JP4341599B2 - Power grid interconnection stabilization apparatus and power grid stabilization method - Google Patents

Description

  The present invention relates to a power system stabilization device and a power system stabilization method for stabilizing a small-scale power system.

  In the conventional distribution system, the distribution system and the distributed power source and the new energy power source were individually connected, but the new small-scale system facilities such as the distribution system and the small-scale power system were not interconnected. However, along with new energy technology innovation, power distribution systems such as fuel cells and distributed power sources such as new energy power sources, wind power generation, and solar power generation are connected to the distribution system in various forms. Opportunities tend to increase.

  In addition, the conventional AC system and AC system interconnection are performed by DC transmission interconnection (hereinafter referred to as BTB) or asynchronous interconnection by DC transmission. However, the asynchronous interconnection is a system connection on a large scale like the power system, and the power fluctuation is controlled by adjusting the output at the power plant. A large-scale system such as an electric power system can easily control power flow, but a distributed power source in a distribution system has a problem in that output tracking is not sufficient and control performance is not good. Furthermore, the BTB used in the power system has been applied to the transmission system that is a higher voltage system than the distribution system of the power company, but cannot be applied because the power distribution system is small and difficult to control the power flow. It was.

  On the other hand, a small-scale power system is an extremely small-scale system and consists of photovoltaic power generation, wind power generation, various distributed power sources, fuel cells, and loads, where the power source is likely to fluctuate. In the event of an accident, when the power supply system is disconnected from the power distribution system and enters a single operation state, the supply-demand balance deteriorates and power supply becomes more difficult.

  Japanese Patent Application Laid-Open No. 7-67257 (hereinafter referred to as Patent Document 1) describes a BTB (DC power transmission interconnection) that connects between power systems, and a BTB that determines and commands the amount of power transmitted to the BTB based on the system information. An electric power system stabilizing device is described that includes a power transmission amount command unit, and a BTB power transmission amount adjustment unit that outputs a power amount narrowing amount to the BTB from a command signal from the BTB power transmission amount command unit and accident information.

  In JP-A-10-304570 (hereinafter referred to as Patent Document 2), the BTB converter is started to be a DC interconnection, and the stabilization control device controls the BTB converter based on the frequency information of both systems. A technique is described in which power necessary for maintaining the system frequency is interchanged to achieve stabilization.

JP-A-7-67257 JP-A-10-304570

  In the technologies described in Patent Documents 1 and 2, when one power system is a small-scale power system, the small-scale power system is an extremely small system, so that supply and demand balance is not achieved in the small-scale power system alone, and independent operation is possible. In addition, there is a problem that the distributed power supply cannot be followed sufficiently and supply and demand cannot be adjusted only within a small-scale power system.

  An object of the present invention is to provide a system stabilizing device capable of stabilizing the frequency of a small-scale power system linked to a large-scale power system.

  According to one feature of the present invention, an electric power system stabilizing device is a power system stabilizing device that controls transmission power transmitted to a DC power transmission line interconnecting a first electric power system and a second electric power system. The first power system frequency detecting means for detecting the frequency of the first power system, the second power system frequency detecting means for detecting the frequency of the second power system, and the first power frequency detecting means. Of the transmission power transmitted to the DC power transmission line based on the difference between the component of the frequency detected by the step below the predetermined cycle and the component of the frequency detected by the second power frequency detection means below the predetermined cycle DC transmission line transmission power target value calculation means for calculating a target value, and transmission for controlling transmission power transmitted to the DC transmission line based on the target value of transmission power calculated by the DC transmission line transmission power target value calculation means Power control means Lies in the fact that the obtaining things.

  Other features of the present invention are described in the detailed description section for carrying out the invention.

  ADVANTAGE OF THE INVENTION According to this invention, the system stabilization apparatus which can stabilize the frequency of the small-scale electric power system connected with the large-scale electric power system can be provided.

  The present invention installs a BTB in the grid connection line when the grid connection between the power distribution system of the power company and the new energy power source and / or the distributed power source and the small-scale power system having a load is established. The present invention relates to a system interconnection stabilization device that stabilizes a power distribution system and a small-scale power system by a control device that gives a command to the BTB so as to control. In this embodiment, the small-scale power system is a power system having a maximum demand power of 1 MW or less.

