RU2564539C1 - System for determining synchronising power of synchronous machine - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: system includes digital recorder of electric mode parameters and parameters set at the tested point of the power system; computing facilities and output recorder containing human-machine interface. The computing facilities comprise calculation and analytic unit, which includes a control unit for a set of measurements coming from the digital recorder of electric mode parameters and operating parameters of the synchronous machine (SM), which input is coupled to output the digital recorder of electric mode parameters and SM operating parameters; a unit storing design and experimental SM parameters and characteristics, which input is coupled to one of outputs of the control unit for a set of measurements coming from the digital recorder of electric mode parameters and SM operating parameters; a unit calculating SM synchronising power based on electric mode parameters and SM operating parameters, which inputs are coupled to one of outputs of the control unit for a set of measurements coming from the digital recorder of electric mode parameters and SM operating parameters and output of the unit storing design and experimental SM parameters and characteristics while its output is coupled to input of the human-machine interface displaying data on calculated synchronising power.

EFFECT: determining in real time at the tested point synchronising power of the power system, which represents reaction to occurring oscillation process for further decision making by the dispatcher or respective automatics on measures eliminating such oscillation.

2 cl, 5 dwg, 2 tbl

Description

The invention relates to the electric power industry and can be used in operational dispatch and emergency control systems to determine the synchronizing power of synchronous machines in real time based on measurements of the parameters of the electric mode and the parameters of the machine in electric power systems of alternating current (hereinafter - EES).

State of the art

The present stage of development of the energy sector is characterized by the presence of large concentrated power systems connected by relatively weak ties, which actively include distributed generation capacities. Changing the composition of the generation and the structure of energy consumption leads to a decrease in the constant inertia of the elements of the power systems, increasing the sensitivity of the parameters of the power system as a whole to small disturbances. In order to increase the controllability of energy systems, new equipment is being introduced, equipped with modern high-speed control devices: asynchronous synchronous generators, FACTS, energy storage devices. As a result, in addition to beneficial effects, the power system also acquires some negative properties, which are manifested, in particular, in the appearance of low-frequency (0.1–3.0 Hz) oscillations of its operating parameters.

As a rule, the natural frequencies of electromechanical vibrations are located in the range of 0.1 ÷ 2.0 Hz. In this regard, the appearance in the EES of oscillations at these frequencies can cause resonances in various parts of the EES, leading to disruption of the parallel operation of its individual parts. Participants in low-frequency oscillations can be individual objects, both electric power generation and synchronous load (hereinafter - synchronous machines (SM)) with a certain way configured automatic control systems. Correctly tuned automatic control systems prevent a change in frequency in the system - they dampen, suppress developing oscillations due to synchronizing power. Thus, in order to prevent the development of oscillatory processes leading to disruption of the synchronous operation of EPS, it is important to be able to assess the effectiveness of counteraction of SM with low-frequency oscillations, i.e. quantitative assessment of the synchronizing power of the CM.

Currently, the UES of Russia is operating a monitoring system for system regulators in terms of ARV and excitation systems (CMRS), which monitors the operability of ARV devices and excitation systems (ST) when controlling EPS modes according to the current registration of parameters of the operation mode of generators in various modes work - operational, emergency, special (the mode of limiting the minimum excitation and the mode of limiting the double value of the rotor current) (RU 132637 U1, H02J 3/24, H02J 13/00, 09/20/2013).

The monitoring system of automatic excitation regulators and generator excitation systems, taken as a prototype, contains:

sensors of operating parameters of generators;

measuring transducers that implement the formation of digital operating parameters of controlled generators tied to a single time system;

the analyzer of the operation of the ARV-CB generators of the power plant with specially developed software designed to perform algorithmic processing of the received data;

EES output recorder, which receives signals about the state of the ARV and CB generators from the analyzer of the functioning of the ARV-CB generators of the power plant;

sensors of discrete signals of standard automation of the excitation system of controlled generators and

a local network for communication of measuring transducers and discrete signal sensors with an analyzer of functioning of the ARV-CB generators of a power plant.

The proposed system is similar to the prototype in terms of the initial data and their source: to determine the synchronizing power of the SM, the current and voltage values from the standard current sensors (CT) and voltage (TH) of each of the three phases are used at the monitored point of the EPS (point of connection of the SM to the station buses ), and additionally, voltage and current values of the field winding CM (F) and rotor angle CM (Ang) can be supplied.

The proposed system makes it possible to identify active participants in low-frequency oscillations (generators and / or power plants, synchronous load), which is necessary for the dispatcher or appropriate automation to take the necessary and sufficient measures to prevent impairment of the EPS stability, and also allows to quantify the participation of individual SMs in the process damping of oscillatory processes in EPS.

