JPH0487525A - Power control system - Google Patents

Abstract

PURPOSE:To feed rotary energy corresponding to the phase angle, as an effective power, to a system at high speed by interposing a semiconductor converter between the system and a synchronous machine and connecting with the secondary of a transformer thereby controlling the phase angle of the synchronous machine at high speed. CONSTITUTION:A power system controller connects a system 2 and a synchronous machine 8. A semiconductor converter 12 (inverter) is connected with the system 2 and produces, together with a transformer 13, a voltage Vc having phase shift of 90 deg. from the phase voltage which is then added on the system voltage V2. The amount of phase shift is controlled at high speed by the output voltage of the semiconductor converter. According to the constitution, a semiconductor phase shifter interposed between a system and a synchronous phase modifier controls the phase angle of the synchronous phase modifier at high speed thus controlling the effective power at high speed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a power control system that utilizes the flywheel effect of a semiconductor phase shifter and a synchronous phase modifier.

(Conventional technology) In order to supply high-quality electricity to consumers, it is necessary to stabilize the power system, and an effective method for achieving this is to quickly control active power in response to system fluctuations. It is known that there is. In the United States, active power is controlled by power flow control using a phase-shifting transformer, and the amount of power flow is controlled by switching the taps of the transformer.

In addition, if a power source such as a battery or a rotating machine is directly connected to the grid via an inverter, the effective power can be controlled at high speed.
In this case, inverter equipment with the same capacity as the passing active power is required.

(Problems to be Solved by the Invention) As mentioned above, in the case of using a phase-shifting transformer, the tap switching operation is complicated, and the increase in active power is also gradual, which is not advantageous for system stability. . Furthermore, the method of connecting a rotating machine or the like via an inverter is disadvantageous because it requires inverter equipment with a large capacity.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a power control system that is advantageous for system stabilization.

[Structure of the Invention] (Means and Effects for Solving the Problems) In order to achieve the above object, the present invention provides a power control system that performs power flow control between grids interconnected via transformers. A semiconductor converter is interposed between the transformer and the transformer, and the transformer is connected to the secondary side of the transformer, and the phase angle of the synchronous machine is controlled at high speed.

Therefore, by controlling the phase angle of the synchronous machine at high speed, rotational energy corresponding to the phase angle can be rapidly output and input into the grid as active power.

(Example) Examples will be described below with reference to the drawings.

FIG. 1 is a configuration diagram of an embodiment for explaining a power control system according to the present invention.

In FIG. 1, reference numeral 1 denotes a power system control device, and system 2.
The synchronous machines 8 are connected via transformers 11-1 and 11-2. Reference numeral 12 denotes a semiconductor converter (inverter device), which is connected to the system 2 via the transformer 4, and the phase shift of the voltage is 90° with respect to the phase voltage by the semiconductor converter 12 and the transformer 13.
Voltage that changes phase ■. is generated and added to the grid voltage (2) via a transformer.

In addition, 13-1.13-2 is a voltage injection transformer,
It is connected to the neutral position of each phase winding of the transformer 11-2.

5 is a PT, and 6 is a CT, which are input to the control unit 7.

8 is a synchronous phase modifier, and 9 is a flywheel.

Next, the effect will be explained.

In the power system, the movement of power is expressed by the following equation (1).

p=v −v sinθ/X -----
-(11S However, v,,v,...it&voltage at both ends θ...
・・・・Phase difference X・・・・・・・・・Line glue actance In this case, 9
Voltages with different phases at 0°■. is added to the input voltage v2 (second
Figure (a)). The amount of phase shift is controlled at high speed by the output voltage of the semiconductor converter.

Note that FIG. 2(b) is a vector diagram showing active and reactive power after control.

Now, assuming that the maximum value of the output voltage of the converter is ■, the phase shift range is ±s + n < v c II / vl
), and the maximum controllable power is expressed by equation (2) below.

p = v1 ・V o, / X...
...(2) Also, P and converter installed capacity P. The ratio α with l is given by the following equation (3).

Pc1lP,

Note that by arbitrarily controlling the inverter output voltage value and its phase angle, not only the active power but also the reactive power can be simultaneously controlled at high speed.

In this case, by controlling the input and output power of the semiconductor converter 12, the inertial mass of the synchronous phase modifier can be utilized as a short-time energy storage element.

At this time, the mechanical equation for the synchronous phase modifier is as follows: Jdω / dt = P (/ωa...
・(4) γ ω = dθ /dt...
...(5) γ γ However, J...Inertial mass ω...Shaft angular velocity γ θ...Rotor m mechanical angle γ Pl...Synchronous machine input Constant power is supplied during the current time T Assuming this, the maximum power P that can be supplied and the energy E that can be supplied are determined by the following formula from the above formula and formula (1).

E=E θ /ωoT S Sliding=4E, ωd/ω0 (8) However, ω0=synchronous speed θ: maximum phase shift amount E,: inertia energy ωa1 large shift phase shift speed 1/T ) Po: Rated power T: Inertia constant (ES/Pn) From equations (6) to (8), it can be seen that more energy can be used by shortening the operating time T.

For example, if the maximum phase shift amount is ±30° and the inertia constant is 2 seconds, the rated power can be supplied for 0.16 seconds. Furthermore, JT-
Equivalent to a flywheel generator for power supply of 60 toroidal magnetic field coils (synchronous machine capacity: 200HVA, inertial energy;
8GJ, inertia constant = 40 seconds), 0.
Can supply rated power for 73 seconds.

These active power controls can achieve greater effects by connecting a flywheel as shown in the solid line example, but it is also possible to perform effective control with just the flywheel effect of the synchronous phase modifier itself. . Moreover, the part that is made into a synchronous phase modifier is not limited to this, and it goes without saying that any synchronous machine may be used.

[Effects of the Invention] As explained above, according to the present invention, a semiconductor phase shifter is connected between the grid and the synchronous phase modulator, and the phase angle of the synchronous phase modulator is configured to be controlled at high speed. , produces the effects listed below.

■ Active power can be controlled very quickly.

■ Since the inverter only needs to generate a voltage corresponding to the phase difference, the capacity of the inverter is small compared to the power to be passed.

(2) By arbitrarily changing the inverter output voltage value and the phase relative to the grid voltage, the values and flows of active power and reactive power can be freely controlled.

■ Insulation on the inverter side can be reduced by connecting the inverter side circuit to the neutral point side of the star-connected transformer.

■ Since a synchronous phase modifier is used as a power source, active power control at the demand end is possible, which has a significant grid stabilizing effect.

■ A large system stabilization effect can be obtained by simultaneously controlling active power and reactive power at high speed in combination with a synchronous phase modifier.

■ If a superconducting generator with small internal reactance is used as the synchronous phase modifier in this system, a greater system stabilizing effect can be achieved.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the power control system according to the present invention, and FIG. 2 is a vector diagram of input and output voltages after control. 1... Power control device 2... Power system 4...
Transformer 5...PT6...CT
7... Control unit 8... Synchronous phase adjuster 9
... Flywheel 11 ... Transformer 1
2... Semiconductor converter 13... Phase-shifted voltage injection transformer 14... Synchronous machine impedance patent applicant Norio Ishii, Tokyo Electric Power Company's representative patent attorney

Claims (2)

[Claims] (1) In a power control system that performs power flow control between systems interconnected via a transformer, a semiconductor converter is interposed between the system and the synchronous machine and connected to the secondary side of the transformer, A power control system characterized in that the phase angle of the synchronous machine is controlled at high speed. (2) The power control system according to claim 1, wherein the control output via the semiconductor converter is inputted to a point near the neutral point of the star-connected transformer.