KR101442139B1 - System and method for distributed generation managing using utility side distributed generation - Google Patents

Abstract

There is provided a distributed power supply management method and system for maximizing power generation efficiency of a distributed power source using a distributed power source owned by a power system operator. A distributed power management method according to the present invention is characterized in that a distributed power source (DGu) owned by a power system operator is connected to a feeder to which an independent power generation company owned distributed power source (DGi) is connected, a connection between the feeder and a power system The DGu operates as a slack bus for the DGi, the DGu maintains the power supply operation, and when the reconnection of the power system with the feeder is initiated, the output of the DGi Synchronizing the voltage of the power system with the voltage of the feeder by synchronizing the voltage, and then reconnecting the feeder and the power system.

Description

TECHNICAL FIELD [0001] The present invention relates to a distributed power management method and system using distributed power owned by a power system operator,

The present invention relates to a method and system for managing distributed power sources associated with a power system. And more particularly, to a method and system for managing a distributed power source that can maximize power generation efficiency of a distributed power source by using a distributed power source owned by a power system operator.

Distributed Generation (DG) based on renewable energy is used for supplying electric energy. The distributed power source supplies the power produced by the distributed power source to a region (hereinafter referred to as a 'distributed power grid') where the distributed power source is responsible. However, the distributed power grid is also supplied with electric power from the main grid. Of the power produced by the distributed power source, the remaining power consumed in the load of the distributed power grid may be sold to the power system.

On the other hand, when an islanding operation is detected, the distributed power source must be disconnected from the power system due to problems such as safety against system construction work, damage to system facilities, and the like. This is specified in IEEE 1547-2003. For this reason, it is difficult to perform the power generation of the distributed power source with the maximum efficiency.

Accordingly, it is required to provide a distributed power supply management system and method that can perform distributed power generation with maximum efficiency even in an isolated operation state and prevent a safety problem even when reconnected to the system.

Korea Patent Publication No. 2012-0096774

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to provide a grid-connected feeder connected to an independent power producer's distributed power source (DGi) , It is possible to perform the power generation of the distributed power source with the maximum efficiency even in the isolated operation situation by connecting the power source of the power source company which can perform the voltage synchronization with the system when reconnecting with the system, And to provide a method and system for managing a distributed power source that prevents a safety problem from occurring.

It is another object of the present invention to provide a feeder and a power system which are capable of preventing a power feed to the entire feeder even when a load connected to the feeder exceeds a total amount of power generated by the distributed power source connected to the feeder And to provide a method and system for managing a distributed power supply that can be powered down only for some zones.

The technical objects of the present invention are not limited to the above-mentioned technical problems, and other technical subjects not mentioned can be clearly understood by those skilled in the art from the following description.

According to an aspect of the present invention, there is provided a distributed power management method according to an aspect of the present invention, wherein a distributed power source (DGu) owned by a power system provider is connected to a feeder to which an independent power generation company owned distributed power source (DGi) Wherein the DGu operates as a slack bus for the DGi when the connection between the feeder and the grid Grid is interrupted, the DGu maintaining a power supply operation, And reconnecting the feeder and the power system after synchronizing the voltage of the power system and the voltage of the feeder when reconnection of the system is initiated.

According to one embodiment, the DGu operates as a slack bus for the DGi, and the DGu maintains the power supply operation, wherein the DGi is controlled by the power supply operation of the DGu, May not be able to detect the independent operation state.

According to one embodiment, the DGu operates as a slack bus for the DGi and the DGu maintains a power supply operation, the DGu controlling the DGu such that the magnitude and frequency of the output voltage of the DGu are kept constant Step < / RTI >

According to one embodiment, the step of reconnecting the feeder and the power system comprises the step of: the DGu receiving a signal to initiate reconnection of the feeder and the power system from the breaker between the power system and the feeder, Synchronizing the magnitude and phase of the voltage applied to the feeder with the magnitude and phase of the power grid voltage in the synchronized mode; and, after the DGu has completed the synchronization, And transmitting a connection control signal to the breaker so as to be reconnected. At this time, even though the breaker receives a connection control signal requesting to change from the facility of the power system to the closed state, the breaker is in the open state until the connection control signal for reconnecting the feeder and the power system from the DGu is received It can be to keep.

According to one embodiment, the DGu may be a connection of a power line facility and a control line. Wherein the DGu operates as a slack bus for the DGi and the DGu maintains a power supply operation wherein the DGu is responsive to a system shutdown notification signal received from the power system facility And switching the operation mode to an isolated operation mode. The step of reconnecting the feeder and the power system further includes switching the operation mode to a synchronous mode in response to a reconnection start signal received from the power system facility, Synchronizing the voltage magnitude and phase of the power system with the magnitude and phase of the DGu output voltage in the power mode and the DGu output; And controlling the breaker.

According to one embodiment, the feeder is divided into two or more zones bounded by a breaker, and the distributed power management method is characterized in that the total amount of production of all DGi and DGu in the management zone to which the DGu belongs is greater than the total load Further comprising the steps of: if the DGu is not exceeding, sending the shutdown control signal to the breaker in the management zone to further divide the management zone; and if the sum of all DGi and DGu production in the management zone is less than the total load in the management zone And stopping the power supply operation if the management zone can not be further divided. That is, according to the present embodiment, there is an effect that the feeder can be divided into a plurality of zones to minimize the electrostatic area. Wherein the DGu stops the power supply operation if the total amount of production of all the DGi and DGu in the management zone is less than the total load in the management zone and the management zone can not be further partitioned can do.

According to another aspect of the present invention, there is provided a distributed power supply system including a communication unit for receiving a system shutdown notification signal through a regenerative energy generator, a control line connected to an equipment of a power system, An inverter controller for converting the operation mode into an isolated operation mode in response to the reception of the control signal from the inverter controller and an inverter controller for converting the power generated by the regenerative energy generator into a DC to AC characteristic, And an inverter to which the proprietary distributed power source DGi is connected and to which the feeder is connected. At this time, the inverter controller can control the inverter so that the distributed power system operates in a slack bus with respect to the DGi in the isolated operation mode.

According to an embodiment, the inverter controller can control the inverter to maintain the root-mean-square value and frequency of the output voltage of the inverter in the isolated operation mode.

According to one embodiment, the communication unit receives a signal for starting reconnection of the feeder and the power system from the breaker between the power system and the feeder, and the inverter controller, in response to receiving the reconnection start signal, To the synchronous mode. At this time, the inverter controller controls the inverter such that the magnitude and phase of the voltage of the power system and the magnitude and phase of the output voltage of the inverter are synchronized in the synchronous mode, and the feeder and the power system And may transmit a connection control signal to the breaker to be reconnected.

