RU2432659C2 - System of automatic control of multifunctional power complex - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: system comprises diverse sources of supply and a power accumulator, outlets of which via ac-dc (ac-dc-ac) converters are connected to load buses, and load outlets via power and voltage sensors are connected to inlets of control systems of each ac-dc (ac-dc-ac) converter. As ac-dc (ac-dc-ac) converters are switched, the outlet of their control systems is supplied to the inlet of upper level control system, and its outlet is connected to control circuit of switches of the specified ac-dc (ac-dc-ac) converters.

EFFECT: provision of guaranteed uninterrupted power supply to a passive load.

18 dwg

Description

The invention relates to electrical engineering, in particular to automatic control systems for a multifunctional energy complex (IEC), integrated into a power system operating on a passive load, i.e. heating without EMF and including dissimilar sources of electricity and an energy storage device (NEE). It is used in distribution and small energy systems (up to 10 MW) of guaranteed energy supply to consumers.

IEC systems as energy sources contain basic power plants (EA): synchronous generator (SG), rotated by a diesel engine; asynchronous generator (AG); wind electrical installation (wind turbine), rotated by the wind; whose asynchronous communication with the load is through ac-dc-ac converters powered by the power system and switches. An additional source of electricity for the IEC can be photovoltaic installations (PMTs) connected to the IEC through an ac-dc converter; microhydroelectric power stations (HES), diesel generators (DEZ) and other sources. The heterogeneous nature of sources with a sharply variable electricity generation schedule necessitates the use of an NEE storage device as part of an IEC, which can be used as follows: storage batteries (AB); fuel cells (TE); supercapacitors and other electrochemical sources connected to the IEC through an ac-dc converter.

The objective of the invention is the creation of a system for automatic control of the complex (ACS), capable of providing: the coordinated work of different types of electric power sources; guaranteed power for the passive load in the event of power failure from a basic source or power system; accumulation, storage, charge of NEE, as well as its discharge; stabilization and damping of voltage fluctuations on load buses and when switching various sources.

Known invention ("Harada Seiji", a heterogeneous power supply system, Patent JPA2001177995, class H02J 3/28, published June 29, 2001) [1] a control system for a heterogeneous power supply system that uses PMTs and NEE connected to the power system through one or several ac-dc voltage converters, moreover, these converters are switched by switches that make them alternately connected.

The disadvantage of this invention is the lack of power and voltage regulators that provide guaranteed voltage quality, which is provided by the generators of the power system, that is, it is not a passive load, but an active load. In addition, the interfering influence of the regulators of each of the converters during their switching is excluded, which increases the duration of the voltage drop on the load buses and leads to overload of the converters.

Another invention is also known (L. Gyugyi "Apparatus and method for interline power flow contro". US Patent 5698969, class G05F 1/70, published December 16, 1997) [2], in which one or more ac converters are connected in parallel -dc-ac, regulating the flows of active and reactive power in one or more parallel lines connecting the two power systems. The disadvantage of the invention is that it does not consider the power supply of the passive load and does not take into account the interfering effect of the regulators of the converters.

Closest to the claimed (prototype) is the invention (Bebic Jovan, Lehn Peter, Hybrid power flow controller and method. Patent EP 1573878, class H02J 3/18, published September 17, 2005) [3], which also considers the case of the connection two power systems through an ac-dc-ac hybrid converter, supplemented by a reactive power compensator. The disadvantage of this [3] invention, as well as the second [2] invention, is the lack of power for the passive load and not taking into account the interfering influence of the regulators of the converters.

The proposed SAUK device is designed to provide guaranteed power to a passive load in the presence of heterogeneous power sources containing a diesel-synchronous generator and / or an asynchronous wind turbine generator, an energy storage device (NEE) in the form of fuel cells (TE) or storage batteries (AB). In this case, one or more ac-dc (ac-dc-ac) voltage converters from sources are used, as well as an ac-dc (ac-dc-ac) network converter connected to the power system.

The proposed invention will provide uninterrupted power supply; improving the quality of transients (active power and reactive power); voltage deviation within the permissible norms (norm for failure: not more than 30 s.) according to the Interstate standard GOST 13109-97 "Electric energy. Electromagnetic compatibility of technical equipment. Electric energy quality standards in general power supply systems" [4].

The purpose of the invention, in contrast to the first [1] analogue, is that to ensure uninterrupted power supply and improve the quality of transients during switching of ac-dc (ac-dc-ac) converters, the output of their control systems is fed to the input of the upper-level control system, and its output is connected to the control circuits of the switches of these ac-dc (ac-dc-ac) converters.

A means of achieving this goal is a top-level control system that sets the operation modes of each ac-dc (ac-dc-ac) converter (charge-discharge), power and voltage settings, emergency or switching off control pulses to ac-dc converter switches ( ac-dc-ac).

