JPH08331763A - Independent operation detecting method for rotating-machine system distributed power source - Google Patents

Abstract

PURPOSE: To provide an independent operation detecting method for rotating- machine system distributed power sources excellent in power quality and power supply reliability, and advantageous in point of maintenance too. CONSTITUTION: In a power system composed by connecting a commercial power source l and a rotating-machine system distributed power source 2 through a linkage circuit-breaker 3 and a power receiving circuit-breaker 4, an independent operation condition of a power source is detected by a reactive or effective power controlling function 10 and a frequency relay 90 for detecting a frequency or its change, on condition that the frequency or its variation exceeds a constant quantity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting an isolated operation of a rotating machine distributed power source which is system-interconnected.

[0002]

2. Description of the Related Art Rotating machines (synchronous machines, induction machines) distributed power sources for promoting energy saving and effective utilization of unused energy are rapidly becoming popular. The rotating machine type distributed power source is usually
As shown in FIG. 24, the operation is performed in an interconnection with the grid of the electric power company.

In FIG. 24, 1 (G ₁ ) is a commercial power source of an electric power company as a first power source, 2 (G ₂ ) is a second power source of a rotary machine type distributed power source installed customer It is a machine-type distributed power source. 3 is an interconnection breaker as an interconnection switch, 4 is a power receiving breaker which is a power receiving switch, and 5 is a load.

If a tidal current is flowing through the grid breaker 3 (active power and reactive power), the grid breaker 3 is opened to unbalance the active power and the reactive power of the generator (rotor type distributed power supply 2). Occurs, and the voltage frequency and phase of the generator of the customer change. Therefore, the islanding state can be detected by monitoring changes in frequency and phase. That is, the equation of the mechanical system of the generator (sway equation)
Is expressed by the following formula (however, an approximate formula for a minute change).

(2H / ω ₀ ) (d ² Δθ / dt ² ) + (D / ω ₀ ) (d Δθ / dt) = ΔTm−ΔTe (1) where Δ is the change, θ is the rotation angle of the generator, H is the inertia constant, D is the damping coefficient, Tm is the mechanical (motor) input torque, Te is the electrical output torque, ω ₀ is the rated angular velocity, and P is the active power of the interconnection breaker. , Q is the reactive power of the interconnection breaker, P ₁ and Q ₁ are the active and reactive power outputs of the generator.

Since the input and output of the generator are balanced in a steady state, Δθ, ΔTm and ΔTe are all zero, and the generator is operated at the rated angular velocity (rated frequency). In this case, the active and reactive powers of the interconnection breaker, generator output, and load are P, Q, P ₁ , Q ₁ , (P + P ₁ ) and (Q + Q ₁ ) respectively.

When the interconnection breaker is cut off, the active power P ₁ of the generator is smaller than the active power (P + P ₁ ) consumed by the load, so ΔTe> 0.

Since the prime mover has a slow response, ΔTm≈0 for a while
Therefore, the input / output of the generator becomes unbalanced, and the generator is decelerated (Δθ <0) according to the equation (1), and the frequency drops. Therefore, the islanding state can be detected by the decrease in frequency.

[0009]

When the rotary machine type distributed power source (synchronous machine or induction generator) is in the independent operation state by opening the interconnection breaker, this state is detected and the rotary machine type dispersed power source is detected. Unless the power breaker of the power installation customer is opened, various problems occur in terms of supply reliability, power quality, and security.

Further, when the tidal current of the interconnection breaker is almost zero and the interconnection breaker is opened, there is almost no change in these, and therefore the isolated operation state cannot be detected by such means. That is, when the tidal current of the interconnection breaker is zero (P≈0, Q≈0), even if the interconnection breaker is shut off, △
Since Te≈0, the input / output of the generator remains in a nearly equilibrium state, and Δθ≈0. Therefore, there is almost no change in the amount of electricity such as a change in frequency. Therefore, it is not possible to detect the islanding operation state due to a change in the amount of electricity (frequency) of the customer installed with the rotating machine type distributed power source.

The present invention has been made in view of the above-mentioned problems, and an object thereof is a method for detecting an isolated operation of a rotating machine system distributed power supply, which is excellent in power quality and reliability of power supply and is also advantageous in maintenance. Is to provide.

