT current controller;(AA) PWM switching pattern S/W_2 240 S/W_3 250 S/W_1 310 S/W_4 400

Description

Control Circuit for Switching an Emergency Power System with the Solar Power System

The present invention relates to a grid-connected emergency power switching control circuit, and more particularly, it is possible to automatically supply and cut off AC power to a load from a distributed power source connected to the grid power supply by an inverter command current control algorithm in case of a power failure of the grid power supply. It relates to a switching control circuit of an emergency power system having a photovoltaic system.

In recent years, as the power supply stability problem rises again due to the occurrence of nuclear power plants, an emergency power system that connects a distributed power system and a system that locally produces and consumes power has attracted attention.

Distributed power system refers to small-capacity power generation systems such as renewable energy sources such as solar, bio, wind and fuel cells, instead of system power sources with large-scale power generation such as nuclear power, thermal power, and hydropower.

In the past, the system linkage to the distribution lines of the power generation facilities installed in the consumer market mainly used internal combustion engines, but recently, in the implementation of the Renewables Protfolio Standard (RPS) on the use of new energy by electricity providers. As a result, small-scale power generation facilities using wind power and solar power are rapidly increasing. In addition, in the specific area called the micro grid, the power plant installer himself installs the self-propelled line and connects a plurality of power generation facilities to the self-propelled line to create a new power plant that is connected to the grid power used between the self-propelled lines and related patent technology. Are being developed.

For example, Korean Patent Publication No. 10-1208725 discloses a photovoltaic power generation system. This patent technology detects and controls the phase between the stand-alone power generation system and the commercial power supply when the independent power generation system using solar power selectively switches to the commercial power supply, thereby preventing damages to the power supply and the load during switching. However, it cannot be prepared in case of power failure of the grid power supply (see FIG. 1A).

In addition, in the multi-function power supply system that integrates and controls the solar power generation and the storage battery and the commercial power supply of the Patent Publication No. 10-1139476, 'Synchronous transfer switch 520 is electrically connected to the secondary side of the transformer 500 commercial power It is to be synchronized to the commercial power supply uninterrupted at the time of power failure recovery (see (b) of Figure 1).

However, this patent technology is insufficient for the failure due to the phase difference during the power conversion between the system power supply and distributed power supply due to the power failure recovery, and there is a fear that the operator may suffer an electric shock during the power failure recovery.

When the solar cell module generating DC power is connected to the grid power supply, it is necessary to distribute the photovoltaic power generation system, which is a distributed power supply, to the grid power supply because it needs to be superimposed on the AC power from the grid power supply. . To connect the photovoltaic system to the grid power supply, a power conditioner (PCS) converts the direct current output of the photovoltaic system into alternating current power and tunes its frequency or voltage to the power from the grid power supply. It is used. The output line of AC power from the power conditioner is connected to the distribution line of the distribution panel formed in the consumer's house which consumes power so that the AC power from the photovoltaic system and the AC power from the grid power supply can be supplied to the load together. shall.

However, when the distributed power source is linked to the system power source as described above, the power generated from the distributed power source should not adversely affect the system power source. In order to prevent adverse effects on the system power supply, it is indicated in the Standard Design Guideline for Renewable Energy Facility System of General Buildings and the Distribution Linkage Technology Guideline of Korea Electric Power Corporation. In particular, in the event of a power failure in the system power supply, it is prescribed to separate the distributed power supply from the system power supply.

In other words, if a distributed power source such as a photovoltaic system is operating normally in the event of a power outage, the distributed power supply line of the grid power supply may not be supplied until the distributed power supply is restored before the power failure of the grid power supply that already has a power failure. If distributed power is supplied to the power distribution network, the power failure accident recovery worker may suffer an electric shock. In addition, if power is supplied from the distributed power supply to the system power supply side, it is difficult to find the cause of the power failure accident on the system power supply side. When the system power is returned to the normal state ③ On the system power supply side, there is a risk of failure due to a mismatch between the phase of the AC power and the phase on the distribution line side due to the distributed power supply.

Therefore, the present invention proposes a switching control circuit of an emergency power system having a completely new photovoltaic system that can solve all the above problems while using a grid power supply and a distributed power source through an original inverter command current control algorithm.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and in particular, a power conditioner and a switching control circuit for intermitting a plurality of switching circuits connecting a distributed power source to a system power source are switched by a pre-programmed inverter command current control algorithm. It is an object of the present invention to provide a switching control circuit of an emergency power system having a photovoltaic system that can automatically supply and cut off AC power from a distributed power source connected to the grid power supply when the grid power supply is out of power. It is done.

