The system of uninterrupted power supply for the protection of objects is intended. Uninterruptible and guaranteed power supply system (sbge)

16.06.2019

Project documentation in pdf

ELECTRICAL PART

1.1. Main circuit

The main scheme of the power plant ensures the issuance of 100% of the calculated operating power in all modes of operation of the fish processing complex and may have standby generating capacity.

According to the data of the consumed electrical loads, the maximum operating power consumption is 2019 kW. The installed generating capacity of 3 DGUs is 2.44 MW, which provides a power reserve. The DGU group always has the possibility of switching on the diesel station SDMO X1250 with a capacity of 1000 kW or SDMO V550 C2 440 kW.

The switchgear of the guaranteed power supply system (SGE) is made in the form of 3 cabinets connected to 3 sections of the ASU. Cabinets with circuit breakers are normally disabled. In the event of a power failure at a certain section of the ASU and its absence for a certain time, the corresponding generator starts up and connects to the section buses with simultaneous disconnection of the main input of this section.

Switchgears, busbars and power cables are selected in accordance with the maximum short-circuit currents in terms of thermal and electrodynamic resistance.

Switching equipment corresponds to short-circuit currents in terms of breaking capacity.

The control of generators and SGE switches is local on the control panels of the generators. From the main control panel of the plant in the control room, control of the state of the switches and the normal or emergency state of the generators is provided.

1.2. Power supply system.

The DGU group with an installed capacity of 2.44 MW is designed to operate in emergency mode (no voltage at the main input of the ASU) and is designed on the basis of 2 x 1250 kVA diesel generators of the X1250 type and 1 550 kVA V550 C2 type generator from SDMO .

3 generators G-1, G-2 and G-3 are connected to 3 section busbars of the ASU switchgear of the plant.

Automatic switching on of generators G-1, G-2 and G-3 is ensured by the control panel type MICS Kerys from SDMO. Generators are equipped with standard sets of protections.

Input distribution devices are designed on the basis of Schneider Electric cabinets, devices and bus ducts installed in the reserve room (29), see "Equipment and cable routes layout plan". All electrical equipment that may be energized in the event of insulation failure is connected to the grounding of the power plant system, which in turn is connected to the grounding device of the ASU of the plant.

1.3. Power plant equipment

The guaranteed power supply system (SGE) includes:

2 diesel generator sets X1250 by SDMO with a capacity of 1000 kW each in a container version;

Diesel unit V550 from SDMO with a capacity of 440 kW in a protective casing;

Input (connection) system of guaranteed power supply;

SGE supply system with diesel fuel;

Own needs SGE (cabinet CISP).

The operating mode of diesel stations is peak.

The GE system is a functional complex that includes, in addition to diesel units, the necessary systems for the input of the GE, automation, control and management.

The total electrical power of the SGE system is 3050 kVA. Type of current - variable, 3-phase, frequency 50 Hz. Rated voltage - 0.4 kV. The switchgears for the input of the reserve are designed for switching and transmission of three-phase alternating current with a voltage of 0.4 kV and 4800 A of total current.

A group of 3 diesel generator sets is designed to work offline. The complex of each DGU includes its own 0.4 kV switchgear for input (connection) of generators G-1 ÷ G-3 to ASU sections.

MICS Kerys control panels are installed at each diesel station. Automated system control panel (MICS Kerys control panel) provides the mode of operation with the generation of electricity according to the load (within the limits of the rated power of the generators).

At the output of the generators, an AIPR type switching unit is installed, (for the X1250 diesel stations complete with a DGU for the (existing) V550 C2 DGU, the AIPR 1250 A unit is ordered separately.

1.4. Power supply for own needs of SGE.

Power supply of consumers of own needs of the SGE - from the ASU is provided for the I category of reliability. Auxiliary cabinet SGE SNGP has two independent inputs from different sections of the ASU of the plant and automatic input of the reserve at the input.

On the outgoing feeders of the CISP, it is planned to install automatic switches to protect against short-circuit currents and overload currents. Cable routes from the CISP are supposed to be made openly in a steel tray on cable shelves and in steel pipes when entering the DGU and passing through the walls.