The concept of the grid interconnection stabilization device will be described. If the grid connection is established between the small-scale power system and the distribution system via the BTB and the active power passing through the BTB is set to a constant value, it is not necessary to change the effective power from the small-scale power system to the distribution system. . However, in that case, it becomes difficult to absorb fluctuations in a small-scale power system having sunlight, wind power, and fuel cells. Therefore, (1) the fluctuation of the active power from the small-scale power system to the distribution system is mainly caused by long-period fluctuation,
(2) Since short-period fluctuations can be regarded as random noise, the short-period fluctuations of the small-scale power system and distribution system are statistically offset, and the long-period fluctuations of the active power flowing through the BTB are constant. In addition, the effective power of the BTB is controlled so that the short period component can freely come and go.

  A grid interconnection stabilization apparatus according to an embodiment of the present invention includes a BTB, a grid frequency detection means, a small-scale power grid frequency detection means, a long-period and short-period component separation filter apparatus, a long-period component passage prevention means, and a BTB passage output. It has the grid connection stabilization apparatus which has a calculating means and a BTB passage power flow control means, It is characterized by the above-mentioned.

  First, the system frequency detection device detects the frequency of the power company high-voltage distribution system, and the small-scale power system frequency detection device detects the frequency of the small-scale power system. Next, the frequency of the distribution system and the small-scale power system is separated into the short cycle component and the long cycle component by the long cycle / short cycle component separation means. In the present embodiment, the long-period component refers to a component having a period equal to or longer than a set period set within a period of 30 seconds to 10 minutes. The separated long-period component is made constant by the long-period component passage control means so that it does not pass through the BTB, and a power flow that passes through the BTB by giving an output control signal to the distributed power source in the small-scale power system. To control. From the other short cycle component, the frequency fluctuation amount of the small-scale power system and the distribution system is obtained, and the effective power amount to be supplied to the BTB is obtained by the passage output calculation means. Control is performed by giving a command value with a BTB passage power flow command signal of the BTB passage power flow control means so that only the determined effective power amount flows to the BTB.

  The grid interconnection stabilization apparatus according to the present invention includes BTB passage output calculation means, synchronization force calculation means, and active power control apparatus. The BTB passage output calculation means obtains the frequency fluctuation amount of the distribution system and the small-scale power system. The synchronizing force calculation means divides by the control parameter synchronous reactance, and the synchronizing force integrating circuit integrates. The active power control device integrates the obtained change in active power, performs control so that the target value of active power every 30 minutes is 0 or constant, and obtains the amount of active power to flow to the BTB. As a result, it is possible to achieve both suppression of fluctuations in active power from the small-scale power system to the distribution system and suppression of fluctuations in the small-scale power system.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows the overall configuration of a grid interconnection stabilization apparatus according to this embodiment. The grid interconnection control device 19 in FIG. 1 will be described. The system frequency detection means 11, the small-scale power system frequency detection means 12, the long cycle / short cycle component separation means 13, the long cycle / short cycle component control means 14, the BTB passage power flow calculation means 15, and the BTB passage power flow control means 16. The system frequency detection means 11 monitors and constantly detects the frequency in the distribution system of the electric power company. The small-scale power system frequency detection means 12 constantly detects the frequency in the small-scale power system. The long cycle / short cycle component separating unit 13 separates the frequency detected by the system frequency detecting unit 11 and the small-scale power system frequency detecting unit 12 into a long cycle component and a short cycle component. The long cycle component control means 14 cuts off the frequency of the long cycle components of the distribution system and the small-scale power system detected by the long-cycle and short-cycle component separation means 13 at the BTB 18 and the power supply 17 to be controlled in the small-scale power system. In this way, a signal is given and controlled. The BTB passage power flow calculating means 15 obtains an effective power amount for passing the BTB from the short cycle components separated by the long cycle / short cycle component separating means 13 and calculates and controls the power flow to be 0 or constant. It is. The BTB passage power flow control means 16 gives a signal to the BTB 18 as the BTB passage power flow command signal with the amount of effective power passing through the BTB.

  Next, FIG. 2 will be described. The grid interconnection stabilization device 29 includes a BTB 21 and a grid interconnection control device 24. The grid interconnection control device 24 detects the frequency 25 from the distribution system 22 and detects the frequency 26 from the small-scale power system 23. Based on the detected frequency, the power flow flowing in the BTB 21 is calculated, and the power flow control signal 28 is transmitted to the BTB 21 and the control signal 27 is transmitted to the distributed power source to be controlled in the small-scale power system.