(여기서, P_L은 부하 유효전력, P_bat는 배터리 전력)이고,
최종적인 인버터 지령전류(I_c ^*)는, 상기 부하전류(I_L)와 모드에 따른 상기 계통전류(I_g ^*)의 차에 의해 구해지는

(여기서, Q_L은 부하무효전력)이며,
상기 계통전류(I_g ^*)와 최종적인 인버터 지령전류(I_c ^*)를 구한 식을 통해 전류 제어형 인버터의 전류를 제어함으로써 계통전류의 고조파를 상쇄시키고 역률을 항상 1로 유지 시킬 수 있으며, 부하조건 및 배터리의 상태에 따라 전력을 공급 또는 저장할 수 있도록 하는 것을 특징으로 하는 태양광발전 시스템을 갖는 비상 전원 시스템의 스위칭 제어회로를 제공한다.According to a feature of the present invention for achieving the above object, in the switching control circuit of the emergency power supply system having a photovoltaic power generation system 200, the switching control circuit, the power supplied to the distribution panel 300 (V _g , I _L ) and the third switching circuit 250 and the signal of the grid voltage (V _g ) and the load current (I _L ) detected by the first switching circuit 310 and the emergency switching circuit 400 for switching (I _L ) A power quality compensation and load sharing calculator 531 for calculating and processing the battery power V _bat and I _bat of the charge / discharge system 260 detected by the power output unit) and outputting the grid current I _g ^* ; A phase-locked loop circuit 532 for detecting a phase and a magnitude of the grid voltage V _g ; Phase information (sinwt ^* ) synchronized with the grid voltage (V _g ) detected by the PLL circuit 532, load current (I _L ) and load conditions (V _g ,) for improving the harmonics and power factor of the grid for the distribution panel. I _L ) and the command current (I _c ^* ) of the inverter by receiving the grid current (I _g ^* ) calculated by the power quality compensation and load sharing calculator (531) according to the power (V _bat , I _bat ) state of the battery. An inverter command current generator 533 to generate C); A summer Σ for adding up the inverter command current I _c ^* generated by the inverter command current generator 533 and the inverter current I _c that supplies only the reactive current I _Lq = I _cq required by the load. , 534); A polarized ramp time (PRT) current controller (535) for correcting an error signal (I _err ) between the command current (I _c ^* ) and the actual current of the inverter; In the event of a power outage of the system power supply 100, a power conversion system (PCS) mode function for supplying AC power to the distribution panel 300 through the photovoltaic system 200 and load conditions By using the battery of the charging and discharging system 260 to simultaneously perform a load management (Demand Side Management, DSM) mode function to supply or store power to the distribution panel 300,
The system current I _g ^* required to simultaneously perform the PCS and DSM modes is

Where P _L is the load active power and P _bat is the battery power.
The final inverter command current I _c ^* is obtained by the difference between the load current I _L and the grid current I _g ^* depending on the mode.

Where Q _L is the load reactive power,
The harmonics of the grid current can be canceled by maintaining the grid current (I _g ^* ) and the final inverter command current (I _c ^* ) by controlling the current. It provides a switching control circuit of an emergency power system having a photovoltaic system characterized in that it is possible to supply or store power in accordance with the conditions and conditions of the battery.

According to another embodiment of the present invention, the generation of the switching PWM pattern according to the inverter command current (I _c ^* ), the phase and magnitude of the grid voltage (V _g ), load conditions (V _g , I _L ) and the battery After calculating the active power of the system by measuring the power (V _bat , I _bat ), and calculates the grid current (I _g ^* ) for the active power control by using the equation obtained the grid current (I _g ^* ), The final inverter command current I _c ^{* with} the calculated grid current I _g ^* and the measured load current I _L and the phase information sinωt ^* synchronized with the grid voltage by the PLL circuit 532. The pulse width modulation (PWM) switching pattern is generated to follow the final inverter command current I _c ^* obtained by the following equation.

The present invention as described above is configured so that the power conditioner and the switching control circuit for intermitting a plurality of switching circuits for linking the distributed power source to the system power source is controlled by a pre-programmed inverter command current control algorithm,

In the event of a power outage of the grid power supply, the photovoltaic system automatically supplies AC power to the load grid, and in the event of a power outage recovery of the grid power supply automatically cuts off the supply of alternating power generated by the photovoltaic system. On-grid Power Conditioning System (PCS) mode for switching to charging mode and load management to reduce the maximum power of the load system depending on load conditions and secondary battery (battery) status. There is a unique effect that can simultaneously perform the Management (DSM) mode function.

1 is a view showing an emergency power system according to the prior art
2 is a block diagram of an emergency power system having a photovoltaic system according to a preferred embodiment of the present invention.
3 is a block diagram of a photovoltaic system for an emergency power system having a photovoltaic system according to a preferred embodiment of the present invention.
4 is a block diagram of a distribution panel for an emergency power system having a photovoltaic system according to a preferred embodiment of the present invention.
5 is a block diagram of a control circuit system for an emergency power system having a photovoltaic system according to a preferred embodiment of the present invention.
FIG. 6 is a diagram illustrating a vector diagram of a system analysis and control algorithm for a switching control circuit of an emergency power system having a photovoltaic system according to a preferred embodiment of the present invention.
7 is a block diagram of a switching control circuit for an emergency power system having a photovoltaic system according to a preferred embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. First, in adding reference numerals to the constituent elements of the drawings, it is to be noted that the same constituent elements are denoted by the same reference numerals even if they are shown in different drawings. In the following description of the present invention, a detailed description of known configurations and functions will be omitted when it is determined that the gist of the present invention may be obscured.

