KR20230038012A - Hybrid power plant operation method and system in independent system - Google Patents

Abstract

A method for operating a hybrid power plant in an isolated system of the present invention comprises the steps of establishing a control schedule; determining a control purpose and priority of each PCS with respect to a plurality of PCSs sharing a battery of the ESS; Calculating an ESS charge/discharge amount in each unit time interval to be controlled by the control schedule; distributing the ESS charge/discharge amount to the plurality of PCSs; checking the SOC of the battery while operating each PCS according to the allocated charge/discharge amount and performing a measure according to the SOC; and performing a measure according to the difference between the charge/discharge amount distribution value of the PCS and the charge/discharge amount of the PCS in operation.

Description

Hybrid power plant operating method and system in independent system {HYBRID POWER PLANT OPERATION METHOD AND SYSTEM IN INDEPENDENT SYSTEM}

The present invention relates to a method and system for operating a hybrid power plant in an independent system equipped with an ESS for stabilization while receiving power for load use from an engine generator and a renewable energy generator.

Research on independent grid-type renewable energy generation systems based on new and renewable energy such as fuel cells and solar or wind power generation in order to reduce the centralized large-scale fossil fuel generation and expand the use of new and renewable energy In particular, renewable energy generators (RG) in island and mountainous areas are attracting increasing attention because they have the advantage of not only promoting the use of new and renewable energy but also reducing the cost burden of power generation facilities.

Since renewable energy generated by using natural energy with low energy density is irregular in these renewable energy generators, in order to efficiently supply power according to power demand, renewable energy generators and energy storage devices that store generated electricity (energy storage devices) storage system, ESS) must be used in a mixed form. The necessity of an energy storage device according to the connection of renewable energy within the independent system is as follows.

In the case of an independent system that supplies load power to a diesel generator, which is an engine power plant with rotational inertia separated from a large system, energy storage devices ( ESS) must be installed together. In other words, even if the output of renewable energy fluctuates rapidly, the impact on system operation can be minimized by maintaining the output of the connection point constant through ESS charging and discharging. In addition, when the output of renewable energy is excessive and becomes larger than the load, reverse flow occurs or, on the contrary, when the output is very small and it is difficult to supply the load, it can be solved through charging and discharging of the ESS.

In the case of the existing technology for independent system operation linked with renewable energy, it is an operation technology for adjusting the frequency of the system using the Power Conditioning System (PCS) of the ESS rather than a diesel generator. In the case of an independent system with the corresponding structure, since the storage capacity of the ESS must be large, it is difficult to secure economic feasibility due to excessive initial investment, so it is very difficult to actually apply this structure.

In order to secure economic feasibility, an efficient plan is needed to stably operate renewable energy by linking an ESS with an appropriate capacity while frequency-adjusted operation based on a diesel generator like the existing independent system.

In addition, there is an existing technology for frequency adjustment operation based on a diesel generator, but a form of controlling only a diesel generator without controlling renewable energy is proposed, or only control that keeps the output of a renewable energy connection point constant is performed. stay in the structure of

In this case, the engine generator, in particular, the diesel generator is difficult to apply effectively even if controlled by an operating system (Energy Management System) because the output change is not fast. In addition, it is difficult to maximize the effect of reducing fuel consumption by renewable energy. It is necessary to have a plan to reduce the amount of power generated by diesel generators by more actively accepting renewable energy as well as controlling the constant output of the linkage point.

Republic of Korea Publication No. 10-2016-0114802 : Hybrid Power Generation System

In the hybrid power plant structure in which the frequency adjustment function of the independent system is performed by a diesel generator as an engine generator and the ESS is installed at the same connection point in parallel with renewable energy, an independent system capable of achieving both fuel consumption reduction and system stability at the same time It is intended to provide a hybrid power plant operation method and system in the system.

A method for operating a hybrid power plant in an isolated system according to an aspect of the present invention includes establishing a control schedule; determining a control purpose and priority of each PCS with respect to a plurality of PCSs sharing a battery of the ESS; Calculating an ESS charge/discharge amount in each unit time interval to be controlled by the control schedule; distributing the ESS charge/discharge amount to the plurality of PCSs; checking the SOC of the battery while operating each PCS according to the allocated charge/discharge amount and performing a measure according to the SOC; and performing a measure according to the difference between the charge/discharge amount distribution value of the PCS and the charge/discharge amount of the PCS in operation.

Here, the step of confirming the renewable energy generator output limit may be further included.

Here, establishing the control schedule may include selecting one of an HGP mode and an RFM mode for a long time interval; And when the HGP mode is selected, it may include creating an HGP control schedule as outputs for connection points between the ESS and the renewable energy generator in unit time intervals constituting the long-term time interval.

Here, in the step of determining the control purpose and order of the PCS, one of the plurality of PCSs is designated for droop control in which the output is adjusted according to the frequency, and the priority order for performing the charge and discharge amount for the remaining PCSs can be granted.

Here, in the step of distributing to the plurality of PCSs, the ESS charge/discharge amount may be allocated to the PCSs according to the priority within the limit of the maximum output value of one PCS.

Here, in the step of calculating the ESS charge/discharge amount, when the HGP mode is selected, the ESS charge/discharge amount is calculated according to the output value of the connection point prepared for each of the unit time intervals, and when the RFM mode is selected, the independent The output of the engine generator of the system may be first determined between the upper and lower limit output values, and the ESS charge/discharge amount may be calculated according to the determined engine generator output value.

