JP4860960B2 - Power network control system - Google Patents

Description

  The present invention connects a plurality of distributed power sources and loads provided in a specific area by transmission and distribution lines, and is relatively small operated as an interconnection system or a single system for a large-scale transmission and distribution network. The present invention relates to a scale power network control system.

  In recent years, in addition to large-scale power distribution networks such as power companies, a relatively small-scale power network in a specific area composed of a plurality of distributed power sources and loads, and self-operated power distribution networks that connect them. Has come to be used. This can distribute power to a plurality of power consumers including a power consumer having a distributed power source in a predetermined area (community) such as a local government, and supply power between these consumers at low cost. System.

In such a system, it is necessary to balance the total supply power of distributed power sources in a predetermined area (community) and the total demand of consumers who are members of a community organization to control the overall supply-demand balance. In addition, if the power generation capacity of the distributed power supply cannot be compensated for the total demand, the community organization will make up for it with expensive power purchases from other power selling companies (for example, electric power companies such as electric power companies). Balance supply and demand of the entire power system under its jurisdiction. In this case, since the amount of power purchased from outside the community is expensive, it is advantageous in terms of cost to make a contract with a minimum amount of constant power (see, for example, Patent Document 1).
JP 2002-10500 A

  However, in the conventional method, a plurality of distributed power sources and loads are controlled to comprehensively control the supply and demand balance, so the number of devices to be controlled increases and the amount of information exchanged such as supply and demand information and control commands increases. . This is a direction in which the system scale increases, and as the system scale increases, the cost tends to increase and the maintainability tends to deteriorate.

  An object of the present invention is to provide a power network control system capable of calculating a control amount of a distributed power source constituting a power network with as little information as possible and allowing each distributed power source to autonomously perform output control. There is to do.

A power network control system according to the present invention has a large-scale power distribution network in which a plurality of distributed power sources and loads having different inertial methods provided in a specific area and having different power generation methods are connected by power transmission and distribution lines. Is a control system for a relatively small-scale power network that is operated as a single isolated system, and is provided in each of the distributed power sources, and detects the magnitude of system frequency fluctuations in the power network. Means for recovering the supply and demand imbalance from the relationship between the supply and demand imbalance between the power demand and supply in the power network and the magnitude of the fluctuation of the grid frequency. previously determined type power control amount of sharing can occur power, thus determined control amount and the magnitude of fluctuation of the system frequency vignetting with corresponding, and the calling Stores the control characteristic having an output change characteristic of the control amount based on the difference in approach, the control amount calculation means for calculating a control amount corresponding to the magnitude of variation of the detected system frequency based on the control characteristics Each of the distributed power sources is controlled by the control amount obtained by the control amount calculation means so as to suppress the fluctuation when the system frequency varies due to supply and demand imbalance in the power network. power and controlling autonomously generating electric power.

  According to the present invention, when calculating the control amount of each distributed power source, only the system frequency that can be measured at the distributed power source itself is used as the measurement amount necessary for the calculation, so the amount of information necessary for the calculation (measurement) Quantity) and the distributed power supply can independently control the output.

  In addition, when connecting to a large-scale power transmission and distribution network, the system frequency hardly changes even if supply and demand imbalance occurs due to load drop in the power network. Without calculating, the control amount of the distributed power source is calculated using the interconnection power flow. In this case, the amount of measurement required for the calculation may be only the interconnected power flow, the amount of information (measurement amount) required for the calculation is small, and the distributed power supply can independently control the output.

  Furthermore, the control amount of the distributed power source can be calculated regardless of the interconnection state by switching the calculation method of the control amount of the distributed power source using the connection line connection state information with the large-scale power transmission and distribution network.

  Hereinafter, an embodiment of a power network control system according to the present invention will be described in detail with reference to the drawings.

  A configuration of a power network to be controlled by the present invention will be described with reference to FIG. The power network 1 is a relatively small-scale power network in a specific area where a plurality of distributed power sources 21, 22, 23, 24, 25 and a load 14 are connected to each other by a transmission / distribution line 11. This power network 1 is connected to a large-scale transmission / distribution network 100 by an electric power company or the like and a connection line breaker / disconnector (hereinafter referred to as a connection line switch) 13 provided in an electric station 10. It is configured to be interconnected via However, in this embodiment, it is assumed that the connection line switch 13 is open and the power network 1 is operated as a single system separated from the large-scale power transmission and distribution network 100.

