JPH04158270A - Composite load model for analog simulator - Google Patents

Abstract

PURPOSE:To faithfully simulate characteristics based on the behaviors of a plurality of loads on an actual power system by setting a predetermined distribution ratio according to a type of a load or combination thereof. CONSTITUTION:Currents flowing from a transmission line mode 1 to respective basic circuits 42,52,62 are respectively detected by current detectors 45,53,63 via an insulating voltage converter 3. The detected currents collected by the respective circuits 42,52,62 are respectively converted into predetermined distribution ratios by output level adjusters 44,54,64 to be a voltage signal sum by an amplifier 7, which signal is input to a current amplifier 8 as a control command of three-phase current. The amplifier 8 amplifies the control instruction, and its output current is made to be load current of an entire composite load model. At this time the adjusters 44,54,64 are respectively adjusted to realize a desired composite load model according to a load state of an actual system to be analyzed. In addition since a level of the load current by the amplifier 8 can be adjusted by an output level adjuster 9, various load of the actual system can be faithfully simulated.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a composite load model for analog simulators, and more specifically, in analog simulators for analyzing various system phenomena, it is used to model complex loads such as induction motor loads, rectifier loads, constant impedance loads, etc. Concerning a composite load model for expressing the characteristics of multiple loads.

(Prior art) This type of analog simulator uses low voltage (5 to 50 μm)
), low current (5 to 100,100 O), three-phase transmission line model, generator model for Park's basic equation, induction motor model, load model, etc. It is configured as a simulator for system phenomenon analysis. Compared to digital simulators, simulators have recently been in the spotlight because they are superior in terms of changing analysis conditions at any point or point, analyzing data in real time, and performing long-term analyses.

The voltage characteristics of various loads used when analyzing system phenomena using this analog simulator are usually expressed by the following equations.

V, 1+sT.

V, 1+sT.

(Here, P is the active power taken by the load, Q is the reactive power, ■ is the load voltage, P, Q, V are each initial value,
For example, α is a variable value in the range of 0 to 2, S is a Laplace operator, and T1 to T are time constants. ) Note that in an analog simulator, generally, a characteristic calculating section for calculating the voltage characteristics of a load, etc. is constituted by a digital circuit, and an output section of the load is constituted by an analog circuit.

(Problem to be Solved by the Invention) However, according to the above expression, for example, the power generation effect that occurs instantaneously when the input voltage of an induction motor load drops, or the slip that increases with the input voltage drop recovers after the voltage is restored. In addition, when performing constant power control on a rectifier load, etc., the power factor changes when the input voltage drops due to the characteristics of the AC reactor or DC side capacitor, etc. There are cases where the characteristics of the system cannot be sufficiently expressed, and there is a problem in that it is not possible to accurately analyze systems with multiple types of loads.

The present invention has been made to solve the above problems,
The purpose is to provide a composite load model for analog simulators that can faithfully simulate characteristics that correspond to the behavior of multiple types of loads in an actual power system.

(Means for Solving the Problem) In order to achieve the above object, the present invention provides a complex system for an analog simulator connected to a low-voltage and low-current rated power transmission line model of an analog simulator that simulates the power system to be analyzed. In the load model, a plurality of load model basic circuits expressing respective load characteristics such as an induction motor load, a rectifier load, a constant impedance load, etc., means for detecting load current taken by these load model basic circuits, and this means a current amplification device that supplies the output current to the power transmission line model as a control command of a predetermined distribution ratio for each load current detected by the current amplification device; and means for making the level of the output current of the current amplification device variable. There is.

(Function) According to the present invention, the current taken from the grid by multiple loads such as induction motor loads, rectifier loads, and constant impedance loads can be set at any distribution ratio, which is impossible with conventional mathematical expressions alone. It is possible to accurately simulate the behavior of loads during system voltage fluctuations. Furthermore, the load current of the composite load model can be adjusted to an optimal level according to the rated capacity of the system to be analyzed.