Here, in the battery SOC management step, when the battery SOC is to be discharged in a state lower than the normal range, PCS discharge is stopped, and when the battery SOC is to be charged in a state higher than the normal range, to the renewable energy generator Output limits can be set for

Here, in the step of controlling the PCS output change rate, when the PCS charge/discharge amount change rate is greater than the reference value, the final PCS charge/discharge amount may be adjusted to increase or decrease within the reference value.

Here, in the step of checking the renewable energy generator output limit, the renewable energy with the smallest value among the output limit value for preventing overcharging of the PCS, the output limit value due to excessive battery SOC, and the output limit value for meeting the minimum power generation amount of the engine generator Generator output limits can be determined.

In an independent system equipped with an engine generator, a renewable energy generator, and an ESS, the hybrid power plant operating system according to another aspect of the present invention creates a control schedule and uses a plurality of PCSs that share the battery of the ESS. setting unit; a state monitoring unit for monitoring states of the engine generator, the renewable energy generator, a load, and the ESS; The ESS charge/discharge amount is calculated in each unit time period to be controlled by the control schedule, the ESS charge/discharge amount is distributed to the plurality of PCSs, and each PCS is operated according to the allocated charge/discharge amount. SoC of the battery A control unit for performing measures according to the difference between the distribution value of the charge and discharge amount of the PCS and the charge and discharge amount of the PCS in operation; and an operator interface for receiving an operator's selection of the HGP mode and the RFM mode for the control schedule, and outputting an alarm included in the action according to the SoC of the battery and the difference between the charge and discharge amount of the PCS. can do.

Here, the presetting unit includes: a schedule creation unit for creating a control schedule according to the operator's selection of the HGP mode and the RFM mode; and a PCS setting unit designating one of the plurality of PCSs for droop control in which an output is adjusted according to frequency, and giving priority to charge/discharge amount of the remaining PCSs.

Here, the control unit includes: an ESS control unit controlling the plurality of PCSs according to assigned uses and priorities; an emergency decision unit that determines whether or not an emergency situation exists according to a difference between the SoC of the battery and the charge/discharge amount distribution value of the PCS and the charge/discharge amount of the PCS being operated; And it may include an emergency action unit that performs actions and alarms in emergency situations on a case-by-case basis.

Here, the control unit may further include a renewable energy control unit for controlling the renewable energy generator according to the control schedule or action in the emergency situation.

Here, it may further include a storage unit for storing the control schedule, control purpose and order of the plurality of PCSs.

When the method and / or system for operating a hybrid power plant in an independent system according to the spirit of the present invention having the above configuration is implemented, the frequency adjustment function of the independent system is performed by a diesel generator, and the ESS is installed in parallel with renewable energy at the same connection point In a hybrid power plant with a structure to be, there is an advantage that can achieve fuel consumption reduction and system stability at the same time.

The method and/or system for operating a hybrid power plant in an independent system of the present invention has an advantage of contributing to increasing renewable energy capacity through stable operation of an independent system linked to renewable energy.

The method and/or system for operating a hybrid power plant in an independent system of the present invention has an advantage of reducing fuel consumption by reducing the amount of use of an existing diesel generator through the establishment of an eco-friendly power system in an independent system.

The method and/or system for operating a hybrid power plant in an independent system of the present invention, when the ESS is composed of a plurality of PCSs, prioritizes charging and discharging of the PCSs to reduce the time for simultaneously operating several PCSs, This has the advantage of reducing the losses incurred.

1 is a field in which a method for operating a hybrid power plant according to the spirit of the present invention is performed, and is a structural diagram showing a configuration of a hybrid power plant that can be operated as an independent system.
2 is a graph illustrating an operating pattern of a hybrid power plant according to an HGP mode.
3 is a graph illustrating an operating pattern of a hybrid power plant according to RFM mode.
4 is a configuration diagram showing a connection relationship between the hybrid power plant system of FIG. 1 and a power plant operating system according to the spirit of the present invention;
5 is a flowchart illustrating an embodiment of an operating method that can be performed in a hybrid power plant operating system in an isolated system according to the spirit of the present invention.
6 is a flowchart illustrating a specific example of a process of distributing charge and discharge amounts for each PCS.
7 is a flowchart illustrating an example of a specific process of battery SOC management;
8 is a flowchart illustrating an example of a specific process of controlling a PCS output change rate;
9 is a block diagram showing an embodiment of a hybrid power plant operating system in which a hybrid power plant operating method in an isolated system according to the spirit of the present invention is performed.

In describing the present invention, terms such as first and second may be used to describe various components, but the components may not be limited by the terms. Terms are only for the purpose of distinguishing one element from another. For example, a first element may be termed a second element, and similarly, a second element may be termed a first element, without departing from the scope of the present invention.

When a component is referred to as being connected or connected to another component, it may be directly connected or connected to the other component, but it may be understood that another component may exist in the middle. .

Terms used in this specification are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions may include plural expressions unless the context clearly dictates otherwise.

In this specification, the terms include or include are intended to designate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features or numbers, It can be understood that the presence or addition of steps, operations, components, parts, or combinations thereof is not precluded.

In addition, shapes and sizes of elements in the drawings may be exaggerated for clearer description.

1 is a field in which a method for operating a hybrid power plant according to the spirit of the present invention is performed, and is a structural diagram showing a configuration of a hybrid power plant that can be operated as an independent system.

