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First released in 1993, the International Electrotechnical Commission’s IEC 61131 programming standard remains a key element in the programmable logic controllers (PLCs) used in a variety of industries across the globe. The IEC 61131 standard is especially useful in Open Architecture control systems, which use standard programming languages to operate efficiently, accurately, and cost-effectively. Here are some of the benefits of IEC 61131 and how it plays an integral role in Open Architecture control systems.

Open Architecture Control Systems

Open Architecture control systems make adding and upgrading software components easier, which allows third-party vendors to improve their current systems. Upgrading to an Open Architecture control system offers owners and operators several benefits, including costs that are lower than switching to a proprietary system, reduced inventories of spare parts, and simplified maintenance and service requirements. Open Architecture control systems offer a more mature overall design than original systems, lower support costs due to their self-servicing capabilities, and higher standards for software and functionality than original systems. Plus, because Open Architecture control systems use the same controller as other control systems, they also provide increased flexibility for owners.

The Development of IEC 61131 and Its Programming Languages

In developing the IEC 61131 standard, the International Electrotechnical Commission identified five programming languages as the most common for a variety of programmable controllers. The IEC 61131 standard’s languages have been adopted across industries in response to a larger field of automation vendors, increased application complexity, and more diverse methods for implementing various control functions. The IEC 61131’s five programming languages are Ladder Diagram, Instruction List, Function Block Diagram, Structured Text, and Sequential Function Chart. Each language has advantages and disadvantages depending on a control engineer’s desired application.

For example, Ladder Diagram has the advantages of universal language acceptance and increased ease of changing code, while Instruction List and Structured Text offer European acceptance and increased PLC ease of execution. Structured Text is also much easier for controls engineers to learn and use, and it allows complex mathematical operations to be implemented with ease. Sequential Function Chart makes final user maintenance simpler and is especially useful in applications that contain repeating processes or processes with interlocks and concurrent operations.

The Benefits of the IEC 61131 Standard in Open Architecture Control Systems

PLCs that use one of the IEC’s programming languages are beneficial in several ways. Users and vendors can expect less waste of human resources thanks to decreased training, debugging, and system maintenance times. The software will also experience fewer errors and increased performance. Controllers from different locations, projects, or companies can be used together harmoniously. And thanks to IEC 61131, various programming techniques are now applicable in a wider range of environments with more connectivity, which helps protect investments.

For decades, Petrotech has provided clients across industries with innovative and reliable control systems and turnkey services. Our products help improve efficiency while decreasing waste and downtime in a variety of settings, including oil production rigs, processing plants, hydroelectric power plants, and other facilities. To learn more about what Petrotech can do for you, download one of our white papers or request a quote.

The main difference between droop and isochronous control modes lies in their relationship to frequency. In isochronous mode, generators maintain a constant frequency, whereas droop mode allows for changes in frequency in response to changes in load. This guide explains the implications of these differences and applications of the two modes.

When to Use Droop Control Mode

Because droop mode accommodates changes in frequency, it allows multiple generators to work in tandem by dividing loads in proportion to their power. It is useful when employed in grids with multiple generators and when dealing with loads with higher degrees of variance.

In droop mode, a generator’s output and frequency are inversely proportional. When frequency decreases, output increases. If a generator has a 5% droop setting, for example, then a 5% decrease in frequency will increase the unit’s power output by 100%. If, on the other hand, the frequency rises by 1%, the unit will decrease its power output by 20%.

Disadvantages of Droop Control Mode

Problems will occasionally arise when a generator in droop control mode encounters a large load. If the load is tripped, the frequency will reach a value above its nominal value when it settles. If, on the other hand, a large generating unit shuts down, the frequency will settle at a steady-state value below its nominal value. Both cases require secondary and tertiary frequency controllers to return the frequency to its nominal value.

When to Use Isochronous Control Mode

Isochronous mode is typically used when a generator either stands alone or is the largest unit on a grid. In this mode, the energy admitted to the prime mover is regulated very tightly in reaction to load changes, which, in droop control mode, would cause changes in frequency.

