JPH01163472A - Control method for idling operation of variable speed hydraulic machine - Google Patents

Abstract

PURPOSE:To stabilize the electric power system of a hydraulic machine by simultaneously carrying out effective power control in the direction of suppressing the variation in frequency of the power system in addition to ineffective power control. CONSTITUTION:While always monitoring the frequency variation of an electric power system, the effective power of a generator motor 1 is regulated in accordance with the variation. That is, when a frequency is temporarily increased, a load power applied to the generator motor 1 is increased and the energy of this amount is stored as the rotation increasing energy of a hydraulic machine 2 while, on the contrary, when the frequency is temporarily lowered, the load power applied to the generator motor 1 is lowered. Control is performed so as to tide over the resultant lack of the amount of driving energy of the hydraulic machine 2 by compensating the consumption of the inertia energy of the hydraulic machine itself.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to a hydraulic machine that is directly connected to a generator or motor that can be driven electrically at a variable speed and that has a power converter on the primary or secondary side. In particular, the present invention relates to an idle operation control method suitable for stabilizing an electric power system.

[Conventional technology]

As a publicly known example related to the present invention, a. ! ! ``Study of two-axis excitation current control system for electric motors'' ``b. Electric power technology handbook (Denki Shoin, supervised; Kazuno Fudeno (Sayaten)
) PL-64, Section 7.5.3.

P5-81 Section 9.4 is known.

Among these, the above-mentioned known examples describe the principle and method of phase control operation of a synchronous motor and a hydraulic machine driven by the motor.

However, there is no mention of a harmonic operation control method for a variable-speed hydraulic machine equipped with a power converter and capable of variable-speed operation, or, of course, there is no attempt to achieve active power control, which is the subject of the present invention, at the same time as phasing control, that is, reactive power control. There is no such way of thinking.

Furthermore, known example a discloses a method for controlling a two-axis excitation current of a generator motor for a variable speed pumped storage power generation system.

Figure 4 is an explanatory diagram, in which the secondary side of the generator/motor 1, that is, the rotor side, is excited with variable frequency by the power converter 3 (CYC), and the power frequency of the primary side, that is, the stator side of the generator/motor is kept constant. Variable speed power generation in which the rotation speed of the rotor is made variable while maintaining f! It is about i-motivation. 17 APs
While R (output control device) compares the output command (i.e., active power command) not shown in the figure with the output of the actual output detector 16,
A command is given to R37 (exciting current control device) to determine the value Ig of the direct axis current equivalent to the effective power that should be achieved. On the other hand, AVR36 (
Voltage control device) (not shown) Voltage command and voltage detector 3
The actual power generation/motor voltage detected in step 9 is compared, and a horizontal axis current value id corresponding to the voltage that should be obtained is commanded.

In addition to the above 1g+id, the ACR (exciting current controller) 37 inputs the actual slip phase angle O5 detected by the phase detector 7;
Each phase voltage command V is determined in consideration of the actual each phase current im.

Note that 38 is a current detector for the generator/motor, and 40 is a transformer for the three power converters. By the way, this known example does not mention at all a method of controlling a hydraulic machine during idling operation.

In particular, there is no disclosure of the concept of contributing to the stabilization of the power system by taking advantage of the variable speed feature to release energy stored in the inertia effect of the rotating part, and by controlling the active power so as to store energy therein.

[Problem that the invention seeks to solve]

The present invention aims to provide a method for controlling the idling operation of hydraulic machinery that makes full use of the variable speed characteristics of variable speed machines and contributes to the stabilization of the power system. It also enables active power control to suppress fluctuations in

[Means for solving problems]

While constantly monitoring frequency fluctuations in the power system, the active power of the generator/motor is adjusted in response to these fluctuations. In other words, when the frequency temporarily increases, the load power applied to the generator/motor is increased and this amount of energy is stored as rotational increase energy of the hydraulic machine, and conversely, when the frequency temporarily decreases, the load power applied to the generator/motor is stored. The load power applied to the hydraulic machine is reduced, and as a result, the insufficient driving energy of the hydraulic machine is compensated for by consumption of the inertial energy of the hydraulic machine itself.

Note that when the frequency fluctuation of the power system is below a predetermined level, constant speed operation is performed and only reactive power control is performed.

