CN1177230C - Microcomputer based electric power digital dynamic realtime emulation method - Google Patents

Abstract

The present invention relates to a digital dynamic real-time simulation method of an electric power system based on a microcomputer, which belongs to the technical field of electric power system simulation. The method comprises the steps that firstly, differential equations for describing an electric power network are established; a parameter used for solving the differential equations is provided according to the test requirements of equipment; the differential equations are solved on a PC for working out a corresponding electric parameter digital signal of the equipment to be tested according to the parameter and the actual motion parameter of the equipment; the digital signal is converted from a digital quantity to an analog quantity; an analog signal is carried out with power conversion for causing the analog signals to be matched with the equipment to be tested, and is inputted into the equipment to be tested; the equipment to be tested outputs a feedback analogue signal which is converted into a digital signal for being used as an operating parameter. The simulation method proposed by the present invention uses a simulation program to replace a physical material object for carrying out a real-time closed loop test to the equipment, such as relay protective devices, controllers, etc., shortens the experimental time, reduces expenses, strengthens the flexibility and the safety of an experiment, and greatly increases the experimental efficiency.

Description

Electric power digital dynamic realtime emulation method based on microcomputer

Technical field

The present invention relates to a kind of electric power digital dynamic realtime emulation method, belong to the simulation study and the testing of equipment technical field of electric system based on microcomputer.

Background technology

At present, different means are adopted in the dynamic real-time test of research of the off-line simulation of electric system and equipment respectively, that is:

1, the research of the off-line simulation of electric system is main relies on large-scale simulation software to carry out on PC, that is to say that the mathematical model of utilizing the various elements of electric system on computers carries out analytical calculation to its dynamic behaviour, be a kind of pure Digital Simulation, can not connect actual physical equipment and carry out real-time simulation.

2, the test of the dynamic real-time of equipment mainly utilizes dynamic simulation experiment to carry out; promptly adopt scaled actual physical device simulation practical power systems; then protective device and controller being inserted in this system for simulating and test, is a kind of pure object simulating emulation.Its shortcoming is that simulation system small scale, setup time are long, the experiment cost is high, and it is huge to establish the investment of dynamic model experiment chamber.

Summary of the invention

The objective of the invention is shortcoming at prior art, a kind of electric power digital dynamic realtime emulation method based on microcomputer is proposed, the advantage of comprehensive prior art, the technology of employing micro computer Digital Simulation, but increase a kind of analog interface, finally realize dynamic simulation experiment.

The electric power digital dynamic realtime emulation method based on microcomputer that the present invention proposes may further comprise the steps:

1, sets up the differential equation group of describing electric power networks;

2,, provide and find the solution the used parameter of differential equation group according to the test request of Devices to test in the electric power networks;

3, parameter and the Devices to test actual operation parameters that provides according to test request found the solution differential equation group on PC, calculates the corresponding electric parameter digital signal of Devices to test;

4, above-mentioned digital signal is carried out the conversion of digital quantity to analog quantity;

5, above-mentioned simulating signal is carried out Power Conversion, itself and Devices to test are mated, and with its input Devices to test;

6, feedback analog signal of Devices to test output becomes digital signal with this conversion of signals, feeds back to above-mentioned the 3rd step as operational factor.

The electric power digital dynamic realtime emulation method that the present invention proposes based on microcomputer; with the generator of simulated program (software) alternative physical, transformer, power transmission line, motor or the like are in kind equipment such as protective relaying device and controller are carried out real-time closed-loop test; in test process tested person response signal can feed back to software in real time by interface, observe the effect of dynamic interaction.Do like this and shortened experimental period, the reduction expense strengthens the dirigibility and the security of experiment, improves conventional efficient greatly.

Description of drawings

Fig. 1 is the electric power networks structural drawing among the embodiment of the inventive method.

Fig. 2 is the definition of voltage among the embodiment shown in Figure 1, electric current and parameter.

Embodiment

With Fig. 1 system is example, specifies computation process, describes for convenient, and the electric current and voltage of definition each point and parameter name are as shown in Figure 2.

Wherein Es is the Infinite bus system electromotive force, and Zs is the Infinite bus system impedance, and Us is the voltage of Infinite bus system outlet, and Zb is the isolating switch impedance, and Zf is the fault branch impedance, U _LBe circuit L terminal voltage, U _RBe line end voltage, Z _RBe loaded impedance, R ', L ', C ', G ' are that resistance, inductance, electric capacity and the electricity of circuit unit length led, and establishing line length is L, i _sBe circuit breaker current, i _fBe fault branch electric current, i _LBeing line current, also is load current.