The inverter controller receives a power signal from a wire branching at a predetermined point between the breaker and the power system in the synchronous mode and determines an effective value (V _grms ) and a phase (δ _g ) of the voltage of the power system have.

According to another aspect of the present invention, an inverter controller compares a voltage rms value (V _rms ) of a PCC connected to the inverter with a predetermined _rms value in an isolated operation mode A voltage magnitude controller for outputting a voltage magnitude parameter V _mag based on a voltage value of the PCC and a voltage magnitude controller for outputting a voltage magnitude parameter V _mag on the basis of a voltage V of the PCC, to the applied input voltage (V _LS) voltage and the phase shift generated by the phase difference value of the phase control, the PCC that outputs a phase difference (θ) of the received output from the phase shifter and the phase converter for converting and outputting a phase a voltage based on the signal reflecting the size of the voltage parameter (V _mag) a generator control signal for generating a control signal is provided to the inverter It should. At this time, the inverter controller controls the inverter to receive the generated power of the distributed power source and convert it into AC power, and the inverter controls the output power to the feeder through the high frequency filter (L _S ) And switches to the isolated operation mode in response to receiving the system shutdown notification signal through the control line connected to the power system facility.

The inverter controller may switch the operation mode to a synchronous mode in response to receiving a reconnection start signal from the feeder and the power system from the breaker between the power system and the feeder. In the synchronization mode,

In sync mode, and it generates and outputs a voltage level parameter (V _mag) on the basis of a result of comparing a voltage effective value (V _rms) of the PCC to the voltage effective value (V _grms) of the power system, and the phase control unit , the voltage at the sync mode in which a voltage is applied to the phase (δ) of the PCC to the voltage phase (δ _g) resulting voltage (V) of the PCC on the basis of a comparison of the and the high frequency filters both ends of the power system (V _LS The phase difference?

According to the present invention, power generated from the distributed power source connected to the feeder is supplied to the feeder even if the connection to the power system is disconnected from the specific feeder, thereby preventing unconditional power failure.

In addition, even if the feeder and the power system are reconnected while the power of the distributed power source is being supplied, the power characteristics of the power system and the power characteristics applied to the feeder are synchronized in advance before being connected, Damage and the like can be prevented.

In addition, in a situation where a specific feeder and a power system are shut off, even if the load amount connected to the feeder exceeds the total generation amount of the distributed power source connected to the feeder, So that the electrostatic field can be minimized.

1 is a power network diagram of a grid-connected distributed power supply according to the prior art.
2 is a power network diagram of a grid-connected distributed power supply according to an embodiment of the present invention.
3 is a block diagram of a distributed power system according to an embodiment of the present invention.
4 is an example of a circuit diagram of the distributed power supply system shown in FIG.
5 is a detailed block diagram of the inverter controller shown in FIG.
6 is a circuit diagram of the module after replacement of some of the components of the inverter controller shown in Fig.
7 is a circuit diagram of the module after replacement of some of the components of the inverter controller shown in Fig.
8 is a diagram showing the magnitude and phase of each power signal in the circuit diagram shown in FIG.
9 is a power network diagram of a grid-connected distributed power supply according to another embodiment of the present invention.
10 is a flowchart of a control method of the distributed power source DG _{u , 1 shown} in FIG.
FIG. 11 is a flowchart of a control method for reconnecting the distributed power sources DG _{u , 1,} DG _{u , 2 shown} in FIG.
FIG. 12 is a graph showing simulation results of output variation according to time of each distributed power supply shown in FIG. 9 when the power supply capacity in the power network configuration shown in FIG. 9 exceeds the load amount.
FIG. 13 is a graph showing the variation of reactive power (a) of each distributed power supply according to the time flow shown in FIG. 9 when the capacity of the power supply exceeds the load in the power network configuration shown in FIG. 9, (D) of the voltage change (b), the operation change of each of the breakers (c), and the distributed power sources DG _{u, 1,} DG _{u , 2} .
FIG. 14 is a graph showing simulation results of output variation according to time of each distributed power supply shown in FIG. 9 when the power supply capacity in the power network configuration shown in FIG. 9 is less than the load amount.
FIG. 15 is a graph showing the variation of reactive power (a) of each distributed power source according to the time flow shown in FIG. 9 when the power source capacity is less than the load amount in the power network configuration shown in FIG. 9, (D) of the voltage change (b), the operation change of each of the breakers (c), and the distributed power sources DG _{u, 1,} DG _{u , 2} .

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving them will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

Unless defined otherwise, all terms (including technical and scientific terms) used herein may be used in a sense commonly understood by one of ordinary skill in the art to which this invention belongs. Also, commonly used predefined terms are not ideally or excessively interpreted unless explicitly defined otherwise.

It is to be understood that when an element or layer is referred to as being "on" or " on "of another element or layer, All included. On the other hand, a device being referred to as "directly on" or "directly above " indicates that no other device or layer is interposed in between.

One element is referred to as being "connected to " or" coupled to "another element, either directly connected or coupled to another element, One case. On the other hand, when one element is referred to as being "directly connected to" or "directly coupled to " another element, it does not intervene another element in the middle. Like reference numerals refer to like elements throughout the specification. "And / or" include each and every combination of one or more of the mentioned items.

The terms spatially relative, "below", "beneath", "lower", "above", "upper" May be used to readily describe a device or a relationship of components to other devices or components. Spatially relative terms should be understood to include, in addition to the orientation shown in the drawings, terms that include different orientations of the device during use or operation. For example, when inverting an element shown in the figures, an element described as "below" or "beneath" of another element may be placed "above" another element. Thus, the exemplary term "below" can include both downward and upward directions. The elements can also be oriented in different directions, so that spatially relative terms can be interpreted according to orientation.

First, a power network configuration of a grid-connected distributed power supply according to an embodiment of the present invention will be described with reference to FIG.

Referring to FIG. 2, a power network of a grid-connected distributed power source according to the related art will be described with reference to FIG. 1 for convenience of description. The distributed power sources DGi 12, 13, 14 are connected to the feeder 19, and the feeder 19 is connected to the power system 11. A circuit breaker 18 is provided between each bus so that the feeder 19 can be separated by each bus. At this time, the distributed power sources 12, 13, and 14 supply power to the loads 15, 16, and 17 together with the power system 11. However, when the feeder 19 is disconnected from the power system 11 due to intentional or unintentional reasons, the distributed power sources 12, 13, and 14 also stop supplying power to the feeder for safety, 19) has to be out of power.