(Example) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a single line diagram showing the configuration of a composite load model for an analog simulator according to this embodiment. In the figure, reference numeral 1 denotes a power transmission line model corresponding to the system to be analyzed, and an insulated voltage converter 3 with a high input impedance is connected to this power transmission line model 1 via a circuit breaker 2. Note that the current drawn by this isolated voltage converter 3 is designed to be at most 0.1% or less of the rated current value of the system to be analyzed, so that there is no effect on the initial state of the system to be analyzed. It is selected so that there is no

An induction motor load (described later) is connected to the output side of the insulated voltage converter 3 via a current detection device 43 consisting of a current transformer 43A and a current sensor 43B having a current compensation function to avoid imposing a burden on the side to be measured. One end of the opening/closing switch 41 of the model basic circuit 42 is connected, and the other end of this switch 41 is connected to the induction motor load model basic circuit 42. Similarly, a rectifier load model basic circuit 52 is connected to the output side of the insulated voltage converter 3 via a current detection device 53 and a switch 51 consisting of a current transformer 53A and a current sensor 53B. A constant impedance load model basic circuit 62 is connected via a switch 61 and a current detection device 63 consisting of a current sensor 63B and a current sensor 63B. Thereby, the current detection devices 43, 53.63 and each basic circuit 42.52.62 are connected in parallel to each other on the output side of the insulated voltage converter 3.

Here, the induction motor load model basic circuit 42 is composed of a known circuit that calculates the characteristics of the induction motor using the so-called Park's basic equation and obtains a predetermined current.

Further, the rectifier load model basic circuit 52 is configured as shown in FIG. In the figure, 100 is a three-phase full-wave thyristor rectifier model that forms the main part of the basic circuit 52.The input voltage of this rectifier model 100 is as low as about 5V, and the inflow current is as small as several milliamperes, which ranges from hundreds to thousands. V and A equivalent to actual thyristor converters rated from hundreds to thousands.
Care has been taken to obtain C-DC conversion characteristics. Rectifier model 100 is power supply side reactance model +01
, a series-connected thyristor model 102 forming upper and lower arms, a load reactance model 103, and a load resistance model 104, and each thyristor model +0
2 is constructed as shown in FIG. 3(a), and is an ideal thyristor model equipped with a compensation circuit for forward voltage drop and holding current.

The thyristor model shown in Figure 3(a) consists of an anode (A), a cathode (K) and a gate (G) as shown in Figure 3(b).
) is equivalent to one ideal thyristor model with

In Fig. 3(a), 121 is a small capacity thyristor, and its forward voltage drop (around IV) and minimum holding current (about 1/1000 of the rated allowable current) are controlled by the operational amplifier 122, resistors 123 to +25, and diodes. By compensating with 126, Zener diode 127, etc., it is adapted to a simulator with a low voltage and low current rating. In addition, in the figure, resistance 128.129, capacitor +30
131 is a circuit for improving responsiveness, and thyristor 12
1 is a diode connected in series, 132 is a thyristor 1
The phototransistor 132, the light emitting diode 133, and the resistors 134 and 135 constitute a gate drive circuit for the thyristor 121.

Note that in FIG. 2, the thyristor model 102 is shown for convenience.
Although only one phase is shown, in reality three phases are provided. Furthermore, when simulating a single-phase full-wave thyristor rectifier, the thyristor model 102 may be provided for two phases.

Again, in the rectifier load model basic circuit 52 of FIG.
The output signal of the automatic power regulator) 108 is input as a current command value. Further, a voltage detection device 109 is connected to the AC side of the rectifier model 100, and its output signal is applied to the power calculation circuit 110 and the ignition pulse generator 106. The power calculation circuit 110 also includes a voltage detection device 1.
In addition to the output signal of 09, the output signal of the current detection device 53 is also added, and the power detection value calculated based on each of these output signals is sent to the adder 112 to which the power setting value is separately input.
are entered using the symbols shown in the figure.

An APR 108 is connected to the output side of the adder 112, and the APR 108 adjusts so that the power deviation becomes zero.
The adder Ill receives the current command value from 108.
On the output side of , there is an ACR (automatic current regulator) 1 that adjusts so that the current deviation caused by this adder ill becomes zero.
o7 is connected. The output of the ACR 107 and the instantaneous voltage waveform for ignition phase control output from the voltage detection device 109 are applied to the ignition pulse generator +06, and the ignition pulse generated by the ignition pulse generator +06 is is the thyristor model +02 within the rectifier model +00
In addition to this, phase control is performed.

In FIG. 1, the constant impedance load model basic circuit 62 consists of a three-phase pure resistance load or a resistance component and a reactance component obtained from a predetermined rated value.
It is composed of mathematical models, actual impedance elements, etc.

