KR20200041045A - Apparatus for controlling transformer utility for new renewable energy and method thereof - Google Patents

Abstract

Disclosed are a device for controlling a transformer facility for new renewable energy and a method thereof. The device for controlling a transformer facility for new renewable energy comprises: a transformer facility connecting power outputted from a new renewable energy source to a grid; an energy storage device connected to the transformer facility to correspond to and compensate for output fluctuations; and a central control unit, after receiving an output amount of the new renewable energy source and a command of a grid operator to determine an output command of the new renewable energy source, setting the output amount in accordance with a state of the energy storage device for securing a reserve force, adjusting the output command in accordance with a state of the transformer facility, and adjusting output of the new renewable energy source and the transformer facility.

Description

Control device and method of substation facility for renewable energy {APPARATUS FOR CONTROLLING TRANSFORMER UTILITY FOR NEW RENEWABLE ENERGY AND METHOD THEREOF}

The present invention relates to a control device and a method of a substation facility for renewable energy, and more specifically, to respond to output fluctuation by connecting a compensation facility to a dedicated substation that exclusively links renewable energy. It relates to a control device and method for a new and renewable energy substation facility that can minimize the output variability by maintaining the power quality of the connecting point by relaxing the system standards and securing reserve power.

In general, a power system is a system in which power plants, substations, transmission and distribution lines, and loads are integrated to generate power and consume power.

In the power system, the demand and supply must be balanced due to the homogeneity of generation and consumption of power, so the monitoring of power demand must be continuously conducted.

In the early stages of small-scale power systems, monitoring was easy, but as power demand increased and power generation using new and renewable energy increased due to industrial advancement and informatization, power facilities were also scaled up and complicated. The limits are being reached to effectively operate the system.

Background art of the present invention is disclosed in Republic of Korea Patent Publication No. 2013-0098079 (2013.09.04. Public, power supply control device in a substation and its method).

In recent years, large-scale new and renewable energy sources are directly connected to the transmission line, and small-scale new and renewable energy sources are connected to the distribution lines and distribution lines, together with general customers (loads). Will be linked to.

The renewable energy source connected to the distribution general line causes power quality problems such as voltage rise and power factor and harmonics due to fluctuation in output depending on weather conditions, and when the connected capacity is increased, it is a renewable energy source than the power supplied to the distribution load Due to the generation of reverse algae with a large amount of power generated by the company, protection problems and system operation problems have occurred, and KEPCO is limiting the capacity of new and renewable energy per per compressor of the new and renewable energy connected substation (1Bank 50MW).

In order to expand the acceptance of new and renewable energy in line with the explosive increase in the number of new and renewable energy systems, a new and renewable energy substation (integrated new and renewable energy connected to the distribution system and directly connected to the transmission level) is under development, but in the case of simple renewable energy substation Although it is possible to solve the impact on the general load linked to the distribution system, there is a problem that it is impossible to fundamentally solve the power quality problem caused by the new and renewable energy output fluctuation and secure the reserve ratio according to the new and renewable energy output fluctuation.

As such, a large-scale renewable energy power source is directly connected to a transmission-class substation, and power quality standards are applied in consideration of other loads associated with the substation. However, at this point in time, the capacity and installation location of new and renewable energy are continuously increasing, and the expansion of substation facilities (transformer expansion, additional installation of substations) to expand the supply of new and renewable energy is a link point where new and renewable energy is intensively linked. It is necessary to pay attention to and apply the basic requirements.

In addition, it is necessary to perform control of renewable energy within a predictable range from the viewpoint of volatility of new and renewable energy.

The present invention has been devised in accordance with the necessity as described above, and the object of the present invention according to one aspect is to respond to output fluctuation by linking a compensation facility to a dedicated substation that exclusively links renewable energy. It is to provide a control device and method for a new and renewable energy substation facility that can minimize the output variability by maintaining the power quality of the connecting point by relaxing the system standards and securing reserve power.

A control device for a new and renewable energy substation facility according to an aspect of the present invention includes: a substation facility that connects power output from a new and renewable energy source to a system; An energy storage device that compensates for output fluctuation in connection with a substation facility; And after receiving the output of the new and renewable energy source and the command of the system operator, determine the output command of the new and renewable energy source, set the output quantity according to the state of the energy storage device for securing reserve power, and output the output command according to the state of the substation facility. It characterized in that it comprises; a central control unit for adjusting the output of the renewable energy source and the substation facility by adjusting.