1.5. Grounding of the guaranteed power supply system.

As a SGE grounding conductor, it is planned to create a grounding device consisting of vertical electrodes of a steel angle l = 3m, interconnected by a steel strip 50x5 mm, connected to the grounding device of the ASU of the plant.

The resistance of the combined grounding device is no more than 4 ohms. The project provides for a TN-C-S grounding system.

In the reserve room of the cabinets for input of uninterruptible power supply, an internal grounding loop is constructed, which is connected to the grounding device and to the metal cases of the cabinets of input of the power generator. This room is divided conductor PEN on PE and N. The connection of the GE input cabinets with the ASU of the plant is carried out by 5-wire busbars with separated PE and N.

AUTOMATION

The following automation and control systems have been developed in this set of project documentation:

Voltage control system at the main inputs of the ASU sections and automatic start and connection of the DGU to the corresponding sections;

System automatic feeding fuel from the reserve tank to the generator tanks, depending on their filling.

The system for automatic start and connection of the diesel generator set is made on the basis of the MICS Kerys control panel, which is included in the delivery set (it is ordered separately for the existing G-3).

The automatic fuel supply system is controlled by a special controller for groups of pumps of the SAU-MP type, depending on the position of the level sensors in the DGU fuel tanks.

Control of the SDMO V550 C2 and SDMO X1250 operation is carried out by connecting the standard control panels of the units to the cable network and transferring the main “states” of the systems to the control room.

The operator's workplace is located in the control room of the plant, room 29, see "Plan of the location of equipment and cable routes."

When the values of the controlled parameters of diesel stations go beyond the specified settings, the automation of the station (MICS Kerys) generates an "Accident" event and transmits it to the control room via a cable channel.

The controllers (MICS Kerys panels) are powered from the auxiliary needs of the diesel station, and above from the NGPP cabinet.

1.1. The need for a system

The main problem that one has to face when deciding whether it is necessary to install a diesel generator set (DGU) and an uninterruptible power supply (UPS) at the facility is to ensure power supply in the event of a power outage of the main supply network of consumers of category I and consumers of category I of a special group according to PUE.

Unfortunately, in practice, there are frequent situations when the equipment of a distribution transformer step-down substation (RTP 10/0.4kV or RTP 6/0.4kV) fails, there is a failure in the power grids of the area, etc. Therefore, 2 inputs from the RTP, as required by the PUE, are not enough in practice and at such facilities there is a need to install a diesel generator station - guaranteed power supply, and uninterruptible power supplies - uninterruptible power supply.

The uninterruptible power supply system is used to provide electricity of the required quality (GOST 13109-87) to consumers of category I (PUE gl.1.2.17), in the event of a power failure of the main supply network.

The uninterruptible power supply system is used to provide electricity of the required quality (GOST 13109-87) without breaking the sinusoid of the supply voltage to consumers of category I of the special group (PUE Ch.1.2.17).

2. Description of the solution

2.1. General information

guaranteed power supply for connected consumers;
automatic start (not less than 3 attempts in total) of the diesel generator after 9 seconds when the parameters of the main external power supply network deviate from the requirements of GOST 13109-87 or completely disappear;
automatic load switching from the main external power supply network to the diesel generator and vice versa;
issuing an alarm signal to the dispatcher's post in the event of an emergency event with DGU equipment

uninterrupted power supply (without breaking the sinusoid of the supply voltage) of consumers connected via the UPS; Fully adjustable output voltage.
output voltage of pure sinusoidal form;
high efficiency;
compatibility with diesel generators with a power factor of no more than 1.3;
maximum protection against surges, surges, surges and power outages;
the possibility of parallel connection of several UPSs;
the possibility of autonomous load support for 20 minutes;
the possibility of uninterrupted load switching to power from an external power supply through the built-in and external bypass;
galvanic isolation of input and output circuits;
remote monitoring and control of UPS parameters.

2.2. Solution Structure

Depending on the requirements for the power supply of consumers, different variants construction of power supply circuits. Let's consider several options.

2.2.1. Use of an uninterruptible power supply scheme at the facility

If at the facility only a diesel generator set is used as a backup power source, then such a scheme is called an uninterrupted power supply scheme, and consumers receiving power from the DGU in the event of a power failure of the main supply network are uninterrupted power supply consumers.