In the present invention, the frequency adjustment function of the independent system is performed by a diesel generator as an engine generator that has rotational inertia and consumes fuel, and the ESS is installed in parallel with renewable energy at the same connection point (C) (hybrid power plant: renewable energy + ESS). ESS (10) has two or more PCSs (12-1, 12-2), one performs frequency adjustment by operating a diesel generator and droop, and the remaining PCS charge and discharge according to the control command of the operating system Do it.

The hybrid power plant system shown in FIG. 1 has a configuration in which a battery 14 is shared by a plurality of PCSs 12-1 and 12-2, and although not shown, a diesel generator is further included as an engine generator using fuel do. In another implementation, it should be noted that the diesel generator may be replaced by another generator having rotational inertia, such as a gas turbine, steam turbine, or gas (hydrogen) engine, which generates power from oxidation energy of fuel.

The diesel generator may be directly connected to the connection point, or may be connected via a load of an independent system in charge of the diesel generator.

As a method of controlling the PCS operation of the ESS in operating an independent system composed of a renewable energy generator, a prime mover (diesel) generator, and an ESS, it can be divided into HGP mode and RFM mode according to the purpose of PCS operation.

In the present invention, by applying the HGP mode and the RFM mode, in order to maximize fuel consumption reduction by renewable energy, a diesel generator fuel consumption minimum operation method and a link point constant output operation method for stable operation can be selectively performed. . That is, it has two operation modes, which are selected according to the needs of the operator (member) of the power plant. Both of the above two operation modes have a method of performing and controlling an operation for determining the charge/discharge value of the ESS.

2 is a graph illustrating an operating pattern of a hybrid power plant according to an HGP mode.

3 is a graph illustrating an operating pattern of a hybrid power plant according to RFM mode.

The HGP mode (Hybrid Generation Plant Mode) is for operation such that output at a hybrid power plant connection point is constantly maintained. ESS according to renewable energy output so that a predetermined link point output pattern is used by reflecting the predicted load pattern of the system and the hybrid power plant link point output is determined for each control target time interval so that the link point output pattern can be maintained perform charging and discharging of

The HGP mode has an operational purpose of minimizing the impact of the hybrid power plant on the operation of the diesel power plant, and the diesel generator supplies the remaining load excluding the output value of the hybrid power plant connection point from the total load, and operates stably without sudden output change. this is possible

The RFM mode (Renewable Fraction Maximization Mode) is to operate the economically/environmentally unfavorable diesel power plant to minimize fuel consumption. Considering the maximum and minimum operating capacity of the diesel generator, the diesel generator operates within the operating range (between the minimum operating capacity and the maximum operating capacity), and within the range, renewable energy generation is performed as much as possible. In the RFM mode, the diesel generator operates below the lower limit (minimum load factor) and the ESS performs charging

The RFM mode can supply the maximum load through renewable energy output, maximizing the reduction in system operating costs (diesel power plant fuel cost), and in the event of an abnormality, the output of the diesel generator is increased to restore it to a normal range.

In the present invention, two operation modes are performed, but a specific plan is proposed to enable stable operation by dividing them into a normal state and an emergency state according to the state of the PCS and battery, which are components of the ESS. More specifically, in the case of PCS, the rated capacity is not exceeded due to excessive charge and discharge, and in the case of batteries, the state of charge (SOC) is not excessively low or high.

As a method of classifying a normal state and an emergency state according to the state of the PCS and the battery, the definition of the state according to the PCS charge/discharge amount and the battery PCS is shown in Table 1 below.

However, referring to FIGS. 2 and 3, in the case of the HGP mode, stable operation with a small output fluctuation rate of each driving entity is possible, and in the case of the RFM mode, economical and eco-friendly operation is possible, but the output fluctuation rate of each driving entity is high and the system stability and hardware durability of each driving entity.

Therefore, it is ideal to operate in the third improved mode in which the disadvantages are improved with the advantages of the HGP mode and the RFM mode.

However, for the purpose of operating a hybrid power plant, the weights for various items such as economic feasibility, eco-friendliness, stability, and durability are different for each case (location of power plant, subject, time), and the subject of consideration is also considered in performing the HGP mode and RFM mode. Since there are many parameters that can be used, it is extremely difficult to newly configure a driving mode that combines only the advantages of the two driving modes.

Even in the case of machine learning or big data technologies, which are recently applied in various fields, when there are many parameters to be considered, a large amount of sufficiently accumulated actual operating data is required, making it difficult to learn each of the HGP mode and RFM mode. am.

As a method that can be optimally applied in the field in the above-described practical circumstances, in the present invention, based on the HGP mode and RFM mode that are currently applied or are being applied to the field and are familiar to operators, an improved method for mitigating the corresponding disadvantages for each mode A new control method is formed, and a method of selecting and operating between the improved HGP mode and the improved RFM mode for a long-term time period, which is a relatively long-term control target, is presented to the power plant operator.

4 is a configuration diagram showing a connection relationship between the hybrid power plant system of FIG. 1 and the power plant operating system 100 according to the spirit of the present invention. The main components of the illustrated system are renewable energy (wind power, solar power), ESS and operating system.

In the illustrated system, the renewable energy power plant 80 is connected to the operator's operating system 100 through communication with renewable energy (wind power, solar power), and provides real-time status information (operation/stop, generation amount, etc.) through this. and can be controlled.