According to as above setting, can get the electric current and voltage equation of system:

[E _s]＝[Z _s]·[i _s]+[U _s] (1)

[U _s]＝[Z _b]·[i _s]+[U _L] (2)

$\left[\begin{array}{c}{u}_R\\ i_L\end{array}\right]=\left[\begin{array}{cc}\mathrm{ch}\left(\mathrm{\γl}\right)& -\mathrm{Zsh}\left(\mathrm{\γl}\right)\\ -\frac{1}{Z}\mathrm{sh}\left(\mathrm{\γl}\right)& \mathrm{ch}\left(\mathrm{\γl}\right)\end{array}\right]\left[\begin{array}{c}{u}_L\\ i_L\end{array}\right]---\left(3\right)$

[U _L]＝[Z _f]·[i _f] (4)

[U _R]＝[Z _R]·[i _L] (5)

Wherein

$\left[E_s\right]=\left[\begin{array}{c}{E}_{\mathrm{sa}}\\ E_{\mathrm{sb}}\\ E_{\mathrm{sc}}\end{array}\right],$

$\left[Z_s\right]=\left[\begin{array}{ccc}{Z}_{\mathrm{ss}}& Z_{\mathrm{sm}}& Z_{\mathrm{sm}}\\ Z_{\mathrm{sm}}& Z_{\mathrm{ss}}& Z_{\mathrm{sm}}\\ Z_{\mathrm{sm}}& Z_{\mathrm{sm}}& Z_{\mathrm{ss}}\end{array}\right],$

$\left[i_s\right]=\left[\begin{array}{c}{i}_{\mathrm{sa}}\\ i_{\mathrm{sb}}\\ i_{\mathrm{sc}}\end{array}\right],$

$\left[U_s\right]=\left[\begin{array}{c}{U}_{\mathrm{sa}}\\ U_{\mathrm{sb}}\\ U_{\mathrm{sc}}\end{array}\right],$

$\left[U_L\right]=\left[\begin{array}{c}{U}_{\mathrm{La}}\\ U_{\mathrm{Lb}}\\ U_{\mathrm{Lc}}\end{array}\right],$

$\left[U_R\right]=\left[\begin{array}{c}{U}_{\mathrm{Ra}}\\ U_{\mathrm{Rb}}\\ U_{\mathrm{Rc}}\end{array}\right],$

$\left[i_L\right]=\left[\begin{array}{c}{i}_{\mathrm{La}}\\ i_{\mathrm{Lb}}\\ i_{\mathrm{Lc}}\end{array}\right],$

$\left[i_f\right]=\left[\begin{array}{c}{i}_{\mathrm{fa}}\\ i_{\mathrm{fb}}\\ i_{\mathrm{fc}}\end{array}\right],$

$\left[Z_b\right]=\left[\begin{array}{ccc}{Z}_{\mathrm{ba}}& 0& 0\\ 0& Z_{\mathrm{bb}}& 0\\ 0& 0& Z_{\mathrm{bc}}\end{array}\right],$

$\left[Z_f\right]=\left[\begin{array}{ccc}{Z}_{\mathrm{faa}}& Z_{\mathrm{fab}}& Z_{\mathrm{fac}}\\ Z_{\mathrm{fab}}& Z_{\mathrm{fbb}}& Z_{\mathrm{fbc}}\\ Z_{\mathrm{fac}}& Z_{\mathrm{fbc}}& Z_{\mathrm{fcc}}\end{array}\right],$

$\left[Z_R\right]=\left[\begin{array}{ccc}{Z}_{\mathrm{Rs}}& 0& 0\\ 0& Z_{\mathrm{Rs}}& 0\\ 0& 0& Z_{\mathrm{Rs}}\end{array}\right]$

Make Z ' and Y ' be

$\left[Z^{\′}\right]=\left[\begin{array}{ccc}{R}^{\′}+{L^{\′}}_s\frac{d}{\mathrm{dt}}& {L^{\′}}_m\frac{d}{\mathrm{dt}}& {L^{\′}}_m\frac{d}{\mathrm{dt}}\\ {L^{\′}}_m\frac{d}{\mathrm{dt}}& R^{\′}+{L^{\′}}_s\frac{d}{\mathrm{dt}}& {L^{\′}}_m\frac{d}{\mathrm{dt}}\\ {L^{\′}}_m\frac{d}{\mathrm{dt}}& {L^{\′}}_m\frac{d}{\mathrm{dt}}& R^{\′}+{L^{\′}}_s\frac{d}{\mathrm{dt}}\end{array}\right],---\left(6\right)$