It is advisable to use such a scheme in cases of frequent power outages of the main supply network and the absence of category I consumers of a special group at the facility, who need power supply without breaking the sinusoid of the supply voltage for normal operation.

2.2.2. Use of an uninterruptible power supply circuit at the facility

If the facility uses only an uninterruptible power supply as a backup power source, then such a scheme is called an uninterruptible power supply scheme, and consumers receiving power from the UPS in the event of a mains power failure are uninterruptible power supply consumers.

It is advisable to use such a scheme in cases of infrequent and short-term power outages of the main supply network and if there are consumers of category I of a special group at the facility.

2.2.3. The use of an uninterruptible and uninterrupted power supply scheme at the facility combined

If the facility uses both a diesel generator set and an uninterruptible power supply as a backup power source, then such a scheme is called an increased reliability scheme using uninterruptible and uninterrupted power supply.

In the event of a power failure in the main supply network, a command is sent to the diesel generator set to start it. At the moment of starting the DGU (5-10 seconds), consumers of guaranteed power supply remain without voltage for a short time. Power supply to consumers of uninterrupted power supply is restored when the DGU reaches the nominal frequency and voltage.

During the start of the genset, the UPS switches to batteries, and the uninterruptible power supply consumers are supplied from the UPS batteries for as long as necessary to start the diesel generator set. Thus, the power supply of uninterruptible power supply consumers is carried out without breaking the sinusoid of the supply voltage.

When the supply voltage of the external power grid is restored when switching consumers from the DGU to the external supply network, consumers of guaranteed power supply remain without voltage for a short time. Thus, the power supply of consumers goes into normal mode. The diesel generator set, after a complete stop, goes into standby mode.

Power supply from the DGU is possible for a period of time determined by the fuel reserve in the fuel tank of the DGU and the specific fuel consumption (the value of this parameter depends on the load), as well as the possibility of refueling the DGU during operation. If the power supply from the main input is not restored before the end of the fuel resource in the standard fuel tank, the DGU automation unit will stop the diesel generator.

It is advisable to use such a scheme for objects that require increased reliability of the power supply.

3. Creation of a system of uninterrupted and guaranteed power supply at the facility

3.1. Necessary conditions for creating an uninterruptible power supply scheme at the facility

diesel generator sets must have an MTBF of at least 40,000 hours;
operation of DGU with power load less than 50% long time is not recommended, and with a load of less than 30% - leads to the refusal of the supplier from warranty obligations for equipment;
the time of emergency start and load acceptance from the standby mode in the hot standby is no more than 9 seconds.
enable repair work and routine maintenance of a diesel generator set without disturbing the normal operation of the power supply system;
provide remote control of the DGU operation;
eliminate the possibility of parallel operation of the DGU with external system power supply;

3.2. Necessary conditions for creating an uninterruptible power supply scheme at the facility

a single failure of any SBP element should not lead to a complete loss of system operability;
the average service life of the SBP is at least 10 years;
avoidance of overloads of neutral cables of input electrical networks and equipment of transformer substations;
work for a long time in the mode of shutting down the external power grid and providing power to critical consumers from the UPS;
ensuring the possibility of carrying out repair work and routine maintenance of the UPS without disrupting the normal operation of the power supply system;
providing remote control of work and UPS;
execution of the correct completion of technological processes in the event of an external power failure and the expiration of the battery autonomy resource.

3.3. Necessary conditions for creating an uninterruptible and guaranteed power supply scheme at the facility combined

UPS class - on-line, as the only one that protects the load from all existing power failures;
UPS power is selected based on the load power;
The UPS must be supplied with rechargeable batteries. In general, the battery backup time is selected in the range of 5-10 minutes;
to reduce the non-linear distortion of currents introduced by the UPS into the mains, UPSs with IGBT rectifiers with 12-pulse rectifiers or with active rectifiers are used;
it is desirable to select a UPS with a system for a smooth transition of the UPS to power from battery to mains;
power of DGU and UPS are selected in the ratio: DGU/UPS= 1.3;
The genset must be equipped with an automatic output voltage regulator and an electronic speed controller for the drive motor.

As the experience of "SIC" shows, the choice of links of the uninterruptible and uninterrupted power supply system, taking into account the above requirements, ensures a coordinated and stable joint operation of the UPS and DGU. An additional advantage of this scheme over the previous two is the almost unlimited offline operation time, i.e., the complete independence of the power supply of the critical load (consumers of category I and consumers of category I of the special group) from main network failures.