In the illustrated system, the ESS 10 is composed of two or more PCSs 12-1 to 12-3 and a battery 10 that they share, and is installed in parallel at the same connection point as the renewable energy generator 80 and perform charging and discharging. According to the policy of the present invention, one PCS (12-1) performs Droop operation in synchronization with the diesel generator 30, and the remaining PCSs (12-2, 12-3) follow the command according to the spirit of the present invention. charging and discharging by Like the renewable energy generator 80, it is linked to the operating system 100 through communication, and through this, it is possible to provide status information (charge/discharge amount, SOC, etc.) and control.

The hybrid power plant operating system 100 monitors (collects data) the entire system (renewable energy, ESS, diesel generator, load) in real time and performs calculations according to the operating logic presented in the present invention. All information (status monitoring, calculation results) can be visually expressed through HMI (Human-Machine Interface) and delivered to the operator in real time.

The hybrid power plant operating system 100 in an isolated system according to the spirit of the present invention may be built as a SW and / or HW module inside the isolated system operating system, or installed in parallel in the same place as the isolated system operating system. there is.

5 is a flowchart illustrating an embodiment of an operating method that can be performed in a hybrid power plant operating system in an isolated system according to the spirit of the present invention.

The purpose of the hybrid power plant operation method proposed in the present invention is to calculate and control the final appropriate charge/discharge value of the ESS after calculation using the state data of facilities and loads. The operation logic has a different calculation method depending on the operation mode (HGP mode, RFM mode), and is repeatedly performed in real time at regular intervals.

The method for operating a hybrid power plant in an independent system shown in FIG. 4 includes establishing a control schedule for an output of a connection point (S100); For the plurality of PCSs of the ESS of the independent system, determining the control purpose (method) and priority of each PCS (S200); Calculating an ESS charge/discharge amount in each time interval subject to control of the control schedule (S300); Distributing the ESS charge/discharge amount to the plurality of PCSs according to whether the charge/discharge amount is normal/abnormal (S400); Checking the SoC of the battery while operating each PCS according to the allocated charge/discharge amount and taking action according to the SoC (S500); and performing a measure according to the difference between the charge/discharge amount distribution value of the PCS and the charge/discharge amount of the PCS in operation (S600).

Depending on the implementation, a step (S700) of checking the renewable energy output limit in an emergency may be further included.

Hereinafter, detailed operation processes of each step will be described.

In the step of establishing the control schedule (S100), control schedules are established for each of the two operation modes (HGP mode and RFM mode). In particular, establishing a control schedule for the HGP mode is meaningful.

In the case of the HGP mode control schedule, the hybrid power plant's link point output pattern is established in advance through the system load prediction or existing load pattern analysis, and the corresponding schedule (link point output pattern and load pattern) is reflected in the operating system.

In the case of RFM mode, depending on the implementation, no schedule is provided, or a separate temporal schedule is not provided, but an optimal rpm level according to conditions is specified (eg, step-by-step rpm level regulation according to load/peak season), or a diesel power plant As a plan for operation, a schedule consisting of rpm patterns or fuel supply patterns can be established.

In the PCS prioritization step (S200), one of the PCSs of the ESS in this system automatically performs droop control in which the output is adjusted according to the frequency, and the remaining PCS performs output control according to the calculated charge and discharge amount can be set to do so.

At this time, when the remaining PCS is two or more, if the corresponding value is equally distributed in a state where the charge/discharge amount is small, the loss in the PCS increases and the efficiency decreases. To prevent this, the maximum output value of the PCS is set based on the PCS rated capacity, and if the charge/discharge amount is less than the maximum output value, the output command for all values is given to one PCS according to the set priority. If it is greater than the maximum output value, it is possible to reduce the loss occurring in the PCS by reducing the time for operating two or more PCSs simultaneously by executing the output command to the lower priority PCS by the exceeded value.

For example, the PCS assigned to the Droop control may perform output control according to the Droop control signal of the diesel generator.

Steps S100 and S200 can be regarded as performing a kind of setting for operation before operation of the hybrid power plant, and may be performed in reverse order or concurrently.

In the ESS charge/discharge amount calculation step (S300), the ESS charge/discharge amount calculation method differs according to the two modes (HGP, RFM) applied in the present invention. negative (-) when discharging, positive (+) when discharging)

First, in the case of the HGP mode, the ESS charge/discharge value for each time interval to be controlled is calculated according to the linkage point output schedule previously input to the operating system, for example, as shown in Equation 1 below.

In the case of the load pattern, the weight is reflected in the formula by considering the error with the current value.

So that the error is reflected in the calculation of the charge/discharge value.

On the other hand, in RFM mode, when the diesel generator is operated between the upper and lower output values (maximum or minimum load factor × rated capacity), renewable energy is controlled to generate maximum power without separate ESS control. That is, the output value of the diesel generator is first determined between the upper and lower limit output values, and the ESS charge/discharge amount is calculated according to the determined output value of the diesel generator. For example, the ESS charge/discharge amount may be calculated as a deficiency/excess of the estimated renewable energy generation amount of the determined diesel generator output value for the expected load amount in the corresponding unit control section.

The upper and lower limit output values may be determined according to Equations 2 and 3 below, for example.

If it is out of the upper/lower limits, it is restored to the normal range through ESS control.

In Equations 1 to 3, the definition of each parameter is as follows.

P _ESS : ESS charge/discharge amount [kW]

P _HGP : HGP mode connection point output schedule value [kW]

P _renew : Renewable energy generation value [kW]

: 계통 부하 스케쥴값 [kW]

: Grid load schedule value [kW]

: 계통 부하 현재값 [kW]

: Grid load present value [kW]

WF _load : load error weight [%]

CAP _diesel : Rated capacity of diesel generator [kW]

: 디젤발전기 최소 부하율 [%]

: Diesel generator minimum load factor [%]

: 디젤발전기 최대 부하율 [%]

: Diesel generator maximum load rate [%]

6 is a flowchart illustrating a specific example of a process of distributing charge and discharge amounts for each PCS.