According to the power network configuration of the grid-connected distributed power source of the present invention shown in FIG. 2, even if the feeder 19 is in an islanding state in which connection with the power system 11 is blocked, The electric power produced by the feeders 12, 13, 14, and 30 is supplied to the feeder 19.

Since the distributed power source 30 possessed by the power system provider disclosed in the present invention plays the role of a slack bus, each of the independent power generator owned distributed power sources DGi (12, 13, 14) It is possible to supply the generated power to the feeder 19 continuously.

When the distributed power source 30 possessed by the power system provider disclosed in the present invention is reconnected between the feeder 19 and the power system 11, the voltage of the power system 11 and the voltage of the feeder 19 are pre-synchronized Even if power is supplied to the distributed power sources 12, 13, 14 and 30 while the connection between the feeder 19 and the power system 11 is cut off, It does not cause.

Hereinafter, the distributed power source owned by the power system operator is denoted by DGu, and the independent power generator owned distributed power sources (12, 13 and 14) are denoted by DGi.

As shown in FIG. 2, the DGu 30, which is introduced according to the present invention, may be a control line connected to a power system facility 20 of a power system operator operating a power system 11. That is, the DGu 30 can be controlled by the power system operator through the control line. The DGu 30 can be controlled by the power system operator but must be connected directly to the feeder 19 to which the DGi 12, .

3 is a block diagram of a distributed power system (DGu) 30 according to an embodiment of the present invention. 3, the DGu 30 according to the present embodiment includes a regenerative energy generator 41, a communication unit 42, an inverter controller 43, an inverter 44, And a high-frequency filter 45.

Each component in FIG. 3 may also refer to software or hardware such as a field-programmable gate array (FPGA) or an application-specific integrated circuit (ASIC). However, the components are not limited to software or hardware, and may be configured to be in an addressable storage medium and configured to execute one or more processors. The functions provided in the components may be implemented by a more detailed component or may be implemented by a single component that performs a specific function by combining a plurality of components.

The AC power output from the DGu 30 is applied to the feeder 19 through a point of common coupling (PCC) The voltage and current at the junction 50 can be seen to be equal to the output voltage and current of the inverter 44 that passed through the high-frequency filter 45. Therefore, in the present specification, it is referred to as a voltage and a current at the connection point 50 in the same sense as the output voltage and current of the inverter 44. [

3, the voltage and current at the power grid connection point 50 are provided to the inverter controller 43 which monitors the output of the inverter 44 and regulates the output of the inverter 44. [ The inverter controller 43 monitors the output of the inverter 44 and controls the operation of the inverter 44. The operation of the inverter controller 43 will be described in more detail with reference to FIGS.

Hereinafter, the operation of each component of the DGu 30 will be described.

The communication unit 42 receives the system shutdown notification signal through the control line connected to the power system facility 20. [ The communication unit 42 may receive a notification signal from the breaker 18 on the feeder 19 or transmit a control signal to the breaker 18. [

The inverter controller (43) for controlling the inverter (44) switches the operation mode to the isolated operation mode in response to the reception of the system shutdown announcement signal.

According to the present invention, there are three operation modes of the inverter controller 43. One is a normal mode when the feeder 19 is connected to the power system 11, the other is an isolated operation mode when the feeder 19 is disconnected from the power system 11, and the other is a feeder 19 ) Is reconnected to the power system 11 in synchronous mode. The normal mode will be described with reference to FIG. 5, the isolated operation mode will be described with reference to FIG. 6, and the synchronization mode will be described with reference to FIG.

The inverter 44 can convert the electric power generated by the regeneration energy generating unit 41 into a DC to AC characteristic so as to have a characteristic according to the control of the inverter controller 43 and then apply it to the feeder 19 to which the DGi is connected . At this time, the high-frequency filter 45 filters the high frequency included in the AC signal output from the inverter 44 and applies it to the feeder 19 via the power grid connection point 50.

4 is an example of a circuit diagram of the DGu 30 shown in FIG. As shown in FIG. 4, the DGu 30 may further include an energy storage system (BESS) 46 for charging the remaining electric power or performing a damping function of electric power in such a manner as to discharge the insufficient electric power. The renewable energy generation unit 41 and the energy storage system 46 may be connected to each other through a bi-directional DC-DC converter.

4, the electric power generated by the regeneration energy generating unit 41 or the electric power discharged from the battery of the energy storage system is converted into AC by the inverter 44 and outputted (V _S ), and V _S Can be applied (V, I) to the power system 11 through the high-frequency filter (L _S ) 45, via the connection point 50, or to a load connected to the feeder via a feeder (not shown). 4 also shows that the inverter controller 43 receives the output powers V and I and provides the inverter 44 with a control signal V _t for controlling the inverter 44. [

As described above, the DGu 30 must operate as a slack bus that keeps the power applied to the feeder 19 in a stable state even if the connection between the feeder 19 and the power system 11 is cut off, and the feeder 19 And the power system 11 are reconnected, it is necessary to synchronize the voltage applied to the feeder 19 with the voltage of the power system. In this regard, the operation of the DGu 30 will be described focusing on the configuration and operation of the inverter controller 43. FIG.

5 is a detailed configuration diagram of the inverter controller 43 shown in Fig. 5, the inverter controller 43 may include a voltage magnitude controller 430, a phase controller 450, a phase converter 440, and a control signal generator 450.

First, the operation of the inverter controller 43 in the normal mode will be described.

Voltage level controller 430 is linked obtained in point (50) V, receives the active power signal (P) generated from the I, active power signal reference value (P _ref) on the basis of a result of comparison with the voltage amplitude parameter (V _mag ). Further, the phase control unit 450 based on the result of comparison with the linkage point (50) V, receives the reactive power signal (Q) generated from the I, a reactive power signal reference value (Q _ref) obtained from the link point (50 ) Between the voltage (V) of the high-frequency filter and the voltage (V _LS ) applied across the high-frequency filter.

The phase converter 440 receives the voltage at the coupling point 50 and the phase conversion value generated from the phase difference, converts the phase, and outputs the converted signal. Next, the control signal generation section 450 a control signal (Vta, Vtb, Vtc) is provided to the inverter 44 based on a signal that reflects the voltage level parameter (V _mag) on the voltage output from the phase shifter 440 .

Considering the above described operation, in normal mode, the DGu 30 adjusts the output to the power system 11 via the feeder 19 such that the active power P and the reactive power Q are fixed I can understand.