  As the distributed power source, for example, a secondary battery 21, a micro gas turbine 22, a fuel cell 23, a wind power generator 24, a synchronous generator 25, or the like is used. Since the synchronous generator 25 has a relatively large capacity and the generated power is output as it is, it has an inertia characteristic as is well known. On the other hand, each of the other power sources 21, 22, 23, and 24 does not have inertia characteristics because the generated power is output via an inverter or the like.

  In this embodiment, only the power sources 21, 22, 23, and 24 having no inertia characteristic are connected to the power transmission / distribution line 11, and power is supplied to the load 14 by these, and the synchronous characteristic having the inertia characteristic is provided. It is assumed that the generator 25 is not connected to the transmission and distribution network 11.

  In this embodiment, as shown in FIG. 1, the power network 1 and the large-scale transmission / distribution network 100 such as an electric power company are not interconnected, and the power network 1 is operated as a single system. In this embodiment, when a disturbance such as a load drop 3 or an emergency stop of a distributed power source occurs in the power network 1 and a power supply / demand imbalance ΔP occurs because the power demand and the supply are not balanced, Is controlled by the magnitude of fluctuations in the system frequency so as to recover the supply-demand imbalance.

For this purpose, each of the distributed power sources 21, 22, 23, and 24 is provided with frequency detection means 31 for detecting the magnitude Δf of system frequency fluctuation in the power network 1, as shown in FIG. That is, the reference frequency f ₀ and the system frequency f is the frequency detection means 31 (in Fig. 1 4) is input, the size Δf of the frequency variation is detected.

  Further, there is provided a control amount calculation means 32 for obtaining a control amount ΔPG of each of the distributed power sources 21, 22, 23, 24 corresponding to the magnitude Δf of the system frequency fluctuation. In other words, the control amount calculation means 32 indicates the relationship (Δf−ΔPG control characteristic) between the magnitude Δf of the fluctuation of the system frequency and the control amount ΔPG for recovering the system frequency to a predetermined value. 21, 22, 23, and 24 are set, and the control amount ΔPG is obtained based on this setting relationship (Δf−ΔPG control characteristic).

  And when the fluctuation | variation of a system frequency arises by the electric power supply-and-demand imbalance in the electric power network 1, the generated electric power is controlled autonomously by each distributed power source 21,22,23,24 so that this fluctuation | variation may be suppressed.

  Details will be described below. First, the following work is performed to determine the set values to be stored in the distributed power sources 21, 22, 23, 24 in advance.

  In the power network 1, it is grasped how much the system frequency f fluctuates when a power supply and demand are not balanced and a supply and demand imbalance ΔP occurs due to disturbance such as load drop or emergency stop of a distributed power source. This is called a ΔP-Δf characteristic in the power network 1.

The ΔP-Δf characteristic, that is, the frequency change Δf when the supply / demand imbalance ΔP occurs is obtained by the following equation (1a) when the power supply is disconnected and by the equation (1b) when the load is removed. As other methods, actual measurement or simulation may be used.

Here, _{K G} frequency characteristic constant of the power supply, the frequency characteristic constant of _{K L} is the load, the unit is [% / Hz]. This represents how much the power supply or load changes when the frequency changes by 1 Hz, and this value is an empirical value or a value obtained by an existing method.

  Next, it is determined which distributed power supply output PG is controlled to eliminate the supply and demand imbalance ΔP. Which distributed power source is to be controlled is determined in consideration of the control priority of the distributed power source, output characteristics, efficiency, power reserve, and the like.

  As an example of the control pattern of the distributed power source, for example, when it is desired to control and determine the control priority of the distributed power source for the reason of controlling from the efficient distributed power source, each distributed power source 21, 22, 23 and 24, and the amount that each distributed power source bears in order to eliminate the supply and demand imbalance ΔP (the maximum amount ΔPGmax that can increase the output and the maximum amount ΔPGmin that can decrease the output) are determined. Then, based on the ΔP-Δf characteristic in the power network 1, the control priority of the distributed power source, and the maximum burden (ΔPGmax, ΔPGmin), each of the distributed power sources 21, 22, 23, 24 when the frequency fluctuation occurs is determined. Determine the control pattern. That is, it determines how much the output of the distributed power source is increased or decreased with respect to the frequency change Δf (output increase / decrease amount ΔPG). As described above, this is called the Δf-ΔPG control characteristic of each distributed power source 21, 22, 23, 24.

