Mohammad Reza Dadash Zadeh

Laboratory Investigation of IEC 61850-9-2-Based Busbar and Distance Relaying With Corrective Measure for Sampled Value Loss/Delay

After successful implementation of IEC 61850-8-1-based GOOSE at several power substations worldwide, major protective device vendors are currently developing interoperable products for IEC 61850-9-2-based time-critical sampled value (SV) messages over the digital process bus. Unlike GOOSE, the same SV message is not repeated several times and, therefore, it is important to analyze the impact of SV loss or delay on protection functions. This paper presents the hardware implementation of a typical IEC 61850-9-2-based process bus communication network for digital protection systems to investigate the proposed corrective measure for SV loss/delay. For the detailed testing, various process bus devices (e.g. protection intelligent electronic devices (IEDs), merging units (MUs), etc.) are developed over industrial embedded systems with a hard-real-time platform. The SV estimation algorithm is implemented as a part of bus differential and transmission-line distance protection IEDs, and it is tested for various SV loss/delay scenarios and power system fault conditions.

Implementation and Testing of Directional Comparison Bus Protection Based on IEC61850 Process Bus

A directional comparison bus protection unit (DCBPU) can provide a high speed bus fault clearing in the IEC61850 process-bus environment. This technique is based on superimposed fault direction for each circuit connected to the protected bus. In this paper, the implementation and testing of a superimposed directional comparison technique for bus protection based on an IEC61850 process bus is investigated. Design, hardware implementation, and related issues of DCBPU are described. A unique test setup is proposed and developed for testing DCBPU, including merging unit simulator, traffic generator, prototype DCBPU, and Ethernet switches to simulate the real IEC 61850-based substation automation process bus. Test results are reported.

Investigation of Neutral Reactor Performance in Reducing Secondary Arc Current

The majority of transmission-line faults are temporary short circuits. The short circuit arc is usually self-extinguishing after opening the transmission-line circuit breakers. High-speed reclosure of transmission-line circuit breakers can improve system stability. As the voltage level increases, arc deionization time increases as well, endangering system stability. Application of automatic single-phase reclosing makes it possible to increase system stability even for extremely high voltage transmission lines. Automatic single-phase reclosing is used to clear single-phase-to-ground faults, which are about 80% of the transient faults. In order to have successful fast reclosing, different methods are used to extinguish the arc. One of the common methods is to use a single-phase reactor in the neutral of shunt reactor, when transmission line is compensated with shunt reactors. As of now, the effect and parameters of this neutral reactor are usually determined based on the steady-state analysis without exact system and arc modeling. In this research work, the investigation of a neutral reactor application is performed for transposed and untransposed transmission lines using transient simulation with appropriate models. Then, guidelines for selecting the appropriate amount for the neutral reactor are proposed.

Communication-Aided High-Speed Adaptive Single-Phase Reclosing

A new communication-aided high-speed single-phase reclosing algorithm is proposed in this paper for transposed transmission lines based on predicted and measured voltage of faulted phase. Analytical analysis based on the distributed line model is performed to derive an equation which can be used to predict the faulted phase voltage after arc extinction in case of transient faults. Error analysis is performed to determine the sensitivity of the predicted voltage to various sources of error. The performance of the proposed technique is verified for a 500-kV transmission line with and without shunt reactor and with different grounding options for several cases simulated in PSCAD/EMTDC which include detailed arc, voltage, and current transducer models and different possible errors in measurement and transmission-line parameters.

A New DFT-Based Current Phasor Estimation for Numerical Protective Relaying

A new algorithm has been developed for phasor estimation of the current signal within numerical protective relays which effectively filters out harmonics, noise, and decaying dc offset. Analytical analysis is presented to show the effect of decaying dc on discrete Fourier transform (DFT)-based phasor estimation. Based on the presented theory, a new method is proposed to first estimate the decaying dc characteristic of the current signal and second to compensate the unwanted effect of decaying dc on current phasor in the phasor domain. The proposed technique adds few basic mathematical operations to conventional DFT by employing the proposed two interim variables to characterize the decaying dc component. The proposed algorithm has been comprehensively evaluated in Matlab and compared with the conventional methods used in modern commercial relays for a wide variety of signals including different levels of decaying dc magnitude and time constants, offnominal frequency operation, signal distortion due to current transformer saturation, and transmission-line series compensation in the presence of harmonics and noise. Standard performance indices including rise time, settling time, and overshoot are considered for evaluation and comparison study.