$\left[Y^{\′}\right]=\left[\begin{array}{ccc}{G}^{\′}+{C^{\′}}_s\frac{d}{\mathrm{dt}}& {C^{\′}}_m\frac{d}{\mathrm{dt}}& {C^{\′}}_m\frac{d}{\mathrm{dt}}\\ {C^{\′}}_m\frac{d}{\mathrm{dt}}& G^{\′}+{C^{\′}}_s\frac{d}{\mathrm{dt}}& {C^{\′}}_m\frac{d}{\mathrm{dt}}\\ {C^{\′}}_m\frac{d}{\mathrm{dt}}& {C^{\′}}_m\frac{d}{\mathrm{dt}}& G^{\′}+{C^{\′}}_s\frac{d}{\mathrm{dt}}\end{array}\right],---\left(7\right)$

Then γ and the Z in the equation (3) is defined as follows:

γ ²＝Z′Y′

$Z=\frac{Z^{\′}}{\mathrm{\γ}}=\frac{Z^{\′}}{\sqrt{Z^{\′}{Y}^{\′}}}=\sqrt{\frac{Z^{\′}}{Y^{\′}}}$

Because equation (3) be the variable coefficient transcendental equation, be difficult to find the solution, the therefore general solution under lossless case according to implicit expression trapezoidal method and equation (3), what can obtain its lumped resistance Bergeron equivalent model just goes the ripple and the wave equation of instead going:

$u_f(x-\mathrm{ct})=\frac{Z}{2(Z+\frac{R}{4})}[u_L(t-\mathrm{\τ})+(Z-\frac{R}{4})\·i_L(t-\mathrm{\τ})]+\frac{R}{2(4Z+R)}[u_R(t-\mathrm{\τ})+(Z-\frac{R}{4})\·i_R(t-\mathrm{\τ})]$

$u_r(x+\mathrm{ct})=\frac{Z}{2(Z+\frac{R}{4})}[u_R(t-\mathrm{\τ})-(Z-\frac{R}{4})\·i_R(t-\mathrm{\τ})]+\frac{R}{2(4Z+R)}[u_L(t-\mathrm{\τ})-(Z-\frac{R}{4})\·i_L(t-\mathrm{\τ})]---\left(8\right)$

R in the equation (8) is the resistance of whole circuit, and τ is row ripple passing time on the line.

Find the solution above equation, can obtain the electric current and voltage value of system's each point at given time.

Each coefficient of equation determines that by each component parameters in the system component parameters and differential equation coefficient physical relationship are:

Rated voltage in the corresponding Infinite bus system model of Es, Zs is then common definite by Infinite bus system capacity of short circuit, rated voltage and resistance-reactance-ratio example, and general Zs positive sequence and zero sequence impedance equate that establishing the Infinite bus system capacity is S, and the resistance-reactance-ratio example is r _RX, then have:

$Z_{\mathrm{ss}}=\frac{E_s^2}{S}(r_{\mathrm{RX}}+j\sqrt{1-r_{\mathrm{RX}}^2})$

Z _sm＝0

Isolating switch impedance Z b when the isolating switch three-phase is closed, has Z by the decision of equipment actual operation parameters _Ba=Z _Bb=Z _Bc=Z _On, when the isolating switch three-phase disconnects, Z is arranged _Ba=Z _Bb=Z _Bc=Z _OffIf, the tripping of isolating switch phase, the resistance of then tripping phase is off resistance, other phase resistances are closed resistance.

Fault branch impedance Z f and fault resstance R _Fault, resistance R after the fault clearance _NormalRelevant with fault type, during earth fault, the resistance of fault phase is R _Fault, non-fault phase resistance is R _Normul, mutual resistance is 0, during phase-to phase fault, the alternate mutual resistance that breaks down is R _Fault, under the normal condition, every phase self-resistance is R _Normnl, mutual resistance is 0.