  FIG. 4 is a diagram showing an example of the ΔP-Δf characteristic in the power network 1 and the burden amount of each distributed power source. In the power network 1, the supply and demand imbalance ΔP is 35 kW (when the load is dropped = the power supply excess side is corrected). Δf changes 0.35 Hz when the power is lost = the power supply shortage side is negative). Also, the control priority of the distributed power source for eliminating the supply / demand imbalance ΔP is as follows: distributed power source 21 (secondary battery: BTR), distributed power source 22 (micro gas turbine: MGT), distributed power source 23 (fuel) Battery: FC). Then, the maximum burden amount (ΔPGmax, ΔPGmin) of each distributed power source is set as follows: BTR21: ΔPGmax = + 10 kW, ΔPGmin = −10 kW, MGT22: This is an example of -15 kW. The Δf-ΔPG control characteristics of each distributed power source in this case are as shown in FIGS. 5a, 5b, and 5c.

  That is, while the magnitude Δf of the frequency fluctuation is between +0.1 and −0.1, the BTR 21 with the priority “1” changes the output in the range of −10 kW to +10 kW. Similarly, when the magnitude of the frequency variation Δf is between +0.1 and −0.1 to +0.2 and −0.2, the MGT 22 with the priority “2” is in the range of −10 kW to +10 kW. Change the output with. Further, when the frequency fluctuation magnitude Δf exceeds +0.2 and −0.2 to +0.35 and −0.35, the priority level “3” FC23 is in the range of −15 kW to +15 kW. Change the output.

  The Δf-ΔPG control characteristics of each distributed power source obtained as described above are stored in advance in the control amount calculation means 32 of the corresponding distributed power sources 21, 22, 23, 24.

  As another control pattern of the distributed power source, when it is desired to control the distributed power sources 21, 22, and 23 simultaneously, the Δf-ΔPG control characteristics of the distributed power sources 21, 22, and 23 are shown in FIG. 6b and set as shown in FIG. 6c. When frequency fluctuations occur, BTR, MGT, and FC are all controlled (maximum burden amounts ΔPGmax and ΔPGmin of each distributed power source are the same as in the example of FIG. 5). FIG. 7 shows the burden amount of each distributed power source on the ΔP-Δf characteristic in the power network 1.

  Furthermore, as another control pattern of the distributed power source, when it is desired to quickly suppress the frequency fluctuation, the control priority order and the burden amount are not determined, that is, without setting the control characteristics as shown in FIGS. Supply and demand imbalance may be eliminated by operating according to the output response characteristics of each distributed power source. In this case, control is performed mainly by a distributed power source with fast response, and the output is changed to the maximum output or the minimum output.

Next, the operation during actual operation will be described with reference to the flowchart of FIG. First, in the distributed power, measured momentarily and system frequency f (step 201), calculates a variation Δf of the reference frequency _{f 0} (step 202).

When a disturbance such as a load drop or an emergency stop of a distributed power source occurs at a certain point in time, the supply and demand imbalance ΔP occurs without balancing the power demand and supply, and the system frequency f fluctuates greatly (large Δf) (step 203). . For this reason, the output increase / decrease amount (control amount) ΔPG of the distributed power source corresponding to the frequency change Δf is calculated by the preset Δf-ΔPG control characteristic (step 204). And thus controls the output PG of the distributed power supply based on (step 205), to eliminate the supply-demand imbalance in the power network 1, to recover the power system frequency f to the reference frequency f _0. The calculation method of ΔPG according to Δf is calculated from the Δf-ΔPG control characteristic obtained in advance as described above and stored in advance in each distributed power source and the calculated Δf.

  The above description is for the case where only the power sources 21, 22, 23, and 24 having no inertia characteristic are connected to the transmission / distribution network 11 as the distributed power source. Next, only the synchronous generator 25 having the inertia characteristic is transmitted. A case will be described in which power is supplied to the load by the synchronous generator 25 (one is shown in the figure but a plurality is provided) connected to the distribution network 11.

  In this embodiment, when a disturbance such as a load drop 3 or an emergency stop of a distributed power source occurs in the power network 1, the power demand and the supply are not balanced and a supply and demand imbalance ΔP is generated. This is based on the rate of change in frequency and eliminates the imbalance between supply and demand.

That is, when frequency fluctuations due to supply / demand imbalance occur, the rate of change df / dt of the system frequency f measured from time to time is calculated, the amount of supply / demand unbalance ΔP is estimated using the rate of change df / dt, and ΔP An output increase / decrease amount (control amount) ΔPG is calculated from the estimated value and the distributed power output PG ₀ before occurrence of frequency fluctuation.

Here, the estimation method of the supply and demand imbalance amount ΔP and the calculation method of the control amount ΔPG are as follows. That is, using the frequency change rate df / dt (= Δf _c ), the supply and demand imbalance amount ΔP is estimated by the following equation (2a), and using this ΔP and the distributed power output PG ₀ before the occurrence of the frequency fluctuation, , (2b) is used to calculate the control amount ΔPG.