To explain the merits of the invention are given drawings (figures 1-6). Figure 1 shows a simplified diagram of the proposed device ACS. Figure 2 shows a more detailed diagram taking into account the power and voltage sensors, the settings of the regulators and the keys that specify the operating modes of the ac-dc (ac-dc-ac) converters. Figure 3 illustrates the state of the switches and the passage of control pulses of each ac-dc (ac-dc-ac) converter. The effect of the quality of transients when switching ac-dc (ac-dc-ac) converters is illustrated by graphs (Figs. 4-6), and Fig. 4 corresponds to an unfavorable variant of ac-dc (ac-dc-ac) converters switching, leading to failure voltage on load tires; 5 corresponds to the absence of a load voltage drop, but the regulators of the ac-dc (ac-dc-ac) converters interfere with each other, overloading the ac-dc (ac-dc-ac) converters by reactive power; 6 corresponds to the use of the recommended circuit, which ensures the absence of a voltage drop of the load and smooth switching of the ac-dc (ac-dc-ac) converters without their overload.

The equivalent circuit of the power part of the multifunctional energy complex (IEC) in the minimum configuration is shown in figure 1, where the following notation is accepted:

1 - synchronous generator SG 6 kV;

2,2 ′ - ac-dc (ac-dc-ac) converter circuit breakers;

3 - load equivalent reduced to a voltage of 6 kV;

4.4 ′ - respectively, transformer transformers 6/35 kV and 6 / 0.4 kV;

5.5 ′ - respectively, 6 kV switchgear and 0.4 kV switchgear with filters;

6.6 ′, respectively, phase reactors of ac-dc (ac-dc-ac) converters;

7.7 ′ - ac-dc (ac-dc-ac) converters (inverters) of voltage on GDP and SPP, respectively;

10 - system synchronization and common mode;

11- control panel (SCHUDG);

12, 13 (12 ′, 13 ′) are, respectively, modular control systems and phase-pulse devices of the network and autonomous AC-dc (ac-dc-ac) converters;

14 (14 ′) - AC-dc (ac-dc-ac) converter control units;

15 (15 ′) - top-level control keys, top-level control unit SCHUDG;

16 - control unit DG (AG);

17 (17 ′) - mode control keys for AC-dc (ac-dc-ac) converters;

21 - aggregate level control system;

22 - top level control system.

The proposed device ACS is shown in figure 2, where the following designations are accepted:

No. / No. 1-10 - correspond to the elements of the IEC power circuit (figure 1);

No. / No. 11-22 - correspond to the elements of the control system ACS (figure 2),

which consists of the following functional blocks:

1) signal measurement and conversion systems (indicated in dotted

squares (figure 1) and solid squares (figure 2));

2) common-mode and synchronization system (block 10);

3) aggregate control system:

- block 11-SCHUDG;

- block 12, 13 - СУП.С and ФУУ ПС for AC-dc (ac-dc-ac) PS network converter;

- block 12 ′, 13 ′ —SUP.A and FIU PA for the autonomous converter ac-dc (ac-dc-ac) PA.

The indicated blocks SOUP and FIU are intended for vector control

. Выходными сигналами каждой СУП является угол управления α и коэффициент модуляции m, по которым ФИУ ИМП ПС выдает импульсы управления преобразователей ас-dc (ac-dc-ac) ПС (ИМП ПС) и ПА (ИМП ПА).AC-dc (ac-dc-ac) converters and correspond to those given in the second [2] invention. In addition, they are supplemented by power regulators P and Q and voltage regulators U, which are shown as aperiodic links of the form

. The output signals of each control system are the control angle α and the modulation coefficient m, according to which the FIU IMP PS gives the control pulses of the converters as-dc (ac-dc-ac) PS (IMP PS) and PA (IMP PA).

The aggregate level control system corresponds to the dashed element 21.

The top-level control system that performs the functions of the control unit of the complex corresponds to element 22 (Fig. 2), which consists of control units for AC-dc (ac-dc-ac) PS and PA converters, respectively 14 and 14 ′, corresponding keys 15 and 15 ', allowing or prohibiting the passage of control pulses of the PMP PS and IMP PA and controlling the switches of 2 ac-dc (ac-dc-ac) converters, DG (AG) control unit - 16, ac-dc (ac-dc) control mode keys -ac) 17 (for PS) and 17 ′ (for PA). These keys correspond to two possible modes: s - charge, p - discharge. In the general case, the charge mode corresponds to the power flow from the network to the direct current side of the ac-dc (ac-dc-ac) converters, the discharge mode is vice versa.

The power and voltage settings shown by the "oval" in figure 2 are part of block 22; circuit breakers 2, for simplicity, are connected to control units 14, 14 ′ and 16 by single-line communications; in reality, there are two channels: the state of the circuit breaker and its control. Overcurrent protection circuits not shown.

The operation of the ACS unit 22 is illustrated by a graph (Fig. 3), which corresponds to the mode: in the interval:

0.0-0.3 s DG works; 0.3-0.6 s operating PS; 0.6-0.9 s PA; 0.9-1.5 s operating PS;

In the time interval: 0.0-0.3 s, the DG operates, after which the DG is turned off, which corresponds to the schedule (Fig. 3 a).