In droop mode, load increases cause the frequency to decrease, but because energy is quickly supplied to the prime mover in isochronous mode, the frequency remains constant. Likewise, load decreases cause frequency to increase in droop mode, but because the energy directed to the prime mover is quickly reduced in isochronous mode, the frequency is maintained.

Disadvantages of Isochronous Control Mode

In isochronous mode, the generator maintains a constant speed regardless of the load. Issues arise when multiple generators in isochronous mode are operating on the same grid (or parallel to each other) and the load changes. If all of the units are in isochronous mode, they will start competing to respond first. In the case of parallel generators, one will assume the entire load, while the other will receive none of it. When multiple generators are working synchronistically on the same grid, using droop control mode is preferable.

Isochronous Loadshare Control Mode

Petrotech’s Isochronous Loadshare control algorithm allows multiple generators to operate in isochronous control on a common bus. This is advantageous because the bus load can vary from 0 to the total generating capacity of all the units on the bus without deviations in bus frequency or units tripping off line. The generators will pick up and reject load quickly to maintain frequency while the Loadshare controller trims them back to equal loads.

At Petrotech, our goal is to help companies produce energy safely and effectively. Whether you’re looking for a new application or have an older system that requires retrofitting, we’ll work to increase its efficiency, cut downtime, and protect your staff. If you’re interested in our services, request a quote today.

A mechanical engineering term, “turbomachinery” describes machines that transfer energy between a rotor and a liquid or gas. Turbines and compressors both fall into this category. Turbines use a fast flow of water, air, or gas to generate shaft power; while compressors pressurize substances by transferring energy from the rotor to a fluid or gas. Turbines and compressors often work in conjunction with each other.

Due to the size, expense, and potential hazards of turbomachinery, companies use control systems to monitor and maintain proper function. Staying up-to-date with innovations in turbomachinery controls can help organizations implement effective solutions.

The Purpose of a Turbomachinery Control Solution

As technology advances and processes evolve, the need for an updated, effective turbomachinery control solution (TCS) is evident. When turbines, compressors, and centrifugal pumps work together efficiently, the potential for danger or equipment damage is minimized. However, when systems are not regularly analyzed, tested, and monitored, even small disruptions can have significant consequences.

Maintaining an effective TCS is more than just responsible policy; federal and state laws require adherence to highly specific safety standards, which must be observed regardless of the cost. Efficient, customized TCS systems should prioritize safety and maximize return on investment.

Critical Elements of a TCS

TCS systems vary depending on equipment requirements, safety protocol, and customizations, but certain components are crucial to an effective TCS. They include the following:

  • Speed control to prevent machines from functioning at hazardous speeds
  • Turbine temperature control to avoid over-firing the engine
  • Surge protection for operating machinery within the thin margins between regular operations and the surge safety line
  • Load control to balance work between compressors for optimal efficiency
  • Sequencing of valves and motors for safe startup and shutdown of the machinery
  • Protection functions to safely shut down the unit when critical parameters deviate outside of safe ranges
  • Establishing a standard operating environment in which alarms and variables are managed via an interface

TCS Trends and Innovations

Turbomachinery control solutions continue to include increasingly complex features. To keep systems user-friendly, trends are emerging that combine convenience with efficacy, including the following:

  • State-of-the-art modular redundant hardware platforms that are completely open and user-friendly
  • Advanced control algorithms that are well-documented and user-configurable, providing excellent control with the ability for end-users to support themselves
  • High-speed historical trending with long-term data storage and user-friendly visualization tools for easy problem identification
  • Vendor-backed control system maintenance

When choosing a control solution, companies should be aware of the latest TCS updates and advances to ensure optimal maintenance capabilities and overall product satisfaction.