Next, the operation of the inverter controller 43 in the isolated operation mode will be described. Since the DGu 30 receives the system shutdown notification signal through the control line connected to the power system facility, the DGu 30 notifies the fact that the feeder 19 and the power system 11 are disconnected, Can receive. The inverter controller 43 can switch to the isolated operation mode in response to the reception of the system shutoff notification signal via the communication unit 42. [

In the isolated operation mode, the voltage controller 431 and the phase controller 451 shown in FIG. 6 are used for the inverter controller 43 instead of the voltage controller 430 and the phase controller 450 shown in FIG. 5 .

The voltage magnitude control unit 431 outputs the voltage magnitude parameter V _mag based on the result of comparing the voltage effective value V _rms of the connection point 50 with the effective value reference value V _ref . The phase control unit 451 also controls the voltage V of the connection point 50 and the voltage applied to both ends of the high frequency filter 50 based on the result of comparing the voltage frequency f _measured of the connection point 50 with the frequency reference value f _ref The phase difference? Of the voltage (V _LS ).

The operation of the voltage magnitude control unit 431 will be described in more detail. As shown in Fig. 6, the voltage rms values V _rms of the connection points 50 which are converted from the effective value reference value V _ref are added, and the summed signals are passed through the proportional integral (PI) A control signal is generated. Thereafter, V _mag ^gc and the intermediate control signal are summed and the resulting value is the voltage magnitude parameter (V _mag ). V _mag ^gc is a voltage magnitude parameter (V _mag ) value lastly generated by the voltage magnitude control unit 430 in the immediately preceding normal mode.

Therefore, if the voltage rms value (V _rms ) of the connection point 50 is equal to or greater than the reference value, the voltage magnitude parameter (V _mag ) decreases from V _mag ^gc resulting in a decrease in the output voltage magnitude of the inverter (44) The magnitude of the output voltage of the inverter 44 increases as the voltage magnitude parameter V _mag increases from V _mag ^gc if the voltage rms value V _rms of the inverter 44 is less than the reference value, The voltage magnitude remains constant.

Next, the operation of the phase control section 451 will be described in more detail. 6, the voltage frequency f _{measured at} the coupling point 50 and the negative converted frequency reference value f _ref are summed and the summed signal passes through the proportional integral (PI) Is generated. Thereafter, the intermediate control signal and? ^Gc are added together and the resultant value is outputted as the phase difference? _Between the voltage V of the coupling point 50 and the voltage V _LS applied to the high- to be. θ ^gc is the phase difference (θ) between the voltage (V) of the connection point (50) lastly generated by the phase controller (450) in the previous normal mode and the voltage (V _LS ) applied across the high frequency filter (45).

Therefore, when the voltage frequency f _measured of the coupling point 50 is less than the reference value, the phase difference? Input to the phase shifter 440 is smaller than? ^Gc , and as a result, the output voltage frequency of the inverter 44 increases . 5, the input to the phase shifter 440 is a signal obtained by adding the output values of the phase control section 451 which are converted from the phase difference reference value? _Ref . Conversely, when the voltage frequency f _measured of the coupling point 50 is equal to or higher than the reference value, the phase difference? Input to the phase shifter 440 increases more than? ^Gc and consequently the output voltage frequency of the inverter 44 decreases Can be easily understood.

Consequently, the inverter controller 43 in the isolated operation mode controls the inverter 44 so that the magnitude and the frequency of the output voltage of the inverter 44 are kept constant. The DGi 30 connected to the same feeder 19 applies the DGu 30 to the feeder 19 because the DGu 30 applies a constant magnitude and frequency of power to the feeder 19 as described above. It is possible to perform the power supply operation normally without recognizing the isolated operation condition.

Next, the operation of the inverter controller 43 in the synchronous mode will be described. The DGu 30 according to an embodiment of the present invention is configured to start the reconnection of the feeder 19 and the power system 11 from the breaker 18 between the feeder 19 and the power system 11 to which the DGu 30 is connected Signal can be received. The breaker 18 between the feeder 19 and the power system 11 does not close the switch immediately but receives the reconnection start signal even if a connection control signal requesting the power system 11 to change from the equipment to a closed state is received To the DGu (30). The inverter controller 43 receives the reconnection start signal through the communication unit 42 and switches the operation mode to the synchronous mode.

Meanwhile, the DGu 30 according to another embodiment of the present invention may receive the reconnection start signal directly from the power system facility 20 instead of the breaker 18. [ The power system facility 20 controls the start and end of the disconnection when intentional islanding between the feeder 19 and the power system 11 is intentionally taken and the point of time is notified to the DGu 30 in advance You can do it.

The inverter controller 43 is provided with a voltage magnitude control unit 432 and a phase control unit 432 shown in Fig. 7 instead of the voltage magnitude control unit 431 and the phase control unit 451 shown in Fig. 6, 452) is used. In the synchronous mode, the inverter controller 43 controls the inverter such that the magnitude and phase of the voltage of the power system 11 and the magnitude and phase of the output voltage of the inverter 44 are synchronized in the synchronous mode. Thereafter, the inverter controller 43 transmits a connection control signal to the breaker 18 between the power system 11 and the feeder 19 so that the feeder 19 and the power system 11 are reconnected at the completion of the synchronization .

In the synchronous mode, the inverter controller 43 can measure and use the voltage at a predetermined point between the power system 11 and the breaker 18 for synchronization. The DGu 30 may connect the bus bar to a predetermined point past the first breaker 18 in the direction of the power system 11 from the connection point 50 on the feeder 19. Hereinafter, it is assumed that the voltage signal applied through the bus line is the same as the voltage signal of the power system 11.

The voltage magnitude control unit 432 outputs the voltage magnitude parameter V _mag based on the result of comparing the voltage rms value V _rms of the connection point 50 with the voltage rms value V _grms of the power system 11 do. The phase control unit 451 also compares the voltage V of the coupling point 50 with the voltage phase δ ^g of the high frequency filter 50 based on the result of comparing the voltage phase δ of the coupling point 50 with the voltage phase δ ^g of the power system The phase difference? Of the voltage V _LS applied to the gate of the transistor _Q3 .

The operation of the voltage magnitude control unit 432 will be described in more detail. , The effective value (V _rms) voltage of the voltage effective value (V _gref) and notes the associated point (50) switching system (11) are summed, in proportion that the summed signal integration as shown in Figure 7 (PI) An intermediate control signal is generated through the controller. Thereafter, V _mag ^gc and the intermediate control signal are summed and the resulting value is the voltage magnitude parameter (V _mag ). V _mag ^gc is a voltage magnitude parameter (V _mag ) value lastly generated by the voltage magnitude control unit 430 in the immediately preceding normal mode.