4. Decision schemes

4.1. Scheme of guaranteed power supply

4.2. Uninterruptible power supply scheme

4.3. Scheme of uninterrupted and guaranteed power supply

5. Manufacturers of equipment for the implementation of the scheme of guaranteed and uninterrupted power supply

5.1. General principles when choosing a manufacturer

compliance of equipment with Russian standards;
guarantee of quality and reliability of work;
acceptable delivery times;
competent technical support from the manufacturer.

5.2. Manufacturers of diesel generator sets and uninterruptible power supplies

Having considerable experience in creating uninterruptible power supply systems, our company prefers such manufacturers as: F.G. Wilson, Gesan, Cummins, SDMO.

When creating uninterruptible power supply systems at facilities, our company most often uses APC UPSs, and Powerware UPSs are also quite often used, less often - Libert.

In conditions of unstable power supply, it often makes sense to play it safe and protect yourself from unpleasant surprises that can be presented by centralized power networks.

For example, it is often possible to observe how the voltage in the network drops or jumps. This can be most clearly seen by paying attention to how an ordinary incandescent lamp glows - if it flickers or burns half-heartedly, then there is a problem in your electrical network. Insufficient voltage levels or voltage fluctuations can cause malfunction of sensitive equipment, loss of computer data and other unpleasant consequences.

Voltage surges are also possible, most often caused by short circuits or lightning strikes on wires or a substation. Despite the measures taken to protect against thunderstorms, such cases happen from time to time and, in addition to malfunctions, can lead to equipment failure.

In addition to the listed violations of the network, a complete disappearance of voltage is also possible - short-term or rather long. As a result, production is paralyzed, they stop working various systems- communications, security, life support and others.

Therefore, in some cases, it is required to take additional measures and install equipment that will minimize the negative consequences of centralized power grid failures.

There are two types of such systems - uninterruptible power supply systems and uninterruptible power supply systems. Let's take a look at how they differ below.

Differences between uninterruptible and guaranteed power supply systems

An uninterruptible power supply system most often implies the presence of uninterruptible power supplies (UPS), which, if necessary, switch the equipment powered by them to battery operation. During normal utility operation, the UPS batteries are charged. The UPS is also equipped with line filters that help cut off high-frequency interference in the mains, voltage surges, and so on.

Such a measure is effective if you experience short-term power outages or power surges in your network - UPSs cope with such troubles quite effectively. However, in order to maintain the operation of equipment or office equipment during a long shutdown, the resources of uninterruptible power supplies are not enough. All they can do is emergency- will give users a few minutes to turn off office equipment and save the necessary data.

To withstand prolonged power outages, uninterrupted power supply systems, or ESS for short, are required. In addition to uninterruptible power supplies, such a safe system assumes the presence of a diesel generator set (abbreviated as DGU), which performs the role of an emergency power supply unit during a long outage of the central power supply, and the necessary monitoring and control equipment that allows the UPS and DGU to interact in the complex.

Design and uninterruptible power supply installation are justified if there are frequent power outages, and your facility has consumers for whom uninterrupted and high quality power supply is considered critical.

Under such conditions, the losses from failures in the operation of the power grid can be so significant that they repeatedly exceed the cost of purchasing and installing special equipment, you should also take care to install such a connection scheme at strategic facilities or in the case when a power outage can lead to human casualties.

The purpose of the creation of the SGE and the requirements for it

So, in order to create an uninterruptible power supply system at any facility, everything is clear - such a system must guarantee a stable high-quality power supply for responsible energy consumers in case of incorrect operation of centralized power networks. The result of creating such a system at the facility is to ensure the normal operation of the equipment during emergency operation of the central power supply.

When equipping an object with uninterrupted power supply systems, the main groups of especially responsible energy consumers who need to be connected to a protected power grid are distinguished.

First of all, this includes the network equipment that makes up the local computer network- servers, routers, personal computers, etc. Communication equipment (in particular, automatic telephone exchange), life support systems (ventilation and air conditioning systems), various medical equipment, on which the health and life of patients depends, also needs to be safely connected.