The Benefits of Single Vendor Responsibility

Having one entity responsible for the entire control system’s design, delivery, and startup process can help ensure that the turbomachinery control solution is effective and efficient. Turnkey control solutions can be easily integrated into an existing business system or process. Their primary benefit is that they can be customized and modified to fit the current infrastructure of the turbomachinery system. Turnkey services can also lead to high customer satisfaction, as having one vendor handle the installation, labor, and materials will enable them to better focus on quickly addressing customer concerns.

To implement an effective turbomachinery control solution, specific safety guidelines and features relevant to particular equipment must be considered. Another important step is choosing a reliable vendor that offers state-of-the-art control systems and full-service management. At Petrotech, we provide clients across a range of markets with turnkey solutions. To learn more about how we can support your turbomachinery systems, contact our staff by requesting a quote.

Plant operators shouldn’t have to continually monitor or adjust their compression system to maintain optimum air mass flowrates. If a plant’s compression and surge control system is antiquated, it can cause delays in operation times, ultimately resulting in potential lost net gains. Both axial and centrifugal compressors are susceptible to surges, which occur when stalls, or small changes to airflow, escalate and cause instability that completely disrupts the airflow in the compressor. These surges can cause stress to compressor parts such as seals, bearings, and drivers, which can lead to extensive damage when unmitigated. This is where compressor controllers come into play. The EM-400 Stand-Alone Compressor Control from Petrotech can replace antiquated control systems with an easy-to-use control system that can be applied across different markets.

What Makes Petrotech’s EM-400 Superior to Other Compressor Controllers?

As one of Petrotech’s premier stand-alone products, the EM-400 Multi-Body Anti-Surge Compressor Controller provides advanced surge protection for up to three compressors using proven algorithms. With multi-compressors, there can be unnecessary recycling that can occur when compressors tend to surge at low rates. The EM-400 eliminates this unnecessary recycling by defining the surge point over a wide range of process gas conditions, resulting in optimum surge protection. Also, with over 45 touch-screen displays, the full-color interface is both user-friendly and password-protected. Specialized features include information on tuning suggestions, alarm statuses, and our exclusive live compressor performance map, allowing operators to closely monitor the compressor controller’s functions and settings. The EM-400 requires no additional hardware for installation, and its slim body makes it perfect for rack mounting.

How Petrotech’s Proven Algorithm Can Benefit Users

Petrotech’s proven surge control algorithm makes the EM-400 stand out among multi-body anti-surge compressor controllers. With over 40 years of experience in providing compressor control systems for thousands of applications, we’ve been able to configure our software to adapt and automatically compensate for changes in molecular weight, temperature, compressibility, pressure, and compressor rotor speed. There are several industries within the energy supply line that use centrifugal and axial compressors for the transportation of pressurized gases and liquids. From electricity production to processing, all can benefit from the accurate monitoring performed by the EM-400. And while the EM-400 provides standard features found in most standalone surge controllers, such as Load Sharing, Pressure Ratio, Fallback Strategies, and Adaptive Gain, it also offers more uniques features, including but not limited to the following:

  • Live Compressor Map
  • Recycle Transfer Control (RTC)
  • Capacity Control
  • Up to Three Recycle Loops in a Single System
  • Secondary Surge Controller
  • Pressure Override Control
  • Backstop Control
  • Built-in Color Touch Screen HMI Display
  • Built-in Sequence of Events Logging/ Display

How Petrotech Helped One Customer With a Compressor and Surge Control Problem

We were able to help one refinery that was operating with antiquated anti-surge and capacity controls. By developing a Triple-Modular Redundant (TMR) control system for this refinery’s multi-compression system, we were able to help the refinery decrease their operating costs and streamline their system. Learn more about this customer success story.

At Petrotech, we’ve been serving the energy supply line with reliable systems for over 40 years. Our goal is to help your production run safer and operate smarter. If you’re in the market for a compressor controller, the EM-400 Multi-Body Anti-Surge Compressor Controller is the complete solution. Contact us online or call us at +1(504) 620-6600 to request a quote.