[0012]

In order to achieve the above object, the method for detecting the isolated operation of a rotating machine type distributed power source according to the present invention uses a second power source, which is a rotating machine type dispersed power source, as a first power source. By the means for changing the power of the connected power system and the means for detecting the frequency component of the power, the rotating machine type distributed power source is operated independently on the condition that the change in the frequency component exceeds a predetermined amount. It is characterized by detecting the state.

Further, according to the present invention, the power consisting of reactive power or active power of a power system in which a rotating machine type distributed power source is connected to a first power source which is a commercial power source via an interconnection breaker is periodically used. And a means for detecting a frequency or a change thereof detect the islanding operation state of the rotating machine type distributed power supply on condition that the frequency or a change thereof exceeds a certain amount. To do.

Further, there is provided a capacitor corresponding to each phase of the rotating machine type distributed power source, and a bidirectional conduction switch which is connected in parallel to the capacitor via a coil, and the bidirectional switch is an antiparallel switching. It is characterized by comprising a device and having a reactive power control function for conducting the antiparallel switching devices in respective symmetrical electrical angle ranges.

[0015]

Embodiments of the present invention will be described below with reference to FIGS.

FIG. 1 is a power system diagram for carrying out a method for detecting isolated operation of a rotating machine system distributed power source according to an embodiment of the present invention.
The same or corresponding parts as those in FIG. 24 are designated by the same reference numerals. In FIG. 1, 10 is an islanding operation detection unit,
It includes a capacitor 11, a bidirectional conduction switch 13 connected in parallel to the capacitor 11 via a coil 12, and a frequency relay 90. The bidirectional conduction switch 13 is a thyristor 14 connected in antiparallel.
It consists of a and 14b.

In the electric power system of FIG. 1, as shown in FIG. 2, the islanding operation detecting section 10 which combines a reactive power control function for periodically changing the reactive power Q and a frequency (or frequency change) relay 90 is used. , Interconnection breaker (CB
1) When the zero power flow is cut off in 3, the islanding operation is detected by the operation of the frequency relay 90, and necessary sequence processing (cutting of the power receiving breaker (CB2) 4 etc.) is performed.

At the time of system interconnection, the reactive power consumed by the rotating machine type distributed power supply (CGS) consumer by the reactive power control function of the islanding operation detecting section 10 changes as shown in FIG. Since the system is connected, there is no change in frequency. Further, as shown in FIG. 4, there is almost no fluctuation in the voltage of the customer.

When the interconnection breaker 3 is opened, the reactive power of the customer after the interconnection breaker (CB1) 3 is opened with the tidal current of the interconnection breaker being zero is controlled by the reactive power control function. It changes as shown in FIG. As a result, the voltage of the customer decreases as shown in FIG. 4, and the active power consumed by the load also decreases as shown in FIG. In this case, since the generator is accelerated, it rises as shown in FIG.
Can detect islanding.

FIG. 7 is a circuit diagram having a reactive power control function. 11a, 11b and 11c are A-phase,
Capacitors corresponding to B phase and C phase, 12a, 12b, 1
2c is a coil corresponding to A phase, B phase, and C phase, respectively, and 13a, 13b, and 13c are A phase, B phase, and
It is a bidirectional conduction switch corresponding to the C phase.

The reactive power control function is executed by controlling the reactive power by a thyristor in series with a coil in a parallel circuit of a capacitor and a coil as shown in FIG.

FIG. 8 shows a reactive power control method.
The thyristor 14a has a phase voltage Va of 90 ° to 180 °.
At 0 °, the thyristor 14b is symmetrically controlled by the firing pulse in the range of 270 ° to 360 °.

The feature of the present invention is to provide means for detecting an isolated operation by a reactive power control function and a frequency detection relay installed in a customer having a rotating machine type distributed power source. Even if the power flow is cut off in the state of zero, it is possible to detect the islanding operation state by the frequency change. Since this was confirmed by digital simulation, the result will be described with reference to FIGS. 9 to 23.

