JP3097390B2 - Digital governor excitation controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital governor excitation control device, and more particularly to an excitation control device for determining the effective values of a generator voltage, a bus voltage, active power, and reactive power by a cubic method.

[0002]

2. Description of the Related Art A digital governor excitation control device starts and controls a generator, and then connects the generator, its voltage, the number of revolutions, and the phase to the other power system in accordance with the other power system. The load sharing ratio and the reactive power adjustment are performed by the voltage control and the excitation current control.

[0003] In such an excitation control device, the alteration signal of the voltage or current of the generator or the bus is subjected to A / D conversion in order to detect the generator voltage, bus voltage, active power, and reactive power required for various controls. The effective value is obtained from each sampled data.

An effective value calculation from sampling data includes a cubic method having features such as high speed and high accuracy. In the three-product method, an effective value and a vector inner product can be obtained by a product of three consecutive sample data.

For example, FIG. 2 shows active power P and reactive power Q
And the generator voltage V _G (line voltage U-V phase)
The active power P and the reactive power Q are obtained from the sampling data of the generator current _IG (U phase) every 30 degrees according to the following equation.

[0006]

P = V _n-1 * I _n + V _n-4 * I _n-3 Q = V _n-1 * I _n-3 -V _n-4 * I _n Voltage / power by the above-mentioned cubic method The operation is configured as shown in FIG. The figure shows a case in which the effective values of the generator voltage, active power and reactive power are obtained by digital processing. The phase line voltage and current of the generator are sampled by A / D converters ₁₁ to ₁₆ . as uptake obtain sampling data of the basic wave component through digital filter 2 ₁ to 2 _6, 3 ₁ to 3 ₆ of the two-stage, obtains a phase effective value by an effective value calculating unit ₄₁ to _3, the power generation by the sum Find the machine voltage. The bus voltage is obtained by a similar configuration.

[0007] active power P obtains a phase active power in accordance with the above equation by P operation unit 5 ₁ to 5 ₃ from the voltage and current through the digital filter, the active power is determined by the sum. Similarly, the reactive power Q is, Q calculation unit ₆₁ through ₃
, The reactive power of each phase is obtained, and the reactive power is obtained by the sum.

[0008]

In the conventional voltage / power calculation, the sampling cycle is determined from the operating frequency of the generator when the third product method is used. For example, 30
At the rated frequency, sampling for each degree is as follows.

When the frequency is 50 Hz, the sampling period is 1.667.
(Msec) Sampling period = 1.389 when frequency = 60 Hz
(Msec) Here, the frequency of the generator becomes the rated frequency when it is in a linked state with the grid, but changes greatly in the isolated operation separated from the grid. Therefore, for example, when the frequency increases twice, the sampling period also needs to be halved.

As described above, when the frequency doubles, the load factor of the CPU for digital operation becomes two times the rated frequency.
There is a possibility that calculation becomes impossible.

An object of the present invention is to provide an excitation control device capable of performing governor excitation control by calculation by the third product method without increasing the load factor of the CPU even when the operating frequency of the generator changes.

[0012]

According to the present invention, in order to solve the above-mentioned problems, the voltage and current of a generator or a bus are adjusted to the voltages and currents.
A digital governor excitation control device that samples at a sampling cycle corresponding to the frequency of the current, calculates the effective values of voltage and power from the sampled data by the cubic method, and controls the generator voltage and the excitation current from the calculation results. The generator is connected to the grid or connected to the grid.
When the operating frequency of the generator is in the vicinity of the rated frequency when the generator is in the preparation state for performing the operation, the calculation of the effective value and the governor excitation control are all performed, and the generator is disconnected from the system.
Operating frequency of the generator in isolated operating state
Is provided with means for switching processing steps for executing only the minimum necessary calculations and controls when the frequency deviates from the vicinity of the rated frequency.

[0013]

[Function] When the generator is linked to the system, paying attention to the fact that the operating frequency matches the system frequency and that the control for linking can be omitted in isolated operation, the operating frequency of the generator is changed from near the rated frequency. When the operation frequency deviates, only the necessary minimum calculation and control are performed, so that the increase in the CPU load factor is eliminated even in the calculation in which the sampling frequency is increased in response to the increase in the operating frequency.