Thus, the connection point 50, the voltage effective value (V _rms) is not less than the voltage effective value (V _grms) of the power system, voltage size parameter (V _mag) As a result, the inverter 44 by lower than V _mag ^gc of decrease the output voltage level, and conversely if the connection voltage effective value of the point (50) (V _rms) less than the voltage effective value of the electric power system (V _grms), the voltage magnitude as a result, by increasing the parameter (V _mag) is more than V _mag ^gc The magnitude of the output voltage of the inverter 44 increases and the magnitude of the output voltage of the inverter 44 becomes equal to the magnitude of the voltage of the power system 11. [

Next, the operation of the phase control unit 452 will be described in more detail. As shown in Fig. 7, the voltage phase [delta] of the coupling point 50 and the voltage phase [delta] ^g of the negative converted power system are summed and the summed signal passes through the proportional integral A control signal is generated. Thereafter, the intermediate control signal and? ^I are summed and the resultant value is compared with the phase difference? _Between the voltage V of the coupling point 50 and the voltage VLS applied to the high- to be. θ ⁱ is the phase difference (θ) between the voltage (V) of the connection point 50 finally generated by the phase control section 451 in the immediately preceding isolation operation mode and the voltage (V _LS ) applied across the high frequency filter 45 .

Therefore, when the voltage phase? Of the coupling point 50 is equal to or less than the voltage phase? ^G of the power system, the phase difference? Input to the phase shifter 440 is smaller than? ^I , The output voltage phase of the inverter circuit increases. 5, the input to the phase shifter 440 is a signal obtained by adding the output values of the phase control section 452 which are converted from the phase difference reference value? _Ref . Conversely, when the voltage phase? Of the coupling point 50 is equal to or higher than the voltage phase? ^G of the power system, the phase difference? Input to the phase shifter 440 increases more than? ^Gc , It will be appreciated that the output voltage phase is reduced.

In conclusion, the inverter controller 43 in the synchronous mode controls the inverter 44 such that the magnitude and phase of the output voltage of the inverter 44 are synchronized with the voltage magnitude and phase of the power system. Therefore, even after the power system 11 and the feeder 19 are reconnected by closing the breaker 18 again between the power system 11 and the feeder 19 after the synchronization is completed, no problem occurs.

8 is a diagram showing the magnitude and phase of each power signal in the circuit diagram shown in FIG. Since the high-frequency filter 45 is derived minutes (inductive component) 8, the current I can be seen that the phase is delayed by (φ) greater than the voltage V _LS. The phase difference (?) _Between the voltage (V) of the connection point (50) and the voltage (V _LS ) applied across the high frequency filter is an angle with negative values and increases in the counterclockwise direction Able to know. P and Q are the magnitudes of the active power and the reactive power.

Hereinafter, a distributed power management method according to the present invention will be described with reference to a power network configuration diagram of the grid-connected distributed power source shown in Fig. 9, distributed power sources (DG _{i , 1} , DG _{i , 2} , DG _{i , 3} ) owned by independent power generation companies are connected to a feeder 19 - 1 connected to the power system 11, And a distributed power source (DG _{u , 1} , DG _{u , 2} ) possessed by the power system provider are respectively connected. However, the feeder 19-1 shown in Fig. 9 is different from that shown in Fig. 2 by the circuit breakers 18-1, 18-2, 18-3, 18-4, 18-5 and 18-6 And is divided into three zones 51, 52,

DG _{i , 1} and DG _{u , 1} are connected to the first zone 51, DG _{i , 2} is connected to the second zone 52, DG _{i , 3} and DG ₃ are connected to the third zone 53, It is assumed that _{u and 3} are connected.

It is an embodiment of the present invention that the feeder 19-1 is divided into three zones in Fig. 9, and the present invention includes all the embodiments for dividing the feeder 19-1 into two or more zones.

The reason for dividing the feeder 19-1 into two or more zones in the embodiment shown in Fig. 9 is that each distributed power source DG _{i , 1} , DG _{i , 2} , DG _{i , 3} , DG _{u, 1,} DG _{u, 2)} generating capacity summing remain below the sum of the respective load (15, 16, 17) connected to the feeder 19-1, at the same time, the power system 11 and the feeder (19-1 of Of the feeder 19-1 is cut off and the power supply system 11 does not supply power to the feeder 19-1.

₁ , DG _{i , 2} , DG _{i , 3} , and DG ( _i ) when the connection between the power system 11 and the feeder 19-1 is cut off in the power network configuration shown in Fig. _{u, 1, DG u, 2} ) operating the distributed power generation capacity summing to the description by dividing the (first case) and if the power capacity summing short of the combined load capacitance (the second case) or more combined load capacity do. As shown in FIG. 9, it is assumed that the energy storage systems (BESS ₁ and BESS ₂ ) each having a capacity of 100 Kw are connected to the distributed power sources (DG _{u , 1} , DG _{u , 2} )

Table 1 shows the capacity of each dispersed power source and load according to the first case. As shown in Table 1, the total load is 1 MW. Also, the sum of distributed power generation is 930kW (200kW + 180kW + 150kW + 200kW + 200kW). However, since a power of 70 kW, which is insufficient in the energy storage systems (BESS ₁ , BESS ₂ ) connected to the power grid operator owned distributed power sources (DG _{u , 1} , DG _{u , 2} ) is discharged and applied to the feeder 19-1, According to the first case, even if the connection between the power system 11 and the feeder 19-1 is cut off, the distributed power sources DG _{i , 1} , DG _{i , 2} , DG _{i , 3} , DG _{u , 1} , DG _{u , 2} ) can sufficiently cope with the load connected to the feeder 19-1.

Conventionally, even if it corresponds to the first case, the entire power supply to the feeder 19-1 is inevitable because of the safety problem. However, according to when the first case is connected to the dispersion feeder 19-1 Power to the present invention _{(i DG, 1,} DG _{i, 2, i DG, 3,} DG _{u, 1,} DG _{u, 2)} Since sufficient power can be supplied to the load connected to the feeder 19-1, the load connected to the feeder 19-1 can be supplied with power without any limitation.

Hereinafter, the operation of the power system provider-owned distributed power sources (DG _{u , 1} , DG _{u , 2} ) in the case of the first case will be described. First, a control method of the distributed power source DG _{u , 1} shown in FIG. 9 will be described with reference to FIG.