Next, in the step of distributing the charge/discharge amount for each PCS (S400), the calculated charge/discharge amount may be distributed according to the priority of the PCS as shown in the flowchart of FIG. 6, for example.

The formula in the following example is exemplified in the case of two PCSs of the ESS receiving the output command, and when the number of PCSs is greater than this, it is also calculated by the same method, and this also falls within the scope of the present invention. Of course.

), 다시 충·방전량의 크기에 따라 아래와 같이 구분할 수 있다(S410). (A) In case the charge/discharge amount is the steady state value (

), and can be classified as follows according to the size of the charge/discharge amount (S410).

), 하기 수학식 4와 같이 우선순위 PCS 1대에만 지령할 수 있다(S420, S430).If the normal state charge/discharge amount is less than the maximum output value (

), as shown in Equation 4 below, only one priority PCS can be commanded (S420, S430).

), 하기 수학식 5 및 6과 같이, 우선순위 PCS에 최대 출력값을, 후순위 PCS에 나머지 출력값을 지령할 수 있다(S440).On the other hand, if the steady state charge/discharge amount is greater than the maximum output value and less than the maximum output value × 2 (

), and as shown in Equations 5 and 6 below, the maximum output value may be commanded to the priority PCS and the remaining output values to the lower priority PCS (S440).

Here, since the sign of the value is different according to charge and discharge, the formula is different for each case.

), 하기 수학식 7과 같이 PCS에 모두 동일하게 출력값을 지령할 수 있다(S450).(B) In case of abnormal charging and discharging amount (

), the same output values can be commanded to all PCSs as shown in Equation 7 below (S450).

Along with this, necessary alarms are displayed through the operating system according to the charge/discharge state and operation mode (S460) so that the operator (won) of the hybrid power plant can take measures to restore the charge/discharge amount to a normal state (S470). ), in the case of charging, the renewable energy output limit value can be calculated (S480). At this time, the calculated output limit value may be used as a command value when renewable energy is not stopped.

An example of alarm display in each specific case is as follows.

1) During discharge & in HGP mode, the following alarm can be displayed through the operating system to reduce the value of discharge amount. : “Need to change HGP mode schedule due to PCS overload (discharge)”

2) During discharge & RFM mode, the following alarm can be displayed through the operating system to reduce the value of discharge amount. : “Need to start diesel generator or increase output due to PCS overload (discharge)”

3) During charging & in HGP mode, the following alarm can be displayed through the operating system to reduce the charge value: “HGP mode schedule change or renewable energy stop required due to PCS overload (charging)”

At this time, the renewable energy output limit value can be calculated according to Equation 8 below.

4) During charging & RFM mode, the following alarms can be displayed through the operating system to reduce the charging amount value. : “Need to stop diesel generator or stop renewable energy due to PCS overload (charging)”

At this time, the renewable energy output limit value can be calculated according to Equation 8 above.

In Equations 4 to 8 above, the definition of each parameter is as follows.

PMAX : Maximum output value of one PCS [kW]

: 우선순위 PCS의 출력값 [kW]

: Output value of priority PCS [kW]

: 후순위 PCS의 출력값 [kW]

: Output value of subordinated PCS [kW]

: PCS 과충전으로 인한 재생에너지 출력 제한값 [kW]

: Renewable energy output limit value due to PCS overcharging [kW]

Based on the charge/discharge amount distributed to each PCS obtained by sequentially performing the steps S300 and S400, the hybrid power plant operating system according to the spirit of the present invention controls each PCS, so that charge/discharge for the distributed charge/discharge amount is carried out

7 is a flowchart illustrating an example of a specific process of battery SOC management.

The illustrated battery SOC management step (S500) is to ensure that the SOC of the battery is maintained within a normal (proper) range for stable operation of the system. This is because operation is stopped when the SOC of the battery goes out of the normal (proper) range, which can cause problems in system operation.

While operating each PCS according to the distribution amount determined in the step S400 in the target unit time interval, the SOC of the battery shared by the PCSs is checked (S510).

), 정상상태이므로 별도의 동작을 수행하지 않고, 상기 결정된 배분량에 따라 각 PCS들을 계속 운영한다.If SOC is normal at each check point (

), since it is a normal state, no separate operation is performed, and each PCS continues to be operated according to the determined distribution amount.

), 하이브리드 발전소 운영자가 SOC를 정상상태로 회복하기 위한 조치를 취할 수 있도록 충·방전 상태 및 운전모드에 따라 운영시스템을 통해 필요한 알람을 표출할 수 있다. 이때, 만약 방전시의 경우 PCS 방전을 정지하며, 충전시의 경우 재생에너지 출력 제한값을 계산한다.On the other hand, if the SOC is in an abnormal state at a specific check point (

), necessary alarms can be expressed through the operating system according to the charge/discharge status and operation mode so that the hybrid power plant operator can take measures to restore the SOC to a normal state. At this time, in case of discharging, PCS discharging is stopped, and in case of charging, a limit value for output of renewable energy is calculated.

The calculated output limit value is used as a command value when renewable energy is not stopped.

An example of alarm display and emergency action in each specific case is as follows.

