Synchronous camera modulation method

Abstract

To provide a conversion method for a synchronous phase modifier which is highly responsive to power system malfunctions.SOLUTION: When converting a power generation facility of an AC excitation type in a discontinued or idle plant to a synchronous phase modifier 10, a conversion method for a synchronous phase modifier electrically connects a thyristor type exciting device 3 to slip rings 1c and 1d of a synchronous phase machine 1 that had been used as a generator in the power generation facility, to convert the power generation facility to the synchronous capacitor 10 of a static excitation type. The thyristor type exciting device 3 includes: a thyristor rectifier 3a and an automatic voltage regulator 3b connected to the thyristor rectifier 3a.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a synchronous phase modifier conversion method.

Background Art

[0002] In recent years, the introduction of renewable energy such as solar power generation and wind power generation has been progressing. There is also a movement to decommission aging thermal power plants and nuclear power plants. Thus, as the introduction of renewable energy progresses while thermal power plants and nuclear power plants decrease, in addition to the disruption of supply and demand balance and the excess of transmission capacity, voltage fluctuations and frequency fluctuations are likely to occur in the power grid, and reactive power is likely to be insufficient.

[0003] Therefore, it has been proposed to divert the power generation facilities of decommissioned plants or idle plants to synchronous phase modifiers and supply reactive power from the synchronous phase modifiers to the power grid. As such a technique, for example, Patent Document 1 describes that "when diverting the hydrogen-cooled generator equipment of an idle thermal power plant as synchronous phase modifier equipment, the hydrogen gas pressure of the hydrogen-cooled generator is reduced to a predetermined pressure and the driving motor is operated."

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, Patent Document 1 does not describe the change in the excitation method when diverting a hydrogen-cooled generator to a synchronous phase modifier, and there is room to improve the responsiveness to power grid failures in the synchronous phase modifier.

[0006] Therefore, an object of the present invention is to provide a synchronous phase modifier conversion method with high responsiveness to power grid failures. [Means for solving the problem]

[0007] To solve the aforementioned problems, the synchronous phase condenser method according to the present invention is: It is equipped with a turbine and a synchronous machine, to which an AC exciter and a permanent magnet motor are sequentially connected via a shaft. Convert AC-excited power generation equipment from decommissioned or idle plants into synchronous condensers. A method for synchronizing phase condensers. , A turbine removal step of removing the turbine, and a disconnection step of disconnecting the electrical connection used to control the AC exciter and the permanent magnet motor while the AC exciter and the permanent magnet motor remain mechanically connected to the synchronous machine via the shaft, The generator used in the aforementioned power generation facility The aforementioned By electrically connecting a thyristor-type excitation device to the slip rings of a synchronous machine, it becomes a static excitation type synchronous condenser. Includes an excitation device connection process. That's what we decided. Further details will be explained within the embodiments. [Effects of the Invention]

[0008] According to the present invention, a method for synchronous condensing that provides a high degree of responsiveness to power system malfunctions can be provided. [Brief explanation of the drawing]

[0009] [Figure 1] This is a diagram showing the configuration including a synchronous condenser in a synchronous condenser method according to the first embodiment. [Figure 2] This is an explanatory diagram relating to the conversion of a static excitation type synchronous condenser to a synchronous condenser in the method for creating a synchronous condenser according to the first embodiment. [Figure 3] This is a diagram showing the configuration including a synchronous condenser in a synchronous condenser method according to the second embodiment. [Figure 4] This is a diagram showing the configuration including a synchronous condenser in a synchronous condenser method according to the third embodiment. [Figure 5] This is a diagram showing the configuration of the AC excitation power generation equipment before it was converted into a synchronous condenser. [Modes for carrying out the invention]

[0010] The following describes, as an example, the case in which a power generation facility 20 (see Figure 5) from a decommissioned plant is converted into a synchronous condenser 10 (see Figure 1). A "decommissioned plant" refers to a plant where the operation of its power generation facilities has ended. First, the synchronous condenser 10 (see Figure 1) is described, then the power generation facility 20 (see Figure 5) before conversion is briefly described, and finally, the specific method of converting the power generation facility 20 into a synchronous condenser 10 (the method of converting to a synchronous condenser) is described in detail.

[0011] ≪First Embodiment≫ Figure 1 is a configuration diagram including the synchronous condenser 10 in the synchronous condenser method according to the first embodiment. The synchronous condenser 10 shown in Figure 1 is a static excitation type (also called a thyristor excitation type) condenser that supplies reactive power to the power system 50 to stabilize the voltage of the power system 50 and improve the power factor. The synchronous condenser 10 continuously changes the armature current (stator winding current) from lagging current to leading current by continuously changing the field current (rotor winding current). The synchronous condenser 10 also has the function of suppressing voltage disturbances caused by load fluctuations in the power system 50 by the inertial force (electrical and mechanical inertial force) associated with the rotation of the rotor 1b of the synchronous machine 1.