First, when the connection between the power system 11 and the feeder 19-1 is cut off, the first breaker 18-1 and the second breaker 18-2 are opened. When the second breaker 18-2 is opened, a signal s1 indicating this is transmitted to the distributed power source DG _{u , 1} (S10). Accordingly, the distributed power source DG _{u , 1} can know that the connection between the power system 11 and the feeder 19-1 is cut off. According to another embodiment, the distributed power source DG _{u , 1} may be directly supplied with a signal indicating that the connection between the power system 11 and the feeder 19-1 is disconnected from the facility 20 of the power system 11 have.

When the connection between the power system 11 and the feeder 19-1 is cut off, the distributed power source DG _{u , 1} switches the operation mode to the isolated operation mode to keep the magnitude and frequency of the output voltage constant Thereby operating as a slack bus.

Meanwhile, the distributed power source DG _{u , 1} determines whether a signal s3 indicating whether the fifth breaker 18-5 is open is received (S12). When the fifth breaker 18-5 is open, the third zone 53 is separated from the first zone 51 and the second zone 52.

Next, a distributed generation (DG _{u, 1)} determines that the threshold value (critical value) (ε ₁₎ even allowing a sufficient supply of the necessary electric power distributed generation _{(DG u, 1) (S14} ), the third zone The power generation capacity required for the distributed power source DG _{u , 1} is "L1 load + L2 load-distributed power source DG _{i , 1} " when the power source 53 is separated from the first area 51 and the second area 52 ) Generated power - Distributed power (DG _{i , 2} ) Generated power = "250 kW" The power generation capacity of the dispersed power source (DG _{u , 1} ) itself is only 200 kW, but when the power charged in BESS ₁ is discharged, for example, the threshold Speaking (ε ₁₎ is 0.9, it is possible to handle by a 270kW load. Thus, for the first case, the distributed generation (DG _{u, 1)} is the first region 51 and the second zone It is not necessary to transmit the signal t1 for opening the third breaker 18-3 in order to disconnect the first breaker 18-2.

On the other hand, when the fifth breaker 18-5 is closed, that is, when all of the first to third zones 51, 52 and 53 are connected, the power generation capacity required for the distributed power source DG _{u ,} L1 load + L2 load + L3 load-distributed generation (DG _{i, 1)} generation - DG (DG _{i, 2)} generation - distributed generation (DG _{i, 3)} generation - distributed generation (DG _{u, 2)} generation (BESS ₂ is included) = "170kW". distributed generation (DG _{u, 1)} when the power generation capacity of the self is andoejiman outside 200kW discharge the charged electric power to the BESS ₁ can supply a maximum of 300kW, for example, the threshold value (ε ₂₎ The dispersed power source DG _{u , 1 in the} case of the first case is divided into the first zone 51 and the second zone 52 in order to separate the third zone 51 and the second zone 52 from each other, In the case of the first case, the distributed power source DG _{u , 1} is not required to transmit the signal t1 for opening the partial region It is not necessary to perform an operation of opening the breaker in order to separate only the area.

9, when there is an additional zone on the feeder 19-1 other than the third zone 53 in the direction opposite to the power system 11, the distributed power source DG _{u , 2} is also connected to the distributed power source DG _{u , 1} ). That is, in this case, the distributed power source DG _{u , 2} will also perform the operation of FIG. 10 to determine whether to block the further connected region in the opposite direction to the power system 11.

10, when the connection between the power system 11 and the feeder 19-1 is cut off, the connection between the first and second sections 51, 52 and the second section 53 is blocked The following explains the premise.

In the case of the first case, the operation in the case where the connection between the power system 11 and the feeder 19-1 is disconnected and reconnected is described with reference to Fig. A control signal for the closing operation of the first and second breakers 18-1 and 18-2 may be applied from the power system facility 20 in order for the power system 11 and the feeder 19-1 to be reconnected have. At this time, even if the second breaker 18-2 receives the control signal for the closing operation from the power system facility 20, the second breaker 18-2 does not operate until the control signal for the closing operation is received from the distributed power source DG _{u ,} It can wait without performing a closing operation. This is to reduce the impact of connecting the power system 11 and the feeder 19-1 by synchronizing the magnitude and phase of the voltage applied in the feeder 19-1 with the voltage magnitude and phase of the power system 11 .

As shown in FIG. 9, the distributed power source DG _{u , 1} monitors the magnitude of the voltage V _Brk2 between the first and second breakers 18-1 and 18-2 (S20). For example, when the magnitude of the voltage (V _Brk2 ) falls within the reference range, the distributed power source (DG _{u , 1} ) can switch the operation mode to the synchronous mode. Distributed generation (DG _{u, 1)} are the magnitude and phase of the voltage (V _Brk2) between the first and second breaker (18-1, 18-2) by the operation of the inverter controller explained in synchronization mode and point, the feeder ( (BUS 2) connected to the first bus line (19-1) (S21). The distributed power source DG _{u , 1} transmits the control signal c1 for the closing operation to the second breaker 18-2 (S23). When the second breaker 18- (S24), the distributed power source DG _{u , 1} switches the operation mode to the normal mode indicating the power system connection state (S25). Next, the distributed power source DG _{u , 1} also transmits the control signals t1 and t2 for closing the third to sixth breakers 18-3 to 18-6.

Like the second breaker 18-2, the sixth breaker 18-6 also does not perform the closing operation without the control signal of the distributed power source DG _{u , 2} . Distributed generation (DG _{u, 2)} is the 5,6-breaker (18-5, 18-6) monitoring the voltage (V _Brk6) between the point by switching (S27) the operation mode to the synchronized mode, distributed generation (DG _{u , 1} ) to perform voltage synchronization, the sixth breaker closing control, and the switching operation to the normal mode (S28 to S32).

In the case of the first case, the operation of the power-system-provider-owned distributed power source (DG _{u , 1} , DG _{u , 2} ) has been described. Next, in the case of the second case, the operation of the power system provider-owned distributed power source (DG _{u , 1} , DG _{u , 2} ) will be described. Table 2 below shows the capacity and load of each dispersed power source in the case of the second case.

Hereinafter, the operation of the power system provider-owned distributed power sources (DG _{u , 1} , DG _{u , 2} ) will be described in the case of the second case. First, referring to FIG. 10 _, a control method of the distributed power source DG _{u , 1} shown in FIG. 9 for the case of the second case will be described.