SUMMARY OF THE INVENTION

The technical result of the invention is the determination in real time, based on measurements of currents and voltages at a controlled point in the EPS (point of connection of the SM to the busbars of the station) of the synchronizing power of the SM, representing the response to the occurrence of an oscillatory process, for subsequent adoption by the controller or appropriate automation measures to eliminate these fluctuations.

The specified technical result is achieved by the fact that the system for determining the synchronizing power of the CM contains:

- a digital recorder of electric mode parameters and SM operation parameters, in which, based on the current and voltage values, among other parameters of the electric mode, the system frequency, active and reactive power are calculated with an interval of 20 ms; Also, the digital recorder can additionally record the SM operation parameters: voltage and current of the field winding, angle of the rotor position of the machine;

- a complex of computing tools;

- an output recorder containing a human-machine interface.

At the same time, the complex of computing tools contains a calculation and analytical unit, which includes:

- a control unit for the composition of measurements received from the digital recorder of the parameters of the electric mode and the parameters of the SM;

- storage unit for design and experimental parameters and characteristics of the SM;

- a unit for calculating the synchronizing power of the SM based on the parameters of the electric mode and the parameters of the machine.

The output of the calculation and analytical unit is connected to the output recorder containing a human-machine interface that displays information about the participants and parameters of low-frequency oscillations.

The proposed system for determining the synchronizing power is possible using the technology of synchronized vector measurements, as a result of which the voltages and currents are represented as vectors in a coordinate system rotating at a constant speed (usually corresponding to the rated frequency of the alternating current). This technology is used, in particular, and in devices WMSS [1].

Brief Description of the Drawings

In FIG. 1 shows a block diagram of a system for determining the synchronizing power of a synchronous machine:

- block 1 - a digital recorder of the parameters of the electric mode and the parameters of the SM;

- settlement and analytical unit, including:

- block 2 - control unit for the composition of measurements received from the digital recorder of the parameters of the electric mode and the parameters of the SM;

- block 3 - block storage of design and experimental parameters and characteristics of the SM;

- block 4 - block calculating the synchronizing power of the SM based on the parameters of the electric mode and the parameters of the machine;

- block 5 - output recorder with human-machine interface.

In FIG. 2 presents the test results of the proposed system for determining the synchronizing power.

In FIG. 3 presents the results of the assessment of assumptions made in the calculation.

The implementation of the invention

In FIG. 1 shows a block diagram of the inventive device is a system for determining the synchronizing power of a synchronous machine.

The values of current and voltage from the standard current sensors (CT) and voltage (VT) of each of the three phases at the monitored point of the EPS (the point of connection of the SM to the busbars of the station) are received at the inputs of the digital recorder 1 of the electric mode parameters and the SM operation parameters, and can also optionally field voltage and current values of the field winding CM (F) and rotor angle CM (Ang). Based on the values of current and voltage, among other parameters of the electric mode, the system frequency and active and reactive power are calculated with an interval of 20 ms.

The outputs of the digital recorder 1 are the values of the measurements and the parameters obtained from them.

The computational-analytical unit implements the idea that to assess the ability of the SM to maintain synchronous mode when the load angle of the synchronous machine θ deviates from a certain steady-state value θ _o by a certain value Δθ, use the synchronizing moment ∂M / ∂θ and, accordingly, the specific synchronizing power ∂Р / ∂θ [2].

The calculation and analytical unit includes a unit 2 for monitoring the composition of measurements received from the digital recorder 1, a unit 3 for storing the design and experimental parameters of the SM, and a unit 4 for calculating the synchronizing power of the SM based on the parameters of the electric mode and machine operation parameters.

In block 2 of the control of the composition of measurements received from the digital recorder of the parameters of the electric mode and the parameters of the SM, the determination of the availability of measurements necessary to calculate the synchronizing power of the SM is implemented.

The input of block 2 is connected to the output of digital recorder 1.

Block 2 has two outputs. The first of them, marked "D", is used if all the measurements necessary for calculating the synchronizing power are available, namely:

- vectors of voltages and currents of phases of the stator winding SM;

- the value of the SM load angle or the value of the electric angular velocity of rotation of the rotor and the synchronous electric angular velocity of rotation of the stator field.

The second of them, designated “H”, is used in the absence of any of the measurements necessary for calculating the synchronizing power.

The output "D" of block 2 is connected to the input of block 4 for calculating the synchronizing power of the SM based on the parameters of the electric mode and the parameters of the machine. The output "D" is the measurement data necessary for calculating the synchronizing power. The output "N" of block 2 is connected to the input of block 3 for storing design and experimental parameters and characteristics of the SM. The output "H" is the data of available measurements and information about the missing measurements.