Route Length L is directly specified by the user, is R ', L ' if unit length positive sequence and zero sequence resistance, reactance, electric capacity and electricity are led ₁, L ' ₀, C ' ₁, C ' ₀, G ' then has:

$R^{\′}=R^{\′},{L^{\′}}_s=\frac{1}{3}({L^{\′}}_0+2{L^{\′}}_1),{L^{\′}}_m=\frac{1}{3}({L^{\′}}_0-{L^{\′}}_1),{C^{\′}}_s=\frac{1}{3}({C^{\′}}_0+{{2C}^{\′}}_1)$

${C^{\′}}_m=\frac{1}{3}({C^{\′}}_0-{C^{\′}}_1),G^{\′}=G^{\′}$

Loaded impedance Z _RS=R _R+ j ω L _R, R wherein _R, L _RBe the given impedance of user.

In an embodiment, the parameter that provides according to test request has: the rated voltage of Infinite bus system is 500kV, and capacity of short circuit is 20000MVA, the ratio of short-circuit impedance is 0.1, and fault resstance is 1E-6, and resistance is 1E6 after the fault clearance, line length is 100km, and it is 0.01956 Ω/km that positive sequence resistance, reactance, electric capacity and electricity are led, 0.28 Ω/km, 13.5nF, 0, it is 0.01956 Ω/km that zero sequence resistance, reactance, electric capacity and electricity are led, 0.28 Ω/km, 13.5nF, 0.Pull-up resistor is 1000 Ω, and load reactance is 1H.

The equipment actual operation parameters has: breaker closing resistance.

Because

Z _ss＝1.25+j12.44，Z _sm＝0，Z _ba＝Z _bb＝Z _bc＝1E-6，Z _faa＝Z _fbb＝Z _fcc＝1E+6

R′＝0.01956，L′ _s＝0.28，L′ _m＝0，C′ _s＝13.5，C′ _m＝0，G′＝0，Z _Rs＝1000+j314.2

Z＝256.94，τ＝3.3356E-4，R＝1.956

The initial value of getting t=0 emulation constantly is

If investigate the protection that is installed in circuit L end, then answer output voltage [U _L] and electric current [i _L], as step delta t=100us,, can solve according to t=0 initial value and equation (1) (2) (4) (5) (7) constantly

$\left[U_L\right]=\left[\begin{array}{c}-407.99\\ 191.35\\ 216.64\end{array}\right]\mathrm{kV},$

$\left[i_L\right]=\left[\begin{array}{c}-0.3677\\ 0.1423\\ 0.2254\end{array}\right]\mathrm{kA},$

Digital solution when more than being t=100us, according to the conversion coefficient that D/A is provided with, the conversion coefficient of voltage signal is 100000, and the conversion coefficient of current signal is 6000, and then actual simulating signal by the output of D/A card is respectively

$\left[V_u\right]=\left[\begin{array}{c}-4.08\\ 1.914\\ 2.166\end{array}\right],$

$\left[V_i\right]=\left[\begin{array}{c}-0.0613\\ 0.0237\\ 0.0376\end{array}\right],$

Power amplifier is 20 to the enlargement factor of voltage signal, is 6 to the enlargement factor of current signal, and the then actual signal that outputs to equipment to be tested is

$\left[u\right]=\left[\begin{array}{c}-81.60\\ 38.28\\ 43.32\end{array}\right]V,$

$\left[i\right]=\left[\begin{array}{c}-0.3677\\ 0.1423\\ 0.2254\end{array}\right]A,$

Equipment to be tested is failure to actuate according to this electric current and voltage judgement, and according to the equipment actual operation parameters, breaker closing resistance remains unchanged, and proceeds finding the solution of next time point t=200us.

Claims (1)

1, a kind of electric power digital dynamic realtime emulation method based on microcomputer is characterized in that this method may further comprise the steps:

(1), sets up the differential equation group of describing electric power networks;

(2), according to the test request of Devices to test in the electric power networks, provide and find the solution the used parameter of differential equation group;

(3), according to parameter and Devices to test actual operation parameters that test request provides, on PC, find the solution differential equation group, calculate the corresponding electric parameter digital signal of Devices to test;

(4), above-mentioned digital signal is carried out the conversion of digital quantity to analog quantity;

(5), above-mentioned simulating signal is carried out Power Conversion, make itself and Devices to test coupling, and with its input Devices to test;

(6), feedback analog signal of Devices to test output, this conversion of signals is become digital signal, feed back to above-mentioned the 3rd step as operational factor.

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