First, when the connection between the power system 11 and the feeder 19-1 is cut off, the first breaker 18-1 and the second breaker 18-2 are opened. When the second breaker 18-2 is opened, a signal s1 indicating this is transmitted to the distributed power source DG _{u , 1} (S10). Accordingly, the distributed power source DG _{u , 1} can know that the connection between the power system 11 and the feeder 19-1 is cut off. According to another embodiment, the distributed power source DG _{u , 1} may be directly supplied with a signal indicating that the connection between the power system 11 and the feeder 19-1 is disconnected from the facility 20 of the power system 11 have.

When the connection between the power system 11 and the feeder 19-1 is cut off, the distributed power source DG _{u , 1} switches the operation mode to the isolated operation mode to keep the magnitude and frequency of the output voltage constant Thereby operating as a slack bus.

Meanwhile, the distributed power source DG _{u , 1} determines whether a signal s3 indicating whether the fifth breaker 18-5 is open is received (S12). When the fifth breaker 18-5 is open, the third zone 53 is separated from the first zone 51 and the second zone 52.

Next, distributed generation (DG _{u, 1)} determines that the threshold value (ε ₁₎ a sufficient supply of the necessary electric power distributed generation (DG _{u, 1),} even in view (S14). When the third zone 53 is separated from the first zone 51 and the second zone 52, the power generation capacity required for the distributed power source DG _{u , 1} is "L1 load + L2 load-distributed power source DG _{i , 1} ) Power generation - Distributed power generation (DG _{i , 2} ) Power generation = "330 kW".

Distributed generation (DG _{u, 1)} even if the charged electric power to an electric power generation capacity of the self is 200kW, BESS _first discharge it can supply up to 300kW, distributed generation (DG _{u, 1)} are the first and second zones (51, 52 ) Can not afford the load. Accordingly, the distributed power source DG _{u , 1} transmits a signal t1 for opening the third breaker 18-3 to separate the first zone 51 and the second zone 52 (S15) .

In this case, in the second region 52, the power generation capacity (140 kW) of the distributed power source (DG _{i , 2} ) is less than the load (250 kW), so that a power failure occurs.

On the other hand, after the second zone 52 is separated, there is no zone to be separated from the first zone 51. The distributed power source DG _{u , 1} is in a state in which the total amount of production of all the DGi and DGu in the first zone 51 as its management zone is less than the total load in the management zone and the management zone can not be further divided , And a power failure is generated in the management area by interrupting the power supply operation. In this case, all the DGi connected to the feeder in the management zone will also detect the isolated operation and stop operation. In the case of the second case, however, no power failure will occur in the first zone 51 because the sum of the distributed power source capacities of the first zone 51 exceeds the sum of the load amounts. For the same reason, no power failure will occur in the third zone 53 as well.

In summary, even though the total capacity of the distributed power source connected to the feeder 19-1 in the present invention is less than the sum of the load, the feeder 19-1 is divided into two or more zones, , There is an effect that a static electricity is not generated with respect to the entire feeder 19-1 but the static electricity area can be minimized to a partial region of the feeder 19-1.

On the other hand, when the fifth breaker 18-5 is closed, that is, when all of the first to third zones 51, 52 and 53 are connected, the power generation capacity required for the distributed power source DG _{u ,} L1 load + L2 load + L3 load-distributed generation (DG _{i, 1)} generation - DG (DG _{i, 2)} generation - distributed generation (DG _{i, 3)} generation - distributed generation (DG _{u, 2)} generation (BESS ₂ ) = 290 kW When the charged power of the distributed power source DG _{u , 1} is discharged, a maximum of 300 kW can be supplied, but if the threshold value? ₂ is reflected, ). Therefore, also in this distributed generation (DG if _{u, 1)} is the signal (t1) to open a third breaker (18-3) to separate the first region 51 and the second zone (52) (S17).

FIG. 12 is a graph showing the simulation results of output variation according to time in each of the distributed power sources shown in FIG. 9 in the first case. FIG. Fig. 13 is a graph showing changes in reactive power (a), variation in voltage (b) of each dispersed power source according to the time flow of each of the distributed power sources shown in Fig. 9 in the first case in the power network configuration shown in Fig. (C), _and the output voltage frequency change (d) of the distributed power sources DG _{u , 1,} DG _{u , 2} , respectively.

FIG. 14 is a graph showing the output change simulation results of the distributed power supplies shown in FIG. 9 according to time, when the second case in the power network configuration shown in FIG. 9 is used. Fig. 15 is a graph showing variation in reactive power (a), variation in voltage (b) of each dispersed power supply according to the time flow of each of the distributed power sources shown in Fig. 9 in the second case in the power network configuration shown in Fig. (C), _and the output voltage frequency change (d) of the distributed power sources DG _{u , 1,} DG _{u , 2} , respectively.

The results of the distributed power management method of the present invention and the operation of the distributed power system will be clearly understood with reference to Figs. 12 to 14. Fig.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, You will understand. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

Power system 11
Feeder 19
Independent Power Provider Owned Distributed Power 12, 13, 14
Distributed power owned by power system operator 30
Power system equipment 20

Claims (21)