Furthermore, when the rotational speed of the hydraulic machine increases or decreases due to the above-mentioned active power control and is about to leave the variable speed operation band, the active power command is automatically corrected in a direction that protects the variable speed operation band. That is, when the rotation is abnormally increasing, the active power is lowered, and when the rotation is abnormally decreasing, the active power is increased. Moreover, the gain of this N kickback correction circuit is made sufficiently large to overcome even if the above-mentioned power system frequency response type active power control acts adversely, giving priority to maintaining the variable speed operation band.

Moreover, the above-mentioned active power control and reactive power control are realized without contradiction by two-axis excitation current control.

[Effect]

For example, if two-axis excitation current control is used, it is possible to perform active power control as well as reactive power control without causing any contradiction, and the power generation is large enough to perform the idling operation that is the object of the present invention.
Motive drive machine Drive machine Hydraulic machinery has a relatively large inertial effect, and in order to stabilize the power system, even if it is in idle mode, if there is an inertial effect that can be used, it must be fully utilized. In addition, as mentioned above, energy in the power system should be temporarily stored in the inertial effect, or conversely, energy stored in the inertial effect should be temporarily stored in the inertial effect. Although the rotational speed changes due to discharging, since it is a variable speed device, it can be evaluated without any problems as long as it is within a predetermined range.By rationally linking these points, it is possible to calculate the speed during idling operation of variable speed hydraulic machines. In other words, it enables active power control using inertia effect.

〔Example〕

FIG. 1 is a block diagram showing an embodiment of the present invention. 1 indicates an induction type generator motor or induction motor that can be used as both a generator and an electric motor (hereinafter referred to as a generator/motor), 2 indicates a hydraulic machine directly connected to the rotor of the 1 generator/motor, and 3 indicates electric power. converter.

That is, a cycloconverter provides variable frequency excitation corresponding to the slip in the secondary excitation circuit of the generator/motor 1, a speed detector 6 detects the actual rotational speed N of the hydraulic machine, and a slip phase detector 7 for generating electricity/f. ! A slip phase angle O8 is detected which is equal to the difference between the voltage phase of the primary side of the motive l, that is, the power system, and the rotation phase of the secondary side of the motive 1 power generation/'W1 expressed in electrical angle. The rotor of the slip phase detector is the generator/motor 1
A three-phase winding is provided that is connected in parallel with the primary winding, and one Hall converter is provided on the stator side of the slip phase detector at positions that differ by π/2 in electrical angle. A signal in which the voltage phase of the power system as seen from the secondary side of the generator/motor 1 matches is detected by the Hall converter and converted into a slip phase angle O5.

No. is a set speed that determines the steady speed bottom during idle operation of the hydraulic machine. 30 is the adder and this N.

This is to derive the difference ENb between the actual rotational speed N and the actual rotational speed N.

31 is a speed at which the active power command pX1 is given to the generator/motor so as to input the above-mentioned speed deviation εNb, to constantly make this deviation εNb zero, and to ensure the stability of the speed control system of the hydraulic machine. This is the control section. f is the frequency of the power system to which this generator/motor is connected, and fo is its rated frequency Δf, which is the deviation between f and fo. 24 is a speed change rate calculating section, which is an incomplete differentiator circuit with a gain of 1 and a time constant T1.

Reference numeral 25 denotes a fixed band element, which is effective and increases or decreases according to the overshoot when the speed change rate output from the speed change rate calculating section 24 becomes higher than a predetermined value on the plus side or lower than a predetermined value on the minus side. Output power command pX2.

This pX2 acts in the direction of increasing the drive output (@, load from the power system's perspective) of the generator/motor when f and Δf rise sharply, and on the other hand, when f suddenly drops, it acts in the direction of lowering the drive output. It acts to help stabilize the power system.

Figure 3 shows an alternative circuit for the part from Δf to pX2. In this case, it simply responds according to the amount of overshoot when the frequency deviation Δf itself exceeds a predetermined positive value or falls below a predetermined negative value. It is something.

FIG. 2 is a block diagram showing details of the speed control section 31. 31, b is an integral element and if there is even a slight deviation of εNb, that is, N, the output pX1 continues to increase in the desired direction and N is changed to N.
The purpose is to control the output of the generator/motor so as to return the output to zero.

31a is a proportional element for improving the stability of this N control system.

41 is a stationary band element that outputs no output as long as N remains within the variable speed band.When N attempts to overshoot beyond the upper or lower limit of the variable speed band, it is used to detect the amount of overshoot. is an element.