[Simulation Condition] In the system diagram of FIG. 9, the power flow of the interconnection CB (active / reactive power is 0.0071 MW-
j0.00002MVA) and the rated output of the generator 2 is 2 MVA, and the active / reactive power during simulation is 1.88 MW + J0.
628 MVA. Table 1 shows the device constants of the generator 2.

[0025]

[Table 1]

In Table 1, the moment of inertia M includes a generator, a prime mover and a speed reducer, and the simulation was performed with a salient pole machine.

The control circuit constants are set as shown in FIG. 10 for the governor and as shown in FIG. 11 for the automatic voltage regulator (AVR).

The reactive power control function, as shown in FIG.
The reactive power is controlled by a thyristor in series with L in a C, L parallel circuit. The thyristor 14a is 90 ° to 180 ° with respect to the phase voltage Va, and the thyristor 14b is 270 ° to 36 °.
It is controlled symmetrically in the range of 0 ° by the firing pulse. The reactive power control shown in FIGS. 12 to 23 has a maximum capacity of 250 KV.
This is the case where the firing pulse is controlled for A at a cycle of 1.5 Hz.

[Results of Simulation] FIGS. 12 to 15
Shows the A-phase current and reactive power control amount of the interconnection breaker when the tidal current of the interconnection breaker 3 is 1 [A] and the interconnection breaker 3 is shut down at t = 0.04 seconds in the system of FIG. , Power receiving end voltage (customer voltage), power receiving end frequency.

As shown in FIG. 15, the frequency change shows a peak about 0.7 second after the disconnection of the interconnection breaker 0.7 seconds later.
z, -0.4Hz at 1.0 second, + 0.38H at 1.4 second
z.

Normally, when detecting the isolated operation state by frequency, it is desired that the change amount set value is 0.1 Hz and the detection time is within 1 second. According to the present invention, the islanding operation state can be detected under the condition that sufficiently satisfies this condition.

FIGS. 16 to 19 show the A phase of the interconnection breaker when the interconnection breaker has a power flow of 10 [A], (rpm) and the interconnection breaker is shut off at t = 0.5 seconds. It shows the current, reactive power control amount, receiving end voltage (customer voltage), and receiving end frequency. As is apparent from FIG. 19, the islanding operation can be detected under the condition that is sufficiently satisfied as in FIGS. 12 to 15.

20 to 23 show the A-phase current of the interconnection CB, the reactive power control amount, the power receiving end voltage, and the power receiving end frequency when the load of the customer is cut off in the interconnection state. 20 to 23 are for confirming whether or not the islanding operation state is detected by the frequency change due to the imbalance of the input and output of the generator caused by the customer load cutoff in the interconnection state. Immediately after the load is cut off for 0.5 seconds, the frequency change is detected through the timer of 100 to 200 milliseconds. In this case, therefore, there is no risk of erroneous detection as shown in FIG.

[0034]

The present invention is as described above, and has means for changing the electric power of the electric power system in which the second electric power source which is the rotating machine type distributed electric power source is connected to the first electric power source, and the electric power of the electric power system. The means for detecting the frequency component detects the islanding operation state of the rotating machine type distributed power source on the condition that the change in the frequency component exceeds a predetermined amount. It is possible to obtain a method for detecting the isolated operation of a rotating machine system distributed power source, which is excellent and is also advantageous in terms of maintenance.

[Brief description of drawings]

FIG. 1 is a block diagram of a power system showing a method for detecting isolated operation of a rotating machine system distributed power source according to an embodiment of the present invention.

FIG. 2 is a waveform diagram of a reactive power control function of the power system shown in FIG.

3 is a reactive power waveform diagram of the power system of FIG.

FIG. 4 is a customer voltage waveform diagram of the power system of FIG.

5 is a generator output waveform diagram of the power system of FIG.

6 is a frequency characteristic diagram of the power system of FIG.

FIG. 7 is a circuit diagram showing a reactive power control function in a method for detecting isolated operation of a rotating machine system distributed power source according to an embodiment of the present invention.

8 is a waveform diagram for explaining the reactive power control function according to the circuit diagram of FIG.

FIG. 9 is a power system diagram showing a simulation in the present invention.

FIG. 10 is a block diagram showing governor control circuit constants in a power system showing a simulation in the present invention.