In the present invention, the renewable energy source is characterized in that it comprises at least one of a wind generator and a solar generator.

In the present invention, the substation facility is characterized in that it is a dedicated substation facility of a renewable energy source from which load is excluded.

In the present invention, the central control unit is characterized in that it determines the output command based on a set ratio that can secure the reserve power according to the command of the system operator with respect to the total amount of output of the associated renewable energy source.

In the present invention, the central control unit is characterized in that, when setting the output amount of the energy storage device, the system frequency is measured and the required frequency IR is calculated, and then the system frequency adjustment coefficient of the energy storage device is adjusted and set according to the required frequency IR.

A control method of a substation facility for renewable energy according to an aspect of the present invention includes: a central control unit receiving an output amount of a new and renewable energy source and a command from a system operator; Determining, by the central control unit, an output command of the renewable energy source according to a system operator's command; Setting, by the central control unit, an output amount of the energy storage device according to a command of the system operator; The central control unit analyzes the state of the substation facility and determines whether adjustment of the output command is necessary; And if the central control unit needs to adjust the output command, if it is possible to adjust the output command, adjusting the output command.

Adjusting the output command in the present invention is characterized in that the central control unit further comprises the step of limiting the output of the renewable energy source when it is impossible to adjust the output command.

In the present invention, the step of determining the output command of the renewable energy source includes: a central control unit collecting the power supply capability of the substation facility and calculating the stability of the system; Determining, by the central control unit, the stability of the system, if the minimum frequency point is not reached, securing the appropriate PFR required capacity; And determining, by the central control unit, an output command by calculating an output adjustment factor when an appropriate PFR required capacity can be secured.

In the present invention, the central control unit is characterized in that it further comprises the step of determining an output command by reaching the lowest frequency point or by adjusting the output adjustment factor when the proper PFR required capacity cannot be secured.

In the present invention, the step of setting the output amount of the energy storage device includes: measuring a grid frequency by a central control unit; A central control unit calculating a required frequency IR from the grid frequency; And a step in which the central control unit adjusts and sets the system frequency adjustment coefficient according to the required frequency IR.

The control device and method of a substation facility for renewable energy according to an aspect of the present invention are configured to cope with output fluctuation by connecting a compensation facility to a dedicated substation that exclusively links renewable energy. By easing the system standards, it is possible to maintain the power quality of the connecting point and secure reserve power to minimize output variability.

1 is a block diagram showing a control device for a new and renewable energy substation facility according to an embodiment of the present invention.
2 is a flowchart illustrating a control method of a substation facility for renewable energy according to an embodiment of the present invention.
3 is a flowchart illustrating a process of determining an output command of a new and renewable energy source in a method of controlling a substation facility for renewable energy according to an embodiment of the present invention.
4 is a flow chart for explaining a process of determining the output amount of the energy storage device in the control method of a substation facility for renewable energy according to an embodiment of the present invention.

Hereinafter, a control apparatus and method for a substation facility for renewable energy according to the present invention will be described with reference to the accompanying drawings. In this process, the thickness of the lines or the size of components shown in the drawings may be exaggerated for clarity and convenience. In addition, terms to be described later are terms defined in consideration of functions in the present invention, which may vary according to a user's or operator's intention or practice. Therefore, the definition of these terms should be made based on the contents throughout the present specification.

1 is a block diagram showing a control device for a new and renewable energy substation facility according to an embodiment of the present invention.

As illustrated in FIG. 1, the control device for a new and renewable energy substation facility according to an embodiment of the present invention may include a substation facility 20, an energy storage device 40, and a central control unit 30.

The substation facility 20 is a facility for linking electric power output from the renewable energy source 10 including a wind generator and a solar power generator to a system, and a renewable energy source 10 excluding a general load (not shown) It is a dedicated substation facility.

The energy storage device 40 is connected to the substation facility 20 and performs a role similar to the inertia of a synchronous generator (not shown), thereby compensating for active power by responding to output fluctuations due to rapid changes in the system with proper reserve power. have.

The central control unit 30 receives the output amount of the new and renewable energy source 10 and the command of the system operator, determines the output command of the new and renewable energy source 10, and then according to the state of the energy storage device 40 for securing reserve power. By setting the output amount and adjusting the output command according to the state of the substation facility 20, the outputs of the renewable energy source 10 and the substation facility 20 can be adjusted.

In addition, the central control unit 30 may determine an output command based on a set ratio capable of securing reserve power according to a command of a system operator with respect to the total amount of output of the associated renewable energy source 10.