In addition, the output side of each current detection device 43, 53.63 is connected to the output level controller 44, 54.64 of a voltage signal corresponding to the instantaneous current value of each load model basic circuit 42.52.62. (p, u) adjustment amplifier 45, 55.65
are connected to the input side of each. The output signals of these output level adjusters 44, 54, and 64 are input to the current amplification device 8 via the amplifier 7. Here, the current amplifying device 8 takes in the total voltage signal value equivalent to the instantaneous current value required for each load characteristic obtained from each basic circuit 42, 52, 62 as a control command from the amplifier 7, and amplifies this. The power is output to the power transmission line model 1 side via the circuit breaker 2. Further, the output current level of the current amplifying device 8 can be adjusted by an output level adjuster 9 according to the load capacity of the node in the system to be analyzed.

In addition, the output level adjusters 44, 54, 64 and the amplifier 7
It is also possible to construct it by a digital arithmetic circuit.

Next, to explain this operation, the current flowing from the transmission line model l corresponding to the system to be analyzed to each basic circuit 42, 52° 62 is passed through the high impedance insulated voltage converter 3 to the current detection device 43, 53 and 63, respectively. 2, induction motor load model basic circuit 42
Then, a predetermined current is taken according to the load characteristics expressed by Park's basic equation, and the constant impedance load model basic circuit 62 takes a current corresponding to the impedance.

Furthermore, the rectifier load model basic circuit 52 uses a power calculation circuit 110 and an adder 112 based on the current detection value by the current detection device 53 and the voltage detection value by the voltage detection device 109.
, APR 108, adder +11, ACR 107, the control command generated is applied to the firing pulse generator 106 and the thyristor model 102 in the rectifier model 100.
is phase controlled. At this time, since the forward voltage drop and holding current of the thyristor model 102 are compensated even in a simulator with a low voltage and low current rating, it is possible to obtain firing control characteristics similar to those of the thyristor that constitutes the rectifier load in the actual system. is possible.

The currents taken by the basic circuits 42, 52.62, respectively detected by the current detection devices 43, 53.63 in this way, are converted into predetermined distribution ratios by the output level regulators 44, 54.64, and the amplifier 7 becomes the total voltage signal value equivalent to the instantaneous current value required for each load characteristic, and this signal is used as a control command for the three-phase current in the current amplifier device 8.
The control command is amplified in the 6@flow amplifying device 8 inputted to the control command, and its output current is used as the load current of the entire composite load model. At this time, by adjusting the output level adjusters 44, 54, 64, each basic circuit 42, 52, 6
Since the load current distribution ratio according to 2 can be arbitrarily set, it is possible to realize an arbitrary composite load model according to the actual load state of the system to be analyzed.

In addition, since the level of the load current generated by the current amplifier 8 can be adjusted by the output level controller 9, even if the rated capacity of the system to be analyzed changes, the current taken by the composite load model can be adjusted to a value equivalent to the actual load current. can be set to faithfully simulate the various loads of the actual system.

In the above embodiment, the output level adjusters 44, 54°6
The output signals of 4 are synthesized by the amplifier 7 and the current amplification device 8
Although this is a control command for the output level adjuster 44
, 54 and 64 output signals for each basic circuit.
It may also be input to an individual current amplification device as a control command.

(Effects of the Invention) As described in F below, according to the present invention, by setting a predetermined distribution ratio according to the types of loads and their combinations, various types of loads can be handled, which was impossible with conventional simple mathematical expressions. Since the behavior can be expressed, it has the effect of faithfully reproducing the load characteristics etc. during voltage fluctuations in an actual system.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a block diagram of a basic rectifier load model circuit, and FIG. 3(a) is a circuit diagram of an ideal thyristor model. FIG. 5(b) is an equivalent circuit diagram of FIG. 1(a). ■...Power line model 2...Breaker 3...Insulated voltage converter 7...Amplifier 8...Current amplification device 9...Output level adjuster 41, 51, 6]...
- Switch 42... Induction motor load model basic circuit 43.53.
63... Current detection device 44.54.64... Output level adjuster 45.55.
65... Adjustment amplifier 52... Rectifier load model basic circuit 62... Constant impedance load model basic circuit 100
...Three-phase full-wave thyristor rectifier model +02...Thyristor model

Claims (1)

[Claims] In a composite load model for an analog simulator that is connected to a low voltage and low current rated power transmission line model of an analog simulator that simulates a power system to be analyzed, an induction motor load, a rectifier load, a constant impedance load, etc. A plurality of load model basic circuits expressing each load characteristic such as, means for detecting load current taken by these load model basic circuits, and control commands for each of the load currents detected by this means at a predetermined distribution ratio. A composite load model for an analog simulator, comprising: a current amplifying device for supplying its output current to the power transmission line model; and means for varying the level of the output current of the current amplifying device.