Reference numeral 42 denotes an N kickback gain unit which generates a p×3 active power command correction signal in accordance with the amount of overshoot detected by the above-described stationary band element 41. That is, the N kickback circuit consisting of 41 and 42 corrects the active power when N is about to go out of the variable speed band (to prevent N from running out of control further).

As is clear from FIG. 1, PΣ is a composite signal of the active power commands pXl and pX2 and the above-mentioned active power correction signal Px3.

Reference numeral 16 denotes a power detector for detecting the actual drive output p of the power generation/motor 1. Reference numeral 15 denotes an adder in which the deviation εP between PΣ and P is obtained. The APR (output control device) 17 gives a direct axis current command Iq to the excitation current control bag @37 according to this power deviation ff1p. The excitation current control device 37 inputs the horizontal axis current command I, the direct current command 11, and the actual slip phase angle Os, as in the prior art example shown in FIG. decide. vo is a set value of the voltage of the generator/motor, and 33 is a reactive power controller AQR, and the voltage set value Vo is corrected by this output ΔVo. VΣ is a composite signal of Vo and ΔVo, ■ is the actual voltage of the generator/motor, and 35 is an adder for determining the deviation ε between VΣ and V.

The AVR 36 is a voltage control device that determines the horizontal axis current I6 according to this voltage deviation ξ9. In the above, PΣ→
15→ε, -+ApR→■1→37→3→1→16→P
→15 control loop can be called an active power control system. The stability and speed of this active power system are determined by the APR (
It is appropriately set by the gain of the integral element and proportional element in the output control device (output control device) 17.

On the other hand, the control loop of ■Σ→35→εV→36→■4→37→3→1→voltage detector (not shown)→V→35 is a voltage control system, and the stability and quick solubility of this voltage control system are AVR36. (
It is set appropriately by the gain of the integral element and proportional element in the voltage control device). Also No → 30 → εNb → 31 → pX
The control loop of 1→27→the above active power control system→6→N→30 is a speed control system. The quick solubility and stability of this speed control system are set to a desired level by adjusting the gains of the proportional element 31a and the integral element 31b in the speed control section 31.

By the way, the key point in the present invention is to allow temporary follow-up fluctuations in active power p when fluctuations in power system frequency f are large during idle operation.

Therefore, the proportional element 31a and the integral element 3 in the speed control section 31
Care must be taken not to increase the gain of 1b excessively.

In other words, if the response speed of the speed control system is made too fast, pX
This is because even if 2 occurs, it quickly disappears due to the reverse fluctuation of pXl. However, as a result of suppressing the response speed of the speed control system in this way, temporary fluctuations in the rotational speed N are unavoidable. However, as mentioned above, since it is a variable speed machine, normal operation can be continued as long as N is within the variable speed band.

However, when N tries to jump out of the variable speed band, priority should be given to maintaining the variable speed band over the f response function described above, and this is achieved by the N kickback circuit described above, and the 42N kickback gain section. The gain also needs to be set to a fairly high value.

It should be noted that the present invention can be easily applied to a variable speed system in which a power converter is provided on the primary side of a generator/motor.

The ability to continue normal operation will be explained below with reference to FIG. FIG. 5 is an explanatory diagram of the operation of the variable speed hydraulic machine of the present invention and the electric power system connected thereto. Δ of (a)
kW indicates a sudden power supply and demand imbalance that occurs in the power system, in which case some load elsewhere on the power system is cut off, and the total power supplied to the power system becomes larger than the load in the power system. This means that the total sum has increased. As a result, the frequency f of the power system increases as shown in (b).

As a result, the frequency f of the power system increases as shown in (b). Then, the f response function of the hydraulic machine of the present invention connected to the same power system operates, and the active power command pX2 becomes (c).
It changes like this.

On the other hand, each power plant connected to the same power system is supposed to reduce its output as f changes due to the action of AFC (dead weight frequency control device) and the like. The solid line (d) is the sum total of the reduction in power supplied by each of these power plants. Active power command pX
2, the actual drive output (motoring) p of the generator/motor of this variable speed hydraulic machine changes. As a result, the rotational speed N of the hydraulic machine is accelerated as shown in (to), which is detected and the aforementioned speed control system responds to the active power command pX1.
tries to lower the rotational speed N and responds as shown in (e).

However, as mentioned above, since the response speed of the speed control system is relatively low, the sum of pX2 and pXl is dominated by pX2 immediately after this disturbance, resulting in a response almost similar to (c). However, after that, when reaching time tb, pX2 naturally decreases due to the action of time constant T1, and the sum of pX2 and pXl is reversed from positive to negative.