2 to 7, the emergency power system having a photovoltaic power generation system of the present invention is a system power supply 100, photovoltaic power generation system 200, distribution panel 300, emergency switching circuit 400, control circuit Comprising a system 500 and a load 600, the solar power generation system 200 causes the photovoltaic system 200 to the power distribution panel 300 without voltage fluctuations or leakage of high frequency current in the event of a power failure of the grid power supply 100 supplied from KEPCO. To control the supply and shut down automatically.

Referring to FIG. 2, the grid power supply 100 refers to a power line before a bus that sends power supplied from a distribution substation to a building of a power consumer, and is not described herein.

2 and 3, the photovoltaic system 200 has a solar cell module 210 including a solar cell and an electrical circuit for converting solar radiation into electrical energy. The solar cell module 210 is determined in consideration of the normal load 610 and the preload 620.

In addition, the photovoltaic power generation system 200 stably converts the inverters 221 and 222 for converting DC power generated from the solar cell module 210 into AC power and the converted AC power (100 to 220V) to the distribution panel 300. When a plurality of power conditioners (Power Conditioners, PCS, 220a, 220b) and the system power supply 100 are interrupted, the AC power generated in the photovoltaic system 200 is supplied to the distribution panel on the load side. 300 and a power conversion system 230 having second and third switching circuits 240 and 250 having an opening and closing function to cut off power supplied from the photovoltaic system when the power failure of the grid power supply is normally restored. Has

Here, the plurality of power conditioners 220a and 220b built in the power conversion system 230 are connected to the generated direct current from the solar cell module 210 so as to be connected to the AC power of the grid power source input through the distribution panel 300. As a means for converting and controlling the power into AC power, when the power supply on the grid power supply 100 is detected due to a power failure, the distributed power supply (or the power generation of the photovoltaic system) is quickly stopped. If necessary, the distributed power supply can be separated from the distribution line. When the distributed power source generated in the photovoltaic system 200 is linked to the system power source 100, power generated from the distributed power source should not adversely affect the system power source side. In particular, if the distributed power supply is operating in the event of a power outage on the system power supply side, the distribution line or the distribution network on the system power supply side, which should not be charged originally because of a power outage, is charged by the distributed power supply. This is because when an electric shock accident or the system power supply returns to a normal state, a failure may occur due to a mismatch between the phase of the AC power on the power supply side and the phase on the distribution line side. In addition, when electric power is supplied from the distributed power supply to the system power supply side, it is difficult to search for a fault occurrence position in the system power supply. In the event of a power failure on the grid power supply, the power conditioner of the distributed power supply quickly stops the operation of the distributed power supply when it detects that the power supply on the grid power supply is interrupted, and if necessary, switches the distributed power supply from the distribution line to a mechanical switch or the like. It is configured to be separated by a breaker.

Therefore, in the preferred embodiment of the present invention, the first / second power conditioners 220a and 220b and the second / second to prevent the adverse effect on the system power supply by the power generated from the distributed power supply in case of power failure of the system power supply The power conversion system 230 having three switching circuits 240 and 250 and the control circuit system 500 for intermittently controlling the power conversion system and the first switching circuit 310 and the emergency switching circuit 400 are specially designed and applied. Detailed description thereof will be provided later.

In addition, the photovoltaic system 200 according to the embodiment of the present invention includes a charge / discharge system 260 for charging and discharging a DC power generated in the solar cell module 210 to a battery.

As the secondary battery (battery) incorporated in the charge / discharge system 260, a lithium ion battery, a nickel hydride battery, a lead acid battery, or the like is used. The secondary battery (battery) is controlled to be charged and discharged by the power conditioner 220 of the power conversion system 230 so as to be above a predetermined charge level. In the embodiment of the present invention, the predetermined charge level is an ideal charge level that can supply all of the power required for the operation of the photovoltaic system 200 from the secondary battery (battery).

Meanwhile, referring to FIGS. 2 and 3, the plurality of power conditioners 220a and 220b according to an exemplary embodiment of the present invention may provide direct current power generated by the solar cell module 210 of the photovoltaic system 200. A first power conditioner (PCS, 220a) is provided to convert the AC power to the distribution panel 300, the first power conditioner (PCS, 220a), the solar power in the event of power failure of the system power supply (100) At the same time as the operation of the power generation system 200 is stopped, an interruption detection signal is transmitted to the breaker S / W ₂ of the second switching circuit 240 of the power conversion system 230 and the breaker S of the emergency switching circuit 400. / W ₄ ) to keep the breaker off.