Constant Here, Delta] f _c is the frequency change rate df / dt, M in the unit inertia constant of the equivalent contraction generator [sec] when a power network 1 promises equivalent reduced to an equivalent system model one load one generator Is a value obtained and set in advance, and a value obtained by weighted averaging with the rated output of each synchronous generator in the power network. PG ₀ is the power generation amount [MW] of each distributed power source before frequency fluctuation occurs.

The equation (2a) can be derived from the equation of motion of the generator as follows. Considering the power network 1 as an equivalent reduced system model of one generator with one load, the mechanical input of the synchronous generator 25 is P _m , the electrical output is P _e (= load power consumption P _L ), and the inertia constant of the equivalent generator If M is M, the following equation (3) is established from the equation of motion of the generator.

With regard to equation (3), if frequency change rate df / dt = Δf _c and supply / demand imbalance amount (P _m −P _e ) = ΔP, ΔP can be obtained by equation (2a).

  The supply and demand imbalance amount ΔP estimated by the equation (2a) will be described with reference to the electric power Pe (= load power consumption PL) at the time of steady operation of the equivalent generator model as an example. 0) is the amount of power generation deficient. Assuming that the frequency change rate df / dt = 0.01 (here, the frequency decrease side is positive and the change in 10 ms), and the unit inertia constant M = 5 seconds of the equivalent generator model, the supply and demand imbalance amount ΔP is ( From equation (2a), 0.01 × 5.0 = 0.05, and the total power generation amount is insufficient by 5% with respect to the total load amount in the power network 1. Therefore, if 5% of the total power generation amount in the power network 1 is increased, that is, if the output is increased by 5% in each distributed power source 25, the supply and demand imbalance is eliminated and the frequency reduction can be suppressed.

Next, when calculating the output increase / decrease amount ΔPG of each distributed power source from the ΔP estimated value, for example, when the output PG ₀ before the frequency fluctuation of the distributed power source 25 is 50 kW, the output increase / decrease amount ΔPG is 50 kW. 5% +2.5 kW.

  Since the system frequency in the power network 1 varies in substantially the same manner, ΔP estimated at each distributed power supply end is substantially the same. Therefore, even in a configuration in which the distributed power sources 25 are distributed in the power network 1, 5% control can be performed uniformly in each distributed power source 25, so that the output of the power network 1 as a whole can be increased by 5%.

Next, operations during actual operation will be described with reference to the flowchart of FIG. First, in the distributed power supply 25, to measure constantly the system frequency f (step 801), calculates a variation Δf of the reference frequency _{f 0} (step 802).

When a disturbance such as a load drop or an emergency stop of a distributed power source occurs at a certain point in time, the power demand and supply are not balanced and supply and demand imbalance occurs, and the system frequency f fluctuates greatly (large Δf) (step 803). When frequency fluctuations occur in this way (large Δf), the rate of change df / dt of the system frequency f measured every moment is calculated (step 804). Further, the supply / demand imbalance amount ΔP is estimated using the rate of change df / dt (step 805). Then, an output increase / decrease amount ΔPG is calculated from the estimated ΔP value and the distributed power output PG ₀ before the occurrence of frequency fluctuation (step 806). The output increase / decrease amount (control amount) ΔPG determined in this way is used to control the output PG of the distributed power source 25 (step 807), the supply / demand imbalance of the power network 1 is eliminated, and the system frequency f is set to the reference frequency f. Restore to _zero .

  Next, a case where a synchronous generator 25 having inertia characteristics and other types of power generation devices 21, 22, 23, and 24 are mixed as a distributed power source in the power network 1 will be described.

  In this case, in the distributed power source having no inertia characteristic other than the synchronous generator 25, for example, the secondary battery 21, the micro gas turbine 22, the fuel cell 23, etc., the control amount is calculated by the procedure described in FIG. That is, ΔPG corresponding to Δf is calculated from the Δf-ΔPG control characteristic stored in advance in each distributed power source and the calculated Δf.

On the other hand, in the synchronous generator 25 having inertial characteristics, the control amount is calculated according to the procedure described in FIG. That is, ΔP is estimated by the equation (2a) using the frequency change rate df / dt (= Δf _c ), and ΔPG is calculated by the equation (2b) using ΔP and the distributed power source PG ₀ before the occurrence of the frequency fluctuation. calculate.