[0012] As shown in Figure 1, the synchronous condenser 10 comprises a synchronous machine 1, an excitation transformer 2, a thyristor-type excitation device 3, an instrument transformer 4, an instrument current transformer 5, a drive unit 6, and a drive inverter 7. The synchronous machine 1 is a rotating machine driven under no load. Note that the term "no load" includes cases where the synchronous machine 1 is subjected to some load. The synchronous machine 1 comprises a stator 1a, a rotor 1b, slip rings 1c, 1d, and brushes 1e, 1f.

[0013] The stator 1a comprises a stator core (not shown) and stator windings (not shown) wound around the stator core. The stator windings are connected to the power system 50 sequentially via the phase-separated busbar M1 and the main transformer 41. The rotor 1b comprises a rotor core (not shown) that rotates integrally with the shaft F1 and rotor windings (not shown) wound around the rotor core.

[0014] The slip rings 1c and 1d are metal annular members that rotate integrally with the rotor core. These slip rings 1c and 1d have the function of maintaining the electrical connection between the rotor winding (not shown) of the synchronous machine 1 and the thyristor rectifier 3a. One slip ring 1c is connected to one end of the rotor winding of the synchronous machine 1 via wiring K1. The other slip ring 1d is connected to the other end of the rotor winding of the synchronous machine 1 via wiring K2.

[0015] Brush 1e electrically connects the thyristor rectifier 3a and the slip ring 1c. Brush 1e is connected to the thyristor rectifier 3a via wiring K3 and is in contact with the slip ring 1c. The other brush 1f electrically connects the thyristor rectifier 3a and the slip ring 1d. Brush 1f is connected to the thyristor rectifier 3a via wiring K4 and is in contact with the slip ring 1d. For example, carbon brushes can be used as such brushes 1e and 1f. In addition, a field circuit breaker (not shown) may be provided to switch the electrical connection or disconnection between the rotor winding of the synchronous machine 1 and the thyristor rectifier 3a.

[0016] The excitation transformer 2 is a transformer that transforms the AC voltage of the power system 50 to a predetermined voltage and applies it as a power source to the thyristor rectifier 3a. As shown in Figure 1, the primary side of the excitation transformer 2 is connected to the power system 50 and the secondary side is connected to the thyristor rectifier 3a. The primary side of the excitation transformer 2 may be connected as follows: In addition to the phase-separated busbar M1 that connects the synchronous machine 1 and the main transformer 41, the primary side of the excitation transformer 2 may be connected to a predetermined busbar such as the high-voltage busbar M2 (see Figure 2).

[0017] The thyristor type excitation device 3 is a device that adjusts the excitation current of the synchronous machine 1 by controlling the thyristor ignition angle. As shown in FIG. 1, the thyristor type excitation device 3 includes a thyristor rectifier 3a and an automatic voltage regulator 3b (Automatic Voltage Regulator: AVR).

[0018] The thyristor rectifier 3a is a rectifier that converts AC power into a predetermined DC power based on the control of the automatic voltage regulator 3b. As such a thyristor rectifier 3a, for example, a uniform bridge type composed of a plurality of thyristors (not shown) may be used. Also, as the thyristor rectifier 3a, a hybrid bridge type including a thyristor (not shown) and a diode (not shown), or a saturated bridge type including a diode (not shown) and a reactor (not shown) may be used.

[0019] As shown in FIG. 1, the input side of the thyristor rectifier 3a is connected to the secondary side of the excitation transformer 2. The output side of the thyristor rectifier 3a is connected to the slip ring 1c through the wiring K3 and the brush 1e in sequence, and is also connected to the slip ring 1d through another wiring K4 and the brush 1f in sequence.

[0020] The automatic voltage regulator 3b is a device that controls the thyristor ignition angle of the thyristor rectifier 3a and is connected to the thyristor rectifier 3a. By controlling the thyristor ignition angle in this way, the excitation current (DC current) of the synchronous machine 1 is adjusted. As a result, the reactive power output from the synchronous machine 1 is adjusted. The reactive power of the synchronous machine 1 is supplied to the power system 50 from the stator winding (not shown) through the phase separation bus M1 and the main transformer 41 in sequence.

[0021] For example, when the field of the synchronous machine 1 is weakened and excited for leading-phase operation, the rotor winding (not shown) of the synchronous machine 1 functions as a reactor that absorbs lagging-phase current from the power system 50. Conversely, when the field of the synchronous machine 1 is strengthened and excited for lagging-phase operation, the rotor winding (not shown) of the synchronous machine 1 functions as a capacitor that absorbs leading-phase current from the power system 50. In addition, if the voltage drops and reactive power becomes insufficient due to load fluctuations, power flow changes, or faults such as broken wires in the power system 50, the aforementioned lagging-phase operation is performed. Therefore, lagging-phase operation is often performed when stabilizing the voltage of the power system 50.

[0022] The instrument transformer 4 shown in Figure 1 is a transformer for measuring the AC voltage of the power system 50. The primary side of the instrument transformer 4 is connected to the phase-separated busbar M1 via wiring K5, and the secondary side is connected to the automatic voltage regulator 3b via another wiring K6. The automatic voltage regulator 3b calculates the AC voltage of the power system 50 based on the voltage of the secondary side of the instrument transformer 4 and the turns ratio of the primary and secondary sides of the instrument transformer 4.