) & 방전시 & HGP 모드에서는, SOC 적정 범위 회복(SOC 상향)을 위해 운영시스템을 통해 다음 알람을 표출할 수 있다(S530, S550). : “HGP 모드 스케쥴 변경 또는 디젤발전기/재생에너지 기동 필요”1) Low SOC (

) & during discharge & in HGP mode, the following alarm can be displayed through the operating system to recover the proper SOC range (SOC increase) (S530, S550). : “Need to change HGP mode schedule or start diesel generator/renewable energy”

In addition, as an emergency measure, PCS discharge can be stopped.

) & 방전시 & RFM 모드에서는, SOC 적정 범위 회복(SOC 상향)을 위해 운영시스템을 통해 다음 알람을 표출할 수 있다(S530, S550). : “디젤발전기/재생에너지 기동 필요”2) Low SOC (

) & during discharge & RFM mode, the following alarm can be expressed through the operating system to recover the SOC proper range (SOC increase) (S530, S550). : “Need to start diesel generator/renewable energy”

In addition, as an emergency measure, PCS discharge can be stopped.

On the other hand, since the possibility of burden or risk is low when charging at low SOC (example of S520), it proceeds without any special measures.

) & 방전시 & HGP 모드에서는, SOC 적정 범위 회복(SOC 하향)을 위해 운영시스템을 통해 다음 알람을 표출할 수 있다(S540, S560). : “HGP 모드 스케쥴 변경 또는 디젤발전기/재생에너지 정지 필요”3) High SOC (

) & during discharge & in HGP mode, the following alarm can be expressed through the operating system to recover the proper SOC range (SOC lowering) (S540, S560). : “Need to change HGP mode schedule or stop diesel generator/renewable energy”

In addition, the renewable energy output limit value can be calculated according to Equation 9 below.

) & 방전시 & RFM 모드에서는, SOC 적정 범위 회복(SOC 하향)을 위해 운영시스템을 통해 다음 알람을 표출할 수 있다(S540, S560). : “HGP 모드 스케쥴 변경 또는 디젤발전기/재생에너지 정지 필요”high SOC (

) & during discharge & RFM mode, the following alarm can be displayed through the operating system to recover the SOC proper range (SOC lowered) (S540, S560). : “Need to change HGP mode schedule or stop diesel generator/renewable energy”

In addition, the renewable energy output limit value can be calculated according to Equation 9 above.

On the other hand, since the possibility of burden or risk is low when discharging at high SOC (No in S520), it proceeds without any special measures.

In Equation 9, the definition of each parameter is as follows.

SOC: battery charge [%]

: SOC의 적정 범위 하한값 [%]

: SOC lower limit of appropriate range [%]

: SOC의 적정 범위 상한값 [%]

: upper limit of the appropriate range of SOC [%]

: SOC 과다로 인한 재생에너지 출력 제한값 [kW]

: Renewable energy output limit value due to excessive SOC [kW]

8 is a flowchart illustrating an example of a specific process of controlling a PCS output change rate.

In the illustrated PCS output change rate control step (S600), when the charge and discharge amount of the PCS rapidly changes in the independent system, the frequency changes rapidly, which can cause instability in system operation (generator stress, power failure due to generator dropout) Bar, in order to prevent this, the charge and discharge amount of the PCS is controlled so that it does not change rapidly.

If there is a large difference between the PCS charge/discharge amount distribution value calculated in step S400 and the current PCS charge/discharge amount, the operating system controls the charge/discharge amount change rate not to exceed a certain range. That is, in order to prevent the PCS output from rapidly changing to the target command value, the corresponding logic is repeatedly performed at regular intervals to change to the target command value over several cycles.

In FIG. 8 , the charge/discharge amount change rate and the reference value are compared (S610), and the following processes are performed according to the result (S620, S630).

)에는, 하기 수학식 10과 같이 앞서 계산된 충·방전량 값을 그대로 적용할 수 있다(S620).1) When the charge/discharge amount change rate is less than the reference value (

), the previously calculated charge/discharge amount value can be applied as shown in Equation 10 below (S620).

)에는, 다시 현재값과 계산값을 비교한다(S630).2) When the charge/discharge amount change rate is greater than the reference value (

), the current value and the calculated value are compared again (S630).

), 하기 수학식 11에 따른 충·방전량 값을 그대로 적용할 수 있다.As a result of comparison, if the calculated value is greater than the current value (

), the charge and discharge value according to Equation 11 below can be applied as it is.

), 하기 수학식 12에 따른 충·방전량 값을 그대로 적용할 수 있다.As a result of comparison, if the calculated value is smaller than the current value (

), and the charge/discharge value according to Equation 12 below can be applied as it is.

In Equations 10 to 12, the definition of each parameter is as follows.

: 우선순위 PCS의 최종 출력 지령값 [kW]

: Final output command value of priority PCS [kW]

: 우선순위 PCS의 출력 현재값 [kW]

: Current output value of priority PCS [kW]

PCR: Reference value for rate of change in charge and discharge amount of PCS [kW]

It should be noted that the above equations were prepared based on the best PCS in order of priority, and the final charge/discharge amount values of the remaining PCSs can be determined by the same method.

Among the parameters constituting the above equations, values other than expected/estimated values are values at the current point in time, recently measured values that can actually be obtained, considering the interval between sensing operations or the delay time in the sensing process. will apply

The steps S500 and S600 are performed as a confirmation (check) process while charging and discharging the distributed charge and discharge amount in each PCS, and are performed in reverse order or concurrently, depending on the implementation It can be.