That is, it is possible to calculate available resources by adjusting the ratio of the associated renewable energy source 10 to the total output amount. In the case of the linked new and renewable energy source 10, the maximum output capacity of the linked new and renewable energy source 10 is based on this, because it generally follows MPPT (Maximum Power Point Tracking) control to produce the maximum output according to a given condition. For, it is possible to determine a certain ratio of output commands to secure reserve power by the system operator's commands.

Here, the central control unit 30 sets the output amount of the energy storage device 40 within a range of maintaining a proper capacity (SOC) to secure the reserve power of the system, and charges for efficient operation of the linked renewable energy source 10. After performing the discharge algorithm first (Load shifting, Ramp rate control, etc.), the spare capacity is calculated as a resource that can be supplied to the system in real time, and a feedback loop is constructed based on this set value to generate the new renewable energy source (10). The output command can be adjusted.

At this time, the central control unit 30 measures the system frequency when setting the output amount of the energy storage device 40, calculates the required frequency IR (Inertia Response) that can maintain the frequency fluctuation rate, and then stores the energy storage device 40 according to the required frequency IR ), It is possible to secure the power system reserve by adjusting and setting the grid frequency adjustment coefficient.

As described above, according to the control device for a new and renewable energy substation facility according to an embodiment of the present invention, by configuring a compensation facility in association with a dedicated substation dedicated to linking the new and renewable energy exclusively to respond to output fluctuations. By easing the system standards, it is possible to maintain the power quality of the connecting point and secure reserve power to minimize output variability.

Figure 2 is a flow chart for explaining a control method of a substation facility for renewable energy according to an embodiment of the present invention, Figure 3 is a new and renewable in a control method of a substation facility for renewable energy according to an embodiment of the present invention Flowchart for explaining the process of determining the output command of the energy source, Figure 4 is for explaining the process of determining the output amount of the energy storage device in the control method of a new and renewable energy substation facility according to an embodiment of the present invention It is a flow chart.

As shown in FIG. 2, in the method of controlling a substation facility for new and renewable energy according to an embodiment of the present invention, first, the central control unit 30 receives the output amount of the new and renewable energy source 10 and a command from a system operator. (S10).

The central control unit 30 may monitor the state of the renewable energy source 10, the substation facility 20, and the energy storage device 40 to receive the output amount of the renewable energy source 10.

After receiving the output amount of the new and renewable energy source 10 and the command of the system operator in step S10, the central control unit 30 determines the output command of the new and renewable energy source 10 according to the command of the system operator (S20).

Here, the central control unit 30 outputs the output command of the new and renewable energy source 10 based on a set ratio capable of securing reserve power according to the command of the system operator with respect to the total amount of output of the linked new and renewable energy source 10. Can decide.

That is, it is possible to calculate available resources by adjusting the ratio of the associated renewable energy source 10 to the total output amount. In the case of the linked renewable energy source 10, since it generally follows the MPPT (Maximum Power Point Tracking) control to produce the maximum output according to a given condition, based on this, the linked renewable energy source 10 After calculating the maximum output capacity of, it is possible to determine the output command of a certain ratio to secure the reserve power by the command of the system operator based on this.

Here, Ppos: Active power resource that can be supplied to the system [MW]

Pneg: Active power resource that can be absorbed from the system [MW]

ESSmargin: Supply free capacity among ESS linked operation capacity [MW]

Pwind.mppt: Maximum output capacity of connected wind generator [MW]

Ppv.mppt: Maximum output capacity of connected solar power generator [MW]

Kwind: Coordinated wind generator output adjustment factor

Kpv: Coordinated photovoltaic generator output adjustment factor

Kdroop: System frequency adjustment factor of ESS power generation facility

If, in the case of a system composed of a plurality of substation facilities for renewable energy, the sub-linkage does not individually control the renewable energy source 10, but the ability to supply the active / reactive power of the substation facility 20 connected to the system. After gathering and evaluating the stability of the system, it is possible to supply the necessary and constant emergency / emergency reserve power according to the operating conditions and the participation ratio of the new and renewable energy source 10 as the supply capacity from each substation facility 20 to the upper system collected. Can be calculated. Thereafter, a new output adjustment coefficient (Kgain) reflecting this may be calculated to allow the output command of the new and renewable energy source 10 to be adjusted in an integrated manner.

After determining the output command of the renewable energy source in step S20, the central control unit 30 sets the output amount of the energy storage device 40 according to the command of the system operator (S30).