Security and security systems (video surveillance, security and fire alarm, emergency lighting and fire extinguishing system, etc.), also fully justify connecting to a protected power supply network, since the consequences of failure of such systems can be quite serious.

As for the requirements for the operation of uninterruptible power supply systems, the main ones are stable and uninterrupted power supply to all consumers powered by the system, maximum protection against voltage surges and high accuracy of the output current parameters in terms of compliance with existing standards.

Also, when designing and creating an uninterruptible power supply system, it is important to take into account the convenience and efficiency of use, for which modern SHEs have a high degree of work automation.

So, necessary condition for such a system is a prompt response to the whims of the power grid and automatic transfer of consumers to work from a secure network. When the parameters of the central power supply are normalized, the system also automatically turns off.

In addition, the possibility of remote administration of the system, if necessary, and the availability of means for informing the administrator about the problems that have arisen, are important.

Structure and principle of operation of the SGE

Since each object has its own characteristics, the configuration of the uninterrupted power supply system in each case is developed for specific conditions.

However, despite the fact that quite often when developing the SGE one has to resort to non-standard solutions, schematically such systems usually look similar.

The main units of the system, first of all, are an autonomous power source (usually a diesel generator), one or more uninterruptible power supplies (UPS), as well as DC power plants. Also, such a safe and reliable solution involves the use of system control and management tools and special software.

During normal operation of the centralized power supply network, the diesel generator set is in standby mode, and the connected equipment is supplied with power through uninterruptible power supplies. The UPS itself in this situation also charges its batteries, acting as a surge protector.

In the event of a failure in the electrical network, the system controller starts the diesel generator, while this occurs, the operation of the connected equipment is carried out from the UPS. After the DGU has reached the set speed, the load is switched to it, while the UPS batteries are again recharged from the diesel engine.

After the problems of the centralized power network are eliminated, the controller switches the equipment from the power supply from the diesel generator set to the external network. During this process, the consumers are also powered by the UPS. Silence of the diesel engine of the unit is also performed automatically, after the equipment has switched to a regular power supply.

The battery life of consumers from the uninterruptible power supply system depends on the operating life of the DGU (the volume of fuel in the tank and its consumption) and the capacity of the UPS batteries. If the fuel resource is almost exhausted, and the centralized power supply has not been restored, the operator must decide to shut down the work of consumers or continue it until the resources of the DGU and the uninterruptible power supply are completely depleted.

In conclusion - a few tips on what should be guided when choosing a hardware manufacturer for equipment emergency power systems.

The main requirements are guaranteed power supply, its high quality and reliability of the supplied equipment, as well as its compliance with domestic standards. Guided by this parameter, it is important to choose serious companies that have weight and authority in the domestic power equipment market as a supplier.

Such firms, moreover, will be able to guarantee you qualified technical support and maintenance of the supplied equipment. Finally, when supplying equipment, such factors as promptness of delivery and acceptable, economically justified prices for products can also be important.

Stable operation industrial equipment, telecommunications and computing equipment, other computer equipment - the key to stable operation of the enterprise. For this, uninterruptible and guaranteed power supply systems are used, which supply connected consumers with electricity in the event of a power failure in the electrical network.

Solutions from Inter ID

The company "Inter ID" is engaged in the supply of equipment for backup power supply systems and Supplies to them. We will help you choose equipment models depending on the tasks set, we will perform installation, maintenance, preventive maintenance and modernization of the installed complex. The cost of work is calculated individually for each client.

Structure of the SBGE

In SBGE, uninterruptible power supplies (UPS, UPS) and diesel generator power plants (DPP, SGU) are used in parallel, which provide equipment with energy in case of accidents in the main power grids. SSES consist of a general power supply system, SSES, SSES, power distribution network, health monitoring devices and grounding components. The composition of the ESR includes transformer substations, input-distribution devices, distribution and group panels and networks. UPS consists of UPS, switchboards and group networks. SGE contain diesel generator sets, switchboards and devices for automatic start backup power.

Classification

Depending on the design of the equipment and the consequences that the disconnection of devices from the mains leads to, power receivers are divided into 3 categories. A break in the power supply of objects of the 1st category is associated with a disruption in the operation of communication and telecommunications facilities, leads to disruption of technological processes of production, material losses, and creates a threat to people's lives. These devices are provided with two independent power supplies. Interruptions in the operation of ES of the 2nd category lead to a failure in production and downtime, a pair of independent sources are connected to these devices. Disabling EP category 3 does not lead to serious consequences, they are fed from a single source.