  Next, FIG. 3 will be described. FIG. 3 is an explanatory diagram showing details of the BTB passage power flow calculating means 15 of FIG. The frequency change amount calculation means 151 calculates the frequency change amount of the short period component. The synchronization force calculation means 152 calculates the synchronization force. The synchronizing force integrating means 153 integrates the obtained synchronizing force. The active power control means 154 determines the power flow flowing through the BTB obtained by integrating the synchronization force.

Next, the operation will be described with reference to the flowchart of FIG. First, the frequency analysis of the step of S11 is performed by dividing the frequency of the distribution system and the small-scale power system as shown in FIG. 5 and the frequency of the small-scale power system as shown in FIG. Detected by system frequency detection means. Next, in step S12, the system frequency is separated into a long-cycle frequency component as shown in FIG. 7 and a short-cycle frequency component as shown in FIG. Further, fluctuations of about 30 seconds to 2 minutes are separated into short-cycle frequency components, and longer cycles are separated into long-cycle components. On the other hand, the small-scale power system frequency is similarly separated into a frequency component with long-period fluctuation as shown in FIG. 8 and a frequency component with short-period fluctuation as shown in FIG. Next, in step S13, as shown in FIGS. 7 and 8, the frequency of the long period component of the frequency is controlled by the distributed power source to be controlled in the small-scale power system so that the BTB does not pass constant. To do. On the other hand, the short period component of the frequency as shown in FIG. 9 and FIG. 10 obtains the output to pass by the BTB passage output calculating means as shown in FIG. Next, in step S14, the tidal current flowing through the BTB is obtained by the BTB output calculating means 155 shown in FIG. First, the difference between the system frequency as shown in FIG. 9 and the system frequency deviation Δf ₁ and the small-scale power system frequency deviation Δf ₂ is obtained by the frequency variation calculation means 151.

  Next, in step 15, the synchronizing force is obtained by dividing the difference Δf in frequency deviation obtained by the synchronizing force calculating means 152 in FIG. 3 by the synchronous reactance X that is a control parameter of the line. The synchronization power is expressed as follows.

In FIG. 11, assuming that the phase on the grid side is θ ₁ , the phase on the small-scale power grid side is θ ₂ , and the synchronous reactance of the line, which is a control parameter, is X, the flowing active power P can be expressed as the following equation.

但し、Ｘは同期リアクタンス

Where X is the synchronous reactance

  X can be obtained, for example, as the sum of the reactance of the power distribution system and the reactance of the small-scale power system. Next, step S15 will be described.

  From equation (2), the synchronization force can be expressed as:

  Next, the amount of change per hour of the effective power P that passes the target BTB can be expressed by the following equation.

次に、ステップＳ１６では、式（４）で求めた時間毎の有効電力Ｐを図３の同期化力積分手段１５３によって積分することにより、ＢＴＢを通過させる有効電力目標値Ｐを次式で表すことができる。

Next, in step S16, the active power target value P that passes through the BTB is expressed by the following equation by integrating the effective power P for each time obtained by the equation (4) by the synchronizing force integrating means 153 of FIG. be able to.

  The power flow is controlled so that only the active power target value P obtained by Expression (5) flows through the BTB. The obtained active power target value P is set to 0 or constant within a predetermined range (for example, 30 minutes) as shown in FIG. 12 by the active power control means 154 of FIG. For example, the time range for integration with the time of Expression (5) is about 5 minutes, and the active power target value P is obtained every 5 minutes. Next, in step S17, the control amount is obtained so that the obtained active power target value P is 0 or constant within a predetermined time period (for example, 30 minutes). That is, control is performed so that supply and demand every 30 minutes are the same amount at the same time.

  The present invention installs a BTB that controls power flow on a grid connection line when a high-voltage distribution system of a power company and a small-scale power system having small-scale system facilities are connected to the grid. As a result, the balance between supply and demand can be adjusted between the distribution system and the small-scale power system even if the followability of the distributed power source of the small-scale power system is poor. Furthermore, the small-scale power system and the power distribution system can be stabilized by controlling the power flow flowing from the frequency components of the two systems to the BTB system of the interconnected part to 0 or constant. In the past, distributed power sources could not be introduced in large quantities due to problems of frequency maintenance and voltage maintenance, but tidal current control was performed at the grid connection point in a system that was connected to the system at one point, such as a small-scale power system. By introducing BTB that can be performed, there is an advantage that more distributed power sources can be introduced into the system.