In addition, the plurality of power conditioners 220a and 220b according to an exemplary embodiment of the present invention convert the DC power discharged from the battery of the charge / discharge system 260 into AC power and supply the AC power to the distribution panel 300. And a second power conditioner (PCS, 220b), wherein the second power conditioner (220b) is the charge / discharge system when the breaker (S / W ₂ ) of the second switching circuit 240 is in an open state. a shutter (S / W ₄₎ of the securing driving power from a secondary cell (battery) of 260, the third switching circuit 250, circuit breaker (S / W _3), and emergency switching circuit 400 of the lungs ( On) so that the secondary battery (battery) of the charging / discharging system 260 supplies AC power to the distribution panel 300, or the circuit breaker S / W ₃ of the third switching circuit 250 open (Off) and said first circuit breaker of the second switching circuit _{(240) (S / W 2} ) is closed by the photovoltaic power generation (on) cis Causing (200) such that AC electric power is supplied to the distribution panel 300.

2 and 4, the distribution panel 300 is a means used to link the grid power supply 100 and the photovoltaic power generation system 200 and supply power to the load, and the grid power supply 100. A plurality of branch overcurrents are provided between the first switching circuit 310 and the bus and the normal load 610 and the preload 620 installed between the power distribution line connected to the bus line and the bus line to which the output of the solar power generation system 200 is connected. The circuit breakers 320 and 330 are comprised.

Here, the distribution switchboard includes a branch overcurrent circuit breaker mounted on a substrate, and may include a branch switch, a main overcurrent circuit breaker, a main switch, a supply and demand meter, and a current limiter. The branch overcurrent breaker is the first switch from the power supply side, mounted on the load side at the branches of the trunk and branch circuits, and has the ability to break the overcurrent. A box containing a distribution panel is called a cabinet, and in a broad sense it is also called a distribution panel including a cabinet. Depending on the type of facility, it is classified into an exposed type, a buried type, a semi-filled type, a rainproof type, and a spray type.

Meanwhile, referring to FIGS. 2 and 4, the first switching circuit 310 according to the embodiment of the present invention is configured to automatically disconnect the bus bar from the grid power supply side.

In other words, when the control circuit system 500 detects a power failure in the system power supply 100, the power distribution board 300 responds to a signal transmitted from the switching control circuit 530 of the control circuit system 500. A breaker S / W ₁ of the first switching circuit 310 to be opened according to the above, and an emergency switching circuit driven according to a signal transmitted from the switching control circuit 530 of the control circuit system 500 ( It is configured to be capable of supplying an AC power obtained by converting the DC power output by the secondary battery (battery) which is connected to 400 and built in the charge / discharge system 260 of the photovoltaic power generation system 200 to the bus. When the power failure of the grid power supply is restored, the breaker S / W ₄ of the emergency switching circuit 400 is opened by the transmission signal from the switching control circuit 530 of the control circuit system 500, and then the first switching is performed. The breaker S / W ₁ of the circuit 310 is closed.

Referring back to FIG. 2, the emergency switching circuit 400 is an emergency switching circuit for supplying distributed power to the bus bar of the distribution panel 300 at the time of power failure of the system power supply 100. DC power generated and stored in is converted according to the control command of the power conversion system 230 and the control circuit system 500 is a means for automatically supplying and cutting off the AC power to the distribution panel (300).

2 and 5, the control circuit system 500, as a means for controlling the entire emergency power system according to a preferred embodiment of the present invention, the solar cell module 210 of the photovoltaic system 200 Has an overcharge (overcharge / discharge) voltage / current detector 510 for preventing overcharge in the charge / discharge system 260.

The signal detected by the overcharge (overcharge and discharge) voltage / current detector 510 is transmitted to the switching control circuit 530 of the control circuit system 500 to be processed and again overcharged (overcharge / discharge) by the power conditioner 220. ) can be by-breaker (S / W ₃₎ the increase or or there by pass (by-pass to ground during overcharge opening and closing of the delivery by the third switching circuit 250, a detection signal) to prevent excessive charging (gwachung and discharging).

In addition, the control circuit system 500 includes a voltage / current detector 520 for detecting an abnormal state of AC power supplied to the distribution panel 300 through the first switching circuit 310 and the emergency switching circuit 400. Equipped.

In addition, the control circuit system 500, the breaker of the first / second / third switching circuit (310, 240, 250) and the emergency switching circuit 400 according to the power failure of the emergency power system and the system power supply 100 ( S / W ₁ , S / W ₂ , S / W ₃ , S / W ₄ ) and a switching control circuit 530 for controlling the power conditioner 220.