(DGu) connected to a feeder to which the independent power generator owned distributed power (DGi) is connected;
When the connection between the feeder and the power grid is interrupted, the DGu operates as a slack bus for the DGi, and the DGu maintains a power supply operation; And
And reconnecting the feeder and the power system after synchronizing the voltage of the power system with the voltage of the feeder when the reconnection of the power system and the feeder is initiated,
Wherein the DGu operates as a slack bus for the DGi and the DGu maintains a power supply operation,
Wherein the DGi does not detect the independent operation state even if the connection between the feeder and the power grid is cut off due to the power supply operation of the DGu. delete The method according to claim 1,
Wherein the DGu operates as a slack bus for the DGi and the DGu maintains a power supply operation,
And controlling the DGu such that the magnitude and frequency of the output voltage of the DGu are kept constant. The method according to claim 1,
Wherein reconnecting the feeder and the power system comprises:
Receiving DGu from the power system and a breaker between the power system and the power system and switching the operation mode to a synchronous mode;
Synchronizing the magnitude and phase of the voltage applied to the feeder with the magnitude and phase of the power grid voltage in synchronous mode; And
And transmitting the connection control signal to the breaker so that the DGu reconnects the power system with the feeder after the completion of the synchronization. 5. The method of claim 4,
Even if a connection control signal requesting a change from a facility of the power system to a closed state is received, the breaker is in a state of being maintained in an open state until the connection control signal for allowing the feeder and the power system to be reconnected from the DGu is received. Power management methods. The method according to claim 1,
Wherein said DGu is a connection of said power system facility and a control line. The method according to claim 6,
Wherein the DGu operates as a slack bus for the DGi and the DGu maintains a power supply operation,
Wherein the DGu comprises switching an operation mode to an isolated operation mode in response to a system shutdown notification signal received from the power system facility. The method according to claim 6,
Wherein reconnecting the feeder and the power system comprises:
Switching the operating mode to a synchronous mode in response to a reconnection start signal received from the power system facility;
Synchronizing the magnitude and phase of the voltage magnitude and phase of the power system with the DGu output voltage in the synchronous mode; And
And controlling the breaker between the power system and the feeder such that the DGu reconnects the power system to the feeder after the synchronization is completed. The method according to claim 1,
Wherein the feeder is divided into two or more zones with a boundary of the breaker,
If the total amount of production of all the DGi and DGu in the management zone to which the DGu belongs is less than the total load in the management zone, the DGu further transmits the block control signal to the breaker in the management zone to further divide the management zone Gt; a < / RTI > distributed power management method. 10. The method of claim 9,
Further comprising the step of the DGu stopping the power supply operation if the total amount of production of all the DGi and DGu in the management zone is less than the total load in the management zone and the management zone can not be further divided, How to manage. 11. The method of claim 10,
Wherein the step of stopping the power supply operation by the DGu comprises:
And stopping all DGi connected to the feeder in the management zone. In a distributed power system,
Renewable Energy Generation Division;
A communication unit for receiving a system shutdown notification signal through a control line connected to a power system facility;
An inverter controller for switching the operation mode to an isolated operation mode in response to receiving the system shutdown announcement signal; And
And an inverter for converting the power generated by the regenerative energy generator into a DC to AC characteristic having a characteristic according to the control of the inverter controller and applying the power to the feeder connected to the independent power generation company's own distributed power source DGi,
Wherein the inverter controller controls the inverter such that the distributed power system operates in a slack bus with respect to the DGi in the isolated operation mode,
The inverter controller includes:
Wherein the inverter controls the inverter to maintain a root-mean-square value and a frequency of the output voltage of the inverter in the isolated operation mode. delete 13. The method of claim 12,
The distributed power system further includes a high frequency filter (L _S ) for filtering the high frequency included in the AC signal output from the inverter and applying the filtered high frequency to the feeder via a power grid connection point (PCC)
The inverter controller includes:
A voltage magnitude control unit for outputting a voltage magnitude parameter (V _mag ) based on a result of comparing the voltage rms value (V _rms ) of the PCC with the rms value reference value in the isolated operation mode;
Outputting a phase difference (?) Between a voltage (V) of the PCC and a voltage (V _LS ) applied across the high frequency filter based on a result of comparing the voltage frequency of the PCC with the frequency reference value in the isolated operation mode A control unit;
A phase converter for receiving a voltage at the PCC and phase conversion values generated from the phase difference and converting the phase and outputting the phase; And
And a control signal generator for generating a control signal to be provided to the inverter based on a signal that reflects the voltage magnitude parameter ( _Vmag ) to a voltage output from the phase converter,
Distributed power system. 13. The method of claim 12,
Wherein the communication unit receives a signal for starting reconnection of the feeder and the power system from a breaker between the power system and the feeder,
Wherein the inverter controller switches the operation mode to a synchronous mode in response to receiving the reconnection start signal. 16. The method of claim 15,
The inverter controller includes:
Controlling the inverter such that the magnitude and phase of the voltage of the power system and the magnitude and phase of the output voltage of the inverter are synchronized in the synchronous mode and connecting the feeder and the power system to the breaker A distributed power system for transmitting control signals. 17. The method of claim 16,
The inverter controller includes:
(V _gms ) and phase (δ _g ) of the voltage of the power system by receiving a power signal from a wire branched at a predetermined point between the breaker and the power system in the synchronization mode. 18. The method of claim 17,
The distributed power system further includes a high frequency filter (L _S ) for filtering the high frequency included in the AC signal output from the inverter and applying the filtered high frequency to the feeder via a power grid connection point (PCC)
The inverter controller includes:
A voltage magnitude controller for generating and outputting a voltage magnitude parameter (V _mag ) based on a result of comparing a voltage effective value (V _rms ) of the PCC with a voltage effective value (V _grms ) of the power system in the synchronous mode;
(V) applied to both ends of the high frequency filter and the voltage (V _LS ) of the PCC based on a result of comparing the voltage phase (?) Of the PCC with the voltage phase (? _G ) A phase control unit for outputting a phase difference?
A phase converter for receiving a voltage at the PCC and phase conversion values generated from the phase difference and converting the phase and outputting the phase; And
And a control signal generator for generating a control signal to be provided to the inverter based on a signal that reflects the voltage magnitude parameter ( _Vmag ) to a voltage output from the phase converter,
Distributed power system. Is to applied, but controls the inverter output and receives the generated power of the distributed power converted to ac power, the inverter output power to the feeder via a connection point (PCC) through the high frequency filter (L _S), the drive controller In this case,
A voltage magnitude control unit for outputting a voltage magnitude parameter (V _mag ) based on a result of comparing a voltage rms value (V _rms ) of a PCC connected to the inverter to a predetermined _rms value in an isolated operation mode;
Outputting a phase difference (?) Between a voltage (V) of the PCC and a voltage (V _LS ) applied across the high frequency filter based on a result of comparing the voltage frequency of the PCC with the frequency reference value in the isolated operation mode A control unit;
A phase converter for receiving a voltage at the PCC and phase conversion values generated from the phase difference and converting the phase and outputting the phase; And
And a control signal generator for generating a control signal to be provided to the inverter based on a signal that reflects the voltage magnitude parameter (V _mag ) to a voltage output from the phase converter,
And an inverter controller responsive to receipt of the system shutdown notification signal via a control line connected to the power system facility to switch to the isolated operation mode. 20. The method of claim 19,
Wherein the voltage magnitude control unit comprises:
Generates and outputs a voltage magnitude parameter (V _mag ) based on a result of comparing the voltage effective value (V _rms ) of the PCC with the voltage effective value (V _grms ) of the power system in the synchronous mode,
Wherein the phase control unit comprises:
Voltage in the synchronization mode in which a voltage is applied to the phase (δ) of the PCC to the voltage phase (δ _g) resulting voltage (V) of the PCC on the basis of a comparison of the and the high frequency filters both ends of the power system (V _LS) And outputs the phase difference? 21. The method of claim 20,
And in response to receiving a reconnection start signal from the feeder and the power system from a breaker between the power system and the feeder, switches the operation mode to the synchronous mode.

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