It is explanatory drawing which showed the structural example of the grid connection stabilization apparatus concerning this invention. It is explanatory drawing which showed the relationship between a grid connection stabilizer, a power distribution system, and a small-scale power system. It is explanatory drawing shown about the BTB passage output calculating means of the grid connection stabilization apparatus of FIG. It is explanatory drawing about the flowchart of the grid connection control apparatus of FIG. It is explanatory drawing which showed the example of the frequency of a power distribution system. It is explanatory drawing which showed the example of the frequency by the side of a small scale electric power grid | system. It is explanatory drawing which showed the example of the frequency of the long period component in a power distribution system. It is explanatory drawing which showed the example of the frequency of the long period component in a small scale electric power grid | system. It is explanatory drawing which showed the example of the frequency of the short period component in a power distribution system. It is explanatory drawing which showed the frequency of the short period component in a small-scale electric power system. It is explanatory drawing shown about the relationship between the phase and power flow of a power distribution system and a small-scale power system. It is explanatory drawing shown about the example of control of the BTB power flow control apparatus of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... System frequency detection means, 12 ... Small-scale electric power system frequency detection means, 13 ... Long period short period component separation means, 14 ... Long period component passage prevention means, 15,155 ... BTB passage output calculation means, 16 ... BTB passage Power flow control means, 17 ... distributed power supply in small-scale power system, 18, 21 ... BTB (DC power transmission interconnection), 19 ... grid-connected control device, 22 ... distribution system, 23 ... small-scale power system, 24 ... system Interconnection control device, 25 ... distribution system frequency, 26 ... small power system frequency, 27 ... small power system output control signal, 28 ... BTB power flow control signal, 29 ... system connection stabilization device, 151 ... system frequency Small power system frequency variation calculation means 152... Synchronization power calculation means 153... Synchronization power integration means 154... Active power control means 156.

Claims (3)

  A power system stabilizing device that controls transmission power transmitted to a DC power transmission line that links a power distribution system and a small-scale power system with a maximum demand power of 1 MW or less, the frequency of the power distribution system of the power company being First frequency detection means for detecting, second frequency detection means for detecting the frequency of the small-scale power system, and 30 seconds of the frequency of the distribution system of the electric power company detected by the first frequency detection means A component less than or equal to a period set within a period of 10 minutes and a frequency less than or equal to a period set within a period of 10 minutes from the 30 seconds of the frequency of the small-scale power system detected by the second frequency detection means. A transmission power target value calculation means for calculating a target value of the transmission power transmitted to the DC transmission line based on a difference from the component, and a transmission power target value calculated by the transmission power target value calculation means. There are a DC power transmission line power system stabilizer, characterized in that it comprises a transmission power control means for controlling the transmission power transmitted to. According to claim 1, before Kioku DENDEN force target value calculating means following period set in the range of periods from 30 seconds to 10 minutes in the frequency of the distribution system of the power companies detected by the first frequency detecting means By integrating the difference between the component and the component of the frequency of the small-scale power system detected by the second frequency detecting means within a period of 30 seconds to 10 minutes within a predetermined period, and integrating the difference for a predetermined time A power system stabilizing device that calculates a target value of transmission power transmitted to a DC transmission line. A system stabilization method for controlling transmission power transmitted to a DC transmission line that links a distribution system of an electric power company and a small-scale power system having a maximum demand power of 1 MW or less, and detects the frequency of the distribution system of the electric power company A first frequency detection procedure, a second frequency detection procedure for detecting the frequency of the small-scale power system, and the frequency of the power system distribution system detected by the first power frequency detection procedure from 30 seconds. Less than the period set within the period of 10 minutes from the 30 seconds of the component of the period less than the period set within the period of 10 minutes and the frequency of the small-scale power system detected by the second frequency detection procedure wherein the feed calculate the target value wires transmitted power target value calculation procedure of the transmission power transmitted to the DC transmission line, the transmission power target value target of the transmission power calculated by the calculating procedure on the basis of the difference between the components Power system stabilizing method characterized by having a transmission power control procedure for controlling a transmission power transmitted to the DC transmission line based on.

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