[0023] The instrument current transformer 5 shown in Figure 1 is a current transformer for measuring the alternating current of the power system 50. The instrument current transformer 5 is connected to the phase-separated busbar M1 and also to the automatic voltage regulator 3b via wiring K7. (Phase separation bus connection process) Then, based on the current on the secondary side of the instrument current transformer 5 and the turns ratio of the primary and secondary sides of the instrument current transformer 5, the automatic voltage regulator 3b calculates the AC current of the power system 50. The automatic voltage regulator 3b controls the thyristor rectifier 3a based on the detected values ​​of the AC voltage and AC current of the power system 50.

[0024] The drive unit 6 is an electric motor that accelerates the rotor 1b when starting the synchronous machine 1, and is connected to the rotor 1b via the shaft F1. For example, when starting the synchronous machine 1, the drive unit 6 accelerates the rotor 1b to a predetermined rotational speed that is synchronized with the AC frequency of the power system 50. A clutch (not shown) that switches between transmitting and disconnecting force between the synchronous machine 1 and the drive unit 6 may be provided, and when the rotational speed of the synchronous machine 1 reaches a predetermined value, the clutch may be used to disconnect the transmission of force between the synchronous machine 1 and the drive unit 6. Furthermore, even after the synchronous machine 1 has finished starting, the drive unit 6 may assist in driving the synchronous machine 1 to compensate for any losses incurred by the synchronous machine 1.

[0025] The drive inverter 7 is a power converter that applies a predetermined AC voltage to the drive unit 6. The input side of the drive inverter 7 is connected to the power system 50 via the starting transformer 43. The output side of the drive inverter 7 is connected to the drive unit 6 via wiring K8. Control signals are input to multiple switching elements (not shown) of the drive inverter 7 via signal lines (not shown) from a control panel (not shown). When the on / off state of the switching elements (not shown) is switched to a predetermined state, a predetermined AC voltage is applied from the drive inverter 7 to the drive unit 6. Next, the power generation equipment 20 (see Figure 5) before conversion to the synchronous condenser 10 will be briefly described.

[0026] Figure 5 is a diagram showing the configuration of the AC excitation power generation equipment 20 before it was converted into a synchronous condenser. The power generation equipment 20 before being converted into the synchronous condenser 10 was, for example, used in a decommissioned nuclear power plant or thermal power plant. In the example shown in Figure 5, the power generation equipment 20 is configured with a high-pressure turbine 21 (turbine), a low-pressure turbine 22 (turbine), a synchronous machine 1 (generator), an AC exciter 23, and an AC auxiliary exciter 24 connected sequentially on the same axis. The high-pressure turbine 21 and the low-pressure turbine 22 are rotated by the pressure of steam generated in a reactor or the like (not shown), and electricity is generated by the synchronous machine 1 (generator). The power generated by the synchronous machine 1 is supplied to the power grid 50 via the main transformer 41.

[0027] The high-pressure turbine 21 and the low-pressure turbine 22 convert the kinetic energy of steam into rotational energy, and each is equipped with multiple turbine blades (not shown). The high-pressure turbine 21 is connected to the low-pressure turbine 22 via shaft F2. The low-pressure turbine 22 is connected to the rotor of the synchronous machine 1 (not shown in Figure 5) via shaft F3.

[0028] The AC exciter 23 is a rotating machine that excites the synchronous machine 1, which is a generator. The rotor (not shown) of the AC exciter 23 is connected to the rotor (not shown) of the synchronous machine 1 via shaft F4. The rectifier 25 rectifies the armature current (three-phase AC current) of the AC exciter 23 into a DC current and is equipped with multiple diodes (not shown). A DC field current flows from the rectifier 25 to the rotor winding (field winding) of the synchronous machine 1. As a result, the rotor winding of the synchronous machine 1 functions as an electromagnet.

[0029] Although not shown in Figure 5, slip rings 1c, 1d (see Figure 1) and brushes 1e, 1f (see Figure 1) are installed to maintain the electrical connection between the rotor windings of the synchronous machine 1 and the rectifier 25. These slip rings 1c, 1d, etc. can also be used after conversion to the synchronous condenser 10 (see Figure 1).

[0030] The AC auxiliary exciter 24 shown in Figure 5 is a permanent magnet motor that excites the AC exciter 23, and its rotor (not shown) is connected to the rotor (not shown) of the AC exciter 23 via a shaft F5. The rotors (not shown) of the synchronous machine 1, the AC exciter 23, and the AC auxiliary exciter 24 rotate as a single unit. The outputs of the AC exciter 23 and the AC auxiliary exciter 24 are regulated by an automatic voltage regulator 26. In this configuration, the synchronous machine 1 functions as an AC-excited synchronous generator.