To ensure the operation of the equipment are used:

Uninterruptible power supply systems consist of DGUs that automatically start within 9 seconds after a power outage or deviation of the network parameters from the values regulated by GOSTs;
Uninterruptible power supply systems include the use of a UPS, they are characterized by an adjustable output voltage, parallel connection of several UPSs;
Combined options provide for the simultaneous use of SHE and SBE, they are recommended to be used in cases where increased reliability of power supply is required; they are characterized by the use of an on-line class UPS with protection against possible mains failures, rectifiers to compensate for non-linear current distortion and a backup time of at least 10 minutes.

Differences between SGE and SBE

Uninterruptible power supply systems switch powered equipment to battery operation. In normal operation of the power grid, the batteries installed in the UPS are charged, and the built-in surge filters cut off high-frequency noise and other distortions. It is expedient to use the UPS in case of short-term power outages or power surges for the correct shutdown of devices and saving the necessary information.

In case of long power outages, it is more expedient to use the SGE with diesel generator sets in the composition. When the central power grid is turned off, DGUs play the role of an emergency power supply unit. Special equipment is used for the operation of UPS and DGU in a single complex.

Design

A number of factors are taken into account in the process of developing the GES. There are the following design stages:

The feasibility study is developed on the basis of the terms of reference and is used for infrastructure and industrial facilities;
The feasibility study is used for technically simple linear facilities and is carried out in a reduced volume relative to the feasibility study;
The preliminary design contains calculations of parameters, selection of DGU, UPS and other components, estimate of the work performed;
The working draft contains detailed calculations of parameters and the choice of specific models of equipment;
Working documentation is drawn up after the approval of the working draft; it contains installation diagrams for mounting equipment, connecting equipment, etc.

Depending on the complexity of the objects, the design is carried out in one, two or three stages.

Installation and connection

When installing SBGE at the facility, groups of responsible electricity consumers are distinguished, for which, first of all, backup sources are needed:

Personal computers, routers, routers, servers and other network equipment, automatic telephone exchanges and other means of communication;
Life support systems (ventilation and air conditioning), medical devices;
Security and safety services - ACS, video surveillance, fire alarms, emergency lighting.

For reliable operation of the equipment, static UPSs with on-line support are used. These devices are always on and instantly switch to battery operation in the event of a power failure. The complexes are designed for stable operation of the connected equipment from 15 minutes to a couple of hours. If the power supply is disconnected for longer than the set time period, the generator sets are automatically switched on.

Requirements

The following requirements are imposed on the established SBGE:

Power supply of computer network components, telecommunications and other low-current equipment with specified power quality parameters;
The configuration of the complex provides for the normal operation of the components and connected loads in case of failure of one element;
Automatic and manual control modes, including remote;
Constant monitoring of voltage and other network parameters, statistical accounting;
The required level of compensation for interference from UPS power supplies and rectifiers, external influences, prevention of third-party unauthorized access, equipment malfunction and data loss.

Maintenance

Maintenance of the uninterruptible and guaranteed power supply system includes the service of installed UPSs, maintenance of diesel generators and switchboard equipment. Before carrying out work, a service contract is concluded for the maintenance of these installations, removable batteries, input and output panels to which the UPS is connected.

At maintenance visual inspection of components, cleaning of dust, lubrication of moving parts, oil changes, end-of-life batteries and other wear components, inspection of fasteners. The operation of the UPS from batteries is checked, when switching to bypass, returning from it and other modes. Records of inspection results and troubleshooting are recorded in a special log so that during the next maintenance, engineers pay attention to possible problem areas.

To achieve the highest reliability of backup power supply systems for objects of increased responsibility, namely for backing up electrical consumers of a special group of the first category, integrated systems of uninterrupted and uninterrupted power supply (UBGE) are designed. By complex systems we mean the total work of the diesel generator and . It is in the combination of the functionality of these devices that a complex is formed for the energy protection of critical equipment.