Here, the voltage / current detector 520 and the switching control circuit 530 according to an embodiment of the present invention, a trip coil of the first switching circuit 310 in the event of a power failure of the system power supply 100. The detected voltage / current is transmitted to the switching control circuit 530 of the control circuit system 500. The switching control circuit is computed by a control algorithm that is programmed in advance, and then the first switching circuit. The control commands are sent to the 310 and the emergency switching circuit 400 and the power conversion system 230, and the breakers S / W ₁ , S / W ₂ , S / W ₃ , S / W ₄ are controlled commands. Each switch is opened and closed.

Referring to the operation of the control circuit system 500 according to an embodiment of the present invention in more detail as follows.

First, in the case of power failure of the system power supply 100, the voltage and current signals detected by the first switching circuit 310 are sent to the power conversion system 230 to break the breakers S of the second and third switching circuits 240 and 250. / W ₂ , S / W ₃ ) and the circuit breaker S / W ₄ of the emergency switching circuit 400 are closed (On) to supply AC power to the distribution panel 300.

In addition, when restoring the power failure of the system power supply 100, the voltage and current signals detected by the first switching circuit 310 are sent to the power conversion system 230 to provide the second and third switching circuits 240 and 250. The breakers S / W ₂ and S / W ₃ and the breakers S / W ₄ of the emergency switching circuit 400 are opened to cut off the AC power supplied to the distribution panel 300.

In other words, at the time of power failure of the system power supply 100, after detecting the voltage and current signals of the first switching circuit 310, the detected power failure signal is transferred to the first power conditioner 220a of the power conversion system 230. The first and second power conditioners of the power conversion system 230 may be stopped by sending the second / third switching circuits 240 and 250 and the emergency switching circuit 400 to stop the operation of the photovoltaic system 200. 220a) interrupts the breaker S / W ₂ of the second switching circuit 240 in an open state.

In addition, the second power conditioner 220b of the power conversion system 230 secures driving power from the secondary battery (battery) of the charging / discharging system 260 to break the breaker S / of the third switching circuit 250. W ₃ ) and the breaker (S / W ₄ ) of the emergency switching circuit 400 are closed (On) to cause the secondary battery (battery) of the charge / discharge system 260 to supply AC power to the distribution panel 300. The circuit breaker S / W ₃ of the third switching circuit 250 is turned off, and the circuit breaker S / W ₂ of the second switching circuit 240 is closed. The photovoltaic system 200 causes AC power to be supplied to the distribution panel 300.

In addition, during normal recovery of the system power supply 100, after detecting the voltage and current signals of the first switching circuit 310, the detected normal signal is converted into the first power conditioner 220a of the power conversion system 230. And the second and third switching circuits 240 and 250 and the emergency switching circuit 400 interlocked with each other to operate the photovoltaic system 200 and at the same time the circuit breaker S / of the second switching circuit 240. W ₂ ) and the circuit breaker (S / W ₃ ) of the third switching circuit 250 are closed (On) so that charging is performed in the secondary battery (battery) of the charge / discharge system 260, and at the same time, the emergency switching The circuit breaker S / W ₄ of the circuit 400 is opened to cut off the AC power supplied to the distribution panel 300 so that the system power is supplied to the load 600 through the bus bar of the distribution panel 300. .

The control algorithm of the present invention allows the photovoltaic system 200 to immediately supply AC power to the load system in the event of a power failure of the grid power supply 100 and the distribution of the photovoltaic system 200 during power failure recovery. The maximum power of the load system is reduced depending on the load condition and the state of the secondary battery (battery) of the charging / discharging system 260 and the grid-connected power conditioning system (PCS) mode for immediately shutting off the power. And a control circuit system 500 to perform a demand side management (DSM) mode function.

Referring again to FIGS. 2 and 4, the load 600 is not only at the normal load 610 and the system power supply that need only be supplied with power when the system power supply 100 is operated, but also at the time of power failure of the system power supply. In addition, the electric power consumption which has two types of the preliminary load 620 to which electric power should be supplied is the load in a house.

The normal load 610 is connected to the bus through the branch overcurrent breaker 320, and the preload 620 is connected to the bus through the branch overcurrent breaker 330. In the emergency power system according to the embodiment of the present invention, the AC power from the system power supply 100 and the AC power from the photovoltaic power generation system 200 are applied to the respective loads 610 and 620 through distribution lines in the same house through the distribution panel 300. It is to be supplied.

In addition, when the secondary battery (battery) is in the charged state, the AC power output from the secondary battery (battery) and converted by the power conditioner 220 into direct current according to the power consumption situation on the load side is also used for each load ( 610, 620 to be supplied.

However, since the solar cell module 210 itself has a limitation in responding to sudden changes in load, when the load increases rapidly, the solar cell module 210 is supplied to the load through a charged secondary battery (battery), and when the load decreases, the secondary battery ( Battery) enables efficient operation of the emergency power system when the system power is in a normal state.

Next will be described in detail with respect to the switching control circuit of the emergency power system having a photovoltaic system according to a preferred embodiment of the present invention.