[0031] The high-voltage busbar M2 shown in Figure 5 is the wiring for supplying power to each piece of equipment in the power generation facility 20, including the synchronous machine 1. In the example in Figure 5, the high-voltage busbar M2 is connected to the phase-separated busbar M1 via the in-house transformer 42 and is also connected to the power system 50 via the starting transformer 43.

[0032] For example, if power generation equipment 20 is decommissioned due to the aging of thermal power plants or nuclear power plants, voltage and frequency fluctuations will be more likely to occur in the power grid 50, and reactive power will be more likely to be insufficient. Furthermore, if an AC-excited synchronous generator (i.e., synchronous machine 1 in Figure 5) is directly converted into an AC-excited synchronous condenser, the following may occur.

[0033] In other words, in AC-excited synchronous condensers, there is a response delay due to the reactance component of the AC exciter 23, etc., resulting in a lower response speed in the event of a malfunction in the power system 50 compared to static excitation (thyristor excitation) systems. Furthermore, in AC-excited synchronous condensers, the AC exciter 23 etc. are rotating machines, leading to higher maintenance and operating costs. Moreover, since AC excitation is no longer the mainstream method for condensers, it may become difficult to obtain parts when replacing components. Incidentally, generators in aging plants that are several decades old are almost always AC-excited.

[0034] Therefore, in the first embodiment, when converting an AC-excited synchronous generator (i.e., synchronous machine 1 in Figure 5) into a synchronous condenser, a static-excited synchronous condenser using a thyristor rectifier 3a (see Figure 1) is used. This improves the response speed in the event of a malfunction in the power system 50. Furthermore, the static-excited system has the advantage of lower maintenance and operating costs, as well as easier availability of parts, since there is no rotating machine for excitation.

[0035] Figure 2 is an explanatory diagram regarding the conversion of a static excitation type synchronous condenser 10. Note that the configuration shown in Figure 2 corresponds to that in Figure 1, but Figure 2 also shows the high-voltage busbar M2 and the in-house transformer 42. Also, in Figure 2, the slip rings 1c, 1d (see Figure 1) and brushes 1e, 1f (see Figure 1) are not shown. The dashed box in Figure 2 shows the equipment removed from the aging power generation equipment 20 (see Figure 5).

[0036] Since the synchronous condenser 10 does not particularly need to generate electricity, the high-pressure turbine 21 and low-pressure turbine 22 are removed when the system is converted to a synchronous condenser 10. (Turbine removal process) Additionally, the AC exciter 23, the AC auxiliary exciter 24, and the rectifier 25 (not shown in Figure 2, see Figure 5) are also removed. (Exciter removal process) The drive unit 6 will be installed in the space left after the high-pressure turbine 21 and low-pressure turbine 22 have been removed. In other words, after the high-pressure turbine 21 and low-pressure turbine 22 are removed from the synchronous machine 1, the drive unit 6 will be connected to the synchronous machine 1 via shaft F1.

[0037] A drive inverter 7 is connected to the drive unit 6 via wiring K8. Figure 2 shows an example where power is supplied to the drive inverter 7 from the high-voltage busbar M2, but power may also be supplied to the drive inverter 7 from the power system 50. The installation area of ​​the drive unit 6 and drive inverter 7 is usually smaller than that of a single low-voltage turbine 22. Therefore, if the high-voltage turbine 21 and low-voltage turbine 22 are removed, sufficient space can be secured for the drive unit 6 and drive inverter 7. In addition, the space freed up by the removal of the AC exciter 23 and AC auxiliary exciter 24 can be used, for example, as space for the excitation transformer 2.

[0038] When converting to a synchronous condenser 10, if the decommissioning of the power generation equipment 20 (see Figure 5) has already begun, the main transformer 41 and the in-house transformer 42 may have already been removed. In such cases, workers will install new main transformers and in-house transformers, and the synchronous condenser 10 will be electrically connected to the power system 50 via a designated switchyard (not shown).

[0039] In this way, by placing the excitation transformer 2, drive unit 6, and drive inverter 7, which are newly used in the static excitation system, into the vacant space created by removing the unnecessary equipment, the equipment related to the operation of the synchronous condenser 10 can be placed inside the turbine building (not shown). This eliminates the need for extensive modifications or the creation of specific penetrations in the turbine building when converting to the synchronous condenser 10. As a result, the costs associated with converting to the synchronous condenser 10 can be reduced.

[0040] Power may be supplied to the excitation transformer 2 via one of the power distribution panels (not shown) located in the turbine building (not shown), which has become available due to the decommissioning of the power plant. Alternatively, the automatic voltage regulator 26 (see Figure 5) used in the power generation equipment 20 (see Figure 5) can be used as the automatic voltage regulator 3b (see Figure 2) of the synchronous condenser 10.