A High-Speed Adaptive Single-Phase Reclosing Technique Based on Local Voltage Phasors

In this paper, a new adaptive single-phase reclosing method for high-voltage transmission lines is proposed. This method employs local voltage magnitude and angle of the faulted phase. It is shown in this paper that the proposed method is able to quickly identify the fault type and the arc extinction if the fault is transient. This method is effective for various system configurations, including ideally and partially transposed transmission lines, untransposed lines, as well as transmission lines with or without a shunt reactor. Superior performance of the proposed method has been verified using 550 case studies simulated in PSCAD and Matlab and a real case related to a 765-kV transmission line.

Online Adaptive Real-Time Optimal Dispatch of Privately Owned Energy Storage Systems Using Public-Domain Electricity Market Prices

This paper aims to evaluate and improve the usefulness of publicly available electricity market prices for real-time optimal dispatching (RTOD) of a privately owned energy storage system (ESS) in a competitive electricity market. The RTOD algorithm seeks to maximize the revenue by exploiting arbitrage opportunities available due to the inter-temporal variation of electricity prices in the day-ahead market. The pre-dispatch prices, issued by the Ontario independent electricity system operator, and the corresponding ex-post hourly Ontario energy prices are employed as the forecast and the actual prices. A compressed-air ESS is sized and employed for evaluations due to its lower capital expenditure and its ability to be positively influenced by the availability of waste heat. First, the conventional RTOD algorithm is developed by formulating a mixed integer linear programming problem. It is demonstrated that the forecast inaccuracy of publicly available market prices significantly reduces the ESS revenue. Then, a new adaptive algorithm is proposed and evaluated which adapts the objective function of the optimization problem online based on historical market prices available before real-time. The outcomes reveal that the proposed adaptive RTOD can significantly increase the ESS revenue compared to the conventional algorithm as well as the back-casting method proposed in prior studies.

An Accurate Offline Phasor Estimation for Fault Location in Series-Compensated Lines

In series-compensated transmission lines, current and voltage signals measured by the line protection system include considerable subsynchronous frequency components (SSFCs), which are not sufficiently damped within a typical fault clearing time of the line protection system. This does not allow accurate phasor estimation and, therefore, phasor-based fault location. This paper presents an accurate algorithm which effectively filters out unwanted frequency components and noise to perform accurate phasor estimation for fault location in series-compensated transmission lines. Phasor estimation of a theoretical signal is first evaluated by using the proposed method, direct Prony analysis, and four-cycle discrete Fourier transform algorithm. Then, various fault locations of a 500-kV series-compensated transmission line simulated in PSCAD/EMTDC are used to comprehensively evaluate the performance of the proposed technique. It is shown that the proposed method can effectively attenuate SSFCs and other unwanted frequency components in current and voltage signals, allowing accurate phasor estimation to be obtained.

Research and development of a microgrid control and monitoring system for the remote community of Bella Coola: Challenges, solutions, achievements and lessons learned

Reliance on costly and polluting diesel generators is a major difficulty common to almost all the remote off-grid communities. However, there are oftentimes opportunities to replace at least a part of it with clean renewable energy. This can be achieved by incorporating appropriate energy storage technologies for shifting the energy as well as smart control and monitoring systems. Bella Coola in British Columbia has been the first remote community in Canada that initiated the replacement of a part of its diesel consumption with clean energy. This paper attempts to describe the technical challenges in Bella Coola, proposed solutions with emphasis on the control and monitoring part, a summary of open and closed-loop tests, and the lessons learned from this microgrid project that can be inspiring for future projects.

Real-Time Optimal Dispatch and Economic Viability of Cryogenic Energy Storage Exploiting Arbitrage Opportunities in an Electricity Market

In this paper, the economic viability and profitability of a newly emerging storage technology, i.e., cryogenic energy storage (CES), is investigated. A real-time optimal dispatching algorithm is proposed and developed to optimally dispatch a privately owned CES unit to generate revenue by exploiting arbitrage opportunities in the day-ahead/week-ahead electricity market. Due to its special characteristics, CES can provide significantly more financial and technical benefits in a weekly scheduling compared with common daily scheduling. The electricity price modulation is proposed as a new approach to competitively offer subsidy by the utility regulator to CES owners to fill the gap between current and a stable expected rate of return. Using real-world price data from the Ontario wholesale electricity market, the method is validated. The results reveal significant benefits of weekly usage as compared to daily usage of CES. The efficacy and feasibility of the proposed approach to subsidize CES owners are validated through simulation studies.