KR101706078B1 - Optimization method for hybrid renewable energy system using pinch analysis - Google Patents

Abstract

Disclosed is a method to optimize a hybrid renewable energy system. According to an embodiment of the present invention, the method to optimize a hybrid renewable energy system, including a hydrogen storage system and a battery as an energy storage method, includes: a step of calculating a minimum external power supply amount and available surplus power for the next day from systems except the hydrogen storage system through pinch analysis based on daily power production and consumption; a step of converting the minimum external power supply amount and available surplus power for the next day into monthly values and then calculating power, required from the hydrogen storage system, and power stored in the hydrogen storage system in each monthly time section; a step of calculating pure storable/necessary power of the hydrogen storage system in each time section; a step of calculating a required external power supply amount and a power capacity, accumulated in the hydrogen storage system in each time section for the first year of operation; a step of calculating minimum required power for the first year of operation and available surplus power for the next year, stored in the hydrogen storage system; a step of calculating a required external power supply amount and a power capacity, accumulated in the hydrogen storage system in each time section for a general year of operation; and a step of determining an optimal capacity of the hydrogen storage system based on the accumulated power capacity of the hydrogen storage system, calculated for the general year of operation.

Description

[0001] OPTIMIZATION METHOD FOR HYBRID RENEWABLE ENERGY SYSTEM USING PINCH ANALYSIS [0002]

The present invention relates to a method of optimizing a hybrid regenerative energy system, and more particularly, to an optimization method for optimal capacity design of a hydrogen storage system in a hybrid regenerative energy system including a battery and a hydrogen storage system as energy storage means will be.

Renewable energy such as solar power, wind power, and biomass is attracting attention due to fossil fuel depletion, climate change, and environmental problems. Particularly, in an area where it is difficult to connect with a conventional power grid network, such a renewable energy system is considered to be constructed in an off-grid form. The main problem that arises in off-grid type renewable energy systems is that matching the intermittency of the power supply to the dynamic demand of the load is difficult because of the nature of the renewable energy and the sustainability of the power supply is difficult to maintain. As a solution to overcome this problem, a method of constructing a complex system by combining various kinds of renewable energy sources or a method of constructing a more reliable energy storage system is considered. Particularly, in the latter case, it is required to optimize the energy storage system in a form that can minimize the energy required from the outside in the off-grid system.

In the above-mentioned context, a technique for optimizing the system by applying pinch analysis, which was used for heat-exchange or water-water optimization, to a power system has been proposed (so-called power pinch analysis) . This power pinch analysis has proposed a system optimization method that minimizes external power supply in a system having a battery as an energy storage means.

However, in order to construct a more reliable energy storage system, a hybrid renewable energy system having a hydrogen storage system in addition to a battery has recently been considered. These hybrid regenerative energy systems utilize batteries with fast charge-discharge and high round-trip efficiency for short-term power storage, and hydrogen storage systems with long lifetime and high energy density (mass energy density) characteristics. It can be used for long-term power storage, thereby enabling more reliable energy storage system construction. However, as is known, since the hydrogen storage system is expensive equipment so far, it needs to be optimally designed within a range that does not hinder the system efficiency.

Embodiments of the present invention provide an optimization method for optimal capacity design of a hydrogen storage system in a hybrid regenerative energy system that includes a battery and a hydrogen storage system as energy storage means.

According to an aspect of the present invention, there is provided a method for optimizing a hybrid renewable energy system including a battery and a hydrogen storage system as an energy storage means, wherein, based on a daily power generation amount and consumption amount, Calculating a minimum external power supply amount and a surplus available surplus power in a system other than the storage system; Calculating the power stored in the hydrogen storage system and the required power from the hydrogen storage system at each time interval in units of a month, converting the minimum external power supply amount and the next available available excess power into monthly units; Calculating a net storage / required power of the hydrogen storage system in each time interval; Calculating, for the first year of operation, the power capacity accumulated in the hydrogen storage system and the required external power supply amount in each time interval; Calculating a minimum external power required in the first operation and an excess power stored in the hydrogen storage system for use next year; Calculating a power capacity to be accumulated in the hydrogen storage system and a required external power supply amount in each time period for a normal operation year; And determining an optimal capacity of the hydrogen storage system based on the cumulative power capacity of the hydrogen storage system calculated for the normal operating year.

The optimization method according to embodiments of the present invention enables a hybrid regenerative energy system including a hydrogen storage system as an energy storage means to calculate the optimum capacity of the hydrogen storage system. In particular, such an optimum capacity is an extension of conventional pinch analysis or power pinch analysis, minimizing power required from the outside, and advantageously allowing an optimum value to be quickly found through a relatively simple calculation process.

1 is a block diagram showing an example of a hybrid regenerative energy system (HRES-BH system).
2 is a schematic diagram summarizing the path of the power flow shown in FIG.
FIG. 3 is a chart illustrating daily power production in the system shown in FIG. 1;
4 is a chart illustrating power consumption of a load in the system shown in FIG.
FIG. 5 is a result of calculating the minimum external power supply amount (MOES) and the next available available power (AEEND) based on the power generation amount and the consumption amount illustrated in FIGS.
FIG. 6 is an example of creating a cascade table based on the case illustrated in FIG.
FIG. 7 is a chart illustrating the efficiency of each component in the system shown in FIG. 1;
8 is a result of calculating the capacity of each component of the hydrogen storage system 22 through the above-described method in the illustrated case.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. It is to be understood, however, that the following examples are provided to facilitate understanding of the present invention, and the scope of the present invention is not limited to the following examples. The following embodiments are provided to explain the present invention more fully to those skilled in the art and those skilled in the art will appreciate that there is a need for a more detailed description of a known configuration that may obscure the technical gist of the present invention, Will be omitted.

Embodiments of the present invention provide a system and method for optimal capacity design of a hydrogen storage system in a hybrid renewable energy system including a battery and a hydrogen storage system as an energy storage means in a battery and hydrogen storage systems (HRES-BH system) An optimization method can be provided. Embodiments of the present invention make it possible to extend airborne pinch analysis or power pinch analysis to HRES-BH systems including hydrogen storage systems for such optimization. From this point of view, the optimization method according to the present embodiments can be referred to as extended power pinch analysis or modified power pinch analysis. Hereinafter, an optimization method according to embodiments of the present invention will be described, focusing on the system illustrated in FIG.

1 is a block diagram showing an example of a hybrid regenerative energy system (HRES-BH system). Referring to FIG. 1, the hybrid regenerative energy system S may include one or more renewable energy sources. 1 illustrates a case where the wind power 11, the sunlight 13, and the biomes 12 are combined as a renewable energy source. As is known, such a combination of renewable energy sources is advantageous in matching the intermittence of the supply power, which is a characteristic of the renewable energy, to the demand of the dynamic load 30. However, it is needless to say that the number, kind, and the like of the renewable energy sources illustrated in FIG. 1 may be variously changed as needed.

The hybrid regenerative energy system S may also include a battery 21 and a hydrogen storage system 22 as energy storage means. The energy storage means may store the generated power in excess of the demand of the load 30 and, in the opposite case, provide it to the load 30 as appropriate. In particular, the hybrid regenerative energy system S as illustrated is distinguished from a system in which only the battery 21 is the main energy storage means in that the hydrogen storage system 22 is combined with the battery 21 as energy storage means . The hybrid renewable energy system S exemplified in this respect may be referred to as an HRES-BH system (including Hybrid Renewable Energy System including Battery and Hydrogen storage systems).

The hybrid regenerative energy system (S) or the HRES-BH system (S) can use the battery (21) for short term energy storage and the hydrogen storage system (22) for long term energy storage. As is known, the battery 21 may benefit from short-term energy storage due to fast charge and discharge, high round-trip efficiency, etc., and the hydrogen storage system 22 may have a long lifetime, high energy density, etc. Can benefit from long-term energy storage. Thus, the combination of the battery 21 and the hydrogen storage system 22 may have excellent performance in terms of reliability or efficiency of the entire energy storage means. However, since the hydrogen storage system 22 requires expensive facilities such as a fuel cell and an electrolytic cell, and the facility cost is relatively high, the hydrogen storage system 22 needs to be designed with a minimized capacity within a range that does not hinder system efficiency.

In the hybrid regenerative energy system S as described above, power in excess of the demand of the rod 30 charges the battery 21 first, and then the remaining power can be stored through the hydrogen storage system 22 have. In the hydrogen storage system 22, the residual power may be stored or the stored power may be supplied to the load 30 through the following procedure. The water supplied from the water tank 22e is de-ionized by the deionizer 22b and supplied to the electrolytic bath 22a when the residual power remaining after charging the battery 21 is supplied to the electrolytic bath 22a Supplied together. The electrolytic cell 22a consumes the supplied electric power and water to generate oxygen and hydrogen, which can be stored in the hydrogen tank 22c or the like. Further, when the stored oxygen and hydrogen are supplied to the fuel cell 22f, electric power is generated in the fuel cell 22f, and the generated electric power can be supplied to the rod 30. [ At this time, the water produced as a by-product can be stored in the water tank 22e or the like for regeneration. The process of the hydrogen storage system 22 has been well known and is not directly related to the technical spirit of the present invention, and therefore, a detailed description thereof will be omitted.

The optimization method according to the embodiments of the present invention stores the remaining power that is not stored in the battery 21 in the same day in the hybrid renewable energy system S in the hydrogen storage system 22, The basic concept is that the power stored in the hydrogen storage system 22 is supplied to the load 30 when the generated power and the battery 21 do not satisfy the demand for the load 30 and an external energy source is needed. The optimization method according to the embodiments of the present invention extends the technique of pinch analysis or power pinch analysis to the hybrid regenerative energy system S employing the hydrogen storage system 22, (22).

Meanwhile, FIG. 1 shows a power flow in the hybrid regenerative energy system S as described above. In the illustrated system S, wind power 11 and biomes 12 can generate AC power (alternating current) and sunlight 13 can generate DC power (direct current). The generated power may be directly transmitted to the load 30 via the path a-q or the path d-n. In addition, power exceeding the demand of the rod 30 can be stored in the battery 21 or the hydrogen storage system 22, and the stored power can be provided to the rod 30 via a constant path if necessary. In this process, some power loss may occur, which needs to be considered for the optimal capacity design of the hydrogen storage system 22.

More specifically, AC power exceeding the demand of the load 30 among the AC power generated from the wind power 11 and the biomes 12 can be converted to DC (direct current) by the rectifier 41, A power loss due to the rectifier 41 may occur (loss 1). The AC power (path g) converted to DC and the excess DC power (path c) can be provided to battery 21 primarily via path h to charge battery 21. In this way, loss (7) due to charging efficiency and loss (8) due to self-discharging can be generated in the process of passing through the battery (21).

On the other hand, when the battery 21 is fully charged, the remaining power can be provided to the hydrogen storage system 22 in a secondary manner. First, the residual power may be transferred to the DC / DC ₁ converter 41 via path i for stabilization, and loss may be generated according to the efficiency of the DC / DC ₁ converter 41 (loss 2). The stabilized power can be supplied to the electrolytic cell 22a via the path j, and oxygen and hydrogen can be produced using the deionized water in the electrolytic cell 22a. In this process, a loss due to the efficiency of the electrolytic cell 22a may be generated (loss ③). The generated oxygen and hydrogen may be stored in the storage tanks 22c and 22e, respectively.

If the supply of AC power through the path aq is insufficient for the demand of the AC load 31, DC power may be discharged from the battery 21 via the path mo, which is converted to AC (AC) through the inverter 44 And can be provided to the AC load 31 via the path pq. At this time, a loss may occur at the time of discharging the battery 21 (loss ⑨), and a loss may occur at the time of conversion by the inverter 44 (loss ⑥). In addition, when the battery 21 is completely discharged, hydrogen and oxygen stored in the hydrogen storage system 22 are supplied to the fuel cell 22f to generate power in the fuel cell 22f. (Loss ④). In addition, the power generated in the fuel cell 22f to convert the output of the fuel cell 22f to the DC bus voltage level is transmitted to the DC / DC ₂ converter 43 via the path k, ₂ converter 43, loss may be generated (loss 5). The converted DC power is converted to AC by the inverter 44 and supplied to the AC load 31 via the path lopq. At this time, loss may also occur due to the efficiency of the inverter 44 (loss ⑥).

On the other hand, when the supply of the DC power through the path dn is insufficient for the demand of the DC load 32, the insufficient power can be supplied by the discharge of the battery 21 primarily through the path mn. In this case, a loss may be generated due to the discharge efficiency of the battery 21 (loss 9). Further, the power generated in the fuel cell 22f can be supplied to the DC load 32 via the path ln. In this case, a loss may be generated by the DC / DC ₂ converter 43 (loss?).

Finally, when the demand of the DC / AC load 30 can not be supplied through the path q, n, external power may be additionally supplied from the grid or the like, Gt; DC power < / RTI >

The power flow path as described above can be summarized as shown in FIG. FIG. 2 is a schematic diagram summarizing the path of the power flow shown in FIG. 1, and with reference thereto, the path of the main power flow in the system S as shown in FIG. 1 can be summarized into four paths A to D. The transmission efficiencies of the A to D paths can be calculated by multiplying the efficiencies of the components in the respective paths such as the rectifier 41, the inverter 44, and the converters 41 and 43. Since the efficiency of each component does not exceed 1, the efficiency of each path is expressed in the order of η _A > η _B > η _C > η _D (η _A to η _D are the transmission of paths A to D, respectively Efficiency. Therefore, the optimization method according to the embodiments of the present invention can be based on the following three energy management strategies to improve the overall system efficiency.

First, if the generated power exceeds the demand of the load 30, the generated power may be delivered to the load 30 directly, such as path A or B. Further, if the battery 21 is not in the cushioning state, excess power such as the path C can be transmitted to the battery 21. [ In this case, the excess AC power may be converted to DC by the rectifier 41 as shown in path C. On the other hand, when the battery 21 is in the cushioning state, the excess electric power can be supplied to the electrolytic cell 22a as the path D, and can be stored through the hydrogen storage system 22. [

Second, if the generated power does not meet the demand of the load 30 and the battery 21 is in a cushioning state, the generated power may first be delivered to the load 30 directly as the paths A and B, The battery 21 can be discharged like the path C for the remaining demand of the rod 30. [ At this time, the electric power discharged from the battery 21 may first be supplied with DC power directly to the DC load 32, and then to the inverter 44 and supplied to the AC load 31.

Third, the hydrogen storage system 22 can supply power to the rod 30 if the generated power does not meet the demand of the rod 30 and the battery 21 is completely discharged. The DC power generated in the fuel cell 22f may first be transferred directly to the DC load 32 and then to the AC load 31 via the inverter 44, In this energy management strategy, the hydrogen storage system 22 can be inactivated when the battery 21 is charged or discharged, and can be activated only when the battery 21 is fully charged or discharged.

The optimization method according to embodiments of the present invention can determine the capacity of the hydrogen storage system 22 for system optimization based on the energy management strategy as described above. For convenience of explanation, an optimization method according to the present embodiments will be described below, assuming one case.

FIG. 3 is a chart illustrating a day power generation amount in the system shown in FIG. 1, and FIG. 4 is a chart illustrating a power consumption amount of a load in the system shown in FIG. FIG. 3 illustrates three cases (Case 1 to 3) of daily power production of sunlight, wind power, and biomes, and FIG. 4 shows that the power consumption is commonly applied to Cases 1 to 3.

The optimization method according to the present embodiment uses the minimum output power supply (MOES) and the available available power (Next Excess Electricity) for next ≪ / RTI > Day, AEEND). In this case, the pinch analysis has been known as one of techniques for improving the system efficiency by maximizing the in-system utilization of the medium in the system where the medium such as heat, water is used. In particular, the process of calculating the minimum external power supply (MOES) and the next-available excess power (AEEND) by applying pinch analysis to the power system has been proposed through the following references (so-called power pinch analysis) The detailed procedure for calculating the minimum external power supply (MOES) and the next available maximum power (AEEND) in this specification will be referred to the following references (see Norreniza Mohammad Rozali et al., Process Integration techniques for optimal design of hybrid power systems, Applied Thermal Engineering 2013; 61: 26-35). However, the power pinch analysis of the above reference is based on a system having only a battery as an energy storage means, so that the minimum external power supply amount (MOES) and the next available available power (AEEND) ) Are targeted for the excluded systems.

FIG. 5 is a result of calculating the minimum external power supply amount (MOES) and the next available available power (AEEND) based on the power generation amount and the consumption amount illustrated in FIGS. FIG. 5 is a graph showing a relationship between a minimum external power supply amount (MOES) and a next-day available excess power (AEEND) through a pinch analysis (power pinch analysis) based on the illustrated daily unit of strategic production amount and consumption amount, 3, Case 1 of FIG. 3 is shown from January to April, case 2 of FIG. 3 is shown from May to August, and Case 3 of FIG. 3 is shown from September to December. . Also, in the illustrated results, the maximum value of the battery capacity was assumed to be 61.56 kWh.

Meanwhile, when the minimum external power supply amount (MOES) and the excess power (AEEND) available for the next day are calculated as described above, the optimization method according to the present embodiment calculates It may include the step of calculating the power (needed electricity, NE _HT) is required from the power saving (stored electricity, SE _HT) and the hydrogen storage system 22. At this time, the stored power (SE _HT ) of the hydrogen storage system 22 The required power (NE _HT ) can be calculated through the previously calculated minimum external power supply (MOES) and the next available maximum power (AEEND).

Specifically, the next available excess power (AEEND) can be used to reduce the minimum external power supply (MOES) of the next day. 1, the minimum external DC / AC power supply amount (MOES _AC , MOES _DC ) is transmitted through the path mop or the path mn. In this process, the battery 21 is charged / 44) Loss due to efficiency may occur. Therefore, the excess electric power (WE) in the nth time period can be calculated by the following equation (1).

In the above equation (1), WE _n is an excess power in the nth time interval, n is the number of time intervals, η _dis is the discharge efficiency of the battery, and η _inv is the efficiency of the inverter.

1, the excess power WE is stored in the hydrogen storage system 22 via the path ij, so that the excess power WE is supplied to the DC / DC1 converter 42 and the electrolytic cell 22a. Therefore, the power SE _HT stored in the hydrogen storage system 22 can be calculated by the following equation (2).

In Equation 2, SE _{HT , n} is the power stored in the hydrogen storage system 22 in the nth time interval, n is the number of the time interval, and? _{DC / DC1} and? _EL are the DC / DC ₁ converter 42, And the efficiency of the electrolytic bath 22a.

Next, looking at the required power NE _HT from the hydrogen storage system 22, first, the minimum external power supply amount MOES in the specific time interval n is calculated as the next available usable excess of the previous time interval n-1 (I.e., MOES _n &_gt; AEEND _{n -1} ), the required power may be provided from the hydrogen storage system 22.

In the opposite case, two cases should be considered. First, when the minimum external DC power supply amount (MOES _DC ) in a specific time period (n) is smaller than the next available excess power (AEEND) of the previous time period (n-1) (that is, MOES _{DC , n} <AEEND _{n -1} ), the minimum external DC power supply (MOES _DC ) may be supplied with all of the available excess power (AEEND) available to the battery 21 and the rest supplied by the hydrogen storage system 22. In addition, since all of the available excess power (AEEND) is provided to the external DC power supply (MOES _DC ), the minimum external AC power supply (MOES _AC ) must be supplied by the hydrogen storage system (22). Therefore, the DC / AC power (NE _DC , NE _AC ) required in this case can be calculated by the following equation (3).

In the NE _{DC, n} is _the n th time interval in the equation 3 DC power required from the hydrogen storage system 22, NE _{AC, n} is AC electrical power required from a hydrogen storage system 22 in the n-th time interval, n is the time The interval number, eta _dis , indicates the charging and discharging efficiency of the battery 21. [

On the other hand, when at least the external DC power supply in a given time interval (n) (MOES _DC) is greater than the excessive power (AEEND) available for the next business day in the previous time interval (n-1) (i.e., MOES _{DC, n>} AEEND _{n -1} ), the available excess power (AEEND) can supply all of the minimum external DC power supply (MOES _DC ) and the remainder can supply some external AC power supply (MOES _AC ). Therefore, the DC / AC power (NE _DC , NE _AC ) required in this case can be calculated by the following equation (4).

In the above Equation 4, NE _{DC , n} is the required DC power from the hydrogen storage system 22 in the nth time interval, NE _{AC , n} is the required AC power from the hydrogen storage system 22 in the nth time interval, The interval number, eta _dis represents the charging and discharging efficiency of the battery 21, and [eta] _inv represents the efficiency of the inverter 44. [

1, the calculated DC power (NE _DC ) is transmitted via path kln, and the AC power (NE _AC ) is transmitted via path klop to each load 30 in the hydrogen storage system 22. [ . Thus, after all required power (NE _HT) is to be supplied from a hydrogen storage system 22 can be calculated through Equation (5).

In Equation (5), NE _{HT , n} is the required power to be supplied through the hydrogen storage system 22 in the nth time interval,? _{DC / DC2} ,? _FC and? _Inv are the DC / DC ₂ converter 43, The fuel cell 22f, and the inverter 44, respectively.

Meanwhile, the calculation process as described above and the calculation process thereafter can be performed by creating a cascade table. FIG. 6 is an example of creating a cascade table based on the case illustrated in FIG. The efficiency of each component in the preparation of the integration table of FIG. 6 is assumed as shown in FIG.

Referring to FIG. 6, columns 1 through 3 may be made for each time period, and columns 4 through 6 may be created with the minimum external power supply (MOES) and the next available maximum power (AEEND) 5). Further, the required power NE of columns 7 and 8 can be calculated by the above-described equations 3 and 4, and the excess power WE of the column 9 can be calculated by the above-described equation (1). On the other hand, the required power (N _HT ) from the hydrogen storage system 22 of the column 10 can be calculated by Equation 5 above and the power S _HT stored in the hydrogen storage system 22 of the column 11 Can be calculated by the following equation (2).

Meanwhile, the optimization method according to the present embodiment calculates the required power (N _HT ) and the stored power (S _HT ) of the hydrogen storage system (22) for each time interval as described above, (NE Stored / Needed Electricity, NeE _HT ) of the battery. The net storage / required power (NeE _HT ) can be calculated by the following equation (6). Column 12 of FIG. 6 shows the result of calculating the net storage / required power (NeE _HT ) in the illustrated case.

In Equation (6), NeE _{HT , n} represents the net storage / required power of the hydrogen storage system 22 in the nth time interval. In this case, a positive NeE _HT may denote a net stored electric power (NeSE _HT ), and a negative NeE _HT may denote a net required electric power (NeNE _HT ).

In the meantime, the optimization method according to the present embodiment includes a Hydrogen Tank Electricity Capacity (HTEC) accumulated in the hydrogen storage system 22 of each time interval and a Required External Electricity Source (REES) And a step of calculating At this time, it is noted that the required external power supply amount REES is distinguished from the minimum external power supply amount (MOES) described above in that it is based on the system including the hydrogen storage system 22. [

Referring to column 13 of FIG. 6, the power capacity (HTEC) accumulated in the hydrogen storage system 22 can be calculated by cumulatively summing the net storage / required power (NeE _HT ) of the column 12. However, if the cumulative value is negative, there is no power storage of a negative value. In such a case, the accumulated power capacity (HTEC) may be considered as zero. Therefore, the accumulated power capacity (HTEC) can be calculated by Equation (7).

이면,

If so,

In Equation (7), HTEC _n represents the power capacity accumulated in the hydrogen storage system 22 in the nth time interval, NeE _{HT , and n} represents the net storage / required power (see column 12 in FIG. 6).

The required external power supply amount REES can be calculated by the following equation (8), and the result of calculating the external power supply amount REES required in the illustrated case is the same as that of columns 14 and 15 in FIG.

이면,

If so,

Wherein in Equation 8 REES _{AC, n} is an external AC power supply required by the n th time interval, REES _{DC, n} represents an external DC power supply required in the n-th time _{interval, η FC, η DC / DC2} , η inv is Efficiency of the fuel cell 22f, the DC / DC ₂ converter 43, and the inverter 44, respectively (see the power flow in FIG. 1).

Meanwhile, in the optimization method according to the present embodiment, when the power capacity (HTEC) accumulated in the hydrogen storage system 22 and the required external power supply amount (REES) are calculated as described above, the minimum external power (SES) during the First Operation Year (MEESFOY) and the hydrogen storage system (22) to calculate an Accessible Surplus Electricity for Next Operation Year (ASENNOY) for the next year.

The minimum external power MEESFOY in the first year of operation can be calculated by summing up the required external power supply amount REES in each time interval and can be expressed by Equation 9 below.

In Equation (9), MEESFOY _AC represents the minimum external AC power in the first operation and MEESFOY _DC represents the minimum external DC power in the first operation. In the illustrated case, the minimum external AC / DC power (MEESFOY _AC and MEESFOY _DC ) in the first year of operation is the minimum external AC power required (MEESFOY _AC ) as shown at the bottom of columns 14 and 15 of FIG. 6 is 0 kWh, _AC ) can be calculated as 923 kWh.

On the other hand, the power capacity (HTEC) accumulated in the hydrogen storage system 22 in the last time interval can be defined as an excess power (ASENNOY) usable in the next year. Thus, in the case illustrated in FIG. 6, the next available ASENNOY can be calculated as 56.97 KWh as in the last column of column 13. [

On the other hand, the optimization method according to the present embodiment includes calculating the power capacity (HTEC) accumulated in the hydrogen storage system 22 and the required external power supply amount (REES) for the normal operation year from the first year of operation can do.

The power capacity HTEC accumulated in the hydrogen storage system 22 in the normal operation year can be calculated through the above-described equation (7). However, the excess power available from the first year of operation (ASENNOY) can be cumulatively added in the next year, normal operating year. That is, referring to column 16 of FIG. 6, the excess power (ASENNOY) of the first operation calculated above can be carried forward to the next year, the normal operating year, cumulatively (see the first row of column 16). Further, the external power supply amount REES required in the normal operation year can be calculated by the above-described equation (8), which is shown in columns 17 and 18 in Fig.

On the other hand, the optimization method according to the present embodiment is based on the optimal capacity of the hydrogen storage system 22, based on the accumulated power capacity (HTEC) of the hydrogen storage system 22 calculated for the normal operation year, AHTEC). &Lt; / RTI &gt; At this time, the maximum capacity (AHTEC) may be selected as the maximum among the accumulated power capacities (HTEC) during normal operation. Thus, in the illustrated case, the optimum capacity AHTEC of the hydrogen storage system 22 can be determined to be 177.84 kWh (see column 16 of FIG. 6).

The optimum capacity AHTEC becomes the capacity of the hydrogen storage system 22 that minimizes the external power supply REES required by the pinch analysis theory. In this case, the required external electric power supply (REESNOY) during the normal operation year can be calculated by adding the external electric power supply amount (REES) in each time interval, have.

In Equation (10), REESNOY _AC represents an external AC power supply amount required for a normal operation year, and REESNOY _DC represents an external DC power supply amount normally required for a working year. 6, the required external AC power supply (REESNOY _AC ) and the required external DC power supply (REESNOY _DC ) can be calculated as 0 kWh and 866 kWh, respectively, as in the last row of columns 17 and 18. That is, in the case of the illustrated case, it can be seen that the hydrogen storage system 22 has the optimum capacity (177.84 kWh) and requires AC power of 866 kWh with the minimum external power supply.

On the other hand, if necessary, the optimization method according to the present embodiment is based on the optimum capacity AHTEC of the hydrogen storage system 22 calculated above, and is stored in the electrolytic bath 22a, And determining the capacity of at least one of the hydrogen tank 22c and the fuel cell 22f.

The volume of the hydrogen tank 22c to meet the optimum capacity (AHTEC) calculated above when the thermal density of hydrogen is 0.0658 kWh / mol and the molar volume is 0.0000446 mol / m ³ at 25 ° C. Tank Volume, HTM) can be calculated as shown in Equation (11).

In the equation (11), HTM represents the volume of the hydrogen tank 22c, M _HT represents the initial storage capacity and the margin coefficient considering the seasonal change, H _PT represents the pressure of the hydrogen tank 22c, M _HT represents 2.5 bar, H _PT Can be considered as 200 bar.

On the other hand, the size of the electrolytic cell 22a can be defined as the number of the electrolytic cell cells to be used, which can be calculated by the following equation (12).

In Equation 12, ELEC represents the power capacity of the electrolytic cell 22a, and _EL represents the efficiency of the electrolytic cell 22a (see FIG. 7). In addition, N _EL is the number of electrolytic cells, I _EL is conducting current (A), V _EL is the operating voltage (V), t _AHTEC of the electrolytic cell (22a) indicates a duration related to the optimal dose (AHTEC), I _EL And V _EL can be considered to be 11.32V.

The size of the fuel cell 22f may also be defined based on the number of fuel cell cells used. Similarly to the case of the electrolytic cell 22a, the number of fuel cell cells can be calculated by the following equation (13).

In the above equation (13), FCEC represents the power capacity of the fuel cell 22f, and? _FC represents the efficiency of the fuel cell 22f (see FIG. 7). Also, N _FC represents the number of fuel cell cells, and t _AHTEC represents the duration associated with the optimal capacity (AHTEC). I _FC and V _FC denote the output current and the output voltage of the fuel cell 22f, respectively, for example, I _FC 2.92A, V _FC 4.93V. 8 is a result of calculating the capacity of each component of the hydrogen storage system 22 through the above-described method in the illustrated case.

As described above, the optimization method according to the embodiments of the present invention is characterized in that in the hybrid renewable energy system (S) including the hydrogen storage system (22) as the energy storage means, the optimum capacity of the hydrogen storage system . In particular, such an optimum capacity is an extension of conventional pinch analysis or power pinch analysis, minimizing power required from the outside, and advantageously allowing an optimum value to be quickly found through a relatively simple calculation process.

In addition, embodiments of the present invention as described above can be implemented in the form of a program command for performing various computer-implemented operations or a computer-readable medium in which such a program command is recorded. The readable medium may include program instructions, data files, data structures, and the like, alone or in combination, for example, a magnetic medium such as a hard disk, a floppy disk and a magnetic tape, a CD- Optical media such as floppy disks, and hardware devices specifically configured to store and perform program instructions such as ROM, RAM, flash memory, and the like.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, many modifications and changes may be made by those skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims. The present invention can be variously modified and changed by those skilled in the art, and it is also within the scope of the present invention.

S: Hybrid renewable energy system 11: Wind power
12: Biomes 13: Solar light
21: Battery 22: Hydrogen storage system
22a: electrolytic bath 22b: deionizer
22c: hydrogen tank 22d: oxygen tank
22e: Water tank 22f: Fuel cell
31: AC load 32: DC load
41: rectifier 42: DC / DC ₁ converter
43: DC / DC ₂ converter 44: Inverter

Claims (7)

A method for optimizing a hybrid renewable energy system (S) comprising a battery (21) and a hydrogen storage system (22) as energy storage means,
(MOES) required to be supplied from the outside in the system excluding the hydrogen storage system 22, and a surplus available surplus amount Calculating an electric power (AEEND);
(SE _HT ) stored in the hydrogen storage system (22) at each time interval in units of months, and the power (SE _HT ) stored in the hydrogen storage system Calculating a required power (NE _HT ) from the system (22);
Calculating a net storage / required power (NeE _HT ) of the hydrogen storage system (22) in each time interval;
Calculating, for the first year of operation, a power capacity (HTEC) accumulated in the hydrogen storage system (22) in each time interval and an external power supply amount (REES) required to be supplied from the outside;
(MEESFOY) required to be supplied from the outside in the first operation and calculating an excess power (ASENNOY) stored in the hydrogen storage system (22) for use next year;
Calculating a power capacity (HTEC) accumulated in the hydrogen storage system (22) at each time interval and an external power supply amount (REES) required to be supplied from the outside, for a normal operation year; And
Determining an optimal capacity (AHTEC) of the hydrogen storage system (22), based on a cumulative power capacity (HTEC) of the hydrogen storage system (22) calculated for a typical operating year Optimization of the system. The method according to claim 1,
The power SE _HT stored in the hydrogen storage system 22 is calculated by the following equation (2)
(2)

In SE _{HT, n} are each a time interval in the equation (2) of the power, WE _n is greater than the power in each time interval, η _{DC / DC1} is a DC / DC ₁ converter 42 is stored in the hydrogen storage system 22 Efficiency, eta _EL represents the efficiency of the electrolytic bath 22a,
The excess power (WE _n ) in each time period is calculated by the following equation (1)
(1)

In the above Equation 1, WE _n is the excess power in each time interval, AEEND _n is the surplus available power in each time interval, MOES _DC is the minimum external DC power supply in each time interval, MOES _AC is the minimum external _{Wherein the} AC power supply amount,? _Dis, is the discharge efficiency of the battery (21), and? _Inv is the efficiency of the inverter (44). The method according to claim 1,
Minimum external DC's in a specific time interval (n) at least an external power supply (MOES _n), the previous time interval (n-1) next-day available over-power (AEEND _{n -1)} smaller, a specific time interval (n) of power supply (MOES _{DC, n)} to calculate the power (NE _HT) required from the previous time period (n-1) next-day available over-power (AEEND _n-1) small, the hydrogen storage system 22 than the The required DC / AC power (NE _{DC ,} NE _AC ) is calculated by the following equation (3)
(3)

In the above equation (3), NE _{DC , n} represents the required DC power from the hydrogen storage system 22 at each time interval, MOES _{DC , n} represents the minimum external DC power supply at each time interval, AEEND _{n - 1} represents the previous time interval excess power, η _dis available next-day represents a charge-discharge efficiency of the battery (21), NE _{AC, n} is AC electrical power required from the hydrogen storage system 22 at each time interval, MOES _{AC, n} is at each time interval, And the minimum external AC power supply. The method according to claim 1,
Minimum external DC's in a specific time interval (n) at least an external power supply (MOES _n), the previous time interval (n-1) next-day available over-power (AEEND _{n -1)} smaller, a specific time interval (n) of (NE _HT ) from the hydrogen storage system 22 when the power supply amount (MOES _{DC , n} ) is greater than the next available available power (AEEND _n-1 ) of the previous time period The required DC / AC power (NE _{DC ,} NE _AC ) is calculated by the following equation (4)
(4)

In Equation (4), NE _{DC , n} represents the required DC power from the hydrogen storage system 22 in each time interval, NE _{AC , n} represents the required AC power from the hydrogen storage system 22, MOES _{AC , n} is the minimum external AC power supply in each time interval, AEEND _{n - 1} is the excess power available on the next day of the previous time interval, η _inv is the charging and discharging efficiency of the battery 21, MOES _DC, DC power supply, eta _inv , represents the charging and discharging efficiency of the inverter (44). The method according to claim 1,
The net storage / required power (NeE _HT ) of the hydrogen storage system 22 is calculated by the following equation (6)
(6)

In Equation (6), NeE _{HT , n} is the net storage / required power of the hydrogen storage system 22 in each time interval, SE _{HT , n} is the power stored in the hydrogen storage system 22 in each time interval, NE _{HT , n} represents the required power from the hydrogen storage system (22) at each time interval. The method according to claim 1,
The minimum external power MEESFOY required for the first operation is calculated by summing the external power supply REES required for each of the time intervals,
Wherein the available excess power ASENNOY for the first time of operation is calculated via a power capacity (HTEC) accumulated in the hydrogen storage system 22 during the last time interval. The method according to claim 1,
Wherein the optimal capacity (AHTEC) of the hydrogen storage system (22) is selected as the maximum of the cumulative power capacity (HTEC) of the hydrogen storage system (22) calculated for the normal operating year Optimization method.

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