In block 3, the following design and experimental parameters and characteristics of the SM are stored:

- rated voltage and current of the stator;

- inductive resistance Potier X _p ;

- inductive resistance to scattering of the phase of the armature winding X _σ ;

- idle characteristic;

- characteristic of a 3-phase short circuit.

The input of block 3 is connected to the output “H” of block 2. The output of block 3 is fed with the data of available measurements, as well as design and experimental parameters and characteristics of the SM, which are necessary to determine the synchronizing power of the SM.

The output of unit 3 is connected to the input of unit 4 for calculating the synchronizing power of the SM based on the parameters of the electric mode and the parameters of the machine.

In block 4, the synchronization power calculation is performed. The calculation of the synchronizing power of the CM is performed as follows:

, удельная синхронизирующая мощность P_см(t) для любого момента времени t определяется по следующей формуле (способ 1):- if the value of the load angle of the synchronous machine θ is determined by direct measurements, or by integrating the difference between the instantaneous values of the electric angular velocity of rotation of the rotor ω and the synchronous electric angular velocity of rotation of the stator field (system frequency) [2] $$(\theta ={\displaystyle {\int }_0^t(\omega -{\omega }_c)dt})$$

, the specific synchronizing power P _cm (t) for any time t is determined by the following formula (method 1):

P _cm (t) = ∂P _em (t) / ∂θ (t);

- if there are no direct measurements of the SM load angle or electric rotor angular rotational speed ω, to determine the synchronizing power of the SM, it is necessary to first calculate the SM load angle using the data stored in the storage unit for the design and experimental SM parameters according to the following formula:

In this case, the saturation of the magnetic circuit is taken into account for the known values of the load current and the excitation current at the current time (method 2);

- if there are no measurements of the parameters of the excitation work, the determination of the synchronizing power is performed without taking into account the inconsistency of the parameter values and their dependence on the load and excitation current (method 3).

Thus, by determining the load angle of the synchronous machine, it is possible to determine the synchronizing power for any moment in time. According to the dependence of P _cm (t), in turn, it is possible to evaluate the quality of the system regulators.

The input of block 4 is connected to the outputs of blocks 2 and 3.

The output of block 4 is the value of the calculated synchronizing power CM.

The value of the calculated synchronizing power of the CM is fed to the input of block 5 - the output recorder containing the human-machine interface. The information obtained on the synchronizing power of the SM can be used by the dispatcher both to solve the tasks of the operational dispatch control of the EPS, and the emergency control tasks.

The performance of the proposed technical solution is confirmed by the test results.

As a practical example, the participation of a turbogenerator with a rated power of 800 MW in the damping of low-frequency oscillations that occurred during a technological incident was evaluated [3]. Since the SMPR recorder measured only the currents and voltages of the stator windings, the calculations were performed without taking into account the inconsistency of the values of the SM parameters and their dependence on the load and excitation current (in accordance with method 3).

To illustrate the operation of the system of FIG. Figure 2 shows the obtained dependences of the active power of the generator on its load angle.

The graph of the active power of the generator P _g in this incident is shown in FIG. 2a. In FIG. Figure 2b shows the obtained dependences of the active power of the generator on its load angle θ for one LPS cycle for the indicated intervals.

At intervals of 10 seconds (8 LF cycles), indicated in FIG. 2a, the following values were determined:

- среднее значение мощности генератора; $$R_g^{\mathrm{from}R}$$

- the average value of the generator power;

- минимальное значение мощности генератора; $$R_g^{m\mathrm{and}n}$$

- the minimum value of the generator power;

- максимальное значение мощности генератора; $$R_g^{m\mathrm{but}\mathrm{to}\mathrm{from}}$$

- the maximum value of the generator power;

^cf. θ - average angle generator load;

θ ^min is the minimum value of the generator load angle;

θ ^max is the maximum value of the generator load angle;

^- среднее значение удельной синхронизирующей мощности; $$R_{\mathrm{from}\mathrm{and}nx.\mathrm{at}d}^{\mathrm{from}R}$$

^{- the} average value of the specific synchronizing power;

- минимальное значение удельной синхронизирующей мощности; $$R_{\mathrm{from}\mathrm{and}nx.\mathrm{at}d}^{m\mathrm{and}n}$$

- the minimum value of the specific synchronizing power;

- максимальное значение удельной синхронизирующей мощности. $$R_{\mathrm{from}\mathrm{and}nx.\mathrm{at}d}^{m\mathrm{but}\mathrm{to}\mathrm{from}}$$

- the maximum value of the specific synchronizing power.