  While each distributed power source controls the output PG based on the calculation result of ΔPG, the frequency changes in a direction to return to the value before the occurrence of the disturbance, and finally the value before the occurrence of the disturbance (rated frequency). Therefore, each distributed power source only performs output control for the calculation result of ΔPG until the steady frequency is restored. However, if a new disturbance occurs until the stationary frequency is returned or after returning to the stationary frequency and the frequency change Δf becomes large, ΔPG calculation and output control are performed again, and the new disturbance is generated. Even if it occurs, the frequency is always controlled to the rated frequency.

  According to these embodiments, when calculating the control amount of each distributed power source, the measurement amount necessary for the calculation is only the system frequency that can be measured by the distributed power source itself. The amount (measurement amount) is small, and the distributed power supply can independently control the output.

Next, as shown in FIG. 9, the power network 1 and a large-scale power transmission / distribution network 100 such as a power company are connected via a connection line 12 by a connection line switch 13 in a closed state. Will be described. It should be noted that the interconnecting tide flow rate (the interconnecting tide reference value Pt ₀ ) is determined by a contract with an electric power company such as an electric power company that operates the large-scale power distribution network 100, and is zero or a certain constant value. The following.

In such a state, power demand and supply in the power network 1 change due to disturbance such as load drop or an emergency stop of the distributed power source in the power network 1, resulting in shortage or excess (supply / demand imbalance). These electric powers are exchanged between the large-scale power transmission / distribution network 100 via the interconnection line 12. Therefore, tie line power flow quantity changes with respect to the tie-line power flow reference value Pt _0. In this case, it is necessary to promptly return the interconnected tidal flow to the state before the occurrence of the disturbance based on the contract conditions with the electric power company described above.

  Further, since the supply and demand imbalance due to the disturbance in the power network 1 is absolutely small relative to the system capacity of the large-scale power transmission and distribution network 100, the system frequency hardly changes. Therefore, in this embodiment, supply and demand imbalance in the power network 1 is regarded as a change in the interconnected tidal flow.

  For this reason, as shown in FIG. 9, the connection line monitoring means 5 is provided in the connection line portion, and the presence / absence of connection of the connection line 12 between the power network 1 and the large-scale transmission / distribution network 100 (connection line switching) The open / close state of the device 13) and the connection line power flow at the time of connection of the connection line are detected, and the presence / absence of connection of the connection line 12 and the connection line flow rate are detected in each distributed power source 21, 22, 23, 24, 25. It is configured to notify.

In addition, as shown in FIG. 11, each distributed power source 21, 22, 23, 24, 25 has a connection line power flow from the connection line power flow reference value Pt ₀ and the notified connection line power flow rate Pt. A change amount detecting means 41 for obtaining the change amount ΔPt is provided, and a control amount calculating means 42 is provided. The control amount calculation means 42 regards the change ΔPt in the interconnected power flow as the supply / demand imbalance ΔP of the power network, and sets the control amount ΔPG of the generated power for recovering the supply / demand imbalance ΔP to a preset relationship. Calculate and output using (ΔPt−ΔPG control characteristic).

  As a result, when a fluctuation (change ΔPt) in the interconnected line flow occurs due to power supply / demand imbalance ΔP in the power network 1, each distributed power source 21, 22, 23, 24, 25 is controlled so as to suppress this fluctuation. The generated power can be controlled autonomously.

  Details will be described below. First, the following work is performed to determine the set values to be stored in the distributed power sources 21, 22, 23, 24, and 25 in advance.

  When a disturbance such as a load drop or an emergency stop of a distributed power source occurs in the power network 1 and the power demand and supply in the power network 1 change, there is a shortage or excess of power, that is, supply and demand imbalance ΔP Power is exchanged with the large-scale power transmission and distribution network 100 via the interconnection line 12. Since the supply / demand imbalance ΔP and the interconnected power flow change ΔPt are substantially equal, if the output PG of the distributed power source in the power network 1 is changed by ΔPt, the supply / demand imbalance is eliminated. Therefore, it is determined which distributed power source output PG is to be controlled to eliminate supply and demand imbalance. Which distributed power source is controlled is determined in consideration of the control priority of the distributed power sources 21, 22, 23, 24, 25, output characteristics, efficiency, power generation reserve capacity, and the like.

  As an example of the control pattern of the distributed power supply, for example, when it is desired to control the control priority of the distributed power supply for the purpose of controlling from the efficient distributed power supply, etc., the control priority of each distributed power supply Then, the amount (maximum amount ΔPGmax that can increase the output and maximum amount ΔPGmin that can decrease the output) to be borne by each distributed power source in order to eliminate the supply and demand imbalance ΔP is determined.