Key technical solutions of the switching control circuit of the emergency power system having a photovoltaic system according to an embodiment of the present invention, the power quality compensation and load sharing calculator 531, PLL (Phase-Locked Loop Circuit, 532) , Inverter command current generator 533, summer (Σ, 534), and PRT (Polarized Ramp Time) current controller 535, which is distributed power by inverter command current algorithm in case of power failure of system power supply 100. It is characterized by allowing the solar power generation system 200 to automatically supply and cut off AC power to the load.

First, a system analysis and control algorithm for an emergency power switching control circuit having a photovoltaic system according to an embodiment of the present invention will be described in detail with reference to FIG. 6.

Basically, the load sharing control is performed while performing the PCS function to improve the quality of the system, which can be classified into a power conditioning system (PCS) and a demand side management (DSM) mode.

In addition, the DSM mode is to reduce the maximum power of the system. Looking at the vector diagram according to the operation mode, the discharge mode for supplying power to the load (refer to (b-1) of FIG. 6) and storing the power in the battery It may be classified into a charging mode (see FIG. 6B).

In general, the current controlled inverter can be interpreted as an AC current source, and the grid voltage (V _g ), the load voltage (V _L ), and the inverter voltage (V _c ) are connected in parallel in the same size and phase, and have the same load current. (I _L ) is the sum of the grid current (I _g ) and the inverter current (I _c ), as shown in Equation (1).

(1)

(One)

On the other hand, when the grid current (I _g ) is expressed as the active ingredient and the reactive component is as shown in the following formula (2).

(2)

(2)

Here, the subscript p is an active ingredient of each current, and the subscript q represents an inactive component of each current.

)만을 공급해야 하므로 계통전류 I_g는 부하에서 요구하는 유효전류(

) 성분만을 포함하며, 인버터 전류 I_c는 부하에서 요구하는 무효전류(

) 성분만을 공급한다. (A) As in PCS mode, always grid current (I _g) to improve the quality of the system of Figure 6 is valid, the current (

Grid current I _g is the effective current required by the load.

) And the inverter current I _c is the reactive current (

) Only the ingredients are supplied.

Therefore, the grid current I _g can always supply only the active power component regardless of the load condition and can be obtained as follows.

(3)

(3)

Therefore, the current I _c ^* required for the current controlled inverter to perform the PCS function for improving the harmonics and power factor of the system is expressed as Equation (4).

(4)

(4)

은 부하유효전력이며

은 부하무효전력이다.here,

Is the load effective power

Is the load reactive power.

In addition, as shown in (b) of FIG. 6, in the DSM mode, power may be supplied or stored using a battery according to a load condition, and the PCS function may be simultaneously performed.

을 일정부분 감소시킬 수 있으며 무효전력은 인버터에서 전부 부담하게 된다. 여기서 상기 P_bat는 배터리 전력이다.6B is a mode for discharging the battery power, so that the battery shares a part of the load active power components, so that the power of the system required at the peak load is increased.

Can be reduced to a certain degree, and the reactive power is borne by the inverter. Where P _bat is battery power.

Therefore, the system currents required to simultaneously perform the PCS and the DSM can be obtained from Equation (5).

(5)

(5)

In addition, the final inverter command current I _c ^* can be obtained by the difference between the load current I _L and the grid current I _g ^* that satisfies Equation (3) or Equation (5) according to the mode. )

(6)

(6)

Therefore, by controlling the current of the current controlled inverter, the harmonics of the grid current can be canceled and the power factor can always be maintained at 1, and the power can be supplied or stored according to the load condition and the state of the battery.

Next, a control algorithm for an emergency power switching control circuit having a photovoltaic system according to an embodiment of the present invention will be described in detail with reference to FIG. 7.

The control algorithm of the system according to an embodiment of the present invention generates the inverter command current (I _c ^* ) according to the load condition and the state of the battery to perform the system control algorithm and PCS and DSM functions, and the actual inverter current to the command current (I). _c ^* ) can be classified into a switching control algorithm that generates a PWM switching pattern to follow.

In addition, the information required by the grid control algorithm is the phase and magnitude of the grid voltage (V _g ), the load conditions (V _g , I _L ) and the power of the battery (V _bat , I _bat ). Calculate the active power of the system using these measured values, calculate the grid current (I _g ^* ) for active power control using Equation (5) according to the load condition and battery condition, and calculate the calculated grid current The final inverter by Equation (6) with (I _g ^* ) and the measured load current (I _L ) and the phase information (sinωt ^* ) synchronized with the grid voltage (V _g ) by the PLL circuit 532. Generates the command current I _c ^* . Accordingly, a switching control algorithm for generating a PWM (Pulse Width Modulation) switching pattern to follow the inverter command current is performed.