[0041] When converted to a synchronous condenser 10, a thyristor rectifier 3a is connected to a slip ring 1c (see Figure 1) of the synchronous machine 1 via brushes 1e, etc., and another thyristor rectifier 3a is connected to a different slip ring 1d (see Figure 1) via brushes 1f, etc. Furthermore, an automatic voltage regulator 3b is connected to the thyristor rectifier 3a. (Rectifier connection process) Thus, when converting the AC-excited power generation equipment 20 (see Figure 5) of a decommissioned plant into a synchronous condenser 10, a thyristor-type excitation device 3 is electrically connected to the slip rings 1c and 1d (see Figure 1) of the synchronous machine 1 that was used as a generator in the power generation equipment 20 (see Figure 5) to create a static-excited synchronous condenser 10 (excitation device connection process).

[0042] Furthermore, when converting to a synchronous condenser 10, an "excitation transformer connection process" is performed in which the excitation transformer 2 is connected to the thyristor rectifier 3a. In the "excitation transformer connection process," although it differs from the example in Figure 2, for example, the primary side of the excitation transformer 2 may be connected to the phase-separated bus M1, and the secondary side of the excitation transformer 2 may be connected to the thyristor rectifier 3a. As a result of converting to a synchronous condenser 10, there is a margin in the current capacity of the phase-separated bus M1, making it possible to connect the excitation transformer 2 to the phase-separated bus M1. This reduces the amount of modification required when converting to a synchronous condenser 10 compared to when the excitation transformer 2 is connected to the power system 50, thus reducing costs. Alternatively, the primary side of the excitation transformer 2 may be connected to the high-voltage bus M2.

[0043] Furthermore, when converting to a synchronous condenser 10, a "system connection process" may be performed to electrically connect the thyristor rectifier 3a to the power system 50 so that power is supplied to the thyristor rectifier 3a from the power system 50. This allows power to be supplied to the excitation transformer 2 from the power system 50.

[0044] Before conversion to a synchronous condenser 10, at least an analog relay (not shown) is often connected to the control panel (not shown). Therefore, it is preferable to perform a "replacement process" to replace this analog relay with a digital relay (not shown) when converting to a synchronous condenser 10. This improves the convenience of operating the synchronous condenser 10. The aforementioned control panel is equipment used to control the synchronous machine 1 and is located, for example, in the central control room (not shown). Alternatively, a dedicated control area may be provided inside the turbine building (not shown), separate from the central control room, and the digital relay may be connected to the control panel located in this dedicated area.

[0045] Furthermore, when measuring current, voltage, and power at predetermined locations in conjunction with the operation of the synchronous machine 1, the measurement range and accuracy during operation of the power generation equipment 20 (see Figure 5) may become over-specified (excessive) when operating the synchronous condenser 10. Therefore, when converting to the synchronous condenser 10, it is advisable to perform a "measurement range limiting process" to modify the measurement algorithm of a measuring instrument (not shown) that measures current, voltage, or power at predetermined locations in conjunction with the operation of the synchronous machine 1, thereby limiting the measurement range of the measuring instrument. Alternatively, when converting to the synchronous condenser 10, a "measurement accuracy reduction process" may be performed to modify the measurement algorithm of the measuring instrument to lower its measurement accuracy. Note that the "change in measurement algorithm" includes not only changes to the processing procedure when current, voltage, or power is measured, but also changes to the formulas and data tables used for measurement. In this way, by limiting the measurement range of the measuring instrument or reducing its measurement accuracy, the operating costs of the synchronous condenser 10 can be reduced.

[0046] Furthermore, based on the operating conditions of the static excitation type synchronous condenser 10, the upper limit of the output of the synchronous machine 1 (not shown) when used as the synchronous condenser 10 may be lowered (the output is limited) compared to the output capacity of the synchronous machine 1 when it was used in the aging plant.

[0047] <Effects> According to the first embodiment, when converting the power generation equipment 20 of an aging plant into a synchronous condenser 10, changing from an AC exciter system to a static excitation system can improve responsiveness in the event of a malfunction in the power system 50. Furthermore, in the static excitation system, the upper limit of the voltage applied to the field can be set higher, thereby increasing the recovery voltage after a malfunction in the power system 50 and improving the transient stability of the power system 50. In addition, by using the synchronous machine 1 of the aging plant when converting to a synchronous condenser 10, equipment costs can be significantly reduced compared to installing a new synchronous condenser 10.

[0048] ≪Second Embodiment≫ The second embodiment differs from the first embodiment in that the AC exciter 23 (see Figure 3) and the AC auxiliary exciter 24 (see Figure 3) remain mechanically connected to the rotating shaft of the synchronous machine 1, while being electrically disconnected from the automatic voltage regulator 3b (see Figure 3), etc. Other aspects are the same as the first embodiment. Therefore, the differences from the first embodiment will be explained, and the overlapping parts will be omitted.

[0049] Figure 3 is a configuration diagram including the synchronous condenser 10A in the synchronous condenser method according to the second embodiment. The synchronous condenser 10A shown in Figure 3 includes, in addition to the configurations described in the first embodiment, an AC exciter 23 and an AC auxiliary exciter 24 (permanent magnet motor). These AC exciter 23 and AC auxiliary exciter 24 were used in the decommissioned power generation facility 20 (see Figure 5). That is, before being converted into the synchronous condenser 10A, the AC exciter 23 and the AC auxiliary exciter 24 (permanent magnet motor) were sequentially connected to the synchronous machine 1 via a shaft (see also Figure 5).