[0014]

FIG. 1 is a flowchart of an arithmetic control showing one embodiment of the present invention. Each arithmetic unit ₄₁ to ₃ in FIG. 3, 5 ₁
Calculations such as ５5 ₃ and 6 ₁ ６6 ₃ are performed in processing steps S2 to S5.
From the calculation results, the primary adjustment function calculation (voltage control, field control) and the secondary adjustment function calculation (APFR, limitation, etc.) of the excitation control are also performed in processing step S6.

The execution of these calculations is performed under the condition that the operation frequency of the generator is within the α% range before and after the rated frequency by providing the judgment processing step S1. α is, for example, 5
Set to%.

Under this condition, the generator is in the operating frequency range that is substantially the same as the system frequency, is in a state of being linked to the system or in a preparation state for being linked to the system, and has all the arithmetic functions necessary for linking with the system. Execute the processing used.

Next, when the frequency of the generator exceeds the range of α% before and after the rated frequency, the calculation of the active power P (S4) and the calculation of the reactive power Q (S4) are made according to the judgment in the processing step S1.
5) is omitted, and only the primary adjustment function calculation (S6A) in which the generator voltage calculation (S2), the bus voltage calculation (S3), and the excitation control are omitted from the excitation control is executed.

Under this condition, the generator is in a deceleration control state after the start-up of the generator or disconnection from the system, and only the calculation of the generator voltage and the bus voltage necessary for the isolated operation and the excitation control are performed.

Therefore, only when the operating frequency of the generator is close to the rated frequency, all calculations necessary for the excitation control are executed.
At this time, since the frequency is near the rated frequency,
The sampling frequency required for the calculation by the third product method is also low, and all the calculations and controls can be executed without increasing the load factor of the CPU.

When the operating frequency of the generator greatly deviates from the rated frequency, the necessary minimum calculations and controls are executed. At this time, the required sampling frequency increases as the frequency rises higher than the rated frequency,
By limiting the number of processing steps to the minimum required,
The load factor of U is prevented from rising, and the occurrence of an unprocessable state is prevented.

[0021]

As described above, according to the present invention, when the operating frequency of the generator is near the rated frequency, all of the calculation of the effective value and the governor excitation control are executed, and from the vicinity of the rated frequency. When it deviates, only the minimum necessary calculation and control are executed. Therefore, the operating frequency of the generator is increased and the required sampling frequency is increased, but the load factor of the CPU is not increased. There is an effect that governor excitation control can be performed.

[Brief description of the drawings]

FIG. 1 is an arithmetic control flowchart showing one embodiment of the present invention.

FIG. 2 is a waveform chart for explaining sampling and calculation by the three-product method.

FIG. 3 is a block diagram of sampling and calculation.

[Explanation of symbols]

1 _1, 1 ₆ ... A / D converter 2 _1, 3 ₆ ... digital filter 4 _1, 4 ₃ ... effective value calculating unit 5 _1, 5 ₃ ... effective power computing unit ₆₁ and 62 ₃ ... reactive power calculation unit

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-340314 (JP, A) JP-A-63-314352 (JP, A) JP-A-56-38542 (JP, A) JP-A 63-314 265525 (JP, A) JP-A-61-15599 (JP, A) JP-A-62-88001 (JP, A) JP-A-2-118272 (JP, U) (58) Fields investigated (Int. ⁷ , DB name) H02P 9/00 H02P 9/10

Claims (1)

(57) [Claims] 1. The voltage or current of a generator or a bus,
A digital governor excitation control device that samples at a sampling cycle corresponding to the frequency of the current, calculates the effective values of voltage and power from the sampled data by the cubic method, and controls the generator voltage and the excitation current from the calculation results. The generator is linked to the grid or linked to the grid.
When the operating frequency of the generator is in the vicinity of the rated frequency in the preparatory state, the calculation of the effective value and the governor excitation control are all performed, and the generator is disconnected from the system.
A digital governor characterized by comprising processing step switching means for executing only necessary minimum computation and control when the operating frequency of the generator deviates from the vicinity of the rated frequency in an independent operation state. Excitation control device.