When designing and implementing such, there is a group of factors that affect the choice of backup equipment and its correct operation. They need to be known and taken into account. Here are just a few of them that have the greatest impact on the combined operation of DPP and UPS. Any uninterruptible power supply, supplying the load, consumes electricity, and the form of current consumption is imperfect and differs from sinusoidal. This is due to the occurrence of harmonic distortion of the input current consumption. Any electrical power source that draws electrical energy from an external power supply has this property. Each UPS has its own input current consumption pattern and this is due to the individual input harmonic distortion factor (THDi, Total Harmonic Distortion). Sources of various manufactures have a wide range of THDi values from 3 to 30%, and the character of input current consumption varies from almost sinusoidal to almost pulsed. The task of the developer and manufacturer is to minimize this coefficient by reducing the current consumption to a sinusoidal form. This is achieved in different ways - from installing expensive active LC filters (THD filters) on the UPS to using IGBT technology in the production of the rectifier part of the source. IGBT technology implies the use of Isolated Gate Bipolar Transistors in the design of the rectifier, which provide high-frequency (up to 20 kHz) operation of the rectifier. To date, this technology is the most common and so far the most reliable in the field of manufacturing uninterruptible power supplies.

So, when a UPS with a capacity of 100 kW (with a THD coefficient (THD) ~ 30%) and a diesel generator work together, the power of the latter should exceed the power of the source by 2 times, which will be 200 kW. The coefficient of excess power of a diesel power plant over the power of a UPS directly depends on the coefficient of harmonic distortion and the efficiency of the source. The dependence is clearly visible from the table below.


30	2
20	1,8
10	1,6
5	1,3
3	1,15

Even with minimal input current distortion, it is necessary to leave a reserve of diesel generator power. This reserve is required by the UPS for its own needs, namely for heat losses, which are indirectly expressed by the coefficient useful action, and on the charge of the attached storage batteries (ACB). Therefore, do not believe the craftsmen who claim that the power of a diesel power plant should not exceed the power of the UPS connected to it.

Thus, by choosing a UPS with low input distortion, it becomes possible to buy a diesel generator of not so high power, while saving the funds provided for by the budget. Often, unscrupulous suppliers of power equipment, due to their ignorance theoretical foundations or in order to reduce the overall budget of the system, it is proposed to use a diesel generator set with a lower safety factor in conjunction with a UPS with a high THDi coefficient. Such a system will work smoothly until the load on the UPS reaches the nominal (working) level, after which the diesel generator may stop due to overload or fail.

A one-time load surge on a diesel generator is another parameter that is important when building a SBGE. As you know, its level should not exceed 60-70% of the rated power, since a diesel engine can stall with a larger power surge. UPS manufacturers have provided in the rectifier part the function of "Soft start" ("smooth" start, "soft start"). This means that during an emergency when switching to diesel generator operation, modern high-power UPSs (from 10 kVA) begin to gradually increase the consumed current, thereby preventing overloading of the generator. The UPS recovery time can be programmed from 10 seconds to 5 minutes.

The next factor affecting the correct operation of the SSGE is the load power factor, namely the ratio of the consumed active power to reactive. It is worth remembering that when the load level on the UPS decreases, its input power factor and efficiency also change. For example, at 100% load, the input power factor is 0.99, i.e. The UPS is practically an active load, then at 50% load the power factor can decrease to the level of 0.7-0.5, while the reactive power level increases. This must be remembered when choosing the power of DPP.

When operating a diesel power plant in conjunction with a parallel UPS system, manufacturers of uninterruptible power supplies have provided a programmable possibility of turning on the rectifiers of each source in turn, i.e. if 3 UPSs are connected in parallel in the system, then their rectifiers, which have the “soft” start function, will begin to consume electricity alternately with a delay, for example, of 30 seconds. This is necessary when building systems of uninterruptible guaranteed power supply of high power.

It should be remembered that the UPS and diesel generators, working together, are interconnected only power cables, but at the same time there is an option for sources that allows you to informationally link the UPS and the diesel power plant for the most gentle correct operation, prolonging the overall service life and time between failures of the entire uninterruptible uninterruptible power supply system (UBGE) as a whole. To calculate the SBGE and select equipment, contact reliable companies that are able to possess not only commercial skills, but are also able to provide qualified technical support for your transaction.