  Based on this, the control pattern of each distributed power source when the interconnection power flow changes is determined. That is, the output increase / decrease amount ΔPG is determined as to how much the output of the distributed power source is increased / decreased with respect to the interconnection power flow change ΔPt. As described above, this is called a ΔPt-ΔPG control characteristic of each distributed power source.

  FIG. 12 is a diagram showing an example of the burden amount of each distributed power source with respect to the change ΔPt in the interconnection power flow. The supply and demand imbalance ΔP in the power network 1 is positive when the load is dropped = power supply excess side, When power is lost = Negative power supply is negative. For the change ΔPt in the interconnection line power flow, the power flow directed to the large-scale transmission / distribution network 100 is positive. In this example, a secondary battery: BTR21, a micro gas turbine: MGT22, and a fuel cell: FC23 are used as distributed power sources for eliminating the supply and demand imbalance ΔP, and these control priorities are BTR, MGT, The order is FC. The maximum burdens (ΔPGmax, ΔPGmin) of these distributed power sources 21, 22, 23 are ΔPGmax = + 10 kW, ΔPGmin = −10 kW, and MGT22 is also ΔPGmax = + 10 kW, ΔPGmin = −10 kW, FC23 in the BTR 21 ΔPGmax = + 15 kW and ΔPGmin = −15 kW. In this case, the ΔPt-ΔPG control characteristics of the respective distributed power sources 21, 22, and 23 are as shown in FIGS. 13a, 13b, and 13c.

  The ΔPt-ΔPG control characteristics of each distributed power source obtained as described above are stored in advance in the control amount calculation means 42 of each distributed power source 21, 22, 23.

  Since the ΔPt-ΔPG control characteristic is used to calculate the control amount, any distributed power source may be used regardless of the presence or absence of the inertia characteristic. For example, FC23 in FIG. 12 is replaced with SG25. There is no problem.

  As a control pattern of other distributed power sources, when it is desired to control each distributed power source simultaneously, the ΔPt-ΔPG control characteristics of each distributed power source are set as shown in FIGS. 14a, 14b, and 14c. When the interconnection power flow changes, BTR, MGT, and FC are controlled (the maximum burden amounts ΔPGmax and ΔPGmin of each distributed power source are the same as in the example of FIG. 13). FIG. 15 shows the burden amount of each distributed power source with respect to ΔPt.

  Further, as a control pattern of other distributed power sources, when it is desired to quickly return the grid line flow rate to the state before the disturbance occurrence, the control priority order and the burden amount are not determined, that is, as shown in FIGS. The supply and demand imbalance may be eliminated by operating according to the output response characteristics of the distributed power supply without setting the appropriate control characteristics. In this case, control is performed mainly by a distributed power source with fast response, and the output is changed to the maximum output or the minimum output.

  Next, the operation during actual operation will be described with reference to the flowchart of FIG. First, the interconnection monitoring device 5 that monitors the state of the interconnection line with the large-scale power transmission network 100 confirms whether the large-scale transmission / distribution network 100 and the power network 1 are linked (step 1001). If it is in the interconnecting state, the interconnecting line power flow Pt (effective power flowing through the interconnecting line) is measured (step 1002). And the measurement result of this connection line connection state (closed state of the connection line switch 13) and connection line power flow Pt is transmitted to each distributed power supply (step 1003). In the case of non-interconnection, only the connection line connection state (open state of the connection line switch 13) is transmitted to each distributed power source.

Each distributed power, tie line connection state sent from the tie-line monitoring device 5 receives the tie-line power flow Pt (step 1011), the variation ΔPt from tie-line power flow reference value Pt ₀ Is calculated (step 1012).

  When a disturbance such as a load drop or an emergency stop of a distributed power source occurs in the power network 1 at a certain point in time, the power demand and supply in the power network 1 change, and a shortage or excess of power (= supply and demand) Unbalance ΔP) is exchanged with the large-scale power transmission / distribution network 100 via the interconnection line 12. For this reason, the interconnection line power flow Pt changes greatly (ΔPt large) (step 1013). In this case, an output increase / decrease amount ΔPG of the distributed power source corresponding to the change ΔPt of the interconnection power flow is calculated by a preset ΔPt−ΔPG control characteristic (step 1014), and based on the result, the distributed power source output ΔΔt is calculated. The output PG is controlled (step 1015). As a result, the supply and demand imbalance of the power network 1 can be eliminated, and the interconnection power flow Pt can be returned to the state before the occurrence of the disturbance.