In general, the hysteresis technique is used as a current control algorithm that generates a PWM switching pattern using only the error signal (I _err ) between the actual current and the inverter command current. This has the advantage that the hardware can be easily and easily implemented. It has disadvantages such as problems.

Accordingly, the embodiment of the present invention uses a PRT (Polarized Ramp Time) current controller that can control the current of the inverter robustly even in response to the fast response characteristics and the variation of the inverter DC input voltage, which are advantages of the current control.

2 and 7, the power quality compensation and load sharing calculator 531 calculates a load sharing ratio by compensating power quality supplied from the grid power supply system 100 and the photovoltaic system 200 which is a distributed power supply. a means for processing, the power supplied to the distribution panel (300), (V _g, I _L) the switching (switching), the first switching circuit 310, and a grid voltage (V _g detected in the emergency switching circuit 400 for ) And the system current (I _g ^* ) by calculating the signal for the load current (I _L ) and the battery power (V _bat , I _bat ) of the charge / discharge system 260 detected by the third switching circuit 250. Outputs

The phase-locked loop circuit 532 is a means for detecting the phase and magnitude of the grid voltage V _g supplied to the distribution panel, and the phase difference detected by the phase comparator is converted into a DC voltage through a low pass filter. After inputting to the voltage controlled oscillator (VCO), there is an oscillating circuit including a varactor in the VCO, when the DC voltage corresponding to the phase difference is inputted, the capacity of the capacitor of the varactor changes and the LC resonance circuit Since the oscillation frequency is changed by the furnace, an output frequency fixed in phase of the input reference frequency is generated.

In other words, the phase difference (phase and magnitude) of the input signal and the output signal of the grid voltage (V _g ) with respect to the power supplied to the distribution panel 300 is detected, and the output signal generator and the phase are controlled by a voltage proportional thereto. In other words, it is a circuit that makes the phase of the output signal equal to the phase of the input signal.

The inverter command current generator 533 is a means for generating a command value for performing the information commanded by the switching control circuit 530 in the power conditioner 220, and the system voltage detected by the PLL circuit 532. Load current I controlled by power conditioner 220 of power conversion system 230 and PCS for improving harmonics and power factor of the grid for phase information sinwt ^* and the distribution panel 300 synchronized with (V _g ) _L ) and the load conditions (V _g , I _L ) for the distribution panel and the power (V _bat , I _bat ) state of the secondary battery (battery) built in the charging / discharging system 260. The load factor calculator 531 receives the calculated grid current I _g ^* and generates a command current I _c ^* of the inverter.

In addition, the summer (Σ, 534) has, as a means for adding the drive command current (I _c ^*) and the inverter current (I _c) to correct an error signal from the PRT current controller 535, the drive command current generator Inverter currents for inverters 221 and 222 of power conversion system 230 supplying only the inverter command current I _c ^* generated at 533 and the reactive current I _Lq = I _cq required by load 600. Summing up (I _c ).

In addition, the PRT current controller 535 is a means for correcting an error signal I _err generated between the command current I _c ^* and the actual current of the inverter, and the PRT current applied to the present invention. The controller 535 may robustly control the current of the inverter even in response to the fast response characteristic and the variation of the inverter DC input voltage, which are advantages of the current control.

As such, the emergency power switching control circuit having the photovoltaic power generation system according to the embodiment of the present invention is distributed to the distribution panel 300 through the photovoltaic power generation system 200 which is the distributed power supply in the event of a power failure of the system power supply 100. Supply AC power to the distribution panel 300 using a power conversion system (PCS) mode function to supply AC power and a secondary battery (battery) of the charge / discharge system 260 according to load conditions. Or to perform a demand side management (DSM) mode function to save or save.

In addition, the grid current (I _g ^* ) and inverter command current (I _c ^* ) for simultaneously performing the power conversion system (PCS) mode and load management (DSM) mode according to an embodiment of the present invention, the equation (5) Equation (6) and (6), through the equations (5) and (6), it is possible to control the current-controlled inverter for the inverters 221 and 222 of the photovoltaic system 200 which is the distributed power supply, Supply power to the distribution panel 300 according to harmonic cancellation and power factor improvement, load conditions and battery conditions, or DC to a secondary battery (battery) embedded in the charge / discharge system 260 of the photovoltaic system 200. Make sure to save power.

In addition, in the embodiment of the present invention, the switching PWM pattern generation method according to the inverter command current (I _c ^* ), the phase and magnitude of the grid voltage (V _g ), the load conditions (V _g , I _L ) and the battery After calculating the active power of the system by measuring the power (V _bat , I _bat ), using the above equation (6) to calculate the grid current (I _g ^* ) for the active power control.

In addition, the calculated system current I _g ^* , the measured load current I _L , and the phase information sinωt ^* synchronized with the system voltage V _g by the PLL circuit 532 are expressed by Equation (6). Generate a PWM (Pulse Width Modulation) switching pattern to follow the final inverter command current (I _c ^* ).