[0050] As shown in Figure 3, the AC exciter 23 is connected to the synchronous machine 1 via shaft F4. The AC auxiliary exciter 24 is also connected to the AC exciter 23 via another shaft F5. The rotors (not shown) of the synchronous machine 1, AC exciter 23, and AC auxiliary exciter 24 rotate as a single unit. In other words, the AC exciter 23 and AC auxiliary exciter 24 (permanent magnet motors) remain connected to the synchronous machine 1 via shafts even after being converted into a synchronous condenser 10A.

[0051] These AC exciters 23 and AC auxiliary exciters 24 have the function of imparting inertial force to the synchronous machine 1. In the synchronous condenser 10A, there is no particular need for the AC exciters 23 and AC auxiliary exciters 24 to function as exciters, so the electrical connection between the AC exciters 23 and AC auxiliary exciters 24 and the automatic voltage regulator 3b is disconnected. In other words, when converting to the synchronous condenser 10A, a "disconnection process" is performed to disconnect the electrical connection that was used to control the AC exciters 23 and AC auxiliary exciters 24 (permanent magnet motors). This prevents unnecessary excitation from occurring in the AC exciters 23 and AC auxiliary exciters 24.

[0052] <Effects> According to the second embodiment, since the AC exciter 23 and the AC auxiliary exciter 24 rotate together with the rotor 1b of the synchronous machine 1, the inertial force (mechanical and electrical inertial force) when syncing the phase of the power system 50 is increased compared to the first embodiment. In addition, since the effort required to remove the AC exciter 23 and the AC auxiliary exciter 24 is reduced, the cost associated with converting to a synchronous syncer 10A can be reduced compared to the first embodiment.

[0053] ≪Third Embodiment≫ The third embodiment differs from the first embodiment in that the high-pressure turbine 21 (see Figure 4) and the low-pressure turbine 22 (see Figure 4) are maintained in a state where they are mechanically connected to the rotating shaft of the synchronous machine 1. It also differs from the first embodiment in that the drive unit 6 (see Figure 4) is installed on the side of the slip rings 1c and 1d of the synchronous machine 1. Other aspects are the same as the first embodiment. Therefore, the differences from the first embodiment will be explained, and the overlapping parts will be omitted.

[0054] Figure 4 is a configuration diagram including the synchronous condenser 10B in the synchronous condenser method according to the third embodiment. The synchronous condenser 10B shown in Figure 4 includes, in addition to the components described in the first embodiment, a high-pressure turbine 21 and a low-pressure turbine 22. These high-pressure turbine 21 and low-pressure turbine 22 were used in the decommissioned power generation facility 20 (see Figure 5).

[0055] As shown in Figure 4, the high-pressure turbine 21 is connected to the low-pressure turbine 22 via shaft F2. The low-pressure turbine 22 is connected to the synchronous machine 1 via another shaft F3. The rotors (not shown) of the high-pressure turbine 21, the low-pressure turbine 22, and the synchronous machine 1 rotate as a single unit. In other words, even after conversion to a synchronous condenser 10B, the high-pressure turbine 21 and the low-pressure turbine 22 remain connected to the synchronous machine 1 via shafts. Note that the number of low-pressure turbines 22 is not limited to one; a configuration in which multiple low-pressure turbines, such as so-called A-series, B-series, and C-series low-pressure turbines, are sequentially connected via shafts is also possible.

[0056] Furthermore, when converting to a synchronous condenser 10B, it is preferable to perform a "turbine blade removal process" in which the turbine blades (not shown) of the high-pressure turbine 21 (turbine) and low-pressure turbine 22 (turbine) are removed. After conversion to a synchronous condenser 10B, it is preferable to maintain the high-pressure turbine 21 and low-pressure turbine 22, with their turbine blades removed, connected to the synchronous machine 1 via a shaft. This is because if the high-pressure turbine 21 and low-pressure turbine 22 were to rotate with the turbine blades still attached, energy loss due to windage would be significant.

[0057] Thus, since the high-pressure turbine 21 and low-pressure turbine 22 remain connected to the rotating shaft of the synchronous machine 1, the inertial force when syncing the power system 50 is increased compared to the first embodiment. In addition, since the high-pressure turbine 21 and low-pressure turbine 22 generally have a larger moment of inertia than the AC exciter 23 (see Figure 3) and AC auxiliary exciter 24 (see Figure 3), the inertial force when syncing the power system 50 is increased compared to the second embodiment as well.

[0058] As shown in Figure 4, the drive unit 6 is connected to the synchronous machine 1 via shaft F6 on the side opposite to the high-pressure turbine 21 and low-pressure turbine 22. In other words, the drive unit 6 is connected to the side of the synchronous machine 1 in the axial direction where the slip rings 1c, 1d and brushes 1e, 1f are located. Thus, when converting to a synchronous condenser 10B, it is desirable to perform a "drive unit connection process" in which the drive unit 6 is connected to the synchronous machine 1 on the side opposite to the high-pressure turbine 21 (turbine) and low-pressure turbine 22 (turbine) in the axial direction. This allows the drive unit 6 to accelerate the rotation of the rotor 1b when the synchronous machine 1 is started, and to compensate for the losses of the synchronous machine 1.