  As described above, when the power network 1 is connected to the large-scale transmission / distribution network 100, the system frequency hardly changes even if a supply / demand imbalance due to load drop occurs in the power network 1. Since the amount of change in the interconnection power flow is used without calculating the control amount of the distributed power source, the control amount of the distributed power source can be calculated. Moreover, since the amount of measurement required for the calculation is only the interconnection power flow, the amount of information (measurement amount) required for the calculation is small, and the distributed power supply can independently control the output.

  The above description has been given in the case where the power network 1 is connected to the large-scale transmission / distribution network 100 by the interconnection line 12. However, the power network 1 and the large-scale transmission / distribution network 100 are connected to each other. 12 can be arbitrarily switched to a non-interconnected state by the interconnecting line switch 13 provided in FIG. That is, the power network 1 is not connected to the large-scale transmission / distribution network 100 shown in FIG. 1 and the single-system connection with the large-scale transmission / distribution network 100 shown in FIG. May be operated as

  When the large-scale power transmission / distribution network 100 is not connected, the connection line is open and there is no power flow information. When the connection is made, load drop in the power network 1 or emergency stop of the distributed power source, etc. Even if this disturbance occurs, the system frequency hardly fluctuates because it is connected to the large-scale power distribution network 100 having a large system capacity. In these cases, the appropriate method for obtaining the control amount for each distributed power source has been proposed as described above. Therefore, the method for obtaining the control amount should be selected appropriately according to the presence or absence of interconnection. That's fine.

  Specifically, the frequency detection means 31 and the control amount calculation means 32 set with the Δf-ΔP control characteristics shown in FIG. 3 and the tidal current change detection means 41 and the ΔPt-ΔP control characteristics shown in FIG. The control amount calculation means 42 and the like may be provided, and these may be selected and applied according to the connection line connection state transmitted from the connection line monitoring device 5.

  Hereinafter, a description will be given with reference to the processing flow of FIG. First, the interconnection monitoring device 5 that monitors the state of the interconnection line with the large-scale power transmission network 100 confirms whether the large-scale transmission / distribution network 100 and the power network 1 are linked (step 1601). If it is in the interconnecting state, the interconnecting line power flow Pt (effective power flowing in the interconnecting line) is measured (step 1602). And the measurement result of this connection line connection state (closed state of the connection line switch 13) and the connection line power flow Pt is transmitted to each distributed power supply (step 1603). In the case of non-interconnection, only the connection line connection state (open state of the connection line switch 13) is transmitted to each distributed power source.

  Each distributed power source measures the system frequency f every moment (step 1611), and receives the connection line connection state and the connection line power flow Pt sent from the connection line monitoring device 5 (step 1612). .

  Whether the connection is present or not is determined based on the connection line connection state information (step 1613). As a result, in the case of non-interconnection with the large-scale transmission / distribution network 100, the control amount of the distributed power source is calculated based on the frequency change (steps 1614, 1615, 1616). On the other hand, when connected to the large-scale transmission / distribution network 100, the control amount of the distributed power source is calculated based on the change in the power flow (steps 1624, 1625, 1626). Then, output control of each distributed power source is performed with the control amount obtained in this way.

  In this way, by switching the calculation method of the control amount of the distributed power source using the connection line connection state information with the large-scale power transmission and distribution network 100, the control amount of the distributed power source can be calculated regardless of the connection state. .