FIG. 11 is a block diagram showing circuit constants of an automatic voltage regulator (AVR) in a power system showing a simulation in the present invention.

FIG. 12 is a current characteristic diagram at a connection point showing a simulation result of the rotating machine system distributed power source islanding operation detection method according to an example of the present invention.

FIG. 13 is a reactive power control characteristic diagram showing a simulation result of a rotating machine system distributed power source isolated operation detection method according to an example of the present invention.

FIG. 14 is a characteristic diagram of a voltage at a power receiving end showing a simulation result of a method for detecting an isolated operation of a rotating machine system distributed power source according to an embodiment of the present invention.

FIG. 15 is a frequency characteristic diagram of a power receiving end showing a simulation result of a method for detecting isolated operation of a rotating machine system distributed power source according to an embodiment of the present invention.

FIG. 16 is a current characteristic diagram at a connection point showing a simulation result of a rotating machine system distributed power source isolated operation detection method according to an example of the present invention.

FIG. 17 is a reactive power control characteristic diagram showing a simulation result of a method for detecting isolated operation of a rotating machine system distributed power source according to an example of the present invention.

FIG. 18 is a voltage characteristic diagram of a power receiving end showing a simulation result of a method for detecting an isolated operation of a rotating machine system distributed power source according to an embodiment of the present invention.

FIG. 19 is a frequency characteristic diagram of a power receiving end showing a simulation result of a method for detecting isolated operation of a rotating machine system distributed power source according to an example of the present invention.

FIG. 20 is a current characteristic diagram at a connection point showing a simulation result of a method for detecting isolated operation of a rotating machine system distributed power source according to an example of the present invention.

FIG. 21 is a reactive power control characteristic diagram showing a simulation result of the method for detecting isolated operation of a rotating machine system distributed power source according to an example of the present invention.

FIG. 22 is a voltage characteristic graph of a power receiving end showing a simulation result of a method for detecting isolated operation of a rotating machine system distributed power source according to an example of the present invention.

FIG. 23 is a frequency characteristic diagram of a power receiving end showing a simulation result of a method for detecting isolated operation of a rotating machine system distributed power source according to an example of the present invention.

FIG. 24 is a block diagram of a rotating machine system distributed power system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Commercial power supply which is the 1st power supply 2 ... Rotating machine type distributed power supply which is the 2nd power supply 3 ... Interconnection breaker 4 ... Power receiving breaker 5 ... Load 10 ... Single operation detection device 11 ... Capacitor 12 ... Coil 13 ... Bidirectional switch 14a, 14b ... Thyristor 90 ... Frequency relay

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takaaki Kai 2-1-1 Osaki, Shinagawa-ku, Tokyo Stock company inside the company Meidensha (72) Inventor Toshiro Fujimoto 2-1-1 Osaki, Shinagawa-ku, Tokyo Stock association Shameidensha (72) Inventor Haruo Sasaki 2-17 Osaki, Shinagawa-ku, Tokyo Stock company Shameidensha

Claims (3)

[Claims] 1. A means for changing the electric power of an electric power system in which a second electric power source, which is a rotating machine type distributed electric power source, is connected to the first electric power source, and a means for detecting a frequency component of the electric power,
A method for detecting an isolated operation of a rotating machine type distributed power supply, comprising detecting an isolated operation state of the rotating machine type distributed power supply on the condition that a change in the frequency component exceeds a predetermined amount. 2. A means for periodically changing electric power consisting of reactive power or active power in a power system in which a rotating machine type distributed power supply is connected to a first power supply which is a commercial power supply via an interconnection breaker. And a means for detecting a frequency or a change in the frequency to detect an isolated operation state of the rotary machine-type distributed power source on condition that the frequency or the change exceeds a certain amount. Distributed power supply independent operation detection method. 3. The detection method according to claim 1, wherein the means for changing the electric power is formed by connecting a capacitor corresponding to each phase of the rotating machine type distributed power source and the capacitor in parallel via a coil. A two-way conduction switch, the two-way switch comprising anti-parallel switching elements, and having a reactive power control function for conducting the anti-parallel switching elements in respective symmetrical electrical angle ranges. Method for detecting isolated operation of rotating machine system distributed power source.