Here, the central control unit 30 sets the output amount of the energy storage device 40 within a range of maintaining a proper capacity (SOC) to secure the reserve power of the system, and charges for efficient operation of the linked renewable energy source 10. After performing the discharge algorithm first (Load shifting, Ramp rate control, etc.), the spare capacity is calculated as a resource that can be supplied to the system in real time, and a feedback loop is constructed based on this set value to generate a new renewable energy source (10). The output command can be adjusted.

After determining the output command of the renewable energy source 10 in step S20 and setting the output amount of the energy storage device 40 in step S30, the central control unit 30 analyzes the state of the substation facility 20 connected to the system. (S40).

After calculating the stability of the system based on the active / reactive power supply capability of the substation facility 20 connected to the system in step S40, it is determined whether adjustment of the output command is necessary to secure reserve power to improve the stability of the system ( S50).

If it is not necessary to adjust the output command in step S50, the output of the substation facility 20 is adjusted and controlled based on the determined output command (S90).

On the other hand, if adjustment of the output command is necessary in step S50, the central control unit 30 determines whether the output command can be adjusted (S60).

If it is possible to adjust the output command in step S60, the central control unit 30 adjusts the output command (S70).

However, if it is impossible to adjust the output command as a result of determining the possibility of adjustment of the output command in step S60, the central control unit 30 may limit the output of the renewable energy source 10 (S80).

Thus, according to the output command of the renewable energy source 10 and the output amount of the energy storage device 40, the central control unit 30 adjusts and controls the output of the substation facility 20 to secure output stability (S90).

When determining the output command of the new and renewable energy source 10 in the present invention, the process of calculating and adjusting the output adjustment coefficient (Kgain) for securing the reserve force in order to cope with the output fluctuation will be described in more detail. As described above, the central subsection 30 may calculate the stability of the system by collecting the active / reactive power supply capability of the dedicated substation facility 20 connected to the system (S200).

The reserve power to be supplied to the power system using the substation according to the embodiment of the present invention is divided into Inertia Response (IR) and Primary Governor Response (PGR). The IR and PGR required for the system depend on the parameters of the synchronous generator existing in the system and the overall system size, and can satisfy the relational expression such as Equation (2).

Where H is the system inertia coefficient, Srated is the total system capacity, and J is the generator moment of inertia. Most generators calculate and display the inertia coefficient considering the moment of inertia, but the total inertia coefficient can be obtained by adding the inertia coefficient of each generator as shown in Equation (3).

In this case, when the total equivalent inertia of the system is calculated, when a disturbance occurs in the system, the degree of change in frequency (ROCOF) can be obtained as shown in Equation (4).

Therefore, the frequency characteristic when recovering after disturbance occurs mainly depends on the droop coefficient value R of the generator governor. By integrating the governor parameters of the generators present in the system, the final frequency fss can be calculated after disturbance, which can be calculated as shown in Equation 5.

Maintenance of the normal frequency operating range, which is the goal of improving the acceptance limit using a substation facility, can be converted into the parameters calculated through Equation 5 above.

In order to satisfy the domestic power system reliability maintenance standard of 60 ㅁ 0.2Hz, it is possible to calculate the PGR that can be provided by the energy storage device of the corresponding substation facility and calculate the corresponding coefficient for this.

After calculating the stability as described above, it may be determined whether the lowest frequency point (Frequency nadir Point) is reached (S210).

In step S210, when it is determined whether the lowest frequency point has been reached and the lowest frequency point has been reached, the central control unit 30 adjusts the output adjustment factor Kgain of the renewable energy source 10 (S240).

On the other hand, if it is determined whether the minimum frequency point has been reached or not, the central control unit 30 determines the possibility of securing an appropriate primary frequency response (PFR) capacity (S220). That is, it is possible to compare whether the final frequency is greater than the limiting frequency.

When the proper PFR required capacity can be secured in step S220, the central control unit 30 may determine the output command by calculating the output adjustment coefficient (Kgain) (S230).

On the other hand, if the proper PFR required capacity is not secured in step S220, the central control unit 30 may determine the output command by adjusting the output adjustment coefficient (Kgain) (S240).

On the other hand, when the process for improving the system stability in response to the output fluctuation when setting the output amount of the energy storage device 40 in the present invention in more detail, the central control unit 30 as shown in Figure 4 the system frequency Is measured (S300).

After measuring the grid frequency in step S300, the required frequency IR is calculated from the grid frequency (S310).