In the renewable energy output limit and release step (S700), which is last performed on the flowchart of FIG. 4, the renewable energy output limit values calculated in the emergency state (PCS overcharge or battery SOC excessive) in steps S500 and S600 are mutually Since it may be different, it is to select the optimal (smallest) value and command the target renewable energy.

On the other hand, even when it is confirmed as normal rather than emergency in steps S500 and S600, the amount of power generated by the diesel generator must be greater than the set minimum amount of power. In other words, the generation amount of the diesel generator is determined by the amount of renewable energy generation and the ESS charge/discharge value. [Diesel power generation = load - renewable energy generation - ESS charge/discharge amount], so the diesel power generation must be greater than the minimum power generation, and the final regeneration reflecting this The energy output value may be applied as shown in Equation 13 below.

Even if this is not satisfied, the output limit value is applied.

Finally, if it satisfies the minimum power generation amount of the diesel generator and is in a normal state, the output limit is not performed. Otherwise, the output limit value due to PCS overcharging, the output limit value due to battery SOC excess, and the output limit value due to the minimum diesel power generation amount are set to the smallest value. Directs the output limit to the ideal renewable energy.

1) When the normal state & the minimum generation amount of the diesel generator are satisfied, the output limit can be released as shown in Equation 14 above.

2) In other cases, for example, in an emergency or when the minimum power generation amount of a diesel generator is not satisfied, renewable energy output restrictions may be applied according to Equations 15 and 16 below.

In Equations 13 to 16, the definition of each parameter is as follows.

: 재생에너지 최종 출력 제한 지령값 [kW]

: Renewable energy final output limit command value [kW]

: 디젤발전기 최소발전량 불만족으로 인한 재생에너지 출력 제한값 [kW]

: Renewable energy output limit value due to dissatisfaction with minimum generation amount of diesel generator [kW]

9 is a block diagram illustrating an embodiment of a hybrid power plant operating system in which a method for operating a hybrid power plant in an isolated system according to the spirit of the present invention is performed.

As a hybrid power plant operation system in an independent system equipped with a diesel generator, renewable energy generator and ESS, a preset unit (120 ); A state monitoring unit 110 for monitoring states of the engine generator, the renewable energy generator, the load, and the ESS; The ESS charge/discharge amount is calculated in each unit time period to be controlled by the control schedule, the ESS charge/discharge amount is distributed to the plurality of PCSs, and each PCS is operated according to the allocated charge/discharge amount. SoC of the battery A control unit 160 that performs measures according to the difference between the distribution value of the charge and discharge amount of the PCS and the charge and discharge amount of the PCS in operation; and an operator interface (180) for receiving the operator's selection of the HGP mode and the RFM mode for the control schedule, and outputting an alarm included in the action according to the SoC of the battery and the difference between the charge and discharge amount of the PCS. ) may be included.

Depending on implementation, a storage unit 150 for storing the control schedule, control purpose and order of the plurality of PCSs may be further included.

More specifically, the presetting unit 120 includes a schedule creating unit 122 that creates a control schedule according to the operator's selection of the HGP mode and the RFM mode; and a PCS setting unit 124 that designates one of the plurality of PCSs for droop control in which an output is adjusted according to frequency and gives priority to the remaining PCSs for performing charging and discharging amounts. .

The schedule preparation unit 122 may perform step S100 of FIG. 5 and the PCS setting unit 124 may perform step S200. The controller 160 may perform steps S300 to S700 of FIG. 5 .

More specifically, the control unit 160 includes an ESS control unit 162 that controls the plurality of PCSs according to assigned uses and priorities; an emergency determination unit 164 that determines whether or not an emergency situation exists according to a difference between the SoC of the battery and the charge/discharge amount distribution value of the PCS and the charge/discharge amount of the PCS being operated; And it may include an emergency action unit 166 that performs actions and alarms in emergency situations on a case-by-case basis.

Depending on the implementation, the control unit 160 may further include a renewable energy control unit 168 for controlling the renewable energy generator according to the control schedule or action in the emergency situation.

The state monitoring unit 110 receives operation values or measured values from the diesel generator, renewable energy generator, and ESS of FIG. 4 through a communication means, or receives measured values from sensors installed at each point on the independent system. there is.

The ESS control unit 162 may instruct each PCS to operate with a charge/discharge amount designated for each PCS according to the above-described processes.

The emergency determination unit 164 checks whether the SOC of the battery is within an appropriate range while performing step S500 of FIG. 5 , and determines an emergency state if it is out of the appropriate range.

The emergency determination unit 164 calculates the charge/discharge amount distribution value calculated in steps S300 and S400 so that the rated capacity is not exceeded due to excessive charge/discharge amount of the PCS during step S600 of FIG. ·As the difference in discharge amount, the PCS charge/discharge amount change rate is compared with the reference value, and if it is out of the reference value, it is determined as an emergency state.

The emergency action unit 166 outputs various alarm phrases in the emergency state described above to the operator interface 180 in steps S500 and S600 of FIG. 5, and stops the PCS in conjunction with the ESS control unit 162 emergency measures such as, performing emergency measures such as stop in conjunction with the renewable energy control unit 168, and emergency measures such as stop and emergency operation in conjunction with a diesel generator control unit (not shown) can be performed. .

The operator interface 180 supports an operation in which the hybrid power plant operator designates one of the HGP mode and the RFM mode for a long time period in step S100, and outputs various alarm phrases in steps S500 and S600. and the PCS to be operated in the droop mode may be input from the hybrid power plant operator in step S200.