The stand-alone ac-dc converter switch (ac-dc-ac) is switched on continuously: 0.0 - 1.5 s. The switch of the AC-DC converter (ac-dc-ac) of the PS is turned off in the time interval: 0.6-0.9 s, which is illustrated in the graph (Fig. 3, b).

The control pulses from the output of block 15 (FIG. 2), the AC-dc (ac-dc-ac) PS converter, are supplied with a delay of 0.05 s, and then 0.1 s (relative to the operation of the network switch), to ensure stable synchronization PS (see figure 3, c).

The control pulses of the autonomous AC-dc (ac-dc-ac) PA converter from the output of block 15 ′ (Fig. 2) are shown in Fig. 3, d. It can be seen that, at the moment of 1.0, pulses are fed to the substation from PA to ensure the proper quality of transients, which correspond to the curves in Fig.6. The supply of pulses to the PA can be resumed at the moment of 1.2 s (i.e., with a delay of 0.2 s relative to the supply of pulses to the PS).

It should be noted that the stand-alone ac-dc (ac-dc-ac) converter for its intended purpose must be constantly connected to the load buses, working either on charge or on discharge of the drive. Therefore, a short interruption in the supply of pulses should be a necessary measure for the successful switching of ac-dc (ac-dc-ac) converters while maintaining the quality indicators of the transition mode.

The influence of the quality of the transient switching processes of AC-dc (ac-dc-ac) PS and PA converters is illustrated by graphs (Figs. 4-6). The graph (figure 4) shows the most unfavorable option for switching PS and PA, when simultaneously with the connection of the PS (at the moment of 0.9 s), block 15 is activated and sends control pulses to the PS. The graph (figure 4) shows the curves:

a) active capacities: PN loads (upper curve), PP1 for substation, PP2 for PA, [MW]

b) reactive power: loads QN, QQ1 for substations, QQ2 for PA, [MBA]

c, d) respectively for the load voltage - UN, [V] and load currents IN top

curve and IPT for the DC side of the PS, [A].

From the analysis of the graphs (Fig. 4), it follows that the supply of pulses to the PS at the moment of 0.9 s is not ensured by coordination with the common-mode system, which leads to the reset of the active and reactive load power, the graphs (Fig. 4 a, b), and to an unacceptable decrease in voltage at the load, the schedule (Fig. 4 c), for a time of the order of 0.1 s. The graph (figure 5) with the same designation of the curves differs from the graph (figure 4) in that the control pulses of the PA are not blocked on the switching interval from the PA to the PS. At a time of 0.9 s, a network switch is connected, and then in 1.0 s, block 15 supplies control pulses to the MS. Switching, judging by the graphs (Fig. 5 a, c, d) is successful, however, the reactive power and voltage regulators of the PA and PS counteract each other (see the graph of Fig. 5 b), which adversely affects the overload of these ac-dc converters (ac-dc-ac) and especially the stand-alone AC-dc (ac-dc-ac) PA converter.

Figure 6 shows the recommended operating order of blocks 15 and 15 ′, which corresponds to the graphs (figure 3), that is, the simultaneous removal and supply of pulses to PA and PS, respectively, at a time of 1.0 s. Moreover, as can be seen from Fig.6 a, b, the switching of the ac-dc (ac-dc-ac) converters occurs without strong fluctuations, there is no counteraction of the Q and U regulators. The voltage drop of the load, the graph (figv), short-term 0.05 s and insignificant. The possibility of parallel operation of the ac-dc (ac-dc-ac) PS and PA converters, as well as the DG generator, is realized by the distribution of power settings after the completion of the switching of ac-dc (ac-dc-ac) converters, starting from the moment of 1.2 s . Emergency switching of ac-dc (ac-dc-ac) converters, for example, when overcurrent protection is triggered or other violations occur, is carried out according to the signals received at the input of blocks 14 (14 ′) (protection circuits not shown). After the appearance of these signals, block 15 (15 ′) is activated inertialessly, which blocks the passage of pulses to the corresponding ac-dc (ac-dc-ac) converter.

Information sources

[one]. JPA2001177995, class H02J 3/28, published June 29, 2001.

[2]. US patent 5698969, class G05F 1/70, published December 16, 1997.

[3]. EP1573878, class H0253 / 18, published September 17, 2005

[four]. Interstate standard GOST 13109-97 (enforced by resolution of the Gosstandart of the Russian Federation of August 28, 1998 N 338) "Electric energy. Electromagnetic compatibility of technical equipment. Electric energy quality standards in general power supply systems."

Claims (1)

An automatic control system for a passive load power supply complex containing heterogeneous power sources and an electric energy storage device, the outputs of which are connected to load buses through ac-dc (ac-dc-ac) converters, and the load outputs are connected to the inputs of each converter's control systems via power and voltage sensors ac-dc (ac-dc-ac), characterized in that, in order to ensure uninterrupted power supply and improve the quality of transients during switching of ac-dc (ac-dc-ac) converters, the output of their control systems supplies connected to the input of the upper-level control system, and its output is connected to the control circuits of the switches of the specified ac-dc (ac-dc-ac) converters.

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