The calculation results are given in table. one.

имела место при наибольшей амплитуде низкочастотных колебаний. После разгрузки генератора ее величина увеличилась до 34,82 МВт/град и перед затуханием достигла величины 41,06 МВт/град.The average specific synchronizing power characterizes the amount of energy applied by the generator to damping the oscillatory process. From table 1 it is seen that the smallest value $$R_{\mathrm{from}\mathrm{and}nx.\mathrm{at}d}^{\mathrm{from}R}=26.15M\mathrm{AT}t/gR\mathrm{but}d$$

took place at the largest amplitude of low-frequency oscillations. After unloading the generator, its value increased to 34.82 MW / deg and before attenuation reached 41.06 MW / deg.

The influence of the assumptions made in the calculation without taking into account the inconsistency of the SM parameter values and their dependence on the load and the excitation current was evaluated in the MATLAB medium using the model of a two-district system presented in Chapter 12 “Power System Stability and Control” [4]. As an example, PSS generators 1, 2, 4 were deduced from the work, as a result of which decaying LFBs of active power of generators with an amplitude of up to 50 MW and a frequency of 0.55 Hz are observed. In FIG. 3a is a graph of the LFK of active power P _g fixed on the generator 3. FIG. 3b shows the active power P _r of the generator 3 by the generator load angle values θ, derived from the measurements (method 1) and calculating (method 3). The calculation results are given in table. 2.

From table 2 it is seen that the assumptions adopted in method 3 for the model lead to an increase in the amplitude of oscillations of the generator load angle and a decrease in specific synchronizing power. At the same time, the nature of the process is preserved, which makes it possible to perform an evaluation analysis.

Thus, the operation example presented for illustration confirms that the proposed system allows one to determine the amount of synchronizing power developed by the SM in the process of damping oscillations.

Implementation of the proposed technical solution can be carried out using modern digital signal processing and calculation tools.

As digital recorders of electric mode parameters, standard multifunctional measuring transducers of WAMS or SMPR systems [1] can be used, which provide signal conversion and vector processing. As an output recorder containing a human-machine interface, the AS SI SMPR terminal can be used (Automated information gathering system SMPR). Thus, the blocks for determining the presence and parameters and participants of low-frequency oscillations can be introduced into the monitoring system of transient modes of EPS.

Information sources

1. Mogilko RN: Transient monitoring system for RAO UES of Russia facilities, Energetik magazine, 7/2006.

2. Ivanov-Smolensky A.V. Electric cars: textbook. for university students studying in the field of training. diplomats. specialists "Electrical Engineering, Electromechanics and Electrotechnology": in 2 tons / A.V. Ivanov-Smolensky. 2nd ed., Revised. and add. M .: Publishing House MPEI, 2004.

3. Assessment of the participation of the synchronous generator in the damping of low-frequency oscillations according to the data of synchronized vector measurements. A.S. Berlin, A.S. Gerasimov, Yu.P. Zakharov, P.Yu. Kovalenko, A.N. Moiseichenkov. Bulletin of the South Ural State University. A series of "Energy", 2013. - Volume 13. - No. 2.

4. P.S. Kundur. “Power System Stability and Control”: McGraw-Hill Professional, 1994. - 1176.

Claims (2)

1. A system for determining the synchronizing power of a synchronous machine (SM) in AC power systems, comprising a digital recorder of electric mode parameters and synchronous machine operation parameters installed at a controlled point in the power system; a complex of computing means and an output recorder containing a human-machine interface, characterized in that the complex of computing means comprises a computational and analytical unit, which includes a unit for monitoring the composition of measurements received from the digital recorder of the parameters of the electric mode and the parameters of the synchronous machine; a unit for storing design and experimental parameters and characteristics of the synchronous machine, the input of which is connected to one of the outputs of the unit for monitoring the composition of measurements received from the digital recorder of the parameters of the electric mode and operation parameters of the synchronous machine; a unit for calculating the synchronizing power of a synchronous machine based on the parameters of the electric mode and the parameters of the machine, the inputs of which are connected to one of the outputs of the control unit of the composition of measurements received from the digital recorder of the parameters of the electric mode and parameters of the synchronous machine, and the output of the storage unit for design and experimental parameters and characteristics of the synchronous machine, and the output is connected to the input of the output recorder that displays information about the calculated synchronizing power. 2. The system according to claim 1, characterized in that a standard multifunctional measuring transducer of the transient monitoring system of the electric power system is used as a digital recorder of electric mode parameters, and a transient monitoring system registration center is used as an output recorder containing a human-machine interface electric power system.

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