Depending on the implementation, the operator interface 180 may share some of the interface means such as the user console of the independent system operating system mentioned in the description of FIG. 4 .

The above description is merely an example of the technical idea of the present invention, and various modifications and variations can be made to those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention, but to explain, and the scope of the technical idea of the present invention is not limited by these embodiments. The protection scope of the present invention should be construed according to the claims below, and all technical ideas within the equivalent range should be construed as being included in the scope of the present invention.

110: state monitoring unit 120: presetting unit
122: schedule creation unit 124: PCS setting unit
150: storage unit 160: control unit
162: ESS control unit 164: emergency determination unit
166: emergency action unit 168: renewable energy control unit
180: operator interface

Claims (14)

Establishing a control schedule;
determining a control purpose and priority of each PCS with respect to a plurality of PCSs sharing a battery of the ESS;
Calculating an ESS charge/discharge amount in each unit time interval to be controlled by the control schedule;
distributing the ESS charge/discharge amount to the plurality of PCSs;
checking the SOC of the battery while operating each PCS according to the allocated charge/discharge amount and performing a measure according to the SOC; and
Step of taking action according to the difference between the charge/discharge amount distribution value of the PCS and the charge/discharge amount of the PCS in operation
A hybrid power plant operating method in an independent system including a.
According to claim 1,
Steps to Check Renewable Energy Generator Output Limits
Hybrid power plant operating method in an independent system further comprising a.
According to claim 1,
Establishing the control schedule,
selecting one of the HGP mode and the RFM mode for a long time interval; and
When the HGP mode is selected, creating an HGP control schedule as outputs for the connection point of the ESS and the renewable energy generator in the unit time intervals constituting the long-term time interval
A hybrid power plant operating method in an independent system including a.
According to claim 1,
In the step of determining the control purpose and order of the PCS,
One of the plurality of PCSs is designated for droop control in which an output is adjusted according to frequency,
A method of operating a hybrid power plant in an independent system that prioritizes charging and discharging for the remaining PCSs.
According to claim 4,
In the step of distributing to the plurality of PCSs,
A hybrid power plant operation method of distributing the ESS charge/discharge amount to PCSs according to the priority within the limit of the maximum output value of one PCS.
According to claim 3,
In the step of calculating the ESS charge and discharge amount,
When the HGP mode is selected, the ESS charge/discharge amount is calculated according to the output value of the connection point prepared for each of the unit time intervals;
When the RFM mode is selected, the output of the engine generator of the independent system is first determined between the upper and lower limit output values, and the ESS charge and discharge amount is calculated according to the determined engine generator output value. How to operate a hybrid power plant in an independent system.
According to claim 2,
In the battery SOC management step,
When the battery SOC is to be discharged in a state lower than the normal range, the PCS discharge is stopped,
A method of operating a hybrid power plant in an independent system for setting an output limit value for the renewable energy generator when the battery SOC is to be charged in a state higher than the normal range.
According to claim 2,
In the PCS output change rate control step,
A method of operating a hybrid power plant in an independent system in which the final PCS charge/discharge amount is adjusted to increase or decrease within the reference value when the PCS charge/discharge amount change rate is greater than the reference value.
According to claim 7,
In the step of checking the renewable energy generator output limit,
A hybrid power plant operation method in an independent system that determines the renewable energy generator output limit to the smallest value among the output limit value for preventing overcharging of the PCS, the output limit value due to excessive battery SOC, and the output limit value for meeting the minimum power generation amount of the engine generator .
As a hybrid power plant operating system in an independent system equipped with an engine generator, renewable energy generator and ESS,
a presetting unit for creating a control schedule and setting a usage method and order of a plurality of PCSs sharing the battery of the ESS;
a state monitoring unit for monitoring states of the engine generator, the renewable energy generator, a load, and the ESS;
The ESS charge/discharge amount is calculated in each unit time period to be controlled by the control schedule, the ESS charge/discharge amount is distributed to the plurality of PCSs, and each PCS is operated according to the allocated charge/discharge amount. SoC of the battery A control unit for performing measures according to the difference between the distribution value of the charge and discharge amount of the PCS and the charge and discharge amount of the PCS in operation; and
An operator interface for receiving an operator's selection of the HGP mode and RFM mode for the control schedule and outputting an alarm included in the action according to the SoC of the battery and the action according to the difference between the charge and discharge amount of the PCS
A hybrid power plant operating system in an independent system including
According to claim 10,
The preset unit,
a schedule creation unit that creates a control schedule according to the operator's selection of the HGP mode and the RFM mode; and
A PCS setting unit that designates one of the plurality of PCSs for droop control in which output is adjusted according to frequency, and gives priority to charge and discharge amounts for the remaining PCSs.
A hybrid power plant operating system in an independent system including
According to claim 10,
The control unit,
an ESS control unit controlling the plurality of PCSs according to assigned uses and priorities;
an emergency decision unit that determines whether or not an emergency situation exists according to a difference between the SoC of the battery and the charge/discharge amount distribution value of the PCS and the charge/discharge amount of the PCS being operated; and
Emergency action department that performs actions and alarms in emergency situations on a case-by-case basis
A hybrid power plant operating system in an independent system including
According to claim 12,
The control unit,
Renewable energy controller for controlling the renewable energy generator according to the control schedule or action in the emergency situation
A hybrid power plant operating system in an independent system further comprising a.
According to claim 10,
A storage unit for storing the control schedule, control purpose and order of the plurality of PCSs
A hybrid power plant operating system in an independent system further comprising a.

Images