Referring to Figures 2 to 7, the operation of the switching control circuit of the emergency power system having a photovoltaic system according to a preferred embodiment of the present invention will be described in detail.

The present invention is pre-programmed in the power conditioner 220 and the switching control circuit 530 to control the plurality of switching circuits (240, 250, 310, 400) that connects the photovoltaic system (200) which is a distributed power source to the grid power supply (100) By configuring the plurality of switching circuits to be controlled by an inverter command current control algorithm, in the event of a power failure of the system power supply 100, the photovoltaic power generation system 200, which is a distributed power supply, automatically supplies AC power to the load system. In addition, in the event of a power failure recovery of the grid power supply, a grid-connected power conversion system (Power Conditioning System) to automatically switch off the supply of AC power generated in the photovoltaic power generation system 200 which is a distributed power supply to a charging mode, Demand Side Man to reduce the maximum power of the load system according to PCS) mode, load conditions and secondary battery (battery) status There is a unique feature that can perform agement (DSM) mode function simultaneously.

The foregoing description is merely illustrative of the technical idea of the present invention and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the scope of the present invention but to limit the scope of the technical idea of the present invention. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

100: system power supply 200: solar power generation system
210: solar cell module 220: power conditioner
220a, 220b: a plurality of power conditioners 221,222: inverter
223,224 transformer 230 power conversion system
240: second switching circuit 250: third switching circuit
260: charging and discharging system 300: distribution panel
310: first switching circuit 320, 330: branch overcurrent breaker
400: emergency switching circuit 500: control circuit system
510: overcharge voltage / current detector 520: voltage / current detector
530: switching control circuit
531: Power quality compensation and load sharing calculator
532: PLL circuit 533: inverter command current generator
534: summer 535: PRT current controller
600: Load 610: Normal Load
620: spare load

Claims (3)

In the switching control circuit of an emergency power system having a photovoltaic system (200),
The switching control circuit may include a grid voltage V _g detected by the first switching circuit 310 and the emergency switching circuit 400 for switching power V _g , I _L supplied to the distribution panel 300. ) And the load current (I _L ) and the battery power (V _bat , I _bat ) of the charge / discharge system 260 detected by the third switching circuit 250 to calculate and process the system current (I _g ^* ). An output power quality compensation and load sharing calculator 531;
A phase-locked loop circuit 532 for detecting a phase and a magnitude of the grid voltage V _g ;
Phase information (sinwt ^* ) synchronized with the grid voltage (V _g ) detected by the PLL circuit 532, load current (I _L ) and load conditions (V _g ,) for improving the harmonics and power factor of the grid for the distribution panel. I _L ) and the command current (I _c ^* ) of the inverter by receiving the grid current (I _g ^* ) calculated by the power quality compensation and load sharing calculator (531) according to the power (V _bat , I _bat ) state of the battery. An inverter command current generator 533 to generate C);
A summer Σ for adding up the inverter command current I _c ^* generated by the inverter command current generator 533 and the inverter current I _c that supplies only the reactive current I _Lq = I _cq required by the load. , 534);
A polarized ramp time (PRT) current controller (535) for correcting an error signal (I _err ) between the command current (I _c ^* ) and the actual current of the inverter;
In the event of a power outage of the system power supply 100, a power conversion system (PCS) mode function for supplying AC power to the distribution panel 300 through the photovoltaic system 200 and load conditions By using the battery of the charging and discharging system 260 to simultaneously perform a load management (Demand Side Management, DSM) mode function to supply or store power to the distribution panel 300,
The system current I _g ^* required to simultaneously perform the PCS and DSM modes is

Where P _L is the load active power and P _bat is the battery power.
The final inverter command current I _c ^* is obtained by the difference between the load current I _L and the grid current I _g ^* depending on the mode.

Where Q _L is the load reactive power,
The harmonics of the grid current can be canceled and the power factor can be always maintained at 1 by controlling the current of the current controlled inverter through the formula of the grid current (I _g ^* ) and the final inverter command current (I _c ^* ). Switching control circuit of an emergency power system having a photovoltaic system, characterized in that it is possible to supply or store power in accordance with the conditions and conditions of the battery.
delete The method according to claim 1,
The switching PWM pattern generation according to the inverter command current (I _c ^* ), the phase and magnitude of the grid voltage (V _g ), load conditions (V _g , I _L ) and the power of the battery (V _bat , I _bat ) After calculating the active power of the system by measuring, the system current (I _g ^* ) for the active power control is calculated using the equation obtained by calculating the system current (I _g ^* ), and the calculated system current (I _g ^*). The final inverter command current I _c ^* with the measured load current I _L and the phase information sinωt ^* synchronized with the grid voltage by the PLL circuit 532. A switching control circuit of an emergency power system having a photovoltaic system, characterized by generating a PWM (Pulse Width Modulation) switching pattern to follow the inverter command current (I _c ^* ).

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