[0059] <Effects> According to the third embodiment, since the high-pressure turbine 21 and low-pressure turbine 22, with their turbine blades (not shown) removed, rotate coaxially with the rotor 1b of the synchronous machine 1, the inertial force when syncing the power system 50 can be increased compared to the first and second embodiments. In addition, since the effort required to remove the high-pressure turbine 21 and low-pressure turbine 22 is reduced, the cost associated with converting them to a synchronous condenser 10B can be reduced.

[0060] ≪Variations≫ Although the synchronous condenser method according to the present invention has been described in each embodiment above, the present invention is not limited to these descriptions, and various modifications can be made. For example, in each embodiment, the case in which the power generation equipment 20 (see Figure 5) of a "decommissioned plant" is repurposed as a synchronous condenser 10 (see Figure 1) has been described, but it is not limited to this. For example, each embodiment can also be applied when the power generation equipment of an "idle plant" is repurposed as a synchronous condenser. An "idle plant" is a plant in which the power generation equipment remains unused.

[0061] Furthermore, while each embodiment describes the case in which the slip rings 1c, 1d (see Figure 1) and brushes 1e, 1f (see Figure 1) of the synchronous machine 1 of an aging plant are used as they are when converting the synchronous machine 1 to a synchronous condenser, this is not the only case. In other words, when converting the synchronous machine 1 to a synchronous condenser, at least one of the consumables, such as the slip rings 1c, 1d and brushes 1e, 1f, may be replaced with a new one by a worker.

[0062] Furthermore, while the second embodiment (see Figure 3) describes a case where both the AC exciter 23 and the AC auxiliary exciter 24 remain connected to the synchronous machine 1 even after conversion to a synchronous condenser 10, the invention is not limited to this. For example, one of the AC exciter 23 and the AC auxiliary exciter 24 may be connected to the synchronous machine 1, while the other is disconnected. In this case as well, the same effects as in the second embodiment are achieved. In short, it is preferable that at least one of the AC exciter 23 and the AC auxiliary exciter 24 (permanent magnet motor) remains connected to the synchronous machine 1 via a shaft even after conversion to a synchronous condenser 10.

[0063] Furthermore, in the third embodiment (see Figure 4), the case in which the high-pressure turbine 21, low-pressure turbine 22, and synchronous machine 1 are connected sequentially before conversion to the synchronous condenser 10 was described, but the number of turbines mechanically connected to the synchronous machine 1 is not limited to two. That is, before conversion to the synchronous condenser 10, at least one turbine may be connected to the synchronous machine 1 via a shaft. Also, in the case where multiple turbines are connected to the synchronous machine 1 via shafts before conversion to the synchronous condenser 10, some of the multiple turbines may be connected to the synchronous machine 1 and the rest may be disconnected.

[0064] Furthermore, each embodiment can be combined as appropriate. For example, the second embodiment (see Figure 3) and the third embodiment (see Figure 4) can be combined to form the following configuration. That is, when converted to a synchronous condenser 10, the AC exciter 23 and AC auxiliary exciter 24 may be mechanically connected to the synchronous machine 1 via coaxial cable (second embodiment), while the high-pressure turbine 21 and low-pressure turbine 22, with their turbine blades removed, may be mechanically connected to the synchronous machine 1 via coaxial cable. This further enhances the electrical and mechanical inertia of the synchronous condenser 10.

[0065] Furthermore, the order in which the "excitation device connection process," "excitation transformer connection process," "system connection process," "replacement process," "measurement range limiting process," and "measurement accuracy reduction process" described in the first embodiment are performed can be changed as appropriate. Also, the insertion point of the "shutdown process" described in the second embodiment (the insertion point into the process of the first embodiment) can be changed as appropriate. In addition, of the "turbine blade removal process" and the "driver connection process" described in the third embodiment, either process may be performed first, and the insertion point into the process of the first embodiment can also be changed as appropriate.

[0066] Furthermore, when converting the power generation equipment 20 into a synchronous condenser 10, the maximum value of reactive power that can be output from the synchronous condenser 10 may be increased by raising the pressure of the hydrogen gas (cooling gas) sealed in the housing (not shown) of the synchronous machine 1 compared to before the conversion. The higher the pressure of the hydrogen gas in the housing, the denser the hydrogen gas becomes and the higher the cooling performance. This allows a large excitation current to flow through the rotor windings while keeping the temperature of the rotor windings of the synchronous machine 1 below a predetermined upper limit temperature. As a result, a large amount of reactive power can be supplied from the synchronous condenser 10 to the power system 50. In addition, the maximum value of reactive power that can be output from the synchronous condenser 10 may be adjusted by increasing the pressure of the hydrogen gas in the housing (not shown) of the synchronous machine 1 during the daytime and decreasing the pressure of the hydrogen gas during the nighttime.