Here, after measuring an appropriate inertia value in the system facility, an IR capable of maintaining a ROCOF of a predetermined value or more through the energy storage device 40 of the substation facility 20 may be calculated.

Therefore, in order to calculate the IR to secure the minimum frequency margin after disturbance, the inertia H can be inversely calculated based on the ROCOF value.

Here, if the ROCOF regulation is based on 0.5 Hz / s, the minimum time to reach the lowest frequency can be calculated, and among the criteria for maintaining the proper frequency in the system, the operating condition of the emergency frequency is 62 ~ 57.5 Hz. In the example, if the optimal response coefficient of the energy storage device 40 is calculated, the maximum frequency fluctuation rate of the linkage system can be limited in advance. At this time, if the optimum response coefficient is calculated at the maximum frequency variation rate of 0.5 Hz / s, active power supply corresponding to the variable frequency output can be made for up to 5 seconds.

After calculating the required frequency IR in step S310, the grid frequency adjustment coefficient (Kdroop) is adjusted to secure a reserve power for improving the system stability (S320).

As described above, according to the control device for a new and renewable energy substation facility according to an embodiment of the present invention, by configuring a compensation facility in association with a dedicated substation dedicated to linking the new and renewable energy exclusively to respond to output fluctuations. By easing the system standards, it is possible to maintain the power quality of the connecting point and secure reserve power to minimize output variability.

The present invention has been described with reference to the embodiment shown in the drawings, but this is merely exemplary, and those skilled in the art to which the art belongs can various modifications and equivalent other embodiments from this. Will understand.

Therefore, the true technical protection scope of the present invention should be defined by the following claims.

10: Renewable energy source
20: substation equipment
30: central control
40: energy storage device

Claims (10)

A substation facility that connects power output from a renewable energy source to the system;
An energy storage device connected to the substation facility to compensate for output fluctuations; And
After receiving the output amount of the new and renewable energy source and the command of the system operator, determining the output command of the new and renewable energy source, setting the output amount according to the state of the energy storage device for securing reserve power, and depending on the state of the substation facility. And a central control unit that adjusts an output command to adjust the output of the renewable energy source and the substation facility.
According to claim 1, The renewable energy source, Control device for a new and renewable energy substation facility comprising at least one of a wind generator and a solar power generator.
The control device for a new and renewable energy substation facility according to claim 1, wherein the substation facility is a dedicated substation facility of the new and renewable energy source with no load excluded.
The method according to claim 1, wherein the central control unit determines an output command based on a set ratio capable of securing reserve power according to a command of a system operator with respect to the total amount of output of the renewable energy source linked to the system. Control device for substation equipment for new and renewable energy.
The method according to claim 1, wherein the central control unit calculates a required frequency IR by measuring a grid frequency when setting the output amount of the energy storage device, and then adjusts and sets the system frequency adjustment coefficient of the energy storage device according to the required frequency IR Control device for a substation facility for renewable energy, characterized in that.
Receiving, by the central control unit, an output amount of the renewable energy source and a command of a system operator;
Determining, by the central control unit, an output command of the renewable energy source according to a system operator's command;
Setting, by the central control unit, an output amount of the energy storage device according to a command of a system operator;
Determining whether it is necessary to adjust the output command by analyzing the state of the substation facility by the central control unit; And
If the central control unit is required to adjust the output command, if the output command can be adjusted, adjusting the output command; Control method of a new and renewable energy substation facility comprising a.
7. The method of claim 6, wherein adjusting the output command further comprises limiting the output of the renewable energy source when the central control unit cannot adjust the output command. Control method of substation equipment.
The method of claim 6, wherein the step of determining the output command of the renewable energy source,
Calculating, by the central control unit, the stability of the system by collecting the power supply capability of the substation facility;
Determining, by the central control unit, the possibility of securing an appropriate PFR capacity when the stability level of the system is not reached as a result of not reaching the lowest frequency point; And
And determining, by the central control unit, the output command by calculating an output adjustment coefficient when the proper PFR required capacity can be secured.
The method according to claim 8, wherein the central control unit further comprises the step of determining the output command by adjusting the output adjustment factor when the minimum frequency point is reached or the proper PFR required capacity is not secured. Control method of substation facility for renewable energy.
The method of claim 6, wherein the step of setting the output amount of the energy storage device,
Measuring the grid frequency by the central control unit;
The central control unit calculating a required frequency IR from the grid frequency; And
And controlling, by the central control unit, adjusting and setting a grid frequency adjustment factor according to the required frequency IR.

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