As a result, the rotation speed N becomes the target rotation speed No.
going back to.

By the way, the active power control response (pX
2-PXI), the total sum ΔKwx of the power supply and demand unbalance elimination effect of the power system is the sum of the solid line in (d), and eventually becomes like the dotted line in (d). That is, the effect of the present invention is that the solid line in (d) is changed to a dotted line, and the power supply and demand imbalance can be quickly eliminated to suppress fluctuations in the power system frequency f. Of course, as can be seen from the figure, the effect of the present invention is limited to a short period of time immediately after the occurrence of a disturbance, and on a regular basis, it waits for the response of the original power source (various power plants, etc.). However, the response of the original power source generally cannot be made faster due to the constraints of each plant.

Considering this, the role played by the present invention is by no means small. In other words, by having the hydraulic machine of the present invention, the active power response speed of the power system is improved and the fluctuation width of the power system frequency is reduced. It also has the ability to follow relatively fast, short-term power supply and demand imbalances that occur in the power system.

Conventionally, the idle mode has been used for harmonized operation (rotation direction can be in the direction of the water wheel or pump) for the purpose of improving the power factor of the power system, or when a command is given, the guide vane is immediately opened to switch to power generation or pumping mode. However, according to the present invention, it is possible to continue these operations as before while simultaneously exhibiting new functions.

〔Effect of the invention〕

As is clear from the foregoing, the effects of the present invention are that it provides a method for controlling active power as well as reactive power control at the same time when a variable speed hydraulic machine is idling; In addition, this opens the door to contributing to power system stabilization, and it also leads to lighter weight and economicalization of various devices that have been conventionally installed to stabilize the power system.

[Brief explanation of the drawing]

Figure 1 is a block diagram showing an embodiment of the present invention, and Figure 2 is (
FIG. 2 is a block diagram showing details of the speed control section ) 31 in FIG. 1; FIG. 3 is a diagram showing an alternative circuit from Δf to p×2 in FIG. 1, and FIG. 4 is an explanatory diagram of conventional biaxial excitation current control. FIG. 5 is an explanatory diagram of the operation of the hydraulic machine of the present invention and the electric power system to which it is connected. 31 Kyusu no Joji 1. Figure 5 (Brush I) 1.1. Kakuru (1) P::1zu-) Item 5 (t-2) Procedural amendment (method) % formula % Display of the case Patent application No. 318845 of 1988 Name of the invention Variable speed hydraulic machine 9.Relationship with the person who amended the operation control method case Patent applicant name 4.51tT1 type company Hitachi 'A I
New name Kansai Electric Power Co., Inc. Agent

Claims (1)

[Claims] 1. A movable hydraulic machine that has a hydraulic machine, a generator or a motor that is directly connected to the hydraulic machine, and that can be used in electric mode, and a power converter installed on the primary or secondary side of this generator/motor. Regarding the variable speed hydraulic machine that enables high-speed operation, in the idle operation mode that pushes down the water surface in the runner chamber and causes the runner to idle,
While performing reactive power control, there is also a method of detecting and suppressing fluctuations in the frequency of the power system, and simultaneously performing active power control that acts to draw in or take out the energy stored in the inertial effect of the generator/motor or water turbine. A method for controlling idling operation of variable speed hydraulic machinery. 2. Regarding variable speed hydraulic machines that have a power converter on the secondary side of the generator/motor, two axes are used so that the direct axis of the rotor's exciting current is also controlled by the active power control signal, and the horizontal axis is controlled by the reactive power control signal. 1. A method for controlling idling operation of a variable speed hydraulic machine according to item 1, in which both power controls are simultaneously achieved by current control. 3. During idling operation, when the predetermined set speed within the variable speed range and the actual rotation speed are compared and the difference between them is reduced to zero, the signal that controls the active power and the power system frequency fluctuation range or fluctuation rate are large. 2. The idle operation control method of a variable speed hydraulic machine according to claim 1, wherein the active power is controlled by a composite signal of signals that operate when the frequency fluctuation is large and performs active power control in a direction to suppress the frequency fluctuation. 4. Variable speed according to item 3, which is equipped with rotational speed kickback control that automatically corrects the effective command to kick the rotational speed back into the variable speed band when the rotational speed deviates above/below the predetermined variable speed band. Method for controlling idling operation of hydraulic machinery.