[0067] Furthermore, the embodiments are described in detail to clearly explain the present invention and are not necessarily limited to those comprising all the configurations described. In addition, it is possible to add, delete, or replace some of the configurations in the embodiments with other configurations. Furthermore, the mechanisms and configurations described above are those deemed necessary for explanatory purposes and do not necessarily represent all of the mechanisms and configurations shown in the actual product. [Explanation of Symbols]

[0068] 1. Synchronous machine (generator) 1a stator 1b Rotor 1c, 1d slip ring 1e, 1f brush 2. Excitation Transformer 3. Thyristor-type excitation device 3a Thyristor Rectifier 3b Automatic voltage regulator 4. Instrument transformers 5. Current transformers for instruments 6. Drive unit 7. Inverter for drive 10,10A,10B synchronous phase modifier 20 Power generation facilities 21. High-pressure turbine (turbine) 22 Low-pressure turbine (turbine) 23 AC exciter 24 AC auxiliary exciter (permanent magnet motor) 50 Power system F1, F2, F3, F4, F5, F6 shafts M1 phase separation bus M2 High-voltage busbar

Claims

1. A method for converting an AC-excited power generation facility of a decommissioned or idle plant into a synchronous condenser, the facility comprising a turbine and a synchronous machine, with an AC exciter and a permanent magnet motor sequentially connected to the synchronous machine via a shaft, A turbine removal process for removing the aforementioned turbine, With the AC exciter and the permanent magnet motor still mechanically connected to the synchronous machine via the shaft, a disconnection step is performed to disconnect the electrical connection used to control the AC exciter and the permanent magnet motor. A method for converting a system into a synchronous condenser, comprising: an excitation device connection step of electrically connecting a thyristor-type excitation device to the slip ring of the synchronous machine that was used as a generator in the power generation facility, thereby converting it into a static excitation type synchronous condenser.

2. The thyristor-type excitation device includes a thyristor rectifier, When converting to the aforementioned synchronous phase condenser, the process includes an excitation transformer connection step in which an excitation transformer is connected to the thyristor rectifier, In the excitation transformer connection step, the primary side of the excitation transformer is connected to the phase-separated busbar, and the secondary side of the excitation transformer is connected to the thyristor rectifier. A method for synchronous condensing according to claim 1, characterized by the above.

3. The thyristor-type excitation device comprises a thyristor rectifier and an automatic voltage regulator that controls the thyristor firing angle of the thyristor rectifier. When converting to the aforementioned synchronous phase condenser, a rectifier connection step is performed in which the thyristor rectifier is connected to the slip ring and the automatic voltage regulator is connected to the thyristor rectifier, When converting to the aforementioned synchronous phase condenser, the process involves a system connection step in which the thyristor rectifier is electrically connected to the power system, The conversion to the aforementioned synchronous condenser includes a phase separation bus connection step of connecting the aforementioned automatic voltage regulator to the phase separation bus, The thyristor rectifier is controlled based on the detected values ​​of the AC voltage and AC current of the power system. A method for synchronous condensing according to claim 1, characterized by the above.

4. Prior to its conversion to the aforementioned synchronous phase condenser, at least an analog relay was connected to the control panel. The conversion to the aforementioned synchronous phase condenser includes a replacement process of replacing the analog relay with a digital relay. A method for synchronous condensing according to claim 1, characterized by the above.

5. The process includes a measurement range limiting step in which the measurement algorithm of a measuring instrument is modified to limit the measurement range of the measuring instrument that measures current, voltage, or power at a predetermined location associated with the operation of the synchronous machine when the instrument is converted to a synchronous condenser. A method for synchronous condensing according to claim 1, characterized by the above.

6. When converting to the aforementioned synchronous condenser, the process includes a step to reduce measurement accuracy by changing the measurement algorithm of the measuring instrument that measures the current, voltage, or power at a predetermined location associated with the operation of the synchronous machine. A method for synchronous condensing according to claim 1, characterized by the above.

7. A method for converting an AC-excited power generation facility of a decommissioned or idle plant into a synchronous condenser, the facility comprising a turbine and a synchronous machine, with an AC exciter and a permanent magnet motor sequentially connected to the synchronous machine via a shaft, A turbine blade removal process for removing the turbine blades of the aforementioned turbine, An exciter removal step, which involves removing the AC exciter and the permanent magnet motor, The process includes an excitation device connection step, in which a thyristor-type excitation device is electrically connected to the slip ring of the synchronous machine that was used as a generator in the power generation facility, thereby converting it into a static excitation type synchronous condenser. Even after conversion to the aforementioned synchronous condenser, the turbine, with its blades removed, will remain connected to the synchronous machine via the shaft. A method for synchronizing and syncing a motor, characterized by the following.

8. The conversion to the aforementioned synchronous condenser further includes a drive unit connection step of connecting the drive unit to the synchronous machine on the opposite side of the turbine in the axial direction. A method for synchronous condensing according to claim 7, characterized by the above.

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