1 is a system diagram showing an embodiment of a power network control system according to the present invention. FIG. It is a flowchart explaining operation | movement of one Embodiment same as the above. It is a functional block diagram which shows the principal part function of one Embodiment same as the above. It is a characteristic figure explaining the relationship between the electric power supply-and-demand imbalance in the electric power grid | system in one Embodiment same as the above, and the magnitude | size of the fluctuation | variation of a system frequency. It is a characteristic view which shows (DELTA) f- (DELTA) PG control characteristic of the secondary battery which is one of the distributed power supplies at the time of giving a priority to the several distributed power supply in one Embodiment same as the above. It is a characteristic view which shows the (DELTA) f- (DELTA) PG control characteristic of the micro gas turbine which is one of the distributed power sources at the time of giving a priority to the several distributed power sources in one embodiment same as the above. It is a characteristic view which shows the (DELTA) f- (DELTA) PG control characteristic of the fuel cell which is one of the distributed power sources at the time of giving a priority to the several distributed power sources in one embodiment same as the above. It is a characteristic view which shows (DELTA) f- (DELTA) PG control characteristic of the secondary battery which is one of the distributed power supplies in the case of controlling the several distributed power supply simultaneously in one embodiment same as the above. It is a characteristic view which shows (DELTA) f- (DELTA) PG control characteristic of the micro gas turbine which is one of the distributed power supplies in the case of controlling the several distributed power supply simultaneously in one embodiment same as the above. It is a characteristic view which shows the (DELTA) f- (DELTA) PG control characteristic of the fuel cell which is one of the distributed power supplies in the case of controlling the several distributed power supply simultaneously in one embodiment same as the above. It is a characteristic view showing the sharing situation at the time of each distributed power supply controlling output in order to suppress the fluctuation | variation of the system frequency with respect to the electric power supply-and-demand imbalance in one Embodiment same as the above. It is a flowchart explaining the operation | movement of embodiment which estimates the electric power supply-and-demand imbalance of this invention with the change rate of a system frequency. It is a systematic diagram which shows embodiment at the time of cooperating with a large-scale power transmission and distribution network of this invention. It is a flowchart explaining operation | movement of embodiment same as the above. It is a functional block diagram which shows the principal part function of embodiment same as the above. It is a characteristic view explaining the relationship between the electric power supply-and-demand imbalance in an electric power grid | system in embodiment same as the above, and interconnection line power flow change. It is a characteristic view which shows (DELTA) Pt- (DELTA) PG control characteristic of the secondary battery which is one of the distributed power supplies at the time of giving priority to the several distributed power supply in embodiment same as the above. It is a characteristic view which shows the (DELTA) Pt- (DELTA) PG control characteristic of the micro gas turbine which is one of the distributed power sources at the time of giving a priority to the several distributed power sources in embodiment same as the above. It is a characteristic view which shows the (DELTA) Pt- (DELTA) PG control characteristic of the fuel cell which is one of the distributed power supplies at the time of giving priority to the some distributed power supply in embodiment same as the above. It is a characteristic view which shows (DELTA) Pt- (DELTA) PG control characteristic of the secondary battery which is one of the distributed power supplies when controlling the several distributed power supply simultaneously in embodiment same as the above. It is a characteristic view which shows the (DELTA) Pt- (DELTA) PG control characteristic of the micro gas turbine which is one of the distributed power supplies in the case of controlling simultaneously the several distributed power supply in embodiment same as the above. It is a characteristic view which shows the (DELTA) Pt- (DELTA) PG control characteristic of the fuel cell which is one of the distributed power supplies in the case of controlling the several distributed power supply simultaneously in embodiment same as the above. It is a characteristic view showing the sharing situation at the time of each distributed power supply controlling output in order to suppress the fluctuation | variation of the interconnection line power flow with respect to the electric power supply-and-demand imbalance in embodiment same as the above. It is a flowchart explaining the control operation | movement in embodiment which enabled it to open / close arbitrarily the interconnection line switch of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electric power network 3 Load drop 4 System frequency 5 Connection line monitoring apparatus 6 Connection line connection state and connection line power flow 12 Connection line 13 Connection line switch 14 Load 21 Secondary battery which is one of distributed power sources DESCRIPTION OF SYMBOLS 22 Micro gas turbine which is one of distributed power sources 23 Fuel cell which is one of distributed power sources 24 Wind power generation which is one of distributed power sources 25 Synchronous generator which is one of distributed power sources 31 Frequency detection means 32 Control amount calculation means having Δf-ΔPG control characteristics 41 Interconnection power flow change detection means 42 Control amount calculation means having ΔPt-ΔPG control characteristics 100 Large-scale power distribution network

Claims (1)

It is operated as a single system separated from a large-scale power distribution network by connecting multiple distributed power sources and loads with different power generation methods and loads connected to each other by power transmission / distribution lines, which do not have inertia characteristics provided in specific areas. A relatively small power network control system,
A frequency detection means provided in each of the distributed power sources, for detecting the magnitude of the fluctuation of the system frequency in the power network;
Each distributed power source is provided in each of the distributed power sources to recover the supply / demand imbalance from the relationship between the power supply / demand imbalance between the power demand and supply in the power network and the magnitude of the fluctuation of the system frequency. previously obtained control amount of sharing can occur power, thus determined control amount and the magnitude of fluctuation of the system frequency are correlated, and control having an output change characteristic of the control amount based on the difference of the power method A control amount calculating means for storing a characteristic, and obtaining a control amount corresponding to the magnitude of the detected fluctuation of the system frequency based on the control characteristic ,
When fluctuations in system frequency occur due to supply and demand imbalance in the power network, the distributed power sources are autonomously controlled so as to suppress this fluctuation by the control amount obtained by the control amount calculation means. A control system for a power